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  • Articles: DFG German National Licenses  (1,528)
  • 2005-2009
  • 1985-1989  (1,528)
  • 1955-1959
  • 1950-1954
  • 1920-1924
  • 1915-1919
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  • 1860-1869
  • 1850-1859
  • 1987  (1,528)
  • Chemical Engineering  (726)
  • Organic Chemistry  (684)
  • Genetics  (99)
  • Personnel management.
  • ddc:000
  • gene expression
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  • 2005-2009
  • 1985-1989  (1,528)
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  • 1
    Electronic Resource
    Electronic Resource
    Influence of genetic variance on sodium sensitivity of blood pressure (1987)
    Springer
    Journal of molecular medicine 65 (1987), S. 101-109 
    Details
    ISSN: 1432-1440
    Keywords: Blood Pressure ; Hypertension ; Salt ; Sodium ; Genetics ; Twin Model ; Salt Restriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To examine the effect of genetic variance on blood pressure, sodium homeostasis, and its regulatory determinants, we studied 37 pairs of monozygotic twins and 18 pairs of dizygotic twins under conditions of volume expansion and contraction. We found that, in addition to blood pressure and body size, sodium excretion in response to provocative maneuvers, glomerular filtration rate, the renin-angiotensin system, and the sympathetic nervous system are influenced by genetic variance. To elucidate the interaction of genetic factors and an environmental influence, namely, salt intake, we restricted dietary sodium in 44 families of twin children. In addition to a modest decrease in blood pressure, we found heterogeneous responses in blood pressure indicative of sodium sensitivity and resistance which were normally distributed. Strong parent-offspring resemblances were found in baseline blood pressures which persisted when adjustments were made for age and weight. Further, mother-offspring resemblances were observed in the change in blood pressure with sodium restriction. We conclude that the control of sodium homeostasis is heritable and that the change in blood pressure with sodium restriction is familial as well. These data speak to the interaction between the genetic susceptibility to hypertension and environmental influences which may result in its expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01728599
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  • 2
    Electronic Resource
    Electronic Resource
    Hybridization histochemistry (1987)
    Springer
    Cellular and molecular life sciences 43 (1987), S. 741-750 
    Details
    ISSN: 1420-9071
    Keywords: Hybridization histochemistry ; hybridocytochemistry ; in situ hybridization ; gene expression ; histochemical hybridization ; nucleic acid hybridization ; histocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The location of gene expression by hybridization histochemistry is being applied in many areas of research and diagnosis. The aim of this technique is to detect specific mRNA in cells and tissues by hybridization with a complementary DNA or RNA probe. Requirements for optimal specificity, sensitivity, resolution and speed of detection may not all be encompassed in one simple technique suitable for all applications, thus appropriate procedures should be selected for specific objectives. With reference to published procedures and our own extensive experience, we have evaluated fixatives, probes, labels and other aspects of the technique critical to the preservation and hybridization in situ of mRNA and detection and quantition of hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01945351
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  • 3
    Electronic Resource
    Electronic Resource
    Heredity and blood pressure in humans: an overview (1987)
    Springer
    Pediatric nephrology 1 (1987), S. 69-75 
    Details
    ISSN: 1432-198X
    Keywords: Blood pressure ; Essential hypertension ; Genetics ; Epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper presents a review of the genetic transmission of normal blood pressure and of essential hypertension. Familial aggregation of normal blood pressure has been reported in adults, in children and even in newborns. Blood pressure aggregation phenomenon, however, is the result of both a genetic component and shared environmental factors. More specific for each etiological factor were the studies of blood pressure aggregation in twins and in adopted children. Attention was focused on the Montreal Adoption Study. In essential hypertension, a Japanese study is reviewed showing the occurrence of hypertension in the offspring of hypertensive parents. The heterogeneity of essential hypertension is underlined and two of the multiple etiological factors are particularly considered for their genetic component: the response to salt intake and erythrocyte cation fluxes. The conclusion from the literature reviewed is that essential hypertension is a polygenic disease transmitted by polygenic systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00866887
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  • 4
    Electronic Resource
    Electronic Resource
    C4 isotype deficiency in IgA nephropathy (1987)
    Springer
    Pediatric nephrology 1 (1987), S. 136-139 
    Details
    ISSN: 1432-198X
    Keywords: IgA nephropathy ; Genetics ; Complement ; C4 ; Glomerulonephritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract C4 and factor B typing were performed in 37 pediatric patients with primary IgA nephropathy. Null alleles for C4B occurred with a frequency of 26% in patients, as compared to 15% in healthy controls (NS). The phenotype of C4B deficiency (homozygous C4B null), however, was found in 16% of patients and 4% of controls (P〈0.05). Comparison of observed C4B phenotypes with those predicted from the Hardy-Weinberg equilibrium also confirmed an excess of C4B deficiency (P〈0.0005). In contrast, there was no evidence of distortion in the frequencies of the C4A null allele or phenotype, or of the factor B alleles. The data suggest that C4B deficiency may be one of multiple interacting factors contributing to the development of this glomerulopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00849283
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  • 5
    Electronic Resource
    Electronic Resource
    Genetics of cystic kidney diseases (1987)
    Springer
    Pediatric nephrology 1 (1987), S. 397-404 
    Details
    ISSN: 1432-198X
    Keywords: Cystic kidneys ; Genetics ; Prenatal diagnosis ; Linkage studies ; Potter sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Despite the high incidence of cystic kidney diseases, affected families are not usually well informed of the inheritance of these disorders. Genetic counselling must be based on precise diagnostic criteria. Detailed information on the different types of cystic kidney disease is summarized, including clinical features, pathology, radiology, prenatal diagnosis and the risk of recurrence. In addition, a genetic interpretation is given of the Caroli syndrome, Potter sequence as well as congenital hepatic fibrosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00849243
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  • 6
    Electronic Resource
    Electronic Resource
    Genetics of Alport's syndrome (1987)
    Springer
    Pediatric nephrology 1 (1987), S. 436-438 
    Details
    ISSN: 1432-198X
    Keywords: Alport's syndrome ; Genetics ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pattern of inheritance in Alport's syndrome has been controversial for some time. Recent studies have clarified the mode of inheritance in this disease. Alport's syndrome is a heterogeneous disorder made up of a number of genetically distinct syndromes, with an autosomal dominant, an X-linked dominant and a rare autosomal recessive form. Clinical analysis shows that there are many distinct forms with or without nerve deafness, and with early or late occurrence of end-stage renal disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00849250
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  • 7
    Electronic Resource
    Electronic Resource
    Pathologic features in two siblings with the Pena-Shokeir I syndrome (1987)
    Springer
    European journal of pediatrics 146 (1987), S. 283-287 
    Details
    ISSN: 1432-1076
    Keywords: Pena-Shokeir I syndrome ; Facial anomalies ; Ankylosis ; Pulmonary hypoplasia ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two siblings whose clinical and pathologic features were consistent with the “Syndrome of camptodactyly, multiple ankyloses and pulmonary hypoplasia” originally described by Pena and Shokeir were examined at autopsy. Additional features were intrauterine growth retardation, immaturity of the central nervous system (CNS) and atrophy of skeletal muscles. Our data suggest that CNS damage may cause the complicated phenotypic abnormalities of the syndrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00716474
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  • 8
    Electronic Resource
    Electronic Resource
    Epilepsy with primarily generalized myoclonic-astatic seizures: a genetically determined disease (1987)
    Springer
    European journal of pediatrics 146 (1987), S. 550-554 
    Details
    ISSN: 1432-1076
    Keywords: Epilepsy ; Genetics ; Myoclonic-astatic seizures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper presents case reports of patients suffering from myoclonic-astatic and stimulus-sensitive myoclonic seizures, respectively. It gives details of clinical and EEG data in the pertinent families. This is discussed in the context of controversial nosographic concepts of epilepsies with myoclonic seizures, and of the results of extensive family investigations. The findings demonstrate the decisive importance of hereditary factors in the pathogenesis of myoclonic and myoclonic-astatic epilepsy, the genetic background of which is probably polygenic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467351
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  • 9
    Electronic Resource
    Electronic Resource
    Cloning and sequence of the mdh structural gene of Escherichia coli coding for malate dehydrogenase (1987)
    Springer
    Archives of microbiology 149 (1987), S. 36-42 
    Details
    ISSN: 1432-072X
    Keywords: Catabolite repression ; Genetics ; Malate dehydrogenase ; Molecular cloning ; Sequence ; CRP binding site ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate dehydrogenase gene of Escherichia coli, which is susceptible to catabolite and anaerobic repression, has been cloned using plasmic pLC32-38 of Clarke and Carbon (1976). The nucleotide sequence was determined of a 2.47 kbp fragment, containing the mdh structural gene. All information necessary for expression of the mdh structural gene was mapped within a 1.3 kbp SphI-BstEII fragment. Compared with the untransformed wild type, transformations with pUC19 vector, containing this fragment, gave up to 40-fold more malate dehydrogenase activity in both E. coli wild type and mdh mutant recipients. Catabolite repression was not affected in the transformants. A possible CRP binding site in the promotor region of the mdh gene provides evidence for a co-regulation with fumA gene, the structural gene of fumarase, which is also subject to catabolite repression. The structures for transcription initiation and termination were similar to those previously described for E. coli. Amino acid sequence homologies between pro- and eucaryotic malate dehydrogenases are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423133
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  • 10
    Electronic Resource
    Electronic Resource
    Role of polyamines in the synthesis of RNA in mycobacteria (1987)
    Springer
    Molecular and cellular biochemistry 78 (1987), S. 3-8 
    Details
    ISSN: 1573-4919
    Keywords: polyamines ; RNA polymerase ; transcription ; gene expression ; mycobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract All three polyamines — putrescine, spermidine and spermine stimulated the activity of mycobacterial RNA polymerase in vitro although the concentration required for maximal stimulation was different for each of the amines. Spermidine and spermine showed a biphasic effect on the enzyme activity. Stimulation of RNA synthesis by spermidine occurs only at higher DNA template/enzyme ratio. Spermidine stimulates RNA synthesis by acting on the elongation phase of RNA synthesis but it had no effect on initiation phase. Addition of mycobacterial RNA to the assay mixture resulted in the inhibition of RNA polymerase activity and this inhibition could be reversed by spermidine suggesting that spermidine stimulates transcription by binding to nascent RNA and thus destabilizing the short DNA-RNA hybrid region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224418
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  • 11
    Electronic Resource
    Electronic Resource
    Expression of growth-associated genes in various tissues of the fetal and adult rat (1987)
    Springer
    Molecular and cellular biochemistry 75 (1987), S. 61-70 
    Details
    ISSN: 1573-4919
    Keywords: gene expression ; development ; tissue-specific expression ; cell cycle-dependent genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract 4F1, 2A9 and 2F1 represent three of a number of cDNA sequences which have been identified because their cognate RNAs markedly increase when quiescent cells in culture are stimulated with serum. Studies using a variety of cell culture systems have shown that the expression of these genes is modulated by various growth factors and mitogens and thus such genes are considered to be ‘growth-associated.’ Thus far, little information has been obtained with these in vitro systems about the function of these genes. In an attempt to begin to elucidate the role of these genes (if any) in the physiology of the normal cell, we have analyzed the levels of 4F1, 2A9 and 2F1 transcripts in a variety of differentiated organs and tissues of adult and fetal rats. Our results show that each of these growth-associated genes exhibits its own unique pattern of expression, unrelated to the proliferative activity of the tissue. These data suggest that these genes most likely do have specific functions in normal tissue in addition to their role in the induction of DNA synthesis in quiescent cells in culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231609
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  • 12
    Electronic Resource
    Electronic Resource
    The GC box as a silencer (1987)
    Springer
    Bioscience reports 7 (1987), S. 955-963 
    Details
    ISSN: 1573-4935
    Keywords: gene expression ; GC box ; negative regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A DNA control sequence T G GGGCGG AAT GGC , or the “GC” box, has been described in the promoter regions upstream of a number of eukaryotic genes transcribed by polymerase II (for review, see Dynan, W. S. and Tjian, R.,Nature 316:774, 1985). The “GC” box can occur in single or multiple copies and is the binding site for a protein factor, Spl, which activates initiation of transcription. We have observed in the rainbow trout protamine gene 3′ to the TATA box, three “GC” boxes spaced at 80 bp intervals. The first is 5′ to the cap site and possesses the ability to “silence” transcription from the protamine promoter in constructs linking this promoter to the bacterial chloramphenicol acetyl transferase (CAT) coding sequence following transfection to COS-1 cells. A model is proposed to account for the silencing of the protamine gene in all tissues except developing sperm cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01122129
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  • 13
    Electronic Resource
    Electronic Resource
    Genetics of α-amylases from rye endosperm (1987)
    Springer
    Theoretical and applied genetics 73 (1987), S. 440-444 
    Details
    ISSN: 1432-2242
    Keywords: Secale cereale L. ; Genetics ; α-Amylase ; Isozymes ; Modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fifteen inbred lines of rye, F1 and F2 progenies from crosses between lines were studied using polyacrylamide gel electrophoresis. Conventional genetic analysis of α-amylase zymograms showed that the 19 bands detected in the endosperm of germinating caryopses were controlled by three linked structural loci and one independent modifying locus, which influenced the electrophoretic mobility of isozymes. Two codominant alleles were found at the α-Amy1, α-Amy2 structural loci and the M-α-Amy modifying locus while the α-Amy3 locus had three alleles. Double-banded expression of the α-amylase alleles was probably due to the simultaneous presence of modified and unmodified forms of isozymes on the zymogram.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262513
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  • 14
    Electronic Resource
    Electronic Resource
    Morphology and ultrastructure of 11 barley shrunken endosperm mutants (1987)
    Springer
    Theoretical and applied genetics 74 (1987), S. 177-187 
    Details
    ISSN: 1432-2242
    Keywords: Barley ; Grain development ; Mutants ; Ultrastructure ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eleven Na-azide induced barley shrunken endosperm mutants expressing xenia (sex) were characterized genetically and histologically. All mutants have reduced kernel size with kernel weights ranging from 11 to 57% of the wild type. With one exception, the mutant phenotypes are ascribable to single recessive mutant alleles, giving rise to a ratio of 3∶1 of normal and shrunken kernels on heterozygous plants. One mutant (B10), also monofactorially inherited, shows a gene dosage dependent pattern of expression in the endosperm. Among the 8 mutants tested for allelism, no allelic mutant genes were discovered. By means of translocation mapping, the mutant gene of B10 was localized to the short arm of chromosome 7, and that of B9 to the short arm of chromosome 1. Based on microscopy studies, the mutant kernel phenotypes fall into three classes, viz. mutants with both endosperm and embryo affected and with a non-viable embryo, mutants with both endosperm and embryo affected and with a viable embryo giving rise to plants with a clearly mutant phenotype, and finally mutants with only the endosperm affected and with a normal embryo giving rise to plants with normal phenotype. The mutant collection covers mutations in genes participating in all of the developmental phases of the endosperm, i.e. the passage from syncytial to the cellular endosperm, total lack of aleurone cell formation and disturbance in the pattern of aleurone cell formation. In the starchy endosperm, varying degrees of cell differentiation occur, ranging from slight deviations from wild type to complete loss of starchy endosperm traits. In the embryo, blocks in the major developmental phases are represented in the mutant collection, including arrest at the proembryo stage, continued cell divisions but no differentiation, and embryos deviating only slightly from the wild type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00289966
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  • 15
    Electronic Resource
    Electronic Resource
    The effect of the 4B chromosomes of hexaploid wheat on the growth and regeneration of callus cultures (1987)
    Springer
    Theoretical and applied genetics 74 (1987), S. 439-444 
    Details
    ISSN: 1432-2242
    Keywords: Wheat ; Callus ; Regeneration ; Tissue culture ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Calli were initiated from immature embryos of nine lines of hexaploid wheat (Triticum aestivum L. em. Thell). These were the euploid lines Chinese Spring and Cappelle-Desprez, a line of Chinese Spring ditelocentric for the long arm of 4B, four substitution lines of Chinese Spring in which chromosome 4B has been replaced by its homologues from different wheat varieties and substituted into Chinese Spring and a substitution line of Besostaya I 4B into Cappelle-Desprez. The calli from these lines were found to differ in their growth rates and morphogenic and regenerative activities. The substitution of different 4B chromosomes into Chinese Spring significantly increased morphogenesis and shoot regeneration from callus. The potential for developing wheat lines with improved culture characteristics is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00289818
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  • 16
    Electronic Resource
    Electronic Resource
    Analysis of the K1 capsule biosynthesis genes of Escherichia coli: Definition of three functional regions for capsule production (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 242-246 
    Details
    ISSN: 1617-4623
    Keywords: E. coli ; Genetics ; Polysaccharide biosynthesis ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transposon and deletion analysis of the cloned K1 capsule biosynthesis genes of Escherichia coli revealed that approximately 17 kb of DNA, split into three functional regions, is required for capsule production. One block (region 1) is required for translocation of polysaccharide to the cell surface and mutations in this region result in the intracellular appearance of polymer indistinguishable on immunoelectrophoresis to that found on the surface of K1 encapsulated bacteria. This material was released from the cell by osmotic shock indicating that the polysaccharide was probably present in the periplasmic space. Insertions in a second block (region 2) completely abolished polymer production and this second region is believed to encode the enzymes for the biosynthesis and polymerisation of the K1 antigen. Addition of exogenous N-acetylneuraminic acid to one insertion mutant in this region restored its ability to express surface polymer as judged by K1 phage sensitivity. This insertion probably defines genes involved in biosynthesis of N-acetylneuraminic acid. Insertions in a third block (region 3) result in the intracellular appearance of polysaccharide with a very low electrophoretic mobility. The presence of the cloned K1 capsule biosynthesis genes on a multicopy plasmid in an E. coli K-12 strain did not increase the yields of capsular polysaccharide produced compared to the K1+ isolate from which the genes were cloned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330449
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  • 17
    Electronic Resource
    Electronic Resource
    Regulation of NAD metabolism in Salmonella typhimurium: Genetic analysis and cloning of the nadR repressor locus (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 279-287 
    Details
    ISSN: 1617-4623
    Keywords: NAD metabolism ; Regulation ; nadR ; Salmonella typhimurium ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nadR locus (99 min) controls the transcription of several genes involved with either the biosynthesis (nadAB) or recycling (pncB) of NAD in Salmonella typhimurium. Point mutations in this locus were found to cause defects either in the transport of nicotinamide mononucleotide (PnuA-), the regulation of nadAB (NadR-) or both transport and regulation (PnuA-NadR-). Deletions or insertions into nadR always resulted in the PnuA- NadR- phenotypes. Merodiploids constructed with various combiminations of PnuA-, NadR- or PnuA-NadR- strains indicate a single complementation group. The results suggest the NadR product is a bifunctional regulatory protein. Operon fusions to lacZ (nadR:: Mud1-8) were used to show that nadR is not autoregulated and is transcribed in a clockwise direction. The gene was also cloned and located within a 2 kb EcoR1-BglII fragment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330454
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  • 18
    Electronic Resource
    Electronic Resource
    Genetic Significance of the relationship between absolute total finger ridge count and its variability (1987)
    Springer
    International journal of anthropology 2 (1987), S. 141-149 
    Details
    ISSN: 1824-3096
    Keywords: Absolute finger ridge count ; Genetics ; Dermatoglyphics ; India ; Major gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to test the hypothesis of a major gene effect on absolute total finger ridge count (ATFRC), the nature of relationship between mean ATFRC and its variability was evaluated in a series of 47 population samples from India. Regression analysis showed that both the standard deviation and the coefficient of variation are significantly related to mean ATFRC, and about 35% of the variation in ATFRC is explained by the dependent variable coefficent of variation. These results support the hypothesis of a major gene effect on the trait ATFRC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442360
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  • 19
    Electronic Resource
    Electronic Resource
    Transformation of soybean protoplasts from permanent suspension cultures by cocultivation with cells of Agrobacterium tumefaciens (1987)
    Springer
    Plant molecular biology 9 (1987), S. 135-145 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA/RNA hybridization ; gene expression ; marker rescue ; nopaline-synthase ; plant tumor cells ; Ti-plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell wall regenerating protoplasts from soybean cells kept in suspension culture were cocultivated with bacteria which were derived from the nopaline strain C58 of Agrobacterium tumefaciens. When the bacteria carried an oncogenic Ti-plasmid, about 5% of the surviving protoplasts were able to form calli on hormone-free agar in contrast to controls, where bacteria without Ti-plasmid were applied, and where no calli were formed. After isolation of DNA from hormone-independently growing cells further evidence for transformation was obtained by hybridization to Ti-plasmid specific RNA and by rescue of a segment with a bacterial resistance gene which had been inserted before into the T-DNA. Transfer of T-DNA harboring a neomycin-resistance gene activated by the nos-promoter resulted in calli growing on kanamycin. Verification of segments located at the left and the right part of the T-DNA indicated the presence of its entire length in transformed soybean cells. Expression of T-DNA genes was measured by the assay of nopaline-synthase. Cells cultured on agar had a much higher level of nopaline-synthase than fast growing cells in suspension culture. Transferring them to agar or treatment with azacytidine strongly increased synthesis of nopaline-synthase indicating a reversible repression presumably via a methylation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015646
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  • 20
    Electronic Resource
    Electronic Resource
    Light-stimulated accumulation of the peroxisomal enzymes hydroxypyruvate reductase and serine:glyoxylate aminotransferase and their translatable mRNAs in cotyledons of cucumber seedlings (1987)
    Springer
    Plant molecular biology 9 (1987), S. 259-275 
    Details
    ISSN: 1573-5028
    Keywords: cucumber ; gene expression ; hydroxypyruvate reductase ; light regulation ; peroxisomal enzymes ; serine:glyoxylate aminotransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of peroxisomal enzymes in cotyledons of cucumber seedlings is strongly dependent on light. In light-grown seedlings, activities of two peroxisomal enzymes, hydroxypyruvate reductase (HPR) and serine: glyoxylate aminotransferase (SGAT), were barely detectable until three days postimbibition, after which time both activities increased rapidly and linearly for at least three days. In the dark, the activities of these enzymes increased slightly over the same time period, but only to about 5% to 10% of 7-day light-induced levels. When 51/2-day dark-grown seedlings were transferred into white light, activities of HPR and SGAT began to increase after approximately 8 h. HPR protein was shown by an immunoprecipitation assay to increase concurrently with enzymatic activity in both light- and dark-grown cotyledons. Immunoblotting results suggested that the amounts of SGAT-A and SGAT-B, the two subunits of SGAT, also developed along with SGAT activity. The relative levels of translatable mRNAs encoding HPR, SGAT-A, and SGAT-B were also light-dependent, and increased with a developmental pattern similar to enzyme activity and protein levels in light- and dark-grown cotyledons. In 51/2-day dark-grown cotyledons that were transferred to the light, translatable mRNAs for SGAT-A and SGAT-B began to increase within 1 h of illumination and continued of increase rapidly and linearly for the next 24 h in the light to a new steady-state level that was 45 times that of dark controls. Translatable HPR mRNA exhibited a biphasic pattern of accumulation, with a three-fold increase during the first 6 h of illumination, followed by an additional six-fold increase between 8 and 24 h. The accumulation of translationally active mRNA for both enzymes preceded the accumulation of the corresponding protein and enzyme activity by about 8 h. Our data suggest that the rise in enzyme activity depends on an increase in translatable mRNA for these enzymes and is regulated at a pretranslational level, most likely involving transcription of new mRNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166462
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  • 21
    Electronic Resource
    Electronic Resource
    Expression of nodule-specific genes in Phaseolus vulgaris L. (1987)
    Springer
    Plant molecular biology 9 (1987), S. 521-532 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; nitrogen fixation ; nodulins ; Phaseolus vulgaris ; Rhizobium ; root-nodule development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The identification of some nodule-specific host proteins (nodulins) from common bean (Phaseolus vulgaris L.), a tropical ureide-transporting legume, is described. Particularly, the existence and developmental expression of several abundant nodule-specific transcripts of P. vulgaris are shown, including leghemoglobin, nodulespecific uricase and a group that in vitro translates into a cluster of about 30 kDa products. The expression pattern of nodulins in effective (Fix+) nodules compared to ineffective (Fix-) ones is also presented. The modified expression of main nodulins observed between these nodules indicates that different levels and/or factors associated with their regulation are involved. The intracellular infection by Rhizobium as a decisive step in the induction of some P. vulgaris nodulins is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020530
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    Expression of a gene for a light-harvesting chlorophyll a/b-binding protein in Chlamydomonas reinhardtii: effect of light and acetate (1987)
    Springer
    Plant molecular biology 9 (1987), S. 547-563 
    Details
    ISSN: 1573-5028
    Keywords: acetate ; blue light ; Chlamydomonas reinhardtii ; chlorophyll a/b-binding protein gene ; gene expression ; LHCP gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Chlamydomonas reinhardtii, the chlorophyll a/b-binding proteins of photosystem II are encoded in the nucleus by a small family of genes. We have studied the expression of one gene, which we call cabII-1, in a green-in-the-dark strain, which can synthesize chlorophyll in the dark or light, and in a yellow-in-the-dark mutant strain, which is able to make chlorophyll only in the light. In light/dark synchronized cultures of both strains, cabII-1 mRNA abundance increases during the first 6 h of a 12-h light phase, remains high for several hours, then declines. A variety of illumination conditions have been used to analyze the cabII-1 mRNA increase: continuous or intermittent red, blue, or white light, with or without 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of photosystem II. Our results suggest that light induces increased cabII-1 transcript abundance in two ways: 1) by virtue of its role in the light reactions of photosynthesis and 2) by a blue lightstimulated mechanism which is independent of photosynthesis. We have also examined the role of acetate in regulating cabII-1 mRNA levels in the dark. In both green- and yellow-in-the-dark strains, 15 mM Na-acetate, added to synchronized cells in the dark, induces an increase in cabII-1 mRNA abundance with a temporal accumulation pattern very similar to that induced by continuous white light. We suggest that by providing an energy source, acetate stimulates cellular growth, cell cycle progression, and increased cabII-1 mRNA abundance. Interestingly, in cells exposed to light, acetate inhibits the light-induced increase in cabII-1 mRNA abundance by a mechanism which is not yet understood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020532
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  • 23
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    The effect of abscisic acid on the differential expression of α-amylase isozymes in barley aleurone layers (1987)
    Springer
    Plant molecular biology 8 (1987), S. 13-22 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; aleurone layer ; α-amylase ; gene expression ; gibberellic acid ; isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The treatment of barley aleurone layers with gibberellic acid (GA3) results in the synthesis of two groups of α-amylase isozymes. Addition of abscisic acid (ABA) at the same time as GA3 inhibited the synthesis of both groups of isozymes. However, midcourse ABA addition (12 h or later after GA3) had a more inhibitory effect on the high pI α-amylase group than on the low pI α-amylase group. This midcourse inhibition was detectable within 2 h of ABA addition. Northern analysis results using cDNA probes for the high pI and low pI α-amylase groups paralleled the protein synthesis results for both isozyme groups. High pI α-amylase mRNA levels began to decrease within 2 h of midcourse ABA treatment and were less than 10% of the original level by 4 h. The levels of low pI α-amylase mRNA were decreased less by midcourse ABA addition than were high pI mRNA levels. Cordycepin and cycloheximide blocked the effects of midcourse ABA addition on α-amylase mRNA. These observations indicate that ABA inhibits α-amylase expression at the pretranslational level and that protein and RNA synthesis are required for midcourse ABA action to occur. Our results also show that α-amylase mRNA, which has been thought to be very stable, is degraded after midcourse ABA treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016430
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  • 24
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    Expression of a soybean β-conclycinin gene under the control of the Cauliflower Mosaic Virus 35S and 19S promoters in transformed petunia tissues (1987)
    Springer
    Plant molecular biology 9 (1987), S. 315-324 
    Details
    ISSN: 1573-5028
    Keywords: plant transformation ; CaMV promoters ; gene expression ; protein stability ; beta-conglycinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene encoding the α′-subunit of β-conglycinin was ligated to the 19S and 35S promoters of Cauliflower Mosaic Virus and introduced into petunia plants on a disarmed Ti-plasmid using Agrobacterium tumefaciens. Transformed cells were regenerated into whole plants and ummunoreactive polypeptides and hybridizable, polyadenylated mRNA were detected in transformed tissues. Expression from the 35S promoter was 10 to 50 times greater than expression from the 19S promoter. The level of immunodetectable polypeptides was greater in seeds than in leaves or callus tissue. In addition, the pattern of α′-polypeptide breakdown products was distinctive in seeds and leaves. We conclude that in seeds the higher levels of the α′-polypeptide reflect enhanced stability of this protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014906
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  • 25
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    Deviation from morphological intermediacy in interstrain hybrids of rainbow trout, Salmo gairdneri (1987)
    Springer
    Environmental biology of fishes 18 (1987), S. 249-256 
    Details
    ISSN: 1573-5133
    Keywords: Developmental rate ; Genetics ; Inheritance ; Meristic ; Salmonidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Deviations from morphological intermediacy in six first generation hybrids between three hatchery strains of rainbow trout, raised in a common environment, are reported. Hybrids have higher mean counts of four meristic characters than their maternal parental strain in a significantly greater number of cases (18 out of 24). Furthermore, eight of eleven hybrid indices are not intermediate. These results are discussed in reference to several mechanisms and models proposed to account for observed responses of meristic characters to environmental and genetic influences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004878
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  • 26
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    Gene expression in Brassica campestris showing a hypersensitive response to the incompatible pathogen Xanthomonas campestris pv. vitians (1987)
    Springer
    Plant molecular biology 8 (1987), S. 405-414 
    Details
    ISSN: 1573-5028
    Keywords: hypersensitive response ; Brassica campestris ; Xanthomonas campestris pv. vitians ; mRNA induction ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Xanthomonas campestris pv. vitians, a pathogen of lettuce, elicits a hypersensitive response within 12 hours of inoculation into Brassica leaves, characterized by tissue collapse, loss of membrane integrity, vein blockage and melanin production. In contrast, the compatible pathogen, X. c. pv. campestris, has no visible effects on leaves for 48 hours, after which inoculated areas show chlorosis which eventually spreads, followed by rotting. mRNA was prepared from leaves inoculated with suspensions of both pathovars or with sterile medium up to 24 hours following inoculation. In vitro translation of total and poly A+ RNA in rabbit reticulocyte lysate in the presence of 35S methionine followed by separation of the polypeptide products by 2D-PAGE, allowed comparison of the effects of these treatments on plant gene expression. Major changes in gene expression were observed as a consequence of the inoculation technique. In addition, after inoculation with X. c. vitians, up to fifteen additional major polypeptides appeared or greatly increased by four hours. Some of these had disappeared by nine hours and several more had appeared. No major polypeptides disappeared or decreased greatly in intensity following inoculation with X. c. vitians.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015818
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  • 27
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    Cloning of cDNA for phytochrome from etiolated Cucurbita and coordinate photoregulation of the abundance of two distinct phytochrome transcripts (1987)
    Springer
    Plant molecular biology 8 (1987), S. 485-496 
    Details
    ISSN: 1573-5028
    Keywords: coordinate regulation ; Cucurbita phytochrome cDNA ; gene expression ; light regulation ; multiple transcripts ; regulatory photoreceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated several cDNA clones for phytochrome from a dicot, Cucurbita pepo L. cv. Black Beauty (zucchini), and have used them to study the regulation of Cucurbita phytochrome mRNA levels. A cDNA library was constructed from poly(A)+ RNA isolated from etiolated Cucurbita hypocotyl hooks and enriched for phytochrome mRNA by size fractionation. This library was screened with a 32P-labeled fragment isolated from an Avena phytochrome cDNA clone. Several putative phytochrome clones were isolated and mapped by restriction endonuclease analysis. On the basis of this analysis there is no evidence for the expression of multiple phytochrome genes in Cucurbita. Recent sequence analysis has confirmed that the largest of these clones, pFMD1 (∼3.6 kb), does indeed encode phytochrome and that it contains the entire amino acid coding sequence for Cucurbita phytochrome (33). RNA blot analysis has revealed that two polyadenylated phytochrome transcripts (∼5.6 kb and ∼4.2 kb) are present in both cotyledons and hypocotyl hooks of Cucurbita. In etiolated Cucurbita seedlings given a saturating pulse of red light, the abundance of both transcripts coordinately declines to 50–60% of the dark levels within 3 h and reaccumulates to dark levels within 24 h. Reversal of induction of this response by a far-red light pulse immediately following red light treatment is not observed, which is in contrast to the far-red reversibility of the red light promoted decrease in phytochrome mRNA abundance observed in Avena (6). Etiolated seedlings transferred to continuous white light also show a coordinate decrease in the levels of the two RNAs to ∼40% of the dark levels within 3 h. The magnitude of the light-induced decline in phytochrome mRNA abundance in Cucurbita is substantially less than the decrease previously reported for Avena (6).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017994
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    Can cancer chemotherapy enhance the malignant behaviour of tumours? (1987)
    Springer
    Cancer and metastasis reviews 6 (1987), S. 503-520 
    Details
    ISSN: 1573-7233
    Keywords: animal models ; chemotherapy ; gene expression ; metastasis ; tumour progression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cancer chemotherapy is currently undergoing an intensive reappraisal because of its unimpressive performance against the major common cancers. There are a number of possible reasons for this lack of success; one considered here is that under some circumstances anti-neoplastic drug treatment actually increases the malignant behaviour of tumours. Support for this idea comes mainly from experimental studies in which drug treatments increased metastatic spread. Investigation of this phenomenon shows that drug induced modifications of the host, including immunosuppression and vascular damage, can indeed facilitate metastasis. In addition, new data are presented demonstrating that the direct action of drugs on the tumour cells themselves can have similar enhancing effects. The possible mechanisms underlying such direct effects are discussed and the ability of anti-cancer drugs to cause genetic mutations, amplify genes, and alter gene expression are considered. While the nature and extent of this facilitation of tumour malignancy is not fully understood, it is suggested that this possibility should be considered in the design of treatment protocols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047465
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  • 29
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    Development of cell systems to study viral gene transcription at the initial phase of Epstein-Barr virus infection (1987)
    Springer
    Virus genes 1 (1987), S. 73-82 
    Details
    ISSN: 1572-994X
    Keywords: EBV ; gene expression ; immortalization ; cDNA cloning ; Northern blot hybridization ; tonsil lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two infection systems have been introduced in order to study viral gene expression at the initial period of Epstein-Barr virus (EBV) infection which leads to immortalization. The data indicate that major viral gene expression in tonsil lymphocytes at 2 days post-infection (p.i.) with EBV is very similar to that observed in latently infected cells. Both tonsil lymphocyte and BJAB cell (lymphoblastoid cells free of EBV genome) infection with EBV induced similar viral gene transcription. Twelve cDNA clones were prepared from poly(A) RNA of tonsil lymphocytes infected with EBV 2 days p.i. by hybridization with BamHI fragments of EBV DNA. Some cDNAs were derived from primary transcripts of the BamHI-WYHK region, suggestive of splicing of a large transcript. It is possible that a number of cDNA clones may be derived from cellular genes. The derivation of these cDNA clones is being studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00125687
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    DNase I hypersensitivity and expression of the Shrunken-1 gene of maize (1987)
    Springer
    Plant molecular biology 8 (1987), S. 251-264 
    Details
    ISSN: 1573-5028
    Keywords: chromatin structure ; DNase I hypersensitivity ; gene expression ; sucrose synthetase ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The local chromatin structure of the Shrunken-1 (Sh) gene of maize was probed by analyzing DNase I hypersensitivity. Sh encodes the gene for sucrose synthetase, a major starch biosynthetic enzyme, which is maximally expressed in the endosperm during seed maturation. In addition to general DNase I sensitivity, specific DNase I hypersensitive sites were identified in endosperm chromatin that mapped near the 5′ end of the Sh gene. The pattern of hypersensitive sites and their relative sensitivity were altered in other non-dormant tissues that produce little or no enzyme. However, some changes in chromatin structure appear to be independent of Sh gene expression and may reflect general alterations associated with plant development. The chromatin structure of several sh mutations, induced by Ds controlling element insertions, was also analyzed. Although the insertions perturbed expression of the gene, there were no notable effects on local chromatin structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015033
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    Nodulin gene expression during soybean (Glycine max) nodule development (1987)
    Springer
    Plant molecular biology 8 (1987), S. 395-403 
    Details
    ISSN: 1573-5028
    Keywords: Bradyrhizobium ; gene expression ; nodulin ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro translation products of total RNA isolated from soybean nodules at successive stages of nodule development were analyzed by two-dimensional gel electrophoresis. In that way the occurrence of over 20 mRNAs specifically transcribed from nodulin genes was detected. The nodulin genes could be divided into two classes according to the time of expression during nodule development. Class A comprises at least 4 nodulin mRNAs which are found when a globular meristem is present in the root cortex. These class A nodulin genes have a transient expression. Class B nodulin genes are expressed when the formation of a nodule structure has been completed. Bradyrhizobium japonicum nod + fix-mutants, with large deletions spanning the nif H,DK region, still induced nodules showing normal expression of all nodulin genes, indicating that the nif H,DK region is not involved in the induction of nodulin genes. In nodules induced by Bradyrhizobium japonicum nod + fix-mutant HS124 the bacteria are rarely released from the infection thread and the few infected cells appear to be collapsed. All class A and class B nodulin genes are expressed in HS124 nodules with the exception of 5 class B genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015817
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  • 32
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    Differential accumulation of potato tuber mRNAs during the hypersensitive response induced by arachidonic acid elicitor (1987)
    Springer
    Plant molecular biology 9 (1987), S. 335-342 
    Details
    ISSN: 1573-5028
    Keywords: potato tuber ; elicitor ; arachidonic acid ; cDNA cloning ; gene expression ; PR proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of messenger RNAs in potato tuber discs was analysed during the hypersensitive response induced by treatment with the biotic elicitor arachidonic acid. In vitro translation of polysomal poly(A)+ RNAs indicated that the accumulation of some sixteen mRNAs varied following treatment with arachidonic acid, and that the level of thirteen of these was increased. Two cDNA closes (pSTH-1 and-2) were isolated from a library of elicitor-treated tissue cDNAs. Northern blot analysis using these clones as molecular probes indicated that the levels of at least two mRNAs were markedly increased after elicitor treatment. In hybrid-released translation experiments, each of the cDNA clones selected more than one mRNA. Translation of these mRNAs yielded two polypeptides of Mr 45 000 (for the pSTH-1 clone), and three polypeptides of Me 17 000 (for the pSTH-2 clone). The low molecular weight polypeptides may correspond to potato pathogenesis-related (PR) proteins.
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    URL: http://dx.doi.org/10.1007/BF00014908
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  • 33
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 1. A Study of Bimolecular Nucleophilic Substitution at the Boron Atom (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 499-510 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetradentate ligand 2,2′,2″-nitrilotriphenol forms a boron complex III with an intramolecular, transannular N→B dative bond of 1.68 Å in a strained tricyclo[3.3.3.0]undecane chelating system. The complex reacts with nitrogen bases L, such as pyridine, quinuclidine and others, to form complexes III-L, in which the intramolecular B-N bond is replaced by one between B and the external nucleophile. In solution, this displacement reaction is reversible. It was studied by temperature-dependent NMR spectroscopy. The resulting reaction and activation parameters suggest that the reaction is a bimolecular nucleophilic substitution (SN2).
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700303
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    Complexes of 2,2′,2″-Nitrilotriphenol. Part 3. Crystal and Molecular Structures of Three Aluminium Complexes (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 520-533 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal and molecular structures of three Al(III) complexes of the tripod ligand 2,2′,2″-nitrilotriphenolate (I) are presented. They all show 5-coordinate Al in approximately trigonal bipyramidal geometry, with an external nucleophile X occupying the second axial position. X is OH- in[Al(I)(OH)]-[Hquin]+ (quin = quinuclidine), N in [Al(I)(py)] (py = pyridine), and one of the O-atoms of a second molecule in the dimeric [(Al(I))2]. Correlated variations in the axial bond lengths of the trigonal bipyramid are observed: [(Al(I))2]: Al-Nint. = 2.094 Å, Al-Oext. = 1.850 Å; [Al(I)(py)]: Al-Nint. = 2.153 Å, Al-Next., = 1.992 Å; [Al(I)(OH)]-: Al-Nint. = 2.278 Å, Al-Oext. = 1.765 Å. They are interpreted in terms of a dissociative reaction path at the Al(III) centre.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700305
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    Molluscicidal Saponins from Swartzia madagascariensis DESVAUX (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 570-576 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phytochemical investigation of the dried fruits of Swartzia madagascariensis (Leguminosae) afforded the five triterpenoid saponins 1-5. They were shown to be glucuronides of oleanolic acid and of gypsogenin by chemical and spectral means (FAB-MS, 13C-NMR, GC/MS). One of the isolated compounds, identified as 3-O-[O-α-L-rhamnopyranosyl-(1→3)-(β-D-glucopyranosyluronic acid)]oleanolic acid, was responsible for the high molluscicidal activity of Swartzia madagascariensis fruits against the schistosomiasis-transmitting snails Biomphalaria glabrata and Bulinus globosus.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700309
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    The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 587-592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8. In contrast, porcine liver esterase (PLE, EC 3.1.1.1) cleanly hydrolyses 5 to give the isolable 1-methyl-2,4-cyclopentadiene-1-carboxylic acid (13). The latter undergoes thermal dimerization with conservation of the geminal-substitution pattern. The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C2 symmetry. Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acid concentration is used. The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700311
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    Potassium Carboxylates by Direct Carbonylation of Potassium Alkoxides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 593-599 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the K+ alkoxide of linalool (1) in benzene with CO at 425-440 bar and 120-130° for 12-30 h gave the K+ salt of 2,6-dimethyl-2-vinyl-5-heptenoic acid (4a) in a ca. 25% yield based on ca. 65% converted alkoxide. Reaction of the [K+ ⊂ 18-crown-6] alkoxide of 1 with CO at 50-55 bar and 40° for 90-140 h gave a mixture containing mainly the [K+ ⊂ 18-c-6] salts of 4a (ca. 62%) and of the homogeranic acids 3a and 6a (together ca. 27% of the mixture) in a ca. 35% combined yield based on 50-60% converted alkoxide. The uncomplexed or complexed K+ alkoxide of (S)-1 gave, with ca. 85% net retention, the K+ salt of (S)-4a. Reaction of the [K+ ⊂ 18-c-6] alkoxide of geraniol (2) with CO at 50 bar and 40° for 65-70 h gave myrcene (10) and geranyl formate (11) in a ca. 40-50% yield each based on ca. 85% converted alkoxide. Reaction of the [K+ ⊂ 18-c-6] alkoxide of 3-pentyl-1,4-pentadien-3-ol (14) at 50 bar and r.t. for 70 h gave a mixture of the [K+ ⊂ 18-c-6] salts of 2-pentyl-2-vinyl-3-butenoic acid (15a) (67%) and the 4-pentyl-2,4-hexadienoic acids 18a and 19a (together 23% of the mixture) in a ca. 90% combined yield based on ca. 65% converted alkoxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700312
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    Synthesis and Copper(I) Complexes of a Series of 9- to 13-Membered N3 Macrocycles (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 680-689 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eight cyclic triamines with ring sizes between 9 and 13 were synthesized by the p-toluenesulfonate method. The open-chain triamines bis(2-aminoethyl)amine (dien) and bis(3-aminopropyl)amine (diprop) were used as starting materials. In some cases, the corresponding dimeric cyclic hexaamines have been isolated and characterized as major by-products. The complexation of Cu(I) by the triamines has been studied potentiometrically in CH3CN/H2O. All ligands L form ternary complexes [Cu(CH3CN)L]+. The corresponding association constants vary between 1011 and 107, decreasing with increasing ring size. In addition, complexes [Cu(CH3CN)yLH]2+, y = 1 or 2, are found as less important species with maximum concentrations of 7 to 50%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700318
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    The Microstructure of Selective Palladium Hydrogenation Catalysts Supported on Calcium Carbonate and Modified by Lead (Lindlar Catalysts), Studied by Photoelectron Spectroscopy, Thermogravimetry, X-Ray Diffraction, and Electron MicroscopyThe following abbreviations and acronyms are used in the text: B. e. : Binding energy [eV], BET: Brunauer-Emmett-Teller (method of surface-area determination by physisorption of N2), AES: Auger electron spectroscopy, XPES: X-ray photoelectron spectroscopy, UPES: Ultraviolet photoelectron spectroscopy, ISS: Ionscattering spectroscopy, UHV: Ultrahigh vacuum (10-5 Pa), FTIR: Fourier-transform IR spectroscopy, TGA: Thermal gravimetric analysis, XRD: X-ray diffraction, XDA: Energy dispersive microanalysis, SEM: Scanning electron microscopy, TEM: Transmission electron microscopy, FWHM: Full width at half maximum. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 627-679 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed analysis of the system Pd + Pb on CaCO3 is presented. This system known as Lindlar catalyst is used for selective hydrogenations of C≡C bonds to C=C bonds. It was found to consist of seven distinct chemical phases. Essential ingredients are solid solutions of hydrogen and oxygen in Pd. The latter phase enables the metal particles to be attached to the support via an orientational relationship calcite (113)∥Pd + O (111). The addition of Pb neither changes the micromorphology of the disk-shaped Pd particles nor does it modify the electronic structure of Pd as studied by chemisorption experiments. The addition of Pb seems to block certain active sites and, thus, to enhance the selectivity. The support was found to be a multi-domain mixture of calcite and aragonite with domain sites of several hundred Å. The free surface of the pore-free solid is covered by a calcium-hydroxide carbonate. This phase as well as several other Pb phases seem to represent only spectator materials. Verification of this as well as finding the correlation between structure and function of the various components requires a kinetic analysis which is outside the scope of this paper. It is demonstrated that a variety of analytical techniques is required to unravel the complex nature of such a ‘simple' catalyst’ as it is Pd on CaCO3.
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    Verapliquinones: Novel Diprenylquinones from an Aplidium sp. (Ascidiacea) of Ile-Verte Waters, Brittany (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 621-626 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Aplidium sp. (Ascidiacea), collected in French Atlantic waters near the Ile Verte, is shown to contain verapliquinone B (2) and verapliquinone D (6) as the first examples of linear diprenylquinones of the neryl type, besides their respective isomers 1 and 5 of the geranyl type.
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  • 41
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    Fe(II)-Induced Fragmentation Reaction of γ-Hydroperoxy-α,β-enones. Part 1. Synthesis of 13(14→8)-abeo-Steroids (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 701-716 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some steroidal analogues embodying the hitherto unknown 13(14→8)-abeo skeleton have been synthesized by Fe(II)-induced rearrangement (tandem β-fission/reductive alkylation) of 14α-hydroperoxy-7-en-6-ones. The configurational assignment was made by thorough analysis of NMR spectra; the structure of one of the products was unambiguously assessed by X-ray single-crystal analysis.
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    URL: http://dx.doi.org/10.1002/hlca.19870700320
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  • 42
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    Light-Induced, Thermal, and Acid-Catalyzed π-Skeletal Rearrangements of Five-Ring-Annelated HeptalenesPresented in part by H.-J.H. in a lecture at the ETH in Zürich, 1985. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 742-759 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that, upon irradiation in CDCl3 solution, 5,6,8,10-tetramethylheptalene-1,2-dicarboxylic anhydride (6) rearranges to its double-bond-shift (DBS) isomer 7 in an equilibrium reaction (Scheme 2). The isomer 7 is DBS stable at -50°. At ca. 30°, a thermal equilibrium with 97.8% of 6 and 2.2% of 7 is rapidly established. Similarly, the ‘ortho’-anhydrides 9 and 11 (Schemes 4 and 5) can be rearranged to their corresponding DBS isomers 12 and 13, respectively. Whereas 12 is DBS stable at 30° (at 100° in tetralin, 94.0% of 9 are in equilibrium with 6.0% of 12), the i-Pr-substituted isomer 13 is already at 30° in thermal equilibrium with 11 leading to 98.7% of 11 and 1.3% of 13. It is shown by rearrangement of diasteroisomeric ‘ortho’-anhydrides of known relative and absolute configuration (Scheme 6) that the DBS in such five-ring-annelated heptalenes occurs with retention of the configuration of the heptalene skeleton as already established for other heptalene compounds. It is found that the DBS process may also take place under acid catalysis (e.g. HCl/CH3OH), thus yielding 9 from 12 (Scheme 9). The ‘ortho’-anhydrides 21 and 23 (Scheme 10) which are isomeric with 9 and 11 (Scheme 3) undergo rapid DBS' already at room temperature. The thermal equilibrium 21⇄22 consists of 18% of 21 and 82% of 22 at 30° and that of 23⇄24 of 17% of 23 and 83% of 24 at -30°. From these equilibrium mixtures, the pure DBS isomer 22 can be obtained by crystallization. Again, these rapid DBS' occur with retention of configuration of the heptalene skeleton (Fig. 4).
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    Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-PhenylnonafulvenHerrn Prof. Dr. Hans Nitschmann zum 80. Geburtstag gewidmet52. Mitt. über Fulvene, Fulvalene; 51. Mitt. [1]; Kurzmitt. [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 862-880 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-PhenylnonafulveneExperimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT-; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.
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    Field-Desorption Mass Spectra of Fern Phloroglucinols Containing Three to Six Ring ConstituentsDedicated to the late Prof. Peter Brown (12.IX.1938-15.III.1981), Dept. of Chemistry, Arizona State University, Tempe, Arizona 08521, U.S.A., Whose premature death was a great loss to his friends and collegues. The last letter which we received from him (November 15, 1980) contained the first FD mass spectra of five relatively large fern phloroglucinols which he had successfully analyzed. Two of these spectra, in which no thermal rearrangement and /or fragmentation was observed, are reproduced in this article (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 881-893 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It has been previously shown that the structural analysis of the title compounds by electron-impact ionization (EI)mass spectrometry is complicated by extensive, if not complete, thermal rottlerone-type rearrangement and/or fragmentation reactions. The use of a ‘softer’ ionization technique such as field desorption (FD) is, therefore, required in order that these compounds may be characterized in terms of their molecular size and composition. In this report, the FD mass spectra of typical representatives of this class of compounds are described along with the attempted suppression of undesirable thermal reactions by the optimization of the emitter temperatures.
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  • 45
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    Structures and Electrical Properties of Some New Organic Conductors Derived from the Donor Molecule TMET (S,S,S,S,-Bis(dimethylethylenedithio) tetrathiafulvalene) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 942-953 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf-6, AsF-6, SbF-6, I-3 (incommensurate), and 3:2 with tetrahedral anions BF-4, CIO-4, ReO-4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.
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    Bildung tricyclischer Thietan-Derivate durch intramolekulare(2+2)-Cycloaddition (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 992-994 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Thietane Derivatives via Intramolecular (2+2) CycloadditionOn irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b, synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a,b, undergo an intramolecular (2+2)-cycloaddition reaction of the C=S and C=C bonds to give the tricyclic thietane derivatives 3a,b.
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  • 47
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    Photochemical Synthesis of 2-Alkylidene-1,3-cyclocalkanediones. Preliminary Communication (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 995-996 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis (λ = 254 nm) of 4-(tert-butyl)-4,6,7,8-tetrahydro-7,7-dimethy-2H-1-benzopyran-2,5(3H)-dione (3a) in t-BuOH affords 2-(2,2-dimethylpropylidene)-5,5-dimethyl-1,3-cyclohexanedione (1a) in 80% yield via homolysis of the lactone O—CO bond and subsequent ketene elimination.
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    Some Cyclic Oligopeptide with S2n Symmetry (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1012-1016 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some cyclic oligopeptides formed by an equal number of alternating D- and L-amino-acid residues have been synthesized by using the hydrochloride of the open-chain peptide acid as precursor and the mixed-anhydride condensation method. The cyclic oligopeptides (tetra-, hexa-, and octavaline, hexaleucine, and hexaphenylalanine) form very stable H-bonded structures (IR-amide band at 3270-3290 cm-1) which are insoluble in common organic solvents. In CF3COOH/CDCI3 (25°), they yield 1H-NMR spectra snowing the expected equivalency of the various amino-acid residues.
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    Strukturaufklärung ungewöhnlicher Umlagerungsprodukte von S-(1-Alkenyl)sulfoximiden mit Hilfe der Stossaktivierungsmassenspektrometrie (CAD-MS) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1041-1049 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure Determination of Unusual Rearrangement Products of S-(1-Alkenyl)sulfoximides by Collisionally Activated Dissoication Mass Spectrometry (CAD-MS)The Molecular ions of s-(l-alkenyl)--N-(p-tolyl)sulfoximides 1 are transformed into the N(phenylsufenyl)sulfonamides 3+ by a 1,2-migration of the alkenyle group to the O-atom of the sulfoximide function followed by a 2,3-sigmatropic rearrangement. The structure of the production e has been unambiguouslydetermined by the CAD method, showing the identity of the ion e (m/z368) obtained from 1a and from 4a.
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    URL: http://dx.doi.org/10.1002/hlca.19870700416
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  • 50
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    Reaktionen von 1,2-Bis(trimethylsilyl)iminen mit Selen-und Tellur-halogeniden (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1076-1078 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 1,2-Bis(trimethylsilyl)imines with Selenium and Tellurium HalogenidesThe reactions of benzil-bis(trimethylsily)imine and phenanthrene-9,10-bis(trimethylsilyl)imine with SeOCl2, SeCl4 and TeCl4 are described.
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    Remote Tricarbonyl(diene)iron Substituent Effect on Ester Heterolysis. The Solvolyses of 5,6,7,8-Tetramethylidenebicyclo[2.2.2]oct-2-yl Methanesulfonate and of its Tricarbonyliron Mono- and Dinuclear ComplexesPart of Ph.D. thesis of J.-C. Zwick, Ecole Polytechnique Fédérale de Lausanne, 1987. Part of this work has been presented at the Fall Meeting of the Swiss Chemical Society in Bern, Oct. 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1079-1094 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Buffered acetolyses and hydrolyses of 5,6,7,8-tetramethylidenbicyclo[2.2.2]oct-2-yl methanesulfonate (17), of its ‘syn-endo’ (18), ‘syn-exo’ (19), ‘anti-endo’ (20), ‘anti-exo’ (21) tricarbonyliron complexes and of its ‘anti-exo,syn-endo’ (22) and ‘anti-endo,syn-exo’ (23) bis(tricarbonyliron) dinuclear complexes have been investigated (product analysis and kinetics). In contract with the solvolyses of the uncomplexed mesylate 17, the solvolyses of the complexed esters can be highly chemo- and stereoselective. The nature of the products (non-rearranged bicyclo[2.2.2]oct-2yl vs. rearranged bicyclo[3.2.1]oct-2-yl derivatives) depends on the relative configuration of the tricarbonyl(diene)iron moieties and on the medium. The rates of solvolyses of 17 are only slightly affected by complexation of one or both s-cis-butadiene units with Fe(CO)3 groups, except in the cases where the diene moiety ‘anti’ with respect to the mesylate is complexed onto its ‘endo’ face (20,23). In these cases, significant rate-retardation effects are observed, consistent with the inductive effect of the Fe(CO)3 substituent. Such retardation effects are overwhelmed by competing accelerating homoallylic participation by uncoordinated ‘anti’ -diene moieties (18,19) or, as in the case of the ‘anti-exo’-Fe(CO)3 complexes 21 and 22, by possible direct metal participation to the ionization process.
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    URL: http://dx.doi.org/10.1002/hlca.19870700421
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    Synthetic Models of the Active Site of Cytochrome P-450. 1st Communication. The Synthesis of a Doubly-Bridged Iron(II)-Porphyrin Carrying a Tightly Bound Thiolate LigandPresented in part at the ‘Gordon Research Conference’ on the ‘Chemistry and Biology of Pyrroles’, New Hampshire, 27.7.-1.8.86 (W.-D.W.), and at the ‘Swiss Chemical Society’ meeting, Bern, 10.10.86 (B.S.). (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1173-1193 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The doubly-bridged iron(II)-tetraphenylporphyrin derivative 6, carrying a sterically fixed S- ligand in the ‘proximal’ position and the substrate at the ‘distal’ site, was synthesised as an enzyme model for cytochrome P-450. Compound 36, the CO complex of 6, displays a split Soret band (403 and 457 nm) similar to the native cytochrome P-450.
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    Stereoselektive Alkylierung an C(α) von Serin, Glycerinsäure, Threonin und Weinsäure über heterocyclische Enolate mit exocyclischer DoppelbindungZughörige Kurzmitteilungen: [1] (Weinsäre) [2] (Threonin) [3] (Serin) [4] (Glycerinsäure).Siehe auch die Diskussionen in den vor kurzem erschienenen Übersichtsartikeln [5][6]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1194-1216 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steroselective Alkylation at C(α) of Serine, Clyceric Acid, Threonine, and Tartaric Acid Involving Heterocyclic Enolates with Evocyelic Double BondsThe chiral, non-racemic title acids are converted to methyl dioxolane-(cf. 13), oxazoline-(4) and oxazolidinecarboxylates (cf. 9). Deprotonation by Li(i-Pr) 2N at dry-ice temperature gives solutions of the lithium enolates A-D With exocyclic enolate double bonds. These are stable crough with respect to β-elimination (Scheme 1) to be alkylated with or without cosolvents such as HMPA or DMPU The products are formed in good to excellent yields and, with the exception of the tartrate-derived acetonlde (see Scheme 2), with diastereoselectivities above 90%. While the tartrate-and threonine-derived enolates (A and B, resp.) are chiral due to the second stereogenic center of the precursors, the serine- and glyceric-acid-derived enolates (Aand B, resp.) are chiral due to the second sterogenic center of the precursors, the serine-nd glyceric-acid-derived enolates are non-racemic due to a tert butyl-substituted (pivalaldehyde-derived) acetal center (C and D, resp.). The products of alkylation can be hydrolyzed to give α-branched tartaric acid (Scheme 2), allothreonine (Scheme 3), serine (Scheme 4), and glyceric-acid derivatives (Scheme 5) with quaternary stereogenic centers. The configurations of the products are determined by NOE-NMR measurements and by chemical correlation. These show that the dioxolane-derived enolates A and D are alkylated preferentially from that face of the ring which is already substituted (‘syn’-attack), while the dihydrooxazol-and oxazolidine-derived enolates B and C are alkylated from the opposite face (‘anti’-attack). The ‘syn’-attack is postulated to arise from strong folding of the heterocyclic ring due to electronic repulsion between the enolate π-system and non-bonding electron pairs on the heteroatoms (see Scheme 6).
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    Novel Synthesis of Agaritine, a 4-Hydrazinobenzyl-Alcohol Derivative Occurring in Agaricaceae (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1261-1267 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 4-hydrazinobenzyl alcohol (3 was prepared (58%)) by diiobutylaluminiumhydride reduction of methyl 4-hydrazinobenzoate (4), whereas LiA1H4 or LiBh4 reduction of4 proceeded further to yield (via intermediate 3) (4-tolyl)hydrazine (5). The alcohol 3 was stable under O2-free conditions and exhibited no tendency to eliminate H2O, neither thermally nor with H+ catalysis. Oxidation of 3 with SeO2 yielded 4-(hydroxymethyl)benzine-diazonium ion (8), identified by its azo coupling product 9 with 2-naphthol. Condensation of 3 with 1-benzyl 5-Hydrogen N-(benzyloxycarbonyl)-L-glutamate (10) in presence of dicyclohexylcarbodiimide afforded 81% of N2-(benzyloxycarbonyl)-L- glutamic acid 1-(benzyl-ester) 5-{2-[4-(hydroxymethyl)phenyl]hydrazide} (11) which upon controlled hydrogenolysis (quinoline-sulfur-poisoned Pd/C catalyst) gave 82% of L-Glutamic acid 5-{2-[4-(hydroxymethyl)phenyl] hydrazide} (1), i. e. agaritine, a metabolite of Agaricus bisporus. Without poisoning of the catalyst, hydrogenolysis of (11) yielded L-glutamic acid 5-[2-(4-tolyl)hydrazide] (12).
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    The Solid and Solution Conformations of (±)-Corycavine (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1482-1486 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of corycavine, a protopine-type alkaloid, has been determined by X-ray analysis. A conformational feature observed is the existence of a strong electrostade interaction between the N- and C-atom at a distance of 2.618 Å. Such an interaction stabilizes the 10-membered ring conformation of the structure. Analyses of NMR spectra indicate that corycavine has the same conformation in solution as in the crystal state.
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    Dimethylformamide-Exchange Mechanism on Some First-Row Divalent Transition-Metal IonsPart 33 of the series ‘High-Pressur NMR Study’. Part 32: [1].Taken in part from the diploma work of C. Cossy, Université de Lausanne, 1983.This work was presented in part at the 24th International Conference on Coordination Chemistry, Athens, Greece, August 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1516-1525 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of temperature on the dimethylformamide exchange on Mn(DMF)2+6 and Fe(DMF)2+6 has been studied by 13C- and 17O-NMR, respectively, yielding the following kinetic parameters: k298 equals; (2.2±0.2). 106 S-1, ΔH≠ = 34.6 ± 1.3 kJ mol-1, ΔS≠ = -7.4 ± 4.8 J K-1mol-1 for Mn2+ and K298 = (9.7 ± 0.2).105 S-1, Delta;H≠ = 43.0 ± 0.9 kJ mol-1, ΔS≠ = + 13.8 ± 2.8 J K-1mol-1 for Fe2+. The volumes of activation, ΔV≠ in cm3mol-1, derived from high-pressure NMR on these metal ions, together with the previously published activation volumes for Co2+ and Ni2+ (+2.4 ± 0.2 (Mn2+), +8.5 ± 0.4 (Fe2+) +9.2 ± 0.3 (Co2+), + 9.1 ± 0.3 (Ni2+)) give evidence for a dissociative activation mode for DMF exchange on these high-spin first-row transition-metal divalent ions. The small positive ΔV≠ value observed for DMF exchange on Mn2+ seems to indicate that a mechanistic changeover also occurs along the series, (probably from Id to D), as for the other solvents previously studied (Ia to Id, for H2O, MeOH, MeCN). This changeover is shifted to the earlier elements of the series, due to more pronounced steric crowding for dimethylformamide hexasolvates.
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    URL: http://dx.doi.org/10.1002/hlca.19870700608
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    Two New Antifungal Naphthoxirene Derivatives and their Glucosides from Sesamum angolense WELW (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1551-1557 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two novel naphthoxirene derivatives 1 and 2 their glucosides 3 and 4 have been isolated from the root bark of Sesamum angolense Welw. (Pedaliaceae) by preparative liquid chromatography. The structure of 1 was established by X-ray diffraction analysis. The identities of the other naphthcxirenes were deduced by spectroscopic (IR, UV, 1H-NMR, 13C-NMR, EI-MS, DCI-MS) and chemical methods (oxidation, acid and enzymatic hydrolysis). Compounds 1-3 exhibited antifungal activity. Naphthoxirene 1 was, in addition, cytotoxic to human colon carcinoma cells.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700613
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    On Negative Birefringence in Water-in-Oil Microemulsions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1531-1536 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The occurrence of a negative birefringence in water-in-oil (W/O) microemulsions has been substantiated and analyzed. The analysis is based on the well-established aqueous nanodroplet model of W/O microemulsions. In the particularly investigated water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/aliphatic oil systems, the AOT monolayer exhibits a negative induced intrinsic birefringence, which is brought about by the pronounced polarizability of the alkyl moiety of the AOT molecule approximately perpendicular to the direction of its permanent dipolement.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700610
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    Erratum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2246-2246 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700829
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2305-2306 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700830
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  • 61
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    Herstellung und Charakterisierung in Membranen von Ionophoren mit Selektivität fü Natrium-Ionen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 153-157 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Neutral Sodium-Selective Ionophores and their Characterization in Membrane ElectrodesDifferent ionopbores based on N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide (1) have been prepared by substitution of the aromatic ring carrying the ether O-atoms. Substituents of widely different electronegativity (CH3, CH3O, CHO, CN NO2, Br) do not relevantly influence the ion selectivity.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700119
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  • 62
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    Complexes of 3,3′-Oxybis[(diphenylphosphino)methylbenzene] with Ni(II), Pd(II), Pt(II), Rh(I), and Ag(I). How Important is Backbone Rigidity in the Formation of trans-Spanning Bidenatate Chelates?? (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 158-170 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] (1) forms monomeric, trans-square-planar complexes MX2(1) (M = Ni, Pd, Pt; X = Cl-, Br- I-, and, in part, N3-, NCS-, CN-, NO3-) as well as Pt(H)Cl(1), Pt(H)Br(1), and RhCl(CO)(1). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl2(1)]2 and cis-[PtCl2(1)]n (mean value of n ≈ 4-5) 31P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl(1)·0.5 (CH3)2C=O·0.39 C6H12 (space group C2/c,a = 21.02 Å, b = 14.57 Å, c = 24.79 Å, β = 99.77°, V = 7531.4 Å3, Z = 8) confirms the presence of three-coordinate Ag(I), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700120
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    Aza-2-dienes-1,3. Partie 5. Préparation de N-aminoimidazoles, 3H-pyrroles, triazolo[1,2,4][1,5-a]pyrazines et imidazo[1,2-a]pyrazines (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 187-195 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Aza-1,3-dienes. Access to N-Aminoimidazoles, 3H-Pyrroles, [1,2,4]Triazolo[1,5-a]pyrazines, or Imidazo[1,2-a]pyrazinesNucleophilic attack of 5-(dialkylamino)-2-aza-1,3-diene-1,1-dicarbonitriles (or their 1-methoxycarbonyl analogous) by hydrazines or hydrazdes gives substituted N-aminoimidazoles, [1,2,4]triazolo-[1,5-a]pyrazines, or α-dihydrazino derivatives. With α-amino esters (or analogous), imidazo[1,2-a]pyrazines are produced. Addtion of cyanide anions occurs also with formation of substituted 3H-pyrroles. Structures and rationalisation of this nucleophilic attack are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700123
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    Syntheses of Tetrahydrolipstatin and Absolute Configuration of Tetrahydrolipstatin and Lipstatin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 196-202 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipstatin (1), a natural product, and tetrahydrolipstatin (2) are pancreatic lipase inhibitors. Non-stereoselective and partially stereoselective syntheses of 2 are used to establish the absolute configuration of tetrahydrolipstatin and lipstatin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700124
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    Ring-Open Analogues of Adenine Nucleoside. Aminoacyl Derivatives of Cyclo- and Acyclo-Nucleosides (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 219-231 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of acyclic analogues of ribo- and deoxyribonucleosides is described. These compounds (Table 3) are both poor substrates and poor inhibitors of adenosine deaminase. The synthesis of dinucleotides from these analogues is also described, and the activity along with the inhibitory properties of some of them are studied against deaminase enzyme. These nucleotides are resistant to degradation by phosphodiesterases. HCl impregnated on silica gel is an excellent reagent for the preparation of the chloromethyl ether precursors of acyclo-nucleosides. A general and rapid procedure is developed for the preparation and isolation of the 5′-aminoacyl derivatives of robo- and arabinonucleosides. Quinoline has a marked effect on aminoacylations without racemization. Compounds 35a, b possess remarkable antiviral effects in vitro. A procedure is also developed for the conversion of acyclo-ribonucliosides 13e, f to acyclo-deoxyribonucleosides 11e, f.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700127
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    Functionalisation of saturated hydrocarbons. Part 9Part 8:[1].. Oxidation of patchouli alcohol by the ‘gif system’: Isolation and organoleptic properties of three new ketonic derivativesDedicated to Prof. Vlado Prelog on the occasion of his 80th birthday (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 273-280 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of patchouli alcohol (1) using the ‘Gif system’ afforded as major isolated products three new ketonic derivatives 16-18. The structures of these compounds were established by spectral techniques including 2D-NMR. Ketones 16-18 display interesting organoleptic properties.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700202
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  • 67
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    Synthese von ω-(5-Oxo-1-cyclopentenyl)alkansäure-methylestern aus 2-Nitrocycloalkanonen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 315-320 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Methyl ω-(5-Oxo-1-cyclopentenyl)alkanoates Starting from 2-NitrocycloalkanonesA convenient synthesis of methyl ω-(5-oxo-1-cyclopentenyl)alkanoates 1 is described. 2-Nitrocycloalkanones 2 are converted to 2-(3,3-dimethoxypropy1)-2-nitrocycloalkanones 4. Treatment of 4 with MeOH/MeONa led to the ring-opened nitronates 5 which underwent a Nef reaction to form the corresponding oxo derivatives 6. Partial hydrolysis of followed by base-catalyzed aldol reaction gave the desired products in high yields.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700207
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    Cyclobut-2-enones from Alkynes via Dichlorocyclobut-2-enonesIn part taken from the Ph.D. thesis of A.A.A., University of Zürich, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 321-328 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [2 + 2]-cycloaddition of dichloroketene (prepared in situ from CCl3COCl and Zn(Cu)) with three alkynes 1a-c to form 2,3-dimethyl-(2a), 2,3-diethyl-(2b) and 3-butyl-4,4-dichlorocyclobut-2-enone (2c) proceeds rapidly in the absence of POCl3. The primary products 2a-c rearrange in situ to the 2,4-dichlorocyclobut-2-enones 3a-c under the influence of ZnCL2 produced during the reaction. ZnCl2 converts both 2a and 3a into a 4:6 equilibrium mixture of the two; this isomerization does not occur with LiCl. The Cl-atoms of both 2a, b and 3a, band of 2c may reductively be removed with Zn(Cu) in AcOH/pyridine to afford the alkylcyclobutenones 4a-c. Without pyridine, this reduction gives ca. 1:1 mixtures of the double-bond isomers 4 and 5 in low yields. The cyclobutenones 2c and 4c may be deuterated by CD3COOD in the presence of pyridine. D-Atom is introduced into 2c at C(4) and at C(γ), and into 4c at C(2) and C(4). A mechanism for this deuteration is considered, which does not involve a cyclobutadienolate 7, but rather a cyclobutenolate of type 8. The reductions of 2 and 3 to 4 might also pass through the same type of intermediate 8.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700208
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    3-(Dimethylamino)-2,2-dimethyl-2H-azirin als α-Aminoisobuttersäure(Aib)-Äquivalent: Cyclische Depsipeptide durch direkte Amid-CyclisierungVorläufige Mitteilung s. [1]; vgl. auch [2]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 329-338 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-(Dimethylamino)-2,2-dimethyl-2H,-azirine as an α-Aminoisobutyric-Acid (Aib) Equivalent: Cyclic Depsipeptides via Direct Amid CyclizationIn MeCN at room temperature, 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1) and α-hydroxycarboxylic acids react to give diamides of type 8 (Scheme 3). Selective cleavage of the terminal N,N-dimethylcarboxamide group in MeCN/H2O leads to the corresponding carboxylic acids 13 (Scheme 4). In toluene/PhSH, phenyl thioesters of type 11 are formed (see also Scheme 5). Starting with diamides 8, the formation of morpholin-2,5- diones 10 has been achieved either by direct amide cyclization via intermediate 1,3-oxazol-5(4H)-ones 9 or via base-catalyzed cyclization of the phenyl thioesters 11 (Scheme 3). Reaction of carboxylic acids with 1, followed by selective amide hydrolysis, has been used for the construction of peptides from α-hydroxy carboxylic acids and repetitive α-aminoisobutyric-acid (Aib) units (Scheme 4). Cyclization of 14a, 17a, and 20a with HCI in toluene at 100° gave the 9-, 12-, and 15-membered cyclic depsipeptides 15, 18, and 21, respectively.
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    URL: http://dx.doi.org/10.1002/hlca.19870700209
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    Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 369-374 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olidThe title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3a). The key step in this transformation is the isomerization of the C=C bond in 3a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid (11a), which, after hydrolysis and decarboxylation, gave 13a. In addition, the syntheses of five other compounds related to 13a are reported.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700214
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    Triaziridine 7. Mitteilung6. Mitteilung: [1].. Stabile pyramidale Konfigurationen an den Stickstoff-Atomen von Dialkyl-und Trialkyl-triaziridinen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 381-389 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl-and Trialkyl-triaziridinesStereochemical features of the recently synthesized nine samples of di- and trialkyl-triaziridines, namely the 1,3-cyclopentylen-(series a) and the two stereoisomers of the diisopropyl derivatives (series b and c), containing as the third substituent an H-atom (2), a CH3 group (3)or a CH2OH group (4), were elaborated on the basis of the 1H-, 13C-, and 15N-NMR spectra. The three N-atoms of the saturated N3-homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2-4 of the series a and b possess twofold symmetry (Cs), while 2-4 of series c are asymmetric. Thus, series c has the trans-configuration at N(2)/N(3) and, consequently, the cis-configuration at N(1)/N(2), while series a and b have the cis-configuration at N(2)/N(3) and -since the all-cis-arrangement is excluded-the trans-configuration at N(1)/N(2). The asymmetry of the trans-configurated 2c turned into twofold symmetry (C2), when a little CF3COOH was added. The 1H- and 13C-NMR data of series b and c of our alkyl-triaziridines exhibit a shielding effect, according to which there are two types of i-Pr groups, i-Pr(a) and i-Pr(b). They differ in the NMR signals of the H- and the C-atoms of their CH groups: the H-atoms of i-Pr(a) are more deshielded by 0.75-1.111 ppm and its C-atoms are more shielded by 10.0-160.0 ppm as compared to the corresponding atoms of i-Pr(b). i-Pr(a) is cis (on the N3-homocycle) to a large substituent (such as i-Pr, Me, CH2OH) and to a lone pair, while i-Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH3 and CH2OH groups at N(1) of 3 and 4 in the series b and c.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700216
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    Synthese eines Nickel(II)-B,C,D-hexadehydrocorrinats durch (A→D)-CyclisierungKurzmitteilung: [1].Professor Dr. Gerhard Quinkert zum 60. Geburtstag gewidmet (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 402-411 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Nickel(II) B,C,D-Hexadehydrocorrinate by (A→D)-Ring ClosureThe B,C,D-hexadehydrocorrin of type 10 fills a gap in the corrin family whose members can occur at different oxidation levels. We report here on the synthesis of a correspondingly protected secocorrin 23 and its convenient cyclization to 10
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700219
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    Studies on the Biosynthesis of Tabtoxin (Wildfire Toxin). Origin of the Carbonyl C-Atom of the β-Lactam Moiety from the C1-Pool (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 412-422 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Re-isolation of Pseudomonas tabaci strain NCPPB 2730 from its host, the tobacco plant, led to an activation of the bacteria in order to produce the β-lactam dipeptide tabtoxin (Wildfire toxin, 1). Incorporation of several 14C-labelled amino acids as well as L-[methyl-13C]methionine, L-[1,2-13C2]- and L-[3,4-13C2]aspartate, rac -[1,2-13C2]glycerol, and [1,2-13C2]acetate into isotabtoxion (2) demonstrated that the building blocks of tabtoxin (1) are L-threonine, L-aspartate, the Me group of L-methionine and a C2-unit derived from the C3-pool (Fig. 3). The Me group of L-methionine provides the carbonyl C-atom of the β-lactam moiety. These findings represent a novel pathway in β-lactam biosynthesis. Mechanistic aspects with respect to the β-lactam ring formation are discussed. A biradical 16 is proposed as an intermediate during the cyclization of a N-formyl-α-amino ketone 15.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700220
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 488-491 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700229
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    On the Purported Structure of Cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 480-487 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the bis(sulfonium salt)7 in a solution of Na2CO3 in H2O/EtOH yielded three main products 8-10. The spectroscopic data of 8 were identical to those which led Mithcell and Sondheimer to assign them to cyclodeca[1,2,3-de: 6,7,8-d′e′]dinaphthalene (3). Our investigations show, however, that the correct structural assignment leads to the structure of 7,7a-dihydrodibenzo[de,mn]naphthacene (8).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700228
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    Masthead (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700101
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    Mehrstufige Redoxsysteme. XLIX. MitteilungXLVIII. Mitteilung:[1]. Mit π-Systemen substituierte 1,3-Dimethylidencyclobutane: Synthese und Eigenschaften (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 929-941 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multistep Redox Systems. 1,3-Dimethylidenecyclobutanes Substituted by π-Syntheses and PropertiesAs potential redox systems 1,3-dimethylidenecyclobutanes are synthesized in which the ‘exo’-methylidene group participates in a cyclopentadienyl (typeC4)or cycloheptatrienyl (type A5) system. Benzo-annellated systems are also described. The formation of the C=C bond by the reaction of thioketones (3 and 31) with diazo compounds is extended to extended to 1,6,7,21, and 24, which so far had not been employed. In some cases, intermediate thiiranes can be isolated (e.g.4) which are smoothly transformed into the target compounds of types C4 and A5 by extrusion of sulfur. The new C=C bonds may be introduced stepwise, thereby allowing the synthesis of unsymmetrically substituted 1,3-dimethylidenecyclobutanes (e.g. 20 and 35). Reduction of by Na does not produce bicyclobutanes but compounds 43 and 44 with one dihydrofulvene unit.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700404
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  • 78
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    Verecynarmin A, a Novel Briarane Diterpenoid Isolated from Both the Mediterranean Nudibranch Molluse Armina maculata and its Prey, the Pennatulacean Octocoral Veretillum cynomorium (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 984-991 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The briarane diterpenoid verecynarmin A (=(-)).(8R,9S,11R,12aR,4Z,6Z)-11,12-epoxy-8,8a,9,10,12,12a,13-octahydro-1,5,8a,12-tetramethylbenzo[4,5]cyclodeca[1,2-b]furan-9-yl acetate; ((-)-1) is shown to be contained in both the Mediterranean nudibranch mollusc Armina maculata(RAFINESQUE) and its prey, the pennatulacean octocoral Veretillum cynomorium(PALLAS). The structure is mainly solved by 1D-NMR, 2D-NMR, and NOE studies of (-)-1. However, the relative configurations at the epoxide and angular methyl centres, as well as the preferred conformation, are established by shift-reagent and NOE studies of diol(-)-4 obtained by epoxide-ring opening of (-)-1 with LiA1H4. The absolute configuration is established via deacetylation of (-)01 followed by Horeau's esterification.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700408
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  • 79
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    Oxidationsreaktionen methyl-substituierter 2,1,3-Benzothiadiazole und 2,1,3-Benzoselenadiazole mit Selen-dioxid (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 997-1000 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation Reactions of Methyl Substituted 2,1,3-Benzothiadiazoles and 2,1,3-Benzoselenadiazoles with Selenium DioxideThe synthesis 5-8 by oxidation of 4-methyl-(1),5-methyl(2), 5,6-dimethyl-2,1,3-benzoselenadiazole (3), and 5,6-dimethyl-2,1,3-benzothiadiazole (4), respectively, with selenium dioxide as well as their spectroscopic properties are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700411
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  • 80
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    Steric Effects on Reaction Rates. Part IX. Force-Field Parameters for Bridgehead and Rigid Tertiary Carbenium Ions (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1017-1024 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular-mechanics calculations for strain of carbenium ions are tested using Bentley's unified reactivity scale for bridgehead solvolysis as reference. Excellent correlations are obtained for solvolytic bridgehead reactivity with the calculated steric-energy difference (ΔEst) between substrate (R—H or R—OH) and cation (R+). After adjustment of appropriate force-field parameters, the approach is successfully extended to the rigid, but planar cations derived from structures 15-20; however, the general set of parameters cannot be applied to highly strained systems such as the cation formed from 17. With all of the 18 sets of parameters tested, the 2-endo-norbornyl derivative 16, is adequately correlated, while the exo isomer 15 exhibits enhanced reactivity by a factor of ca. 102 to 103.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700414
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  • 81
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    Complexes of 2,2′,2″-Nirtilotriphenol. Part IV. Cage Compounds with Phosphorus(III) and Phosphorus(V) (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1063-1069 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,2′,2″-nitrilotriphenol reacts with P(III) and P(V) compounds to form corresponding phosphorus complexes. Syntheses and NMR data of 2,2′,2″-nitrilotriphenyl phosphite (II), 2,2′,2″-nitrilotriphenyl phosphate (III) and of a hydrolysis product of II, 2,2′-[N-(2-hydroxyphenyl)imino]diphenly phosphonate (IV), are reported, as well as crystal structures of II and IV. Phosphite II shows a bicycloundecane framework; no NċPinteraction is present. The phosphonate IV shows two coordinated and one dangling phenol group; the N-atom does not interact with the P-atom. Strong acids protonate II as well as III to form cations: in these, NMR evidence indicates coordination of the N-atom to the P-atom.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700418
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  • 82
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    Octacarbonyldicoblat-Inauced (1,3) H Shits in 1-Methylallenecarboxylates and Allenic LactonesDedicated to Professor Dr. André S. Dreiding (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1070-1075 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The allenecarboxylates 1a,b and allenic lactones 4a,b undergo thermally induced (1,3) H Shifts in the presence of Co2(CO)8. The non-isolated 1,3-dienes 2a,b react further affording the Diels-Alder Adducts 3a,b Scheme 1 in high yields. These adducts were not formed in the case of the 2-vinybutenolides 5a,b. On irradiationin the presence of Co2(CO)8 or Mn2(Co)10, the studied allenes reacted in a different manner, yielding either cyclization products 7 and 8 (Scheme 3) or products 9 and 10, formed via H abstracton and solvent addition (Schemes 4 and 5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700419
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  • 83
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    Brominations of Cyclic Acetals from α-Amino Acids and α- or β-Hydroxy Acids with N-Bromosucinimide (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1104-1114 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of novel electrophilic building blocks for the synthesis of enantiomerically pure compounds (EPC) is described. Thus, the 2-(tert-butyl)dioxolanones, -oxazolidinones, -imidazolidinones, and -dioxanones obtained by acetalization of pivalaldehyde with 2-hydroxy-, 3-hydroxy-, or 2-amino-carboxylic acids are treated with N-bromosuccinimide under typical radical-chain reaction conditions (azoisobuytyronitril/CCl4/reflux). Products of bromination in the α-position of the carbonyl group of the five-membered-ring acetals are isolated or identified (2, 5, and 8; Scheme 1). The dioxanones are converted to 2H, 4H-dioxinones under these conditions (12, 14, 15, 21, and 22; Schemes 2 and 3). The products can be converted to chiral derivatives of pyruvic acid (methylidene derivatives 3 and 6) or of 3-oxo-butanoic and -pentanoic acid (16 and 23). The mechanism of the brominations is interpreted. The conversion of serine to enactiomcrically pure dioxanones 26-28 (Scheme 4) is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700423
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    Addendum (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1229-1229 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700428
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  • 85
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    Mitteilungen - Communications (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1230-1231 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700429
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  • 86
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    Enzyme-Catalyzed Hydrolysis of Some Functionalized Dimethyl MalonatesPresented at the meeting of the Swiss Chemical Society, Berne, October 10, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1250-1254 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the preparation of (+)-(R)-methyl hydrogen 2-(tert-butoxymethyl)-2-methyl-malonate (5e) in synthetically useful amounts from readily available starting material.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700503
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  • 87
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    Diels-Alder-Reaktionen von 2,4-Bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien mit HeterodienophilenTeil der geplanten Dissertation von U. R. [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1255-1260 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diels-Alder Reactions of 2,4-Bis{[(tert-Butyl)dimethylsilyl]oxy}-3-aza--1,3-pentadien with HeterodienophilesThe 2,4-bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien(2) reacts via the Diels-Alder adducts 3, 6a-c, and 8a, b, which cannot be isolated, giving the triazines 4, 7a-c, and the oxadiazines 9a, b. The hydrolysis of 4 in MeOH affords the N-acetyl-acetamid derivative 5. The formula of 9a is proven by an X-ray-structure analysis.
    Notes: No. Abstract.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700504
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  • 88
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    Zwei weitere Iridoid-glycoside und ein Monoterpen-glycosid aus Sambucus ebulus L. (Caprifloiaceae). 3. Mitteilung über die Inhaltsstoffe der Zwergholunderwurzel (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 91-101 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Iridoid Glycosides and a Monoterpene Glycoside from Sambucus ebulus L. (Caprifloiaceae)From the roots of Sambucus ebulus L., two novel valeriana-type ester iridoid glycosides, 6′-O-apiosylebuloside (1) and 7,7-O-dihydroebuloside (3), along with the open-chain monoterpene glycoside 5 were isolated. Their structure elucidation is based mainly on one- and two-dimensional NMR methods. 1H,1H-COSY experiments permitted complete assignment of signals arising from the disaccharide unit in 1. Biogenetically, 3 seems to represent the equivalent of loganin in the valeriana-type series of iridoid glycosides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700111
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  • 89
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    Synthese von ‘D-Isothreonin’ und ‘L-Alloisothreonin’ aus L-Alanin (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 116-120 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ‘D-Isothreonine’ and ‘L-Alloisothreonine’ Starting from L-AlanineStarting from L-alanine, ‘D-isothreonine’ ( = (2R, 3S)-3-amino-2-hydroxybutanoic acid) and ‘L-alloisothreonine’ ( = (2S, 3S)-3-amino-2-hydroxybutanoic acid) were synthesized.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700113
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  • 90
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    Oxidative Breaking of Long-Chain Acetylenic Enol Ethers of Glycerol of the Marine Sponges Raspailia pumila and of Model Compounds with Aerial Oxygen (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1400-1411 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The raspailynes (novel long-chain enol ethers of glycerol having the enol ethers double bond conjugated in sequence, to an acetylenic and an olefinic bond, isolated from the North-East-Atlantic sponges Raspailia pumila and R. ramosa) are stable under normal hydrolytic conditions for enol ethers. In contrast, when their solutions are evaporated, these lipids such as raspailyne Bl (=(-))-3-[(1Z,5Z)-(tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(--2) rapidly react with aerial O2 under normal laboratory-daylight conditions, with rupture of the C=C enol ether bond to give 1-O-formylglycerol (3) and an aldehyde (such as tridec-4-en-2ynal(4) from (-)-2). This reaction must be caused by triplet O2, since thermally generated singlet O2 has no effect on (-)-2 in solution. That the mere presence of an enol-ether moiety conjugated to an acetylenic group is responsible for such a behaviour is demonstrated with the model compounds 1-methoxypentadec-1-en-3-yn-5-ol (6a) and its 5-O-acetyl or 5-O-tetra-hydropyranyl derivatives 6b and 6c, respectively. Resistance to both hydroytic conditions and singlet O2 of these compounds is thought to arise from electron depletion at the enol-ether C(beta;) atom by the acetylenic group. Plausible reaction pathways for enol-ether bond rupture in these compounds by aerial O2 are outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700521
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  • 91
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    Catalytic Intramolecular Palladium-Ene Reactions. Preliminay CommunicationPresented at the ‘4th IUPAC-Symposium on Organometallic Chemistry Directed towards Organic Synthesis’ (OMCOS IV), July 28, 1987, Vancouver, Canada. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1477-1481 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism (D → E → F, Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β-H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd (13 → 14 → 15).
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19870700604
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  • 92
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    Drug-induced modifications of the immune response part 9Part8: [1]4-(Arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenylcycolopropyl)furan-3-carboxamides as Novel Antiallergic Compounds (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1526-1530 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and antiallergic activity of a series of 4-(arylamino)-2,5-dihydro-2-oxo-N-(trans-2-phenyl-cyclopropyl)furan-3-carboxamides 10 are described. Treatment of N-substituted 2-amino-4,5-dihydro-4-oxofuran-3-carboxylic acids 9 with chlorooxobis(2-oxo-1,3-oxazolidin-3-yl)phosphorus (2) and an appropriate aromatic amine in the presence of Et3N, resulted in a novel 3(2H)-furanone-→2(5H)-furanone rearrangement that led to the facile preparation of the new amides 10. The latter exerted a potent antiallergic activity when tested in the dermal vascular permeability and active anaphylaxis assays in rats. The most active compound 10b inhibited the action of serotonin, histamine, and bradykinin by 94, 92, and 100%, respectively, when administered intraperitoneally to rats at doses of 100 mg/kg. The present series of 10 represents a novel class of antiallergic agents.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700609
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  • 93
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    Notiz über die Verwendung von 3-(Arylsulfonyl)-2-cycloalkenonen als 2-Cycloalkinon-Synthese-Equivalente (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1537-1539 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Use of 3-(Arylsulfonyl)-2-cycloalkenones as Synthesis Equivalents of 2-Cycloalkynones3-(Arylsulfonyl)-2-cyclopentenones and 3-phenylsulfonyl-2-cyclohexnone undergo Diels-Alder reactions with cyclopentadiene. Elimination of arylsulfinic acid leads to products, which would have been obtained directly from a Diels-Alder reaction of 2-cyclopentynone or 2-cyclohexynone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700611
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  • 94
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    Inhibition of Electron-Hole Recombination in Substitutionally Doped Colloidal Semiconductor Crystallites (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1596-1604 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The subtitutional doping of 120-Å- sized TiO2 Particles with Fe(III)ions has a profound effect on the charge carrier recombination time in this colloidal semiconductor. In undoped particles, the mean lifetime of an electronhole pair is ca. 30 ± 15 ns. Doping with 0.5% Fe(III) drastically augments the charge-carrier lifetime which is extended to minutes or hours. The slow character of the recombination dynamics in Fe(III)-doped colloids was confirmed by laser photolysis using the characteristic optical of electrons in TiO2 to monitor the time course of the reaction. EPR studies showed the Fe(III) ions to enter the host lattice on Ti(IV) sites, charge compensation taking place through the formation of oxygen vacancies. Valence-band holes produced under band-gap excitation react with these centers it the bulk forming Fe(IV), the conduction band electrons being trapped by Ti(IV) at the particle surface. Presumably, the spatial separation of the trapped electron and hole sites inhibits their recombination.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700617
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  • 95
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    The Radical Anions of 1,2-diphenylcyclohexene and Structurally Related Compounds. Conformational ESR and ENDOR studies (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1558-1568 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR, ENDOR, and TRIPLE resonance studies have been performed on the radical anions of 1,2-diphenylcyclohex-1-ene (4), 1,2-di(perdeuteriophenyl)cyclohex-1-ene ((D10)4) the trans-configurated 3,4-diphenyl-8-oxabicyclo[4.3.0]non-3-ene (5) and its 2,2,5,5-tetradeuterio derivative (D4)5, and 2,3-diphenyl-8,9,10-trinorborn-2-ene (6). The spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} exhibit strong temperature dependence along with a specific broadening of ESR hyperfine lines and proton ENDOR signals. The coupling constant, which bears the main responsibility for these features, is that of the β-protons in the quasi-equatorial positions of the cyclohexene ring, and the experimental findings are readily rationlized in terms of relatively modest conformational changes without invoking the inversion of the half-chair form. The hyperfine data for the β-protons in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} closely resemble the corresponding low-temperature values for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document}, However, the ‘unusual’ features observed for \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} are absent in the ESR and ENDOR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document}, because the half-chair conformation of the cyclohexene ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} is deprived of its flexibility. Although the boat form of this ring in \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} is also rigid, the spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document} are temperature-dependent, due to an interconversion between two propeller-like conformations of the phenyl groups. The pertinent barrier is 30 ± 5 kJ·mol-1. An analogous interconversion presumably takes place in \documentclass{article}\pagestyle{empty}\begin{document}$ 4^{- \atop \dot{}} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 5^{- \atop \dot{}} $\end{document} as well, but, unlike \documentclass{article}\pagestyle{empty}\begin{document}$ 6^{- \atop \dot{}} $\end{document}, it is not amenable to experimental study.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19870700614
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  • 96
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    Synthesis and Formation of Ironcarbonyl Complexes of 3′,3′-Dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane]. Single-Crystal and Molecular Structure of syn,exo2,3-anti,endo5,6-trans-μ-[(1r,2r,3s,4s,5s,6r)-c,2,3,c-η:c,5,6,c-η-(3′,3′-dimethyl-2,3,5,6,-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane])]bis(tricarbonyliron)Interaction between non-conjugated chromophores, Part 27. Part 26, see [1]. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1638-1648 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3′,3′-dimethyl-2,3,5,6-tetramethylidenespiro[bicyclo[2.2.1]heptane-7,2′-oxirane] (3) was derived from 6,6-dimethylfulvene and maleic anhydride. Its reaction with 1 equiv. of ethylenetetracarbonitrile (TCNE) was not regioselective and gave a 1:1 mixture of the corresponding monoadducts 10 and 11. The rate constants of the Diels-Alder additions of 10 and 11 to TCNE were significantly smaller than that of the reaction 3 + TCNE. Monocomplexation of 3 with Fe2(CO)9 was highly exo-face selective giving a mixture of the corresponding monocomplexes 12(anti-exo) and 13(syn-exo). The latter were complexed with Fe2(CO)9 in a non-stereoselective fashion, giving mixtures of the dicomplexes 14(anti-exo, syn-endo), 15(anti-exo,syn-exo), and 16(anti-endo, syn-exo). Exchange of the CO ligands was a faster process for the endo-Fe(CO)3 moieties than for the exo-Fe(CO)3 moieties. Line-shape analysis of the 13C-NMR spectrum of 15 established that one of the exo-Fe(CO)3 groups in 15 rotates ca. 3 times as fast as the other Fe(CO)3 group at 40°. The structure of the anti-endo, syn-exo dicomplex 16 was determined by single-crystal X-ray diffraction studies.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700621
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  • 97
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    New Antifungal Chromenyl Ketones and their Pentacyclic Dimers from Hypericum revolutum VAHLPresented in part at the 34th Annual Congress on Medicinal Plant Research, Hamburg, FRG, 22-27 September, 1986. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1694-1702 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new 2H-1-benzopyranyl ketones 1 and 2 and three new pyrano[3,2-c: 4,5,6-d′ e′]di[1]benzopyrandiyl diketones 3, 4a/4b, and 5 have been isolated from the leaves and twigs of Hypericum revolutum VAHL (Guttiferae). The structure of 3 (hyperevoline) was established by X-ray analysis as 1,1′-[1,13,13a,13b-tetrahydro-5,8,10-trihydroxy-2,2,6,9,13,13-hexamethyl-2H, 7aH-pyrano[3,2-c:4,5,6-d′e′]di[1]benzopyran-4, 11-diyl]bis[2-methyl-1-propanone]. The structures of the isolated compounds were established by spectroscopic (UV, IR, EI-MS, 1H- and 13C-NMR) and chemical (acetylation and acidic dimerization) methods.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700705
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  • 98
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    Mammalian Alkaloids: Configurations of Optically Active Salsoline- and 3′,4′-Dideoxynorlaudanosoline-1-carboxylic AcidsSalsoline and norlaudanosoline are well known alkaloids, and these names will be used in the General Part (for systematic names, see Expert. Part). The systematic name for salsoline is 1-methyl-7-methoxy-1,2,3,4-tetrahydroisoquinolin-6-ol and that for norlaudanosoline, also named tetrahydropapaveroline, is 1-(3′,4′-dihydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol. (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1721-1731 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the optical isomers of (±)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate ((±)-2) was accomplished by reaction of (±)-2 with (+)-(R)-1-phenylethyl isocyanate, separation of the urea diastereoisomers (-)-4A and (+)-4B, and alcoholysis of the ureas in refluxing BuOH. Optically active isoquinoline-carboxylates 2A,B and hydantoins 8A,B isolated were characterized. The absolute configuration of the reaction products was established by X-ray analysis of the optically active hydantoin (+)-8A. Hydrolysis of the methyl isoquinolinecarboxylates 2A,B with 48% HBr soln. at reflux afforded the desired optically active 3′,4′-dideoxynorlaudanosoline-1-carboxylic acids 1A,B required for enzyme-inhibition studies. Details of the X-ray diffraction analysis of (+)-methyl salsoline-1-carboxylate hydrobromide ((+)-11A·HBr) prepared earlier are included. CD spectra of (+)-(S)-methyl 6,7-dimethyl-3′,4′-dideoxynorlaudanosoline-1-carboxylate hydrobromide ((+)-2A. HBr) and (-)-(R)-methyl salsoline-1-carboxylate hydrochloride ((-)-11B·HCl) confirmed the assignment of their (S)- and (R)-configurations, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700707
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  • 99
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    Determination of the Quantum Yield of Intersystem Crossing of Rose Bengal (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1760-1773 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum yield of intersystem crossing (Φisc) of a sensitizer is related to the quantum yield of singlet-oxygen production (Φ(1O2)) by the efficiency of the energy transfer (ϕet) and is an important parameter in the evaluation of potential applications of sensitized photo-oxidations. Using two different laser photolysis techniques, the energy-transfer method and the partial saturation method, Φisc of rose bengal has been determined in MeOH and in aqueous solutions. The results confirm that with Φisc(H2O) = 1.05(± 0.06) and Φisc(MeOH)=0.90(±0.08), the generally assumed relation Φisc · ϕet = Φ(1O2), with ϕet = 1, cannot be maintained any longer (Φ(1O2, H2O) = 0.75 and Φ(1O2, MeOH) = 0.76). During these experiments, a second intermediate has been observed which is produced from the triplet state of rose bengal and, stabilized in a anionic micellar solution, has been shown to be the radical cation of the sensitizer. The efficiency of the electron transfer has been evaluated from transient absorption and bleaching recordings, and it seems conclusive to attribute the results to the difference between Φisc and Φ(1O2).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700712
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  • 100
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    ‘Face-to-Face’-Benzo-anellierte homologe Hypostrophene. Synthesen, Röntgenstrukturanalysen und PE-Spektren (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1816-1842 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ‘Face-to-Face’ Benzo-anellated Homologous Hypostrophenes. Syntheses, X-Ray-Structure Analyses and PE Spectra‘Face-to-face’ Benzo-anellated homologous hypostrophenes (series M), of interest as substrates for [6 + 6]-photocycloaddition reactions, have been synthesized. From X-ray structural analyses of 13b and 13c shortest C—C distances of 2.80(2.76)/2.71 Å and interorbital angles (ω) of 129° (128°)/130° between the benzene rings have been determined. The PE spectra are discussed in the context of transannular π,π interactions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700718
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