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  • 1975-1979  (1,107)
  • 1978  (1,107)
  • Organic Chemistry  (694)
  • Engineering General  (257)
  • Atomic, Molecular and Optical Physics  (156)
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  • 1975-1979  (1,107)
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  • 101
    Electronic Resource
    Electronic Resource
    Inductive, Hyperconjugative and Frangomeric Effects in the Solvolysis of 1-Substituted 3-Bromoadamantanes. Polar effects IV (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1588-1608 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three kinds of polar substitutent effects are observable in the solvolyses of 1-R-substituted 3-bromoadamantanes (VI). This follows from the relationship between products, rate constants k in 80% ethanol, and the inductive substituent constants σ1q of the substituent R. Alkyl groups and electron-attracting substituents at C (1) control the rate by their inductive effects alone, since logk correlates closely with σ1q. However, rates are higher than predicted on the basis of the respective σ1q values when conjugating (+ M)-substituents or electrofugal groups are attached to C(1). These exalted substituent effects are attributed to CC-hyperconjugative relay of positive charge from the cationic center at C(3) to the substituent at C(1). When the substituent is a strong electron donor (e.g. O- and S-), accelerated substitution gives way to heterolytic fragmentation, rates and products then being controlled by the frangomeric effect.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610510
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  • 102
    Electronic Resource
    Electronic Resource
    Ein synthetisches Modell für die Aktivstelle der Coenzym-B12-abhängigen Methylmalonyl-CoA-Mutase (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1565-1587 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic model of the active site of the coenzyme B12 dependent methylmalonyl-CoA mutaseThe synthesis of a bridged cobaloxime with a built-in methylmalonic ester moiety is described. 2-Brommethyl-2-methylmalonic acid dichloride (5) afforded upon reaction with 5-heptin-1-ol (4) the corresponding diester 6. Subsequent treatment of 6 with ozone, dimethylsulfide and hydroxylamine hydrochloride led to the pentadentate ligand: 10-brommethyl-10-methyl-9, 11-dioxo-8, 12-dioxa-nonadecane-2, 3, 17, 18-tetraone tetraoxime (8). Reaction of 8 with cobalt (II) chloride, pyridine and sodium borohydride furnished in 7% yield the bridged cobaloxime 10, which was spectroscopically characterized. Short term irradiation of 10 in methanol caused the exchange of the axial pyridine ligand by a solvent molecule affording 10a, the structure of which has been determined by X-ray crystallography. Long term irradiation of 10 in methanol or ethanol led to irreversible cleavage of the Co, C-bond. Upon alkaline hydrolysis the degradation product afforded methylsuccinic acid in 82-95% yield. No incorporation of solvent protons into this product could be observed. Implications of these findings for the mechanism of the coenzyme-B12 catalysed rearrangement of methylmalonyl-CoA are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610509
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  • 103
    Electronic Resource
    Electronic Resource
    “Push-Pull”-Acetylene für die Peptid-Synthese12. Mitt. über substitituierte Aminoacrylderivate. 11. Mitt.: [1]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1609-1621 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: “Push-Pull” Acetylenes as Reagents for Peptide SynthesisA series of ‘push-pull’ acetylenes 1 is easily available from the corresponding “push-pull” olefins by a simple bromination-dehydrobromination sequence. The versatility of the acetylenes with regard to peptide synthesis is discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610511
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  • 104
    Electronic Resource
    Electronic Resource
    1, 4, 5, 6-Tetrahydro-ν-tetrazin-DerivateZum Teil vorläufig mitgeteilt [1] [2].Diese Arbeit enthält die wesentlichen Ergebnisse der Dissertation von R.D., Universität Giessen, 1977. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1622-1647 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1, 4, 5, 6-Tetrahydro-ν-tetrazin-DerivateThe title compounds 2 and 13 are readily available from α-lithiated N-alkyl-nitrosoamines 1 (see Tables 1 and 2) which decompose at - 73° to yield the N-oxides 2. The ESR. spectra of two derivatives 1 are recorded (Fig. 1), and tentative mechanisms are proposed for the head to head dimerizations (la- 3- 4- 5- 2a and Scheme 1). Coupling of lithionitrosoamines with iodine (-6) and alternative decomposition routes of representatives of this class of organometallics with special substitution [equations (2)-(5)] are reported.The structures of the tetrazines are established by spectroscopic data [ESCA] (Fig. 2), IR., UV., 1H- (cf. Fig. 9) and 13C-NMR., PE. (Scheme 2), by an X-ray analysis of 2a (Fig. 4-8 and Table 3), and by the chemical reactions. The crystal structure of 2a is a twisted boat with non planar terminal nitrogen atoms which reflects the electron repulsion in the 4-atom-6-electron N—N=N≡N-system. Comparisons are made with 2-tetrazenes, the open chain analogues of 13, wherever possible. Raney-Ni reductions of 2 or 13 gives diamines 14 to which is assigned the d, l-configuration through the 1H-NMR. spectra of the aminals 7 and 15. Neither the oxides 2 nor the tetrazines 13 undergo cycloaddition reactions [equation (6) and Section 4].Compound 2a is dimerized to the bis (nitrosoamino)-2-tetrazene 18 by treatment with acid, ZnII, CuI or iodomethane. 2a is oxidized at nitrogen to the ethylene diamine derivative 6a (through 20, with H2O2), or at the CH2-groups of the ring to give oxo-N-oxide 21 (with MnO2 or the ring contracted oxo-tetrazoline-N-oxide 22 (with KMnO4).Pyrolysis or photolysis of the dimethyl tetrahydrotetrazine 13a furnishes the trimer 26 of N-methylimine, but no diazetidine 27. Silver and mercury complexes 29 are obtained from 13a, while Cr(CO)5. THF does not furnish a complex as with azocompounds, but rather replaces N2 in 13a by CO (→ 28). Oxidation with permanganate converts 13a into the oxalic acid derivative 30 with unchanged tetrazine structure.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610512
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  • 105
    Electronic Resource
    Electronic Resource
    Eine einfache Veresterungsmethode im Eintopf-Verfahren (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1675-1681 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple one-pot method for esterificationA one-pot procedure for esterifications of primary, secondary and tertiary alcohols and of phenols in high yield is described. Reaction of oxalylchloride with dimethylformamide in a suitable solvent affords dimethylformamide imidechloride; addition of an acid to the suspension of this reagent furnishes an activated carboxy-group derivative, which is then transformed to an ester by addition of pyridine and an alcohol ro a phenol. Reaction temperatures needed for esterification are low, usually 0° to room temperature, reaction times are short.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610515
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  • 106
    Electronic Resource
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    Cyclooct-1-en-5-yne. Preparation, spectroscopic characteristics and chemical reactivityPresented at the Swiss Chemical Society meeting, 7.10.1977. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1663-1674 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclooct-1-en-5-yne (3) has been obtained as an isolable, but highly reactive hydrocarbon by oxidation of cyclooct-5-ene-1, 2-dihydrazone with lead tetraacetate (Scheme 2). Information regarding the structure and conformational mobility of 3 has been gained from the analysis of its 1H- and 13C-NMR. spectra and was found to agree with the results of force field calculations. Photolysis (206 nm) of 3 in solution has induced cleavage to butatriene and butadiene. The first band in the photoelectron spectrum of 3 (Iv 9.10 eV) is attributed to ionization from a rather delocalized orbital with predominant weight of the double bond p-AO's. Nevertheless, the high reactivity of 3 stems from the strained triple bond as evidenced by the reaction products obtained by pyrolysis, oxidation, Diels-Alder addition, and 1, 3-dipolar addition (Scheme 4).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610514
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  • 107
    Electronic Resource
    Electronic Resource
    Nucleoside und Nucleotide. Teil 11. Phosphorylierung von 1-(2′-Desoxy-β-D-ribofuranosyl)-2(1H)-pyridon und dessen Verhalten bei der Synthese von DinucleotidenTeil 10 s. [1].Für Details s. [2] (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1648-1663 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleosides and Nucleotides, Part 11. Phosphorylation of 1-(2′-Desoxy-β-D-ribofuranosyl)-2(1H)-pyridon and its Behaviour in the Synthesis of DinucleotidesThe behaviour of the unnatural nucleoside 1-(2′-deoxy-β-D-ribofuranosyl)-2(1H)-pyridon (Πd, 1) in the synthesis of dinucleotides with purine deoxynucleotides was studied. The optimized preparation of the protected dinucleoside phosphates (MeOTr) Πd pGibd (5) and (MeOTr) Πd pAbzd (7) using the diester method of Khorana with DCC as condensing agent is described. The removal of the N-acyl- and p-methoxytrityl groups was effected by successive treatment with conc. ammonia solution and acetic acid/water 1:1 at 23° yielding the free dinucleoside phosphates ΠdpGd (9) and ΠdpAd (11). In a similar way, starting from (CNEt) pΠd(15), the dinucleotides pΠdpGibd (16), pΠdpGd (18), pΠdpAbzd (17) and pΠdpAd (19) were synthesized.The nucleotide 1-(5′-O-Phosphoryl-2′-deoxy-β-D-ribofuranosyl)-2(1H)-pyridon (pΠd, 3) was prepared in excellent yield by selective phosphorylation of Πd (1) using phosphorylchloride in triethyl phosphate at -40°. Deoxyadenosine was phosphorylated in the same way.The compounds were characterized by UV. spectroscopy, chromatography and enzymatic degradation.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610513
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  • 108
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    Hydroformylation of 1, 1, 1-d3-2-butene. Isotope Effect on the Product Composition (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1703-1707 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the hydroformylation of 1,1,1-trideuterio-2-butene with Rh4 (CO)12 the deuterated pentanals formed contain 75% of 5,5,5-trideuterio-pentanal, the rest being substantially 2,2-dideuterio-pentanal. On the contrary, using Co2 (CO)8 as the catalyst precursor, position 1 and 4 are formylated to the same extent.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610518
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  • 109
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    Die Aminoalkylierung von Carbonylverbindungen mit Hilfe der Wittig-ReaktionDiese Mitt. soll als 9.Mitt. der früher begonnenen Reihe gelten (s. [1]) und besteht aus Teilen der Dissertation von T.L. [2]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1708-1720 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Aminoalkylation of Carbonyl Compounds by the Wittig-ReactionThe Wittig reaction would be a very suitable way to replace the carbonyl group in aldehydes and ketones by a 2-amino-ethylidene group if a simple and convenient method could be devised for synthesizing (2-amino-ethyl)triphenylphosphonium bromides 3. We have synthesized compounds of type like (2-dialkylaminoethyl)-, (2-morpholino-ethyl)-, (2-(1-imidazolyl)ethyl)-, and (2-(1-triazolyl)ethyl)-triphenylphosphonium bromides (cf. Table 1), by melting at 150° the hydrobromides of triphenylphosphine and of the appropriate 2-amino-ethanol. The phosphonium bromides of type 3 could be converted with ketones by the Wittig reaction into the desired amino-ethylidene compounds of type 2, e.g. 18-22 (Table 2). In the case of the reaction with 4-chlorobenzaldehyde the steric course of the transformation was studied, and conditions were found favoring either cis or trans compounds (e.g. 27a or 27b in the reaction of the phosphonium bromide 11, cf. Table 3).
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610519
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  • 110
    Electronic Resource
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    Edulon A, ein 2H-1-Oxapyrenderivat aus Plectranthus edulis (Labiatae) (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1969-1974 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Edulon A, a Derivative of 2H-1-Oxapyrene from Plectranthus edulis (LabiataeFrom the coloured leaf-glands of the above mentioned East-african labiate we have isolated Edulon A, A new, deeply coloured diterpenoid. Based mainly on spectroscopic arguments, we propose its structure to be (5a R, 1′ ζ)-10-(2′-acetoxy-1′-methylethyl)-6, 7, 9-trihydroxy-3, 5a-dimethyl-4, 5, 5a, 8-tetrahydro-2H,-l-oxapyrene-2, 8-dione (1a). The compound may be regarded as a 4, 5-seco-abietane derivative that has formed new bonds (between C(18 or 19)—COOH and C(12)—OH), and between C(3) and C (11)) by lactonisation and condensation, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610604
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  • 111
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    Synthèse et caractérisation du phosphate de hafnium comme échangeur d'ions (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1984-1989 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation, crystalline structure, properties and behaviour of the hafnium bis (monohydrogen phosphate) monohydrate as a cationic exchanger have been studied. The crystalline product has been characterized by elemental analysis, X-ray Powder patterns, thermal analysis, photoelectron spectrometry and infra red spectroscopy. A layered structure in which the hafnium and phosphorus atoms are disposed in such a way as to form zeolitic-type cavities is suggested. The reversibility of the exchange with respect to sodium ions is discussed and can be related to the water content of the exchanger.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610606
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  • 112
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    Molluscicidal saponins from cornus florida L. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1990-1995 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molluscicidal principle of Cornus florida L. (Cornaceae) has been isolated from the methanolic bark extract by droplet counter-current chromatography (DCC). The structure of the active compounds has been determined as sarsapogenin-O-β-D-xylopyranosyl-(1 → 2)-β-D-galactopyranoside (2) and sarsapogenin-O-β-D-glucopyranosyl-(1 → 2)-β-D-galactopyranoside (3).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610607
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  • 113
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    Radikalinduzierte intramolekulare 1, 4-Verschiebung einer FormylgruppeAuszugsweise vorgetragen am „2nd International Symposium on Organic Free Radicals“ in Aix-en-Provence (17.-23.Juli 1977); vgl. auch[1]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1996-2001 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-induced Intramolecular 1,4-Transfer of a Formyl GroupA further example of a radical-induced intramolecular shift of a functional group in steroids is described. In analogy to the sequence leading to the 1, 4-transfer of cyano groups [3], 11 β-nitrite photolysis was used to generate the appropriate C (18) radical in the 20-hydroxy-11 β-nitrosyloxy-pregnene-21-al 6. Intramolecular addition of the radical center to the double-bond of the specially adjacent aldehyde function, followed by fragmentation of the intermediate cyclic alkoxy radical and subsequent oxidation lead directly to the rearranged 18-formyl compound 10.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610608
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  • 114
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    Über 3,3,6,9,9-Pentamethyl-2,10-diaza-bicyclo-[4.4.0]-1-decen und einige seiner Derivate. Über synthetische Methoden. 13. Mitteilung12. Mitt.: «Notiz über Methoden zur Umwandlung von 1, 2-Dicarbonsäuren in konjugiert ungesättigte Monocarbonsäuren», vgl. [1]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2851-2874 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,3,6,9,9-Pentamethyl-2,10-diaza-bicyclo[4.4.0]-1-decen and some of its derivativesA simple synthesis for the bicyclic amidine 1 (Scheme 3) is described. This base and the salts which were prepared from it show solubility characteristics which make the amidine a potentially useful reagent for salt formation of carboxylic acids and related proton complexes of bidentate ligands. Among the derivatives made from 1 are the sterically strongly hindered N-alkylated amidines 11, 12 and 14 (Scheme 5), as well as the stable crystalline N1-oxidoamidine-N2-oxyl radical 2 (Scheme 6). The ability of the latter to serve as a paramagnetic chelating ligand for metal ions is illustrated by the preparation of a corresponding nickel(II) complex. The radical is also a source for the α-nitronyl-nitrosonium cation 4 which shows in its reactivity towards conjugated dienes and olefines some of the expected resemblance to singlet oxygen.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610812
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  • 115
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    Absolute Configuration of Actinioerythrin (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2881-2887 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD. correlation of (3 S, 3′S)-and (3 R, 3′R)-actinioerythrol diacetate, obtained by total synthesis from β-ionone, with actinioerythrin isolated from the sea anemone Actinia equina L. shows that the natural compound has the (3 S, 3′S)-configuration.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610814
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  • 116
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    Photochemistry of 3-Substituted 1-Iminopyridinium YlidesPart 10 of the series ‘Photochemical Synthesis of 1, 2-Diazepines’. Part 9: [17].. Regiospecific versus non-regiospecific photoisomerization patterns [1] (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2887-2898 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Substituted 1-iminopyridinium ylides 1 undergo photo-induced ring enlargement to 1H-1,2-diazepines. With strongly electron-withdrawing substituents the ring expansion process is regiospecific and leads exclusively to 4-substituted 1 H-1, 2-diazepines. Weak electron-donating substituents, like a methyl group and halogen atoms, do not have any directing effect since both 4- and 6-substituted 1 H -1,2-diazepines are obtained. With strong electron-donating substituents no diazepines are formed; instead one observes photo-induced isomerization to the 2-aminopyridine derivatives, the process being non-regiospecific. Regiospecific photo-induced ring expansion processes are explained in terms of a simple HMO model.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610815
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  • 117
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    Synthèse de l'évernine (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2899-2904 
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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 EverninTwo syntheses of the depside evernin 6 are described. Condensation of methyl acetoacetate and methyl crotonate followed by aromatization and reduction with Raney-Ni led to methyl orsellinate (3). The condensation of everninic acid (4), obtained by partial methylation of 3 and saponification of the methyl ester, with methyl 2, 4-dihydroxy-3, 6-dimethylbenzoate (methyl β-orcin carboxylate) (5) in presence of cyclohexylcarbodiimide gave evernin (6). In a second syntheis methyl dihydroorsellinate (1) was regiospecifically converted into its 4-methyl enol ether and aromatized via the benzene selenenyl derivative to yield methyl evernate (7). Benzylation followed by saponification gave the free acid 8. Methyl β-orcin carboxylate (5) was synthesized in an analogous way from methyl 3,6-dimethyl-2,4-dioxocyclohexanecarboxylate. Condensation of 8 with the methyl ester 5 by treatment with trifluoroacetic anhydride in toluene yielded 9, which could be converted into evernin (6) by hydrogenolysis of the benzyl ether.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610816
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  • 118
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    Anil-Synthese 18. Mitteilung17. Mitt. siehe [1].. Über die Herstellung von Styryl-Derivaten des 3-Phenyl-benzisoxazols (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2904-2940 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of styryl derivatives of 3-phenyl-benzisoxazole3-(p-Tolyl)-1,2-or 2, 1-benzisoxazoles and 6-methyl-3-phenyl-1,2-benzisoxazoles react with anils of aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide or potassium t-butoxide to yield the corresponding 3-(stilben-4-yl)-1,2- or 2,1-benzisoxazoles and the 3-phenyl-6-styryl-1,2-benzisoxazoles respectively (‘Anil Synthesis’). Further, the Schiff's bases derived form chloroanilines and 3-(p-formylphenyl)-1,2-benzisoxazoles yield, with methyl-and p-tolyl substituted heterocyles the corresponding heterocyclic substitued styryl and stilbenyl derivatives.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610817
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  • 119
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    Synthèse photochimique de biaryles et hétérobiaryles à partir d'aryl-et hétéroarylamines, d'un nitrite d'alkyle et d'un substrat aromatique ou hétéroaromatiqueCe travail a été présenté aux journées de Chimie Organique d'Orsay, Septembre 1977. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2941-2948 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical synthesis of biaryls and heterobiaryls from aryl and heteroarylamines, alkylnitrite and aromatic or heteromatic substratesThe photochemical reaction of aromatic and heteroaromatic amines with excess t-butyl nitrite in aromatic solvents (benzene, p-xylene, mesitylene) and in hetero-aromatic solvents (furan, thiophene) leads to biaryls or heterobiaryls. t-Butyl nitrite is more convenient than isopentyl nitrite which gives by-products. This new method has been used to synthesize 28 compounds in 17 to 60% yield.
    Additional Material: 5 Tab.
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    Etudes sur les composés organométalliques. XVIIPartie XVI, s. [1].. Synthèse du tétracyclohexyltitane (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2949-2955 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds. XVII Synthesis of TetracyclohexyltitaniumTetracyclohexyltitanium is prepared by reaction of TiCl4 or Ti(OC4H9)4 with dicyclohexylmagnesium in pentane or ether at - 30°. Some aspects of its reactivity and its decomposition are described.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610819
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    Etude sur les composés organométalliques. XVIIIPartie XVII, s. [1].. Synthèse et caractérisation du μ-oxo-bis (dicyclopentadiènylméthyltitane IV) (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2956-2957 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds. XVII: Synthesis and Caracterisation of μ-oxo-bis(dicyclopentadienylmethyltitane IV)(Cp2TiCH3)2O is obtained by reacting (Cp2TiCl)2O with methyllithium. IR., NMR. and MS. spectrum are reported. Autocatalytic decomposition of the product is inferred from differential thermal analytic measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610820
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  • 122
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    Synthesis, Structure and Photochemical Properties of 4, 4′, 7, 7′-Tetra-substituted 1,1′, 3,3′-Tetraethylbenzimidazolotriazatrimethine Cyanines (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2958-2973 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of sterically hindered 1,1′, 3,3′-tetraethylbenzimidazolotriazatrimethine cyanine dyes, their electron absorption spectra and that of their photo-products (inverse photochromism) is described. Kinetic data of the thermally reversed reaction of the photo-bleached compounds are given. The differences of the electron absorption spectra in this series in this series of dyes are explained by the different degree of distortion of the π-systems which is confirmed by an X-ray investigation.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610821
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  • 123
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    Radical Ions in the Pentalene Series. Part. I. 1,3,5-tri-t-butylpentalene (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2974-2980 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ESR. spectra of the radical anion and cation of 1, 3, 5-tri-t-butylpentalene (II) have been reexamined under higher resolution. With the assistance of the ENDOR. technique, the coupling constants of all protons in II⊖. and II⊖. could be determined. The experimental data agree satisfactorily with the values predicted by the simple MO model which suggests that the π-spin distributions in II⊖. and II⊖. should not strongly differ from those in the corresponding radical ions of parent pentalene (I). As in the case of other non-alternant hydrocarbons, the proton coupling constants for II⊖. are very sensitive to experimental conditions, due to the association of the radical anion with its counterion. Spectra of II⊖. taken at low temperatures (down to 133 and 163 K for ESR. and ENDOR., respectively) have not revealed specific line-broadening which could arise from the bond shift between the two Kekulé-structures of pentalene.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610822
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  • 124
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    Zur Kenntnis der β-Lysin-Mutase-Reaktion: Mechanismus und sterischer Verlauf (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2989-2998 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on the β-lysine mutase reaction: Mechanism and steric courseThe steric course and some mechanistic aspects of the coenzyme-B12-dependent β-lysine-mutase reaction, in which (3 S)-β-lysine is converted to (3 S, 5 S)-3, 5-diaminohexanoate, have been investigated by means of tritium labelling. The reaction involves migration of an hydrogen atom from C(5) of the substrate to C(5′) of coenzyme B12 and back-transfer to C(6) of the product. In the presence of [5′-3H]-coenzyme B12 the enzyme catalyzes the exchange of label between the cofactor and one of the diastereotopic H-atoms at C(5) of the substrate. The exchangeable hydrogen atom is identical with the one specifically involved in the migration reaction. Degradation of the tritiated β-lysine obtained in such experiments yielded a sample of tritiated succinic acid which was shown in an enzymic assay involving partial oxidation with succinate dehydrogenase, to possess the (S)-configuration. Thus, the overall substitution at C(5) occurs with inversion of configuration.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610824
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    Radical Ions in the Pentalene Series [1]. Part II. Dibenzo [b,f]pentaleneThe IUPAC name for dibenzo [b,f]pentalene (III) is indeno [2, 1-a]indene. and its 5, 10-dimethyl derivative (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2981-2988 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton hyperfine data have been determined for the radical anions and cations of dibenzo [b,f]pentalene (III) and its 5, 10-dimethyl derivative (IV). The assignment of the coupling constants to pairs of equivalent protons follows from a simple MO model, the use of which enables one to reproduce satisfactorily the experimental values. The proton hyperfine data, aHμThe meaning of aHμis aH—C(x),H—C(y),whereas only x and y are given in the particular cases., for the radical anion III⊖. correlate fairly well with the π-charge populations ∊μ derived from 1H-NMR. spectra for the carbon centres μ in the dianion III2⊖. The analogous correlation is less good in the case of the radical cation III⊕. and the dication III2⊕., presumably due to the rough approximations involved in the evaluation of the numbers ∊μ for the latter species. The coupling constants aH5,10 for III⊖. and III⊕. are very close to the corresponding values aH4,6 for the radical ions of 1,3,5-tri-t-butylpentalene (II), in accord with the prediction of the MO model. A similarity is also found between the proton hyperfine data for III⊖. and those for the radical anions of structurally related 1,4-diphenyl-1,3-butadiene (V). On the other hand, there are striking changes in the coupling constants of the analogous protons on passing from III⊖. to the radical anions of dibenzo [a,e] cyclooctene (VI) and [16] annulene (VII), as a consequence of raising the symmetry from C2h to D2h and D4h, respectively.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610823
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    On Excited States of Alkyl Bridged [14] Annulenes (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2999-3013 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The linear dichroic absorption spectrum of 1,3,6,8-trans-15, 16-hexamethyl-dihydropyrene has been measured in stretched polyethylene at 77K, and CNDO-CI calculations with inclusion of singly and doubly excited configurations have been carried out on a series of alkyl bridged [14] annulenes with pyrene- and anthracene-shaped perimeters. Transitions to e3g → e4u type 1B states are well described, and the results indicate that additional low-energy excited states originate from e3g→ e5g and e2u → e4u type configurations interacting strongly with doubly excited configurations of the e3g, e3g → e4u, e4u type. The second excited singlet state responsible for the weak transition observed between the 1L bands may be assigned to one of these additional states, but it is probably of complex nature, similar to the ‘phantom’ state in linear polyenes.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610825
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  • 127
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    Die Struktur der durch Halogenierung von Furfural in Wasser gebildeten Oxydationsprodukte (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 3103-3107 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Structures of the Oxidation Products formed by Hologenation of Furfural in WaterThe oxidation products formed on halogenating furfural in water are cis/trans-2,5-dihydroxy-2-(dihydroxymethyl)-2,5-dihydrofuran (5) and cis/trans-2,6-dihydroxy-2 H-pyran-3 (6H)-one (6) as shown by 1H- and 13C-NMR.-spectroscopy. A new, simple high-yield preparation of 5- and 6- solutions is described, in which sodium bromate is used as the oxidizing agent.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610838
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  • 128
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    Structural Studies of Crystalline Enamines (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 3108-3135 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal structure analyses of five crystalline enamines together with recently published structural data for two other enamines reveal varying degree of pyramidality at the enamine nitrogen atom. The pyramidality appears to be most pronounced in enamines from piperidine and morpholine, less so in enamines derived from prolinoid amines. A pyrolidine enamine obtained from a derivative of cyclohexane-1,4-dione seems to have a virtually planar enamine group. The implications of these findings for current stereochemical problems in enamine chemistry are discussed.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610839
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  • 129
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    Zum stereochemischen Verlauf der elektrophilen Substitution an CH-Gruppen in α-Stellung zum N-Atom behinderter Amide Vorläufige Mitteilung (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 3100-3102 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Sterochemical Course of Electrophilic Substitution at CH Groups in α-Position to the N-Atom of Hindered AmidesIt is shown by 1H-NMR. analysis of the aminoalcohol derivatives 4b and 4c that the lithiation/hydroxyalkylation with acetone of 1-nitroso-and 1-(2,4,6-triiso-propylbenzoyl)-4-phenyl-piperidine leads to configurationally different products. The assigned cis and trans configuration of the substituents in 4b and 4c, respectively, is compatible with the electronic structures 2 and 1, respectively, which were previously proposed for the lithio-derivatives 3 involved in such transformations.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610837
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  • 130
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    Electronic structure of TCNQ, studied with HAM/3 (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 331-347 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure of tetracyanoquinodimethane (TCNQ) is calculated using the new semiempirical method HAM/3. The calculated photoelectron spectrum is in reasonable agreement with the measured spectrum. The excitation energies are obtained directly in HAM as the differences of the energies of the unoccupied and the occupied orbitals. The calculated UV spectrum is in good agreement with the measurements. The weak band at 5.3 eV, which earlier had been assumed to correspond to a forbidden transition, is allowed according to HAM. The electron affinity is also in reasonable agreement with the measured value. An explanation has been given for the experimental observation of several resonance states (negative electron affinities). p-Quinodimethane has also been studied.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130307
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    Symmetry forcing and convergence properties of perturbation expansions for molecular interaction energies (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 271-287 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The convergence properties of perturbation theories for molecular interaction energies are tested by performing high-accuracy high-order numerical calculations for a ground-state hydrogen atom interacting with a proton. It is shown that a strong symmetry forcing used in the Eisenschitz-London-Hirschfelder-van der Avoird (EL-HAV) theory leads to rapidly convergent perturbation expansion whereas a weak symmetry forcing, peculiar to the Murrell-Shaw-Musher-Amos (MSMA) theory, is not able to guarantee the convergence of the resulting perturbation series. The perturbation expansion introduced recently by Jeziorski and Kolos and corresponding to an intermediate symmetry forcing is shown to converge rapidly ensuring the correct asymptotic behavior of the interaction energy calculated through second order. Despite the divergence of the resulting perturbation series the MSMA theory is shown to give very useful results at the distances corresponding to the van der Waals minimum. In this region, however, virtually the same results can be obtained by using a simpler theory employing a properly symmetrized wave function of the usual Rayleigh-Schrödinger (RS) polarization theory.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/qua.560140306
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  • 132
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    Nature of the autodetaching sub 2P½ threshold states of the alkali anions (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 333-336 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140312
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130401
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  • 134
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    Scattering theory of dilated three-body Schrödinger operators (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 361-370 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140405
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  • 135
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    Complex coordinate calculations of resonances in N-electron atoms (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 371-382 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a discussion of the functional dependences of the wave functions for bound, resonant, and scattering states on the radial coordinate ρ and the rotation angle α in the complex coordinate method. We conclude that for bound states and resonances, ρ and α are constrained to appear in the wave functions only in the for ρ exp(iα). On the other hand, this constraint is not obtained for the scattering states since the energy of the scattering states depends on α. In addition we suggest a partitioning of the resonant wave function into two parts - a boundlike or “Q-space” part and a scattering like or “P-space” part. With these concepts one can incorporate physical insight into the choice of configurations as one does in other methods and can apply the complex coordinate method to many electron systems with an expected rate of convergence similar to other techniques. Its advantages are that a single calculation yields the position and width of the resonance, only square integrable functions are used, only a solution of a straightforward eigenvalue problem is required unlike some methods, arbitrarily accurate target states are easily incorporated, and polarization terms can easily be explicitly included. Variational calculations for the position and width of the lowest 2S resonance in the negative helium ion are reported using trial wave functions containing 39, 43, 55, 24, and 32 “P-space” configurations, respectively. Values of 19.387 eV and 12.13 meV are obtained for the position and width, respectively, for the resonance over a range in the rotation angle of almost two orders of magnitude. One also finds that inclusion of free-particle-like basis functions improves the representation of the scattering states.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560140406
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    Classical dynamics of the O + ClO → Cl + O2 and Cl + O3 → ClO + O2 reactions (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 659-674 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An explicit function has been derived for the potential-energy surface of the ground state of ClO3 with the six interatomic distances as variables. This surface is valid over all configurations of the atoms. The surface has been used to calculate classical trajectories for the reactions R1: O(3P2)+ClO(2Π3/2)→ O2(3∑g-)+Cl(2)P3/2 and R2: Cl(2P3/2)+O3(1A1)→ClO(2Π3/2)+O2(3∑g-). An appreciable fraction (∼1/3) of the reactive trajectories for R1 go through a long-lived complex ClOO(2A″). The cross section decreases with increasing rotational state of the ClO; and 37% of the energy release is vibrational. The calculated rate constant at 298°K is 2.6 × 10-11 cm3/molecule sec. For reaction R2 there is no evidence of long-lived complexes. The product ClO is predominantly found in the backward-scattering direction. Most of the internal energy is carries off by ClO but O2 carried off most translational energy. An Arrhenius expression has been deduced from calculations at 220 and 300°K to give an A factor of 2.488 × 10-11 cm3/molecule sec and an activation energy of 1.543 kJ/mol.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560140513
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    Theoretical approaches to intramolecular electron transfer processes (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 675-694 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical issues that must be considered for calculating rates of intramolecular electron transfer are discussed. The process itself is well defined only if the ground state is well approximated by a localized electronic function (Robin-Day class I or II). Under those conditions, the linear-response formalism yields the rate as the Fourier transform of the particle-hole propagator. We discuss the validity of electron propagators as approximations to particle-hole propagators, and find that they are valid, for simple models, within the stability range of the Hartree-Fock procedure. The vibronic nature of the transfer process is stressed, and formal schemes are given for calculating direct and through-bridge transfer rates. Outstanding difficulties, and applications to biological systems, are very briefly noted.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/qua.560140514
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    Some symmetry aspects of the local-mode description of vibrational structureAbstracted from an invited talk given by one of us (W.M.G.) at the American Conference on Theoretical Chemistry, Boulder, Colorado, June 1978. (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 703-708 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the local-mode description of vibrational structure, the nuclear coordinates - unlike the usual normal coordinates - do not reflect the molecular symmetry. Accordingly, the local-mode product wave functions must be symmetry adapted. We discuss this simple procedure in light of its implications for the localization of vibrational energy and the dissociation limits of molecular excited states. These properties are in turn related to the separability of the total nuclear Hamiltonian and to the different ways in which the vibrational anharmonicity is “absorbed” by the local and normal coordinates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140516
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140601
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  • 140
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    On the Calculation of the Electronic Reorganization of Canonical and Localized Koopmans' IonsDem Andenken meines Doktorvaters Heinrich Labhart gewidmet (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 864-870 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions and implications for the calculation of self-consistent single determinant wave functions for Koopmans' ions are discussed and a recipe for practical computations is given. The concept of Koopmans' ions has been extended to localized ions and a definition for their reorganization energies is proposed. Calculations on formaldehyde serve as a numerical illustration.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610234
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    Hexakis (methylidene)-cyclohexane (“[6]Radialene”). Chemical and spectral properties (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 844-847 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon flash pyrolysis between 580 to 660°, 2,4,6-tris(chloromethyl)mesitylene (2) leads to products formed through the loss of one, two and three molecules of HCl. The highly reactive chlorine free product is shown to be [6]radialene (1) both by its chemical reactions and by its spectral properties.
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    URL: http://dx.doi.org/10.1002/hlca.19780610232
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  • 142
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    Struktur und Reaktivität eines Triazolobenzodiazepin/Oxalylchlorid-AdduktsAuszugsweise vorgetragen an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft vom 7. bis 10. Oktober 1976 in Genf.Herrn Prof. C. A. Grob zum 60, Geburtstag gewidmet (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 848-863 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure and Reactivity of a Triazolo-benzodiazepine/Oxalyl Chloride AdductReaction of oxalyl chloride with N, N-dimethyl-{8-chloro-6-(0-fluorophenyl)- 4H, 11 H-[1,2,4]triazolo [1,5-α] [1,4]benzodiazepine}-2-carboxamide (6a), the syn-thesis of which is described, leads to the cyclic adduct N, N-dimethyl-{2,12,12-trichloro-13a-(0-fluorophenyl)-11-oxo-10,11,12,13a-tetrahydro-5H, 9H-[1,3]oxazolo [3,2-d] [1,2,4]triazolo [1,5-a] [1,4]benzodiazepine}-7-carboxamide (7a). Upon thermolysis 7a is partly reconverted to the starting diazepine 6a via loss of the elements of oxalyl chloride. Reduction of 7a with sodium borohydride also yields 6ain addition to its dihydro derivative 9. Energetic treatment of 7a with sodium methoxide leads to the unexpected methoxydiazepines 10a and 10b, and mild treatment of 7a with sodium methoxide to the stereoselective formation of the two precursors of 10, namely the chloromethoxy derivative 11 and the dimethoxy derivative 12. Epimerization of 11 followed by nucleophilic substitution gives a mixture of two dimethoxy compounds, 12 and its epimer 14. The configurational assignments of these derivatives are based upon X-ray analysis of 12. A possible pathway for this unexpected substitution reaction is proposed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610233
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  • 143
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    Drüsenfarbstoffe aus Labiaten: Strukturen von 16 Diterpenen (Coleone und Royleanone) aus Coleus coerulescensGÜRKE (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 871-884 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Leaf-gland pigments from labiatae: structures of 16 diterpenoids (coleons and royleanones) from Coleus coerulescens GÜRKEThe Abyssinian labiate Coleus coerulescens has been investigated for its leaf-gland pigments. From the very complex mixture of abietanoic diterpenoids the following pure constituents were isolated and their structures established: (1)Diosphenols: coleon C (1a), 16-O-acetyl-coleon C (1b), coleon W (1f);(2)A/B-trans-6, 7-diketones: coleon D (2b), 16-O-acetyl-coleon D (2c), coleon V (2a);(3)Spiro-coleons: 7,12-bis(O-desacetyl)-coleon N(3a), 12-O-desacetyl-coleon N (3b), coleon O (4), 6,12-bis (O-desacetyl)-coleon R (5a), 12-O-desacetyl-coleon R (5b), 3-O-desacetyl-3-O-formyl-coleon Y (5g);(4)Royleanones: The abeo-compounds 6a, 6b, and 7.Main compounds are 3b, 5e and 5g. This is the first record of a co-occurrence of diosphenols, 6,7-dioxo-coleons, spiro-coleons and royleanones. Preliminary experiments show that solvolytic opening of the cyclopropane-ring followed by tautomerisation, oxidation to hydroxy-p-benzoquinones or elimination to quinomethanes and subsequent nucleophilic attack of the solvent leads to compounds with a 2′-substituted propyl group at C(13), thus supporting the biosynthesis of the unusual coleon E side chain.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610235
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  • 144
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    Synthese der vier stereoisomeren Dihydropalustraminsäuren. 13. Mitteilung über Schachtelhalmalkaloide12. Mitt. [1], 11. Mitt. [2], 10. Mitt. [3].Aus der Diss. von P.C.W., vgl. [4]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 885-898 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of the four stereoisomeric dihydropalustramic acids ([6-(1-hydroxypropyl)-2-piperidyl]acetic acids)(-)-Dihydropalustramic acid, a key product in the structure elucidation of the alkaloid palustrin, has been assigned the threo-cis structure 20 by comparison with the four stereoisomeric (±)-dihydropalustramic acids (threo-cis, threo-trans, erythro-cis, erythro-trans). The latter were synthesized by a new route to α, α′-di-substituted piperidines of this type. Ring closure to the piperidine ring with simultaneous stereospecific formation of the hydroxylated side chain has been achieved by reaction of the stereoisomeric methylesters of 7,8-epoxy-2-decenoic acids with benzylamine. Assignment of the configuration at the piperidine ring is based on careful comparison of the H-NMR. spectra of the N-benzylpiperidines and with the help of lanthanide shift reagents.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610236
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  • 145
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    1H- und 13C-NMR.-spektroskopische Untersuchungen an den vier diastereomeren (±)-Dihydropalustraminsäure-methylestern; Strukturkorrelation mit (-)-Dihydropalustraminsäure-methylester sowie mit dem Alkaloid Palustrin. 14. Mitteilung über Schachtelhalmalkaloide13. Mitt., s. [1a] (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 899-904 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-and13C-NMR. spectra of methyl esters of the diastereomeric (±)-dihydropalustramic acids; structural correlation of (-)-dihydropalustramic acid with the alkaloid palustrinUnambiguous assignment of cis-trans configuration at the piperidine ring of the four diastereomeric methyl esters of the (±)-dihydropalustramic acids is based on the interpretation of 1H- and 13C-NMR. data. (-)-Dihydropalustramic acid, the important degradation product of the alkaloid palustrin is shown to be threo-cis-[6-(1-hydroxypropyl)-2-piperidyl]acetic acid. The same conclusion holds for palustrin and dihydropalustrin. Therefore, palustrin is threo-cis-17-(1-hydroxy-propyl)-1,5,10-triazabicyclo[11.4.0]heptadec-15-en-11-one.
    Additional Material: 4 Tab.
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  • 146
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    Absolute Konfiguration der Equisetumalkaloide (+)-Palustrin, Palustridin ((+)-Monohydrochlorid) sowie der (-)-Dihydropalustraminsäure und weiterer Derivate. 16. Mitteilung über Schachtelhalmalkaloide13., 14. und 15. Mitt. s.[1a-c].Teilweise aus der Dissertation von C.P.W. [1d].Aus der Diplomarbeit von G.M.-M. [2]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 921-928 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Determination of the absolute configuration of alkaloids from Equisetum sp.,e.g. (+)-palustrin, palustridin ((+)-hydrochloride), and (-)-dihydropalustramic acid and derivativesThe absolute configuration of the title alkaloids has been determined using chiroptical methods (ORD., superposition of CD. values of appropriate models and a modified Horeau method). (+)-Palustrin is (13R, 17 S, 1′S)-17-(1-hydroxypropyl)-1,5,10-triazabicyclo [11.4.0]heptadec-15-en-11-on.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610239
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  • 147
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    Synthese von threo-cis/threo-trans- und erythro-cis/erythro-trans-Dihydropalustrin. 17. Mitteilung über Schachtelhalmalkaloide16. Mitt. [1a].Aus der Dissertation von E.W.-S. [1b]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 928-935 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of threo-cis/threo-trans- and erythro-cis/erythro-trans-dihydropalustrinThe first synthesis of a threefold protected spermidine, namely 3-benzyloxycarbonyl-N1-phthaloyl-N2-tosylspermidin (9) is presented. Each of the protecting groups can be removed selectively. After hydrazinolysis the resulting N3-benzyloxy-carbonyl-N2-tosylspermidine (10) has been condensed with methyl (2 E)-cis-7,8-epoxy-2-decenoate to the threo-cis/trans piperidines 17, and with methyl (2 E)-trans-7,8-epoxy-2-decenoate to the erythro-cis/trans piperidines 17, respectively. After catalytic removal of the Z group, the resulting aminoesters 13 and 18, in a melt with imidazole, underwent ring closure to the 13-membered lactames 14 and 19, respectively. reductive deprotection of the N-tosyl group with sodium/ammonia led to the stereoisomeric palustrines 15 and 20, respectively.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610240
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  • 148
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    Abbau von Palustrin zu (-)-Dihydropalustraminsäure ((2R, 6S, 1′S)-[6-(1′-Hydroxypropyl)-2-piperidyl]essigsäure) und Struktur von Palustrin und Palustridin. Mitteilung über Schachtelhalmalkaloide13. und 14. Mitt. s. [1a][1b].Aus der Diss. von C.M.[1c]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 905-921 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Degradation of palustrin to (-)-dihydropalustramic acid ((2R,6S,1′S)-[6-(1′-hydroxypropyl)-2-piperidyl]acetic acid), and the structure of palustrin and palustridinThe structure of the macrocyclic alkaloid palustrin is shown to be 1a. Its piperidine unit can be obtained as (-)-dihydropalustramic acid (6a) by the following sequence of degradation reactions (Scheme 1): catalytic hydrogenation of 1a followed by methylation and Hofmann degradation provides the allyl base 4. the regioselectivity of the Hofmann elimination is explained by intramolecular proton abstraction at C(3) by C(18)-O-. Catalytic reduction of 4 and subsequent acidic hydrolysis yielded 6a and N, N-dimethylputrescine (=N,N-dimethyl-1,4-butanediamine; 7). Loss of the N-alkyl group in the formation of 6a occurs during the catalytic hydrogenation step. This interpretation is supported by the results of model experiments. The position of the double bond in 1a is deduced from the IR. spectrum of the bromo-δ-lactone 19 prepared by treatment of 1a with N-bromosuccinimide at pH 4 (Scheme 3). Some of our previously published results on the degradation of dihydropalustrin (2a) are obviously at variance with the newly proposed structure for palustrin (1a). They can easily be explained by assuming a partial hydrogenolysis of the C(17)-N(1) bond during the preparation of dihydropalustrin from palustrin. Periodate cleavage of dihydropalustramic acid methyl ester (6b) liberates propionaldehyde, which can be trapped by working at pH 7.5 (Scheme 2); at lower pH values it condenses rapidly with the simultaneously generated 3,4,5,6-tetrahydropyridine derivative 15. The structure of the condensation product is proposed to be 16 on the basis of the isolation of its hydrogenation product, an isomeric dihydropalustramic acid (17).
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610238
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  • 149
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978) 
    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.19780610301
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  • 150
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    Mitteilungen (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 936-936 
    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.19780610241
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  • 151
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    Trois quarts de siècle dans cinq siècles de chimie en SuisseConférence présentée au Symposium du 26 mars 1976 à Bâle, organisé par la Société Suisse de Chimie à l'occasion du 75e anniversaire de sa fondation. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 937-949 
    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.19780610302
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  • 152
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    Reduktionsgrad in Photoredox-Systemen (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 950-959 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduction Degree in Photoredox-SystemsThe reduction degree is in many photoredox systems an invariant under irradiation. Therefore it represents an important degree of freedom in these systems. It is possible to define the reduction degree in such a systematic way, that it may also be applied for discussing complicated systems. It would be helpful to have selective electrode material for the examination of photoredox systems. We have succeeded in finding a selective electrode material for the iron in the iron/thionin system as well as in the iron/iodine system.
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    URL: http://dx.doi.org/10.1002/hlca.19780610303
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  • 153
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    Isolation and total synthesis of (E)-6, 10-dimethyl-9-methylidene-undec-5-en-2-one, a constituent of Costus root oil (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 984-989 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (E)-6, 10-Dimethyl-9-methylidene-undec-5-en-2-one (1) has been isolated from Costus root oil. A total synthesis of this compound is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610306
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  • 154
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    Spectra of Organic Molecules in Thin FilmsIn Memorial to Professor Heinrich Labhart (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 960-977 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to investigate molecules and their interactions at interfaces we have developed a new spectroscopic technique based on integrated optics. A significant increase in sensitivity has been predicted and observed. We report here the details of the method and some preliminary spectra of organic dye molecules on thin films.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610304
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  • 155
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    Synthese von 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-on (Hothesimogenin). Partialsynthetische Versuche in der Reihe der Herzgifte, 11. Mitteilung10. Mitt. siehe [1].Über die Pharmakologie von 7 wird an anderer Stelle berichtet werden. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 977-983 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (hothesimogenin)We describe the synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (24-aza-24-desoxa-digitoxigenin) (7), starting from 3-O-acetyl-digitoxigenin (1).
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  • 156
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    Structural Requirements for the Enzymatic Deamination of Cytosine NucleosidesDedicated to Professor Dr. Tadeus Reichstein on the occasion of his eightieth birthday (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1011-1016 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thirty-three 1-β-D-pentofuranosylcytosine nucleosides were examined as substrates of crude cytidine deaminase from mouse kidney. In addition to previous observations of structural features in substrates required for enzymatic deamination [e.g., a free 3′-hydroxyl in the ‘down’ ribo (arabino)configuration] we find that: modification of the aglycon by substitution of a fluorine atom at C(5) results in a several-fold increase in the deamination velocity relative to cytidine whereas insertion of a methyl group at C(5) decreases the deamination velocity. This decrease is even more pronounced when a methyl group is substituted at C(6).Though xylosylcytosine and 3′-deoxy-3′-fluoro-xylo-C are not substrates for this deaminase, those xylofuranosylcytosines bearing good leaving groups (e.g., bromo, mesyloxy, or tosyloxy) at C(3′) are deaminated with substantial deamination velocities. This is probably due to a prior chemical reaction leading to arabino nucleosides bearing a free ‘down’ 3′-hydroxyl.A different situation is obtained with arabino nucleosides. Though ara-C and 2′-deoxy-2′-fluoro-ara-C are substrates for this deaminase, substitution of bulky groups (e.g., chloro, bromo, or mesyloxy) at C(2′) substantially decreases the susceptibility to deamination. An hypothesis is offered to explain these differences between xylo-and arabino-cytosines.The presence of a free hydroxyl group at position 5′ is not essential for enzymatic deamination.
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  • 157
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    Photochemistry of 2-Cyclohexene-imines and 2,3,4,4a,5,6-Hexahydroquinolines. Preliminary communication (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1025-1032 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2-cyclohexene-imines 2b-2d and the hexahydroquinolines 5a, b are synthesized. n,π*-Excitation of these α,β-unsaturated imines leads to (E/Z) isomerization for compounds 2 while compounds 5 are unreactive. No cyclobutanes are formed from 2 or 5 under these conditions in the presence of olefins, and only 2d adds to 2,3-dimethyl-2-butene via the C=N bond to give an azetidine. On π,π* excitation 2 and 5 rearrange to the corresponding β,γ-unsaturated imines 8 and 9 with low efficiency. It is concluded that the failure of such imines to undergo [2+2]-photocycloadditions with olefins is not mainly due to radiationless decay via (E/Z) isomerization.
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  • 158
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    Umamidierungsreaktionen an offenkettigen Amino-amid-Systemen. 1. Mitteilung über Umamidierungsreaktionen (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1039-1049 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transamidation Reaction of Open Chaine Amino-amidesAmino-amides of type 11 with a primary amino and a N, N-disubstituted amide group isomerize under base catalysis completely to amino-amides 16 with a secondary amino and a N-monosubstituted amide group (see Scheme 3). Amino-amides having a secondary instead of the primary amino group are under base catalysis in equilibrium with the corresponding isomeres (Scheme 4). The opening of the proposed tetrahedral intermediate 13 (Scheme 3) takes place under stereo-electronic control (Schemes 5 and 6).
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  • 159
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    Azokupplungen an 3,4-Dimethoxyfuran (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1033-1038 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diazo coupling of 3,4-dimethoxyfuran with aryl diazonium ions3,4-Dimethoxyfuran (1) easily reacts with aryl diazonium chloride in aqueous pyridine in an expected 1, 4-addition reaction. From the isolable primary addition product pyridine is displaced by alcohols, phenols or thiols to yield 4-alkoxy- or 4-phenoxy- or 4-thiophenoxy-derivatives of 2,3-dimethoxy-2-buten-4-olide (3). Attempts to convert them into azo compounds by a base catalysed 1, 6-elimination reaction failed. Oxidation of 3a and 3c with DDQ results in the formation of the mono p-nitrophenylhydrazone of 3, 4-dimethoxymaleic acid anhydride. On the other hand, the thiophenoxy compound 3g is smoothly converted by MnO2 into the authentic furan-2-azobenzene derivative 5.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610313
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    Über die Diskrepanz zwischen klassischer und quantentheoretischer Behandlung photophysikalischer ProzesseIn Memoriam Professor Heinrich Labhart (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1064-1071 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine Vielzahl photophysikalischer Prozesse kann theoretisch durch ein Dreiniveaux-Modell beschrieben werden. Die hier kritisch diskutierten exakten Lösungen der klassischen wie auch der quantenmechanischen Behandlung können im allgemeinen weit voneinander abweichen. Es ist gezeigt, weshalb einerseits die klassische Kinetik bei den bekannten Systemen bisher erfolgreich war und welche Eigenschaften andererseits nötig wären, um die Diskrepanzen merklich in Erscheinung treten zu lassen. Insbesondere lässt eine kurze Analyse der Zeitabhängigkeit neue interessante Effekte in der Pico-und Subpicosekundengegend erwarten.
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    URL: http://dx.doi.org/10.1002/hlca.19780610316
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  • 161
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    Umamidierungsreaktionen an cyclischen Amino-amid-SystemenAuszugsweise vorgetragen an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft in Bern, 8.10.1977.. 3. Mitteilung über Umamidierungsreaktionen2. Mitt. s. [1]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1050-1063 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transamidation Reactions with Cyclic Amino-amidesLactames which are substituted at the nitrogen atom by a 3-aminopropyl residue are transformed under base catalysis to cyclic amino-amides enlarged by 4 ring atoms. The formed ring must be at minimum 12-membered. Scheme 2 illustrates this result: the 8-membered 7 is transamidated in 96% yield to the 12-membered ring 8 (in the presence of potassium 3-aminopropylamid in 1, 3-propanediamine), the 9-membered 10 to the 13-membered ring 11 (97%) and the 11-membered 14 to the 15-membered ring 15. Furthermore, the 13-membered ring 27 (Scheme 5) is transformed to the 17-membered 28. In the case of the 15-membered lactame 15 it is demonstrated that 14 is not formed back under the conditions of the transamidation.Large ring lactames which are substituted at the nitrogen atom by a 3-(alkylamino) propyl group lead under base catalysis to an equilibrium mixture, e.g. the 17-membered 26 is in equilibrium with the 21-membered 29. This result is similar to the behavior of the corresponding open-chain amino-amides [2].Because of transannular interactions, the 11-membered ring 2 is not stable: transamidation of the 7-membered 1 (Scheme 1) doesn't give the expected 2, but its water elimination product 3 in small yield. The N-tosyl derivative of 2, namely 20, is synthesized by an independent route (Scheme 3). Detosylation of 20 yields the 7-membered 1 instead of 2. Concerning the mechanism of this interesting reaction see Scheme 4.
    Additional Material: 1 Tab.
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  • 162
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    Etudes spectroscopiques infrarouge et Raman de spiropyrannes et mérocyanines benzothiazoliniques (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1072-1085 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Infrared and Raman spectroscopic studies of benzothiazolinic spiropyrans and merocyanines
    Notes: Les spectres IR. de cinq spiropyrannes benzothiazoliniques (ét solide et dissous) et les spectres Raman de trois d'entre eux (état solide) ont été enregistrés de 4000 à 400 cm-1 et ont permis une interprétation des vibrations moléculaires de ces composés. Une analyse plus sommaire, faite dans le but de caractériser la structure spiropyrannique a été étendue au moyen de la spectroscopie IR. à une série de vingt et un composés. L'étude IR. a également porté sur deux mérocyanines. Nous avons analysé et essayé d'interpréter les principales perturbations spectrales observées lors du passage d'un composé spiropyrannique (forme fermée) à la forme ouverte.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610317
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  • 163
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    Kristallstruktur eines überbrückten 1,2,3-Oxadiazolidin-5-ons (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1091-1096 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Crystal Structure of a Bridged 1,2,3-Oxadiazolidin-5-one Derivative3-(2-Allylphenyl)-4-phenylsydnone (1) undergoes in solution an intramolecular, 1,3-dipolar cycloaddition reaction to give 2-oxo-1-phenyl-1,5-methano-1,2,4,5,6,11-hexahydro [1,2,3] oxadiazolo [3,2-a] cinnoline (2). The unique 1,2,3-oxadiazolidin-5-one structure of this molecule has been proved by X-ray analysis. The crystal structure has been solved by direct methods and refined by full-matrix least squares calculations to R = 0,046. The crystal system is orthorhombic, space group Pbca, with unit cell dimensions a = 10,546, b = 15,482, c = 16,531 Å.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610319
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  • 164
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    Rhodium (I)-katalysierte Reaktionen der [2+4]-Cycloaddukte aus 3,4-Dimethoxyfuran und Acetylendicarbonsäure-estern (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1134-1138 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [2+4]-Cycloaddition Products of 3,4-Dimethoxyfuran with Acetylenedicarboxylates and Their Transformations under the Influence of Rhodium(I) Catalysts3,4-Dimethoxyfuran (1) readily reacts with acetylenedicarboxylates (2) at room temperature in a [2+4]-cycloaddition to give a mono-(3) and several di-addition products. 90% of the latter consists of the endo-exo compound 4. Under the influence of catalytic amounts of [Rh(CO)2Cl]2 the mixture of mono- and di-adducts in methanolic solution is smoothly transformed into endo-5,5,6-trimethoxy-7-oxabicyclo [2.2.1]hept-2-ene-2,3-dicarboxylateAlle Verbindungen sind racemisch. Die Formeln stellen jeweils nur ein Enantiomeres dar. (5) , 3-hydroxy-4,5-dimethoxyphthalate ( 6) and (I R*, 2 S*, 4 R*, 5 R*, 7 R*, 11 R*, 12 R*) -5,8,8,9,12-pentamethoxy-3,6-dioxatetracyclo [5.3.1.1 2,5 . 0 4,11]dodec-9-ene-1,11-dicarboxylate ( 7).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610327
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  • 165
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    Studies on Heterocyclic Colouring Matters Part IIIPart I, [1]. Part II, [2]. Presented at the 6th International Colour Symposium in Freudenstadt, Germany, September 27-October 1, 1976.: 7a,14a-diaza-7,7a,14,14a-tetrahydroquino[2,3-b]acridine-7,14-diones (5,7a,12,14a-tetraaza-7,7a,14,14a-tetrahydropentacene-7,14-diones)We use this somewhat simpler name throughout, instead of the Chemical Abstracts nomenclature: pyrido [2,1-b] pyrido [1′,2′:1,2]pyrimidino[4,5-g]quinazoline-7,15-dione. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1146-1157 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Aminopyridines react with diethyl 2,5-dioxo-cyclohexane-1,4-dicarboxylate (diethyl succinylsuccinate) to give 7a,14a-diaza-6,7,7a,13,14,14a-hexahydroquino-[2,3-b] acridine-7,14-diones (5,7a,1,14a-tetraaza-6,7,7a,13,14,14a-hexahydropentacene-7,14-diones), which are aromatized to the title compounds. Oxidation of these with a mixture of sulfuric and nitric acids results in the formation of their respective 6,13-quinones, also obtained directly from 2-aminopyridines and diethyl 2,5-dichloro-1,4-benzoquinone-3,6-dicarboxylate. The chromophore of the title compounds is compared with that of quinacridones.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610329
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  • 166
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    Activity, Selectivity, Decay and Long-Term Behaviour of Amination Catalysts (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1169-1174 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A survey of the activity and selectivity of several catalysts for the amination of long-chain aliphatic alcohols with dimethylamine is given. The best results were obtained with Cu-catalysts whose long-term behaviour was investigated. The main reasons for catalyst decay are the irreversible adsorption of dimerization products and the thermal diffusive fusion of Cu-crystallites.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610332
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  • 167
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    Photochemical Behaviour of 17β-Acetoxy-4-aza-1,5-androstadien-3-one: Photo-oxidation vs. Di-π-methane RearrangementPart of the doctral thesis of J. A. Vallet, I.Q.S., Barcelona, 1978. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1165-1168 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The irradiation of the title compound 6 with UV. light and under photosensitized oxidation conditions yields products which are characteristic of the photo-oxidation of the enamide moiety of 6. In contrast to the situation encountered in the case of the irradiation of its carbocyclic and 4-oxa analogues 1 and 2, respectively, no compound resulting from a di-π-methane rearrangement of the Δ1,5(6)-unsaturated system of 6 has been so far detected.
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    URL: http://dx.doi.org/10.1002/hlca.19780610331
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  • 168
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    A Di-π-Methane Rearrangement in the Photolysis of a 4-Oxa-steroidal α,β-Unsaturated Enol-lactonePart of the doctoral thesis of J. A. Vallet, I.Q.S., Barcelona, 1978.. Photochemical reactions VIIIDedicated to Professor Oskar Jeger on his 60th anniversary (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1158-1164 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The irradiation of 17β-acetoxy-4-oxa-1,5-androstadien-3-one (12) yielded the two stereoisomeric spiro-lactones 13 and 14, which result from a di-π-methane photorearrangement. A third product, the oxa-anthrasteroid 15, was also isolated (Scheme 3).
    Additional Material: 1 Ill.
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  • 169
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    Über die Herstellung von substituierten 2,3,4,5-Tetrahydro-1,2,4-triazin-6-carbonitrilen und einige ihrer Abwandlungsreaktionen (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1175-1185 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of substituted 2,3,4,5-Tetrahydro-1,2,4-triazine-6-carbonitriles and some of its Derivatives.The synthesis of 4-substituted 2-aryl-2,3,4,5-tetrahydro-5-imino-3-oxo-1,2,4-triazine-6-carbonitriles (3), 2-aryl-2,3,4,5-tetrahydro-3, 5-dioxo-1,2,4-triazine-6-carbonitriles (4) and some 3-thioxo-derivatives thereof by a novel approach is described. In addition some possibilities for the derivatisation of these compounds are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610333
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  • 170
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    Synthesis and Biological Activity of Four Adrenocorticotropin-(1-24)-tetracosapeptide Analogues with N-Terminal Deletions of Four to Seven Amino-Acid ResiduesAbbreviations: cf. [1]. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1186-1192 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of adrenocorticotropin-(5-24)-eicosapeptide, -(6-24)-nonadecapeptide, -(7-24)-octadecapeptide, and -(8-24)-heptadecapeptide are described. Their biological activities on isolated adrenal cortex cells and adipocytes, on superfused adrenal tissue, as well as on the adenylate cyclase system of isolated cell membranes are summarized.
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    URL: http://dx.doi.org/10.1002/hlca.19780610334
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  • 171
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    A Theoretical Study of Complex Formation between Formaldehyde and Lithium (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1193-1199 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH2O/Li+, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH2O-/Li+, the C2v-conformer of the 2A1-state with the equilibrium bond distances of d(C—O) = 1.23 Å and d (O—Li) = 1.90 Å is calculated to be more stable than the 2B1-state with d (C—O) = 1.34 Å, and d (O—Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610335
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  • 172
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    Préparation de quelques 4-nitroisoxazoles à partir de pseudonitrosites de cétones éthyléniques du type chalcone (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1207-1212 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Synthesis of some 4-Nitroisoxazoles from Pseudonitrosites of ChalconesThe action of dinitrogen trioxide with α,β-unsaturated ketones of the chalcone type leads to pseudonitrosites (Table 1) which are cyclized to 4-nitro-3,5-diarylisoxazoles (Table 2).
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19780610337
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  • 173
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    Ruspolia hypercrateriformisM.R.: Isolierung und Strukturaufklärung von neuen Pyrrolidin-Alkaloiden. 169. Mitt. über organische Naturstoffe168. Mitt. s. [1].Teil der geplanten Dissertation von F. R., Universität Zürich.Frau Professor Asima Chatterjee zum 60. Geburtstag gewidmet (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1200-1206 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ruspolia hypercrateriformis M.R.: Isolation and Structure Elucidation of New Pyrrolidine AlkaloidsThree new pyrrolidine alkaloids have been isolated from Ruspolia hypercrateriformis, which belongs to the plant family of Acanthaceae. The structure of the alkaloids ruspolinone (1), norruspolinone (2) and norruspoline (3) (Scheme 1) has been elucidated by means of spectroscopic data of the pure compounds and their derivatives, by chemical transformation fo 2 to 1 by methylation, by trans-formation of 3 and 2 to identical hydrogenation products, and by comparison of degradation products with synthetically prepared model compounds.
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  • 174
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    Mitteilungen (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1213-1213 
    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.19780610338
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  • 175
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978) 
    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.19780610401
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  • 176
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    An Efficient Stereoselective Synthesis of (±)-Sweroside and (±)-secologanin aglucone O-methyl ethers. Preliminary communication (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1221-1225 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A seven-step stereoselective synthesis of (±)-sweroside aglucone O-methyl ether (16a) was achieved in 27% overall yield from 1, 4-cyclohexadiene (4) and methyl diformylacetate (5). Secologanin aglucone O-methyl ether (18a) was then formed from 16a in 90% overall yield by a straightforward process. The key step in the synthesis was a [2+2]-enone-photoannelation of 4 and 5 to form the key intermediate 6 which possessed the desired cis-fused ring configuration, and all the caron atoms needed to complete the synthesis of 16a and 18a.
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    URL: http://dx.doi.org/10.1002/hlca.19780610403
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  • 177
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    7-Oxo-deacetamidocolchiceine and 7-Benzylimino-deacetamido-colchiceine: Two novel products from the base catalysed reaction of (-)-N-Benzylidene-deacetylcolchiceineThe nomenclature chosen derives from the terms colchicine and isocolchicine [1]. Thus compound 4 is named (±)-deacetamidocolchiceine, rather than (±)-trimethylcolchicinic acid, a term frequently encountered.Dedicated to Professor Oskar Jeger on his 60th anniversary (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1213-1220 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird gezeigt, dass bei der Racemisierung der aus natürlichem Colchicin leicht zugänglichen Schiff-Base 1, mit Kaliumhydroxyd in Methanol, neben Benzaldehyd, Benzylamin und (-)-N-Desacetylcolchicinsäure (4), auch die beiden tricyclischen Verbindungen 2 order 5 erhalten werden. Die Überführung des Ketimins 2 in das Diketon 5 gelingt leicht durch saure Hydrolyse. Letzteres kann mit Benzylamin unter den gewählten Racemisierungsbedingungen direkt in (-)-N-Desacetyl-colchicinsäure (4) übergeführt werden. Ein Vergleich der NMR.-Spektren von 5 und seiner beiden Methyläther 6 und 7, mit Substanzen der Colchicin-Reihe, gestattet die Identifizierung von 6 als 7-Oxo-desacetamidoisocolchicin und von 7 als 7-Oxo-desacetamidocolchicin, erlaubt jedoch keine eindeutige Zuordnung der beiden Sauerstoffunktionen im Ring C des Diketons 5. Eine solche konnte jedoch durch eine Röntgenanalyse weiter präzisiert werden. Diese ergibt nämlich, dass das Diketon 5 ein durch Wasserstoffbrücken stabilisiertes Dimeres der Tautomeren 5a (Ring C wie Isocolchicein) und 5b (Ring C wie Colchicein) darstellt.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19780610402
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  • 178
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    Synthese von zwei natürlich vorkommenden Lactonen mit 10gliedrigen Ringen: (±)-Phoracantholid J und I (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1226-1231 
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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 Two Naturally Occurring 10-Membered Ring Lactones: (±)-Phoracantholide J and ITwo 10-membered ring lactones 7 and 11 from the metasternal secretion of the eucalypt longicorn Phoracantha synonyma have been synthesized by the following method. Reaction of the dilithium derivative of 4-pentynoic acid (3) with 4-tetrahydropyranyloxy-1-pentylbromide (2), followed by removal of the protecting group and by esterification with diazomethane, gave methyl 9-hydroxy-4-decynoate (4; s. Scheme 1). Partial hydrogenation of the triple bond in 4 with Lindlar palladium catalyst, followed by saponification lead to cis-9-hydroxy-4-decenoic acid (6). The 9-hydroxydecanoic acid (9) was synthesized by addition of methyl magnesium iodide to methyl 8-formyloctanoate (8) followed by saponification (s. Scheme 2). The hydroxy acids 6 and 9 were converted into the S-(2-pyridyl) thioesters and cyclized in dilute benzene solution under the influence of silver ions to yield (±)-phoracantholide J (7) and I (11) in 74 and 71% yield, respectively.
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    URL: http://dx.doi.org/10.1002/hlca.19780610404
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  • 179
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    Notes on density matrix model for coherent x-ray diffraction (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 801-810 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown how an idempotent density matrix provides a proper model for interpretation of the x-ray coherent diffraction experiment.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130611
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  • 180
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    Electronic structure of SiH2, PH2, and their positive and negative ions (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 39-53 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio LCAO-MO-SCF calculations on SiH2 and PH2 and their positive and negative ions are reported, using a variety of Gaussian basis sets. The charge distribution, bonding, and molecular properties of these ions are compared with the available experimental data.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140105
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  • 181
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    Absorption line shape of two coupled oscillators decaying in the same bath (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 65-69 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper the linear response theory approximation is used to calculate the electromagnetic energy absorption coefficient of two coupled oscillators decaying in the same medium. The model seems to be suitable for the treatment of the infrared spectroscopy of certain isolated molecules trapped in a rare gas crystal.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140107
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  • 182
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    Angular dependence of Gaussian-Lobe orbitals. II. Set of axial Gaussian-Lobe orbitals (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 311-324 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The topological properties of real spherical harmonic representations on the unit sphere have been found to provide a convenient tool to infer the lobe edifices which mimic these orbitals. The prohibitive number of lobes required in such an approach for l 〉 2, can be avoided in using only axial Gaussian-lobe orbitals (AGLO). It is proved that 2l + 1 independent Ylo-like functions correctly span the relevant Ylm (m = -l,l) subspace. The multipolar component analysis of any spatial arrangement of lobes is derived, and allows the optimization of the angular dependence of AGLOS. The cases of d- and f-orbitals are studied in detail and accurate optimized functions are proposed. This method can be easily extended to obtain the atomic orbitals of any azimuthal quantum number l-subspace.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130305
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  • 183
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    Theory of mutations. II. Physical model of genetic stability (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 71-89 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A physical model for genetic stability of DNA is constructed in terms of the “microscopic” model for uninduced point mutations and the electromechanical thermoelastic properties of the macroscopic “global” DNA system. Theoretical considerations show how experimental data from one of the least complicated but useful genetic systems, T4 bacteriophage, support the proton-code model of DNA discussed by Löwdin. The stability of an unperturbed DNA system is treated to illustrate the dynamical coupling between the “global” motion of DNA and the stability at local genetic sites. The method for analyzing a DNA system perturbed by “low-energy” optical or acoustical frequencies is indicated. The model provides a physical explanation for “hot spots” (genetic sites highly susceptible to mutation) and suggests that quantum theory may be as useful in the biological sciences as it is in the physical sciences with respect to designing and interpreting certain experiments in genetics. The incidence of human cancer as a function of chronological age is discussed in terms of the model.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140108
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  • 184
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    Ab initioLCAO-MO-SCF calculation of the electrostatic molecular potential of chlorpromazine and promazine (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 457-468 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrostatic potential V(r) arising from the ab initio LCAO-MO-SCF wave functions of chlorpromazine (CPZ) and promazine (PZ) has been calculated and discussed. In this approximation, the most probable sites of attack and reaction paths of electrophilic reagents are pointed out and compared. The analysis of V(r) shows that the phenothiazine group has strong nucleophilic properties which are influenced by the phenothiazine substituent and that the electrostatic reactivity of CPZ and PZ is decidedly different near the phenothiazine substituent and similar near the side chain N atom. The dependence of V(r) on the accuracy of the wave function has also been discussed by comparing some ab initio results on pyrrole, pyrazole, and imidazole obtained with a large basis set with an ab initio minimum basis set and with CNDO calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130402
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  • 185
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    Floating spherical gaussian orbital model study of some organometallic systems. I. LiCH3, HBeCH3, and CH3BeCH3 (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 529-536 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The floating spherical Gaussian orbital method has been used to study the equilibrium geometries and electronic structures of some organometallic systems like LiCH3, HBeCH3, and CH3BeCH3. The predicted geometries are in good agreement with other theoretical estimates and available experimental results. Electron transfer values from carbon to metal atom and bond energies of Li—C and Be—C bonds are estimated and discussed. The wave functions obtained here have also been used to predict the electron momentum distributions and Compton profiles for LiCH3, HBeCH3, and CH3BeCH3.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130407
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  • 186
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    Incompletely symmetric non-bloch electron states in perfect cubic crystals. II. Density of states in the FCC lattice (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978), S. 153-162 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron density of both the perturbed and unperturbed crystal can be made up of individual terms described by the basis functions of irreducible representations of the crystal point group. For the perfect FCC lattice, a detailed comparison was made between the density of states, calculated in terms of the LCAO wave functions classified according to representations of the crystal point group, and the density of states, provided by the Bloch theory.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140203
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  • 187
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 14 (1978) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560140301
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  • 188
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    Reduced density operators and the N-particle problemThis paper is based on informal opening remarks at the Seminar on Reduced Density Operators held in New Brunswick, Canada, June 1977. (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 67-82 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An historical review of the theory of reduced density operators is given emphasizing the key role of the second order reduced matrix and related new concepts for understanding systems of many interacting fermions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130106
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  • 189
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    Inequalities for fermion density matricesThis paper was presented at the Seminar on Reduced Density Operators held in New Brunswick, Canada, June 1977. (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 125-141 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A partial trace over the occupation numbers of all but k states in the density matrix of an ensemble with an arbitrary number of single-particle states is defined as the (reduced) k-state density matrix. This matrix is used to obtain a complete, practical solution to the problem of determining the representability of the diagonal elements of the one- and two-particle (reduced) density matrices. This solution is expressed as a series of linear inequalities involving the density-matrix elements; the inequalities are identical with those derived previously by Davidson and McCrae by a different method. In addition, our method is used to obtain nonlinear, matrix inequalities on the off-diagonal elements of the density matrices.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130109
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  • 190
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    Theory and practice of MO calculations on organic molecules. I. G. Csizmadia. Elsevier scientific publishing company, Amsterdam, Oxford, New York, 1976. price: $38.50. (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 159-159 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130113
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  • 191
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    Electronic Resource
    Transition moment closure tests for ethylene (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 161-168 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The completeness of a basis set for ethylene is examined relative to its ability to describe transition moments. The double zeta (Dunning contraction) plus polarization plus Rydberg Cartesian Gaussian set does much better for length than for velocity moments. An attempt is made to interpret the transition moment sums for the occupied orbitals.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130202
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  • 192
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    Calculation of excited states of H2O and NH3 by the one-center expansion approximation (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 207-220 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential energy curves with respect to the bond angle are calculated for some excited and ionized states of the H2O and NH3 molecules by the use of the one-center expansion SCF MO and the improved virtual orbital approximations. The calculated equilibrium bond angles and force constants of bending motion are in good agreement with the experimental results.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130206
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  • 193
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    Electronic Resource
    Evaluation of some trigonometric series occurring in infinite chain polymer calculations (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 239-254 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Closed formulas are presented for a number of trigonometric series whose summands contain inverse powers of one or two quadratic forms. It is shown how to arrange the formulas to remove apparent numerical instabilities, and useful numerical approximations are identified together with the range of their validity.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130210
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  • 194
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    Masthead (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130301
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  • 195
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    Electronic Resource
    Attractive-dominant and repulsive-dominant hydrocarbon reactions (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 271-295 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The difference between the expectation values of the total electronic kinetic energy operator (ΔEK), and the operators accounting for the Coulombic interactions between the electrons and nuclei (ΔVen), between all pairs of electrons (ΔVee), and between all pairs of nuclei (ΔVnn) for the product and reactant species in a wide variety of hydrocarbon reactions are calculated using single determinant basis set data reported in the literature. Following Allen, their contributions to ΔET, the difference between the corresponding total molecular energies and thus the reaction heat, are grouped together as a repulsion energy term, ΔErep = ΔEK + ΔVee + ΔVnn, and an attraction energy term ΔEattr = ΔVen. For all but 2 of the 71 individual reactions considered in this paper, the experimental reaction heat at 0°K corrected for zero-point energy contributions, (ΔH00)zpe, is the result of near compensation between far larger ΔErep and ΔEattr terms, in sharp contrast to the much smaller ΔErep and ΔEattr terms which are characteristic of many molecular rotation processes. By matching the sign of (ΔH00)zpe with that of ΔErep or ΔEattr, as the case may be, the reactions are classified as attractive-dominant or repulsive-dominant (46 in the former class and 23 in the latter), a property which is independent of the direction in which the reaction is written. The sign and magnitude of ΔVee, ΔVnn, and ΔVen and reaction category are discussed in relation to the various kinds of structural change involved in going from reactants to products. For the vast majority of reactions, the numerical relationship ΔVee ≈ ΔVnn has been found to hold to within a few percent.
    Additional Material: 15 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130303
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  • 196
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    An ab initio molecular orbital study of the deprotonation of amines (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 349-366 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometries of the amines NH2X and amido anions NHX-, where X = H, CH3, NH2, OH, F, C2H, CHO, and CN have been optimized using ab initio molecular orbital calculations with a 4-31G basis set. The profiles to rotation about the N—X bonds in CH3NH-, NH2NH-, and HONH- are very similar to those for the isoprotic and isoelectronic neutral compounds CH3OH, NH2OH, and HOOH. The amines with unsaturated bonds adjacent to the nitrogen atoms undergo considerable skeletal rearrangement on deprotonation such that most of the negative charge of the anion is on the substituent. The computed order of acidity for the amines NH2X is X = CN 〉 HCO 〉 F ≈ C2H 〉 OH 〉 NH2 〉 CH3 〉 H and for the reaction NHX- + H+ → NH2X the computed energies vary over the range 373-438 kcal/mol.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130308
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  • 197
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    Electronic Resource
    London potential-energy surfaces for symmetrical alkali trimers (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 429-442 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Semiempirical valence bond calculations have been performed on the symmetrical alkali trimers in order to obtain their potential-energy surface, binding energy, and equilibrium geometry. For these calculations original and generalized Rosen-Morse potentials for the ground state and two similar types of new potentials for the triplet state of alkali dimers have been used. At small internuclear distances the potential surfaces show a shallow well which extends into the entrance and exit valleys without an energy barrier. The trimers are found to be stable both in linear and bent configurations, but the most stable configuration in each case is linear and symmetric. The force constants corresponding to stretching and bending deformations of the trimers have been calculated for this configuration. It has been observed that unlike the stretching, the bending deformation does not sensitively affect the energy variation of the ground state of the trimers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130313
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  • 198
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    Electronic Resource
    Restricted hartree-fock method instability (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 469-481 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The explicit forms of the spin density matrix variations which are responsible for the external instability in the restricted Hartree-Fock (RHF) method are found. The RHF open shell instability matrix which guarantees the distorted wave function to belong to the same space as the initial one is derived for arbitrary spin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130403
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  • 199
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    Electronic Resource
    Relativistic symmetry orbitals for the double groups C2v, C∞v, D∞h, and Oh (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 509-528 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relativistic symmetry orbitals are given for molecular LCAO calculations for the double groups: C2v, C∞v, D∞h, and Oh (6-fold) coordination. The atomic orbitals used in the LCAO are of the four component form. A discussion of the comparison between nonre ativistic and relativistic molecular eigenvalues is presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130406
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  • 200
    Electronic Resource
    Electronic Resource
    Quantum pharmacology. W. G. Richards. Butterworths, London and Boston, 1977. price: $24.95, 213 pp. (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 563-564 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130411
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