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  • 2000-2004  (43)
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  • Life Sciences (general)
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  • 1
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The increasing requirements in wastewater treatment have led to the development of new wastewater treatment processes based on the know-how and experience in reaction and process engineering of the chemical industry. Due to their compactness, closed operation and high flexibility, these new processes show a large potential for process integration and significant cost reduction in particular for highly polluted industrial wastewaters.This paper discusses the HCR (high-performance compact reactor) - process, developed at the Mass Transfer Laboratory of the Technical University of Clausthal within the last decade. This process has been realized in more than 30 technical applications with a volume loading of up to 70 kg COD/m3 d and an energy consumption of about 0.4 kWh per kg CODelim.
    Additional Material: 10 Ill.
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  • 2
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 169-174 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nitrogen fixing Anabaena azollae strains isolated from four different Azolla cultures were characterized based on their total protein profile and RAPD profile to study the existing variation among them. As expected, the isolates showed almost similar protein banding patterns, but exhibited differences in 40-70 KDa protein subunits. Polymerase chain reaction of the DNA of the isolates, using four different primers, amplified specific sequences of DNA and showed clear polymorphism among the isolates. The RAPD profile generated the fingerprinting pattern characteristic of each strain based on the sequence of the primers used. Common band sharing observed between the strains A. azollae-RS-KK-SK-AM and A. azollae-RS-KK-SK-RP probably represents maternal inheritance of DNA to the progeny. The polymorphic bands were generated specifically for the isolates A. azollae-RS-KK-SK-RP and A. azollae-RS-KK-SK-AM with primers numbered 2 and 4, respectively, which could be developed as possible markers for these isolates.
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 175-183 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mature seed-derived callus from an elite Chinese japonica rice cv. Eyl 105 was transformed with a plasmid containing the selectable marker hygromycin phosphotransferase (hpt) and the reporter β-glucuronidase (gusA) genes via particle bombardment. After two rounds of selection on hygromycin (30 mg/l)-containing medium, resistant callus was transferred to hygromycin (30 mg/l)-containing regeneration medium for plant regeneration. Twenty-three independent transgenic rice plants were regenerated from 127 bombarded callus with a transformation frequency of 18.1%. All the transgenic plants contained both gusA and hpt genes, revealed by PCR/Southern blot analysis. GUS assay revealed 18 out of 23 plants (78.3%) proliferated on hygromycin-containing medium had GUS expression at various levels. Genetic analysis confirmed Mendelian segregation of transgenes in progeny. From R2 generations with their R1 parent plants showing 3:1 Mendelian segregation, we identified three independent homozygous transgenic rice lines. The homozygous lines were phenotypically normal and fertile compared to the control plants. We demonstrate that homozygous transgenic rice lines can be obtained via particle bombardment-mediated transformation and through genetic analysis-based selection.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 202-202 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 219-233 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The GRAM-positive bacterium Rhodococcus erythropolis K2-3 and the GRAM-negative Ochrobactrum anthropi K2-14 are capable of synergistically degrading 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB). The two strais execute this task in a symbiotic manner, but the nature of the interaction involved in the degradation is only partially understood as yet. An essential first step in elucidating the interaction is to be able to monitor the two strans separately, at the cellular level, within mixed populations. Therefore a method exploiting fluorescently labelled lectin probes was developed. Since Concanavalin A (Con A) binds specifically to R. erythropolis K2-3, it was selected and linked to the fluoresent dye Bodipy 630/650, which has an excitation maximum in the red part of the visible light spectrum. Forward light scatter (FSC) and DNA fluorescence from both strains were also measured to obtain simultaneous information about their physiological states. The three parameters were conveniently monitored by dual and triple excitation flow cytometry in conjunction with double fluorescent staining techniques. In addition, the strains were identified using an epifluorescence microscope. These techniques were found powerful tools for the population analysis of this mixed bacterial system.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 235-274 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A quite unconventional, innovative scientific methodology called “macroscopic pattern analysis” is presented in this paper. This approach is more adequate in the case of complex systems than the well-known microscopic, mechanistic approach. Complex systems are not only attracting more engineering interest, but their scientific treatment is increasingly wanted by society due to the manifold problems in Earth's ecosphere. The macroscopic pattern approach will be explained in depth and illustrated in some case studies from the ecosphere (sustainability, hurricanes and avalanches), where nature serves as a teacher for the solution of the sustainability problem. Then, a series of case studies on macropatterns are described showing the problem-solving capacity for anthropo- and technosphere: sustainability in society with an index of sustainability, the eco-social market economy with eco-tech as an instrument, biokinetics, bioreactor mixing and integrated bioprocessing with models, design of cars and houses and even quality of life as an attempt to quantify macropatterns.The innovations are briefly compared in their problem-solving capacity with known approaches such as the microscopic method in science, technology and society (free market economy), including the evaluation of other indices and cleaner production, industrial ecology and zero emission initiative. Finally, a deeper integration of sciences, ethics, arts and nature will be introduced based on the vision with macroscopic pattern analysis, where the different domains of human life are integratable to effect a reconciliation.
    Additional Material: 22 Ill.
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  • 9
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 17-29 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic behaviour of biofilters intended to remove toluene and xylene from air was studied during transient states. Laboratory scale biofilters were filled with a mixture of peat, bark and wood and inoculated with a mixed microbial population. Toluene and xylene were applied both as single pollutants and as mixtures. Attention was focused on the evaluation of the following transients: the response of biofilters to step changes and peaks in pollutant concentrations, the effect of changes between single and multiple pollutant loadings and the response to shutdown periods.The biofilters demonstrated a good dynamic stability during transient states induced by change in inlet pollutant concentrations. Their time periods did not exceed three hours. No interaction between xylene and toluene degradation was observed during changes in loading with single pollutants or their mixture. The performance interruptions lasting less than 24 hours were found to have no significant influence on the removal efficiency of biofilters. When the biofilters were reacclimated after longer starvation periods, a short temporary decrease in efficiency whose minimum and duration were proportional to the length of a preceding shutdown period was observed. The longest starvation period (7 days) resulted in a reacclimation lasting 7 hours only. Adaptations of a microbial population to new operating conditions as well as sorption/desorption processes were suggested as the main factors influencing the dynamic reponse characteristics.
    Additional Material: 10 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 31-38 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this paper, the in vivo decolourization of the polymeric dye Poly R-478 by semi-solid-state cultures of Phanerochaete chrysosporium BKM-F-1767 (ATCC 24725) was investigated, employing corncob as a support. In order to stimulate the ligninolytic system of the fungus, the cultures were supplemented with veratryl alcohol (2 mM) or manganese (IV) oxide (1 g/l).Maximum manganese-dependent peroxidase (MnP) and lignin peroxidase (LiP) activities of around 2,000 U/l and 400 U/l were attained by the former, whereas the activities reached by the latter were of about 1,500 U/l and 200 U/l, respectively. Furthermore, laccase activity (around 150 U/l) was only detected in manganese (IV) oxide supplemented cultures.The polymeric dye Poly R-478 (0.02 w/v) was added to three-day-old cultures. A percentage of biological decolourization of about 85% was achieved using cultures supplemented with veratryl alcohol, whereas MnO2 cultures showed a rather lower percentage of around 58% after nine days of dye incubation. Moreover, a correlation between MnP activity and Poly R-478 decolourization could be observed, indicating that this enzyme is mainly responsible for dye degradation.In the present work, the in vivo decolourizing capability of the ligninolytic complex secreted by P. chrysosporium was investigated under the above-mentioned cultivation conditions, employing a model compound, such as the polymeric dye Poly R-478.
    Additional Material: 2 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 187-187 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 189-201 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Desulfovibrio vulgaris strain PY1 was isolated from a 3-chlorobenzoic acid (3CBA) degrading anaerobic enrichment culture, using anaerobic Percoll density centrifugation. When grown on pyruvate (20 mM), in the absence of sulphate and under strict anaerobic conditions, this organism converted not only the co-substrates benzoate (BA), 3-amino-BA and 3CBA to the corresponding alcohols but also ten other different halogenated benzoic acids, viz., 4-Cl-, 3-Br-, 4-Br-, 3-I-, 3-F-, 4-F-, 2,4-di-Cl-, 2,5-di-Cl-, 3,4-di-Cl- and 3,5-di-Cl-BA. This was verfied with HPLC and GC/MS spectrometric analyses. The yields of the co-substrate converted after 30 days of growth were between 20% and 88%, depending on the compounds which had been added at initial concentrations of 500 μM. Sulphate, sulphite, thiosulphate and disulphite inhibited the formation of 3-Cl-benzyl alcohol (3CBOH), i.e. a 97 to 99% inhibition, and nitrate and sulphur had no effect (a 7-10% inhibition). In cell-free extracts, the reduction of 3CBA to 3CBOH required strict anaerobic conditions, pyruvate or H2 as electron donors and the addition of methylviologen (MV), FAD, FMN or ferredoxin as electron carriers. The specific activity of the reduction of 3CBA to 3CBOH in crude extract was 5.3 nmol/(mg protein min). The reaction was not inhibited by additions of sulphate or sulphite (5 mM), but was completely inhibited at concentrations of 10 mM 3CBA or 50 mM BA. A carboxylic acid reductase (aldehyde dehydrogenase), which acted on non-activated 3CBA and was responsible for the reduction of 3CBA to 3-Cl-benzaldehyde, was found in the solube fraction (94% of the total activity). These results demonstrate that strain PY1 was able to effectively reduce a wide range of halogenated benzoic acids to the corresponding alcohols.
    Additional Material: 3 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 203-218 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The recent upsurge in information technology has provided the international community with an easy access to professional journals (e.g. Electronic Journal of Biotechnology at http://www.ejb.org; etc.), discussion groups (e.g. bioenergy@cret.org; digestion@crest.org; etc.) and recently to electronic international conferences (e.g. ICIBS; http://www.cid.harvard.edu/cidbiotech, etc.) as well as a series of biotechnological information material (e.g. http://www.psrast.org, etc.) to stay in contact and receive up-to-date information in biotechnology. There is no doubt that this new technology will be more cost effective in future and reach more people in communities around the globe.This review reports on one such an electronic conference aiming at bridging the communication gap between developed and developing countries. This conference dealt with integrated biosystems and has provided an excellent forum for more than 100 active participants from all regions of the world. As has been demonstrated in this review, the conference was able to show the very different approaches towards the use of biotechnology in developed and developing countries, cold and tropical climate regions owing to their different ecological, economical and societal problems. It also demonstrated very clearly that the field of molecular genetics and/or genetic engineering is not a priority issue in developing countries, but rather the need for clean technologies, multiproduct formation through socio-economic integrated biosystems, e.g. incorporating microbial waste management into agro-industries, in human activities and their roles in creating better health conditions, a better environment and sustain development.It is hoped that this review will lead to a greater use of the electronic facilities available to inform and educate both the northern and the southern communities more readily of their needs and requirements to improve understanding and efforts for a sustainable future.
    Additional Material: 4 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 275-288 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The purpose and scope of this article is to introduce capable zeolites into downstream processing of natural compounds, especially flavour compounds like 2,5-dimethyl-4-hydroxy-3(2H)-furan-3-one (Furaneol®Furaeol is a registered trademark of FIRMENICH, Ch). The synthesis and the recovery of Furaneol from L-rhamnose are presented. Therefore adsorption isotherms of the zeolites ZSM5 and DAY with varying modules have been determined and adsorption experiments using model and reaction mixtures of Furaneol synthesis were performed and will be discussed.
    Additional Material: 11 Ill.
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  • 16
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A fermentation process for manufacturing 1,4-piperazinium-(L,L)-dilactate from renewable raw materials and a method for processing this product into L,L-dilactide are described. Lactic acid fermentation with Lactobacillus paracasei was modified in such a way that pH control occurred by using an aqueous solution of piperazine as a correcting agent instead of sodium hydroxide solution. The production of a stoichiometrically composed piperazinium lactate was possible when the pH was 5.0. From 5.0 kg of glucose and 2.15 kg of piperazine, 6.65 kg of 1,4-piperazinium-(L,L)-dilactate were formed in the fermentation process. Separation from fermentation broth, purification and concentration of the product in aqueous solutions were carried out by means of ultrafiltration, nanofiltration and electrodialysis. Total product retention by the membranes used was about 33%. The crystalline salt was obtained by vacuum evaporation. Processing of the 1,4-piperazinium-(L,L)-dilactate into L,L-dilactide was performed in a special glass reactor. A product yield of 70% was achieved. The purified product was characterized by elementary analysis, as well as solubility behaviour, polarity and spectroscopic data. An overall process consisting of the stages fermentation, purification and concentration of piperazinium dilactate as well as cyclization of the latter to dilactide is described.
    Additional Material: 9 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 161-168 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five different chemical reagents and γ-rays were tested for the sanitization of immobilized biocatalysts with high penicillin G acylase (PGA) activity. The most effective chemical reagents were N-cetyl-N,N,N-trimethylammonium bromide (CTAB) and 2-isopropyl-5-methylphenol (thymol). The optimum concentration of CTAB for the treatment of the immobilized enzyme was 0.25% [w/v] and 1 h, for immobilized cells 0. [w/v] and 3 h. The optimum concentration of thymol for the immobilized enzyme was found to be 0.1% [w/v] and 1 h, for immobilized cells 0.27% [w/v] and 2 h. The optimum dose of γ-rays for the sanitization of the immobilized enzyme was established as 3.2 kGy, for immobilized cells as 4.5 kGy.
    Additional Material: 5 Tab.
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  • 18
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 53-64 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An advanced primary treatment process for a municipal waste water was systematically studied, using a bio-flocculation-adsorption, sedimentation and stabilzation process (BSS). It was shown that the organic removal efficiency was higher than that of the traditional primary treatment processes but lower than that of the traditional secondary treatment processes. Both adsorption and bio-flocculation played an important role in the removal of pollutants. The activated sludge within the bio-flocculation-adsorption tank could be considered a bio-flocculent which improved the quality of the effluent from the primary treatment process. As the effluent of the BSS process did not meet the requirements for a typical secondary effluent, the process may be regarded as an advanced (or enhanced) primary treatment process, suitable for waste water containing a high concentration of suspended solids and colloidal particles.
    Additional Material: 7 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 67-73 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concentration of airborne fungal spores and bacteria as related to room temperature, humidity and occupancy levels within a library building in Singapore was determined. Measurement of indoor air quality with respect to microorganisms is of particular importance in tropical environments due to the extensive use of air-conditioning systems and the potential implications for human health. This study has revealed a number of interesting relationships between the concentrations of fungal spores and bacteria in relation to both environmental and human factors. The levels of fungal spores measured in the indoor environment were approximately fifty times lower than those measured outside, probably because of the lowered humidity caused by air-conditioning in the indoor environment. The variation in fungal spore concentration in the outdoor environment is likely to be due to the diurnal periodicity of spore release and the response to environmental factors such as light temperature and humidity. The indoor concentration of fungal spores in air was not clearly correlated to concentrations measured in air outside of the library building and remained relatively constant, unaffected by the difference in the numbers of occupants in the library. In contrast, the indoor concentrations of bacteria in air were approximately ten times higher than those measured outdoors, indicating a signficant internal source of bacteria. The elevated levels of indoor bacteria were primarily attributed to the number of library occupants. Increased human shedding of skin cells, ejection of microorganisms and particulates from the respiratory tract, and the transport of bacteria on suspended dust particles from floor surfaces probably accounts for the strong positive correlation between occupancy levels and the concentration of bacteria in internal air.
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  • 21
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 96-96 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 23
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 87-96 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Preliminary results on the novel use of the bacterium Thiobacillus ferrooxidans (ATCCJ 3598 and ATCC33020) for the micro-machining (or biomachinig) of metals are reported. Biomachning is a controlled microbiological process to selectively form microstrucutures on a metal work-piece by metal removal (or dissolution) using microorganisms. Applying copper and mild steel as work-pieces, it was shown that the mass removed increased proportionately with machining time. In another experiment, the work-pieces were coated with organic photo-resistive materials to mask (i.e. protect) certain regions of the metlas, thereby defining the microstructure to be formed. The unmasked regions were successfully biomachined; the final machined profile was shown to be similar to the coating image on the original metal. Although biomachining proceeded at a slower rate than chemical machining, the undesired leaching of the metal in the region under the masked area (termed undercutting) was not as severely encountered when compared with the latter. This work demonstrates the potential use of microorganisms for the biomachining of metals. As a “green process”, the innovative use of T. ferrooxidans for the micro-machining of metals opens up the possibility of biomachining as an alternative to conventional metal processing.
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  • 24
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the microbial treatment of a sandy model soil artificially contaminated with polycyclic aromatic hydrocarbons (PAHs), a large residual pollution was found. The remainig PAHs were sorbed into the micropores of the soil and were therefore not bioavailable. Using a lab-scale precolator, the microbially pretreated soil was subjected to aftertreatment with surfactants with the aim of further degradation of its pollution. Two commercial nonionic surfatants of the polyethoxylate type, Präwozell F1214/5 N and Sapogenat T-300, were used. The surfactants differ both in their physicochemical properties (CMC value, PAH solubilization capacity, adsorption onto soil) and in their microbial degradability. During aftertreatment under permanently aerobic conditions, only a weak PAH accumulation in the liquid phase was observed, which was due to a low solubilization rate as well as to simultaneous microbial degradation of the dissolved PAHs. Temporary anaerobiosis successfully suppressed the microbial degradation of both the surfactant and the solubilized PAHs, resulting in a more intensive PAH accumulation. But the PAH content of the soil - the essential criterion for evaluating the efficiency of surfactant application - was not decreased to a larger extent with surfactants than without them. To find out why the surfactants failed to act, the surfactant and hydrocarbon distribution among the liquid and solid phases was studied in mixtures of phenantherne-spiked solis and Präwozell-containig liquids; at heavy phenanthrene loading, the aqueous phase was saturated with PAH; at weak loading, it was unsaturated. Model-aided data analysis showed that the soil may contain PAH in two fractions: strongly sorbed into soil pores and, in the case of heavy loading, also weakly attached to the soil surface. The latter is easily extractable, resulting in a PAH-saturated liquid, while strongly adsorbed PAH is only partially dissolved due to competition between the micelles and the soil pores for the PAH. The microbially pretreated soil contains only strongly bound PAHs, which are as difficult to extract by surfactants as they are poorly accessible for microbes.
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  • 25
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Autochthonous bacteriocenoses in semiarid soils in Patagonia were found to be capable of rapidly adapting to high contamination with crude oil. This adaptation at community level is due to the selective enrichment of hydrocarbon-utilizing bacteria always present in these soils. Immediately after a heavy contamination with crude oil, the authochthonous bacteriocenosis contained about 28% hydrocarbon-utilizing bacteria which could be classified into eight ecotypes with characteristic metabolic profiles. Mainly n-alkanes were used as growth substrates of representative strains. After seven months' exposure to crude oil, the bacteriocenosis consisted almost entirely of hydrocarbon-utilizing bacteria. At least fourteen ecotypes were distinguishable, and the majority of representative strains were able to metabolize a broad spectrum of aliphatic and aromatic hydrocarbons. Corresponding to the significant alteration of the physiological diversity, drastic changes to the taxonomic diversity were also found. Whereas at the beginning of the study the autochthonous bacteriocenoses were dominated by GRAM-positive genera of the Actinomycetales (Dietzia, Gordona, Nocardia, Rhodococcus, Streptomyces) with high ecological potency, after just two months' exposure to crude oil, GRAM- negative bacteria (especially Pseudomonas stutzeri) became predominant within the hydrocarbon-utilizing bacteriocenoses accompanied by some GRAM-positive genera of the Actinomycetales with a significantly lower abundance. These findings underline the importance of Pseudomonas and some genera of Actinomycetales for processes of natural attenuation and the technically supported in situ bioremediation of soil polluted by crude oil in Patagonia.
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  • 26
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 149-159 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some parameters of the production of an alkaline protease by Rhizopus oryzae in the solid state fermentation of wheat bran were optimized. Using the optimum parameters of an inoculum age of 7 days, an incubation time of 9 days, an amount of CZAPEK-DOX (liquid medium) of 6 ml/g bran and an incubation temperature of 33°C, an activity of 50 U/g bran was achieved. The initial pH of the CZAPEK-DOX medium had little effect. Re-incubation of mouldy bran with only fresh CZAPEK-DOX yielded 3 times total activity compared to single-cycle fermentation. As for the effect of the amount CZAPEK-DOX medium, the water constituent contributed more to activity increase than did the salt component. The ARRHENIUS activation energies were 23 and 7.9 kcal/mole below and above the optimum of 33°C, respectively. In all the studies, along with protease production, variation of protein content and specific activity were also observed. Attempts were made to explain the effects and also gauge their implications for large-scale production.
    Additional Material: 4 Ill.
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  • 27
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 28
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 29
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Because of the growing utilization of renewable raw materials, the technical use of lignocellulosic fibres from wood and other annual plant materials is becoming increasingly important. The conventional production process of fibreboards is characterized by high-energy consumption and use of ecologically insecure synthetic lesins. Approximately 40 to 45% of the total energy expenditure are used for the thermo-mechanical pulping. Because of high plastication temperatures, an inactive lignin crust on the fibre surface is formed. For that reason, for glueing of the fibres, urea formaldehyde and melamin resins are usually used. The costs for the resin amount to approximately 50% of the entire material costs. In addition, environmental problems are caused. The aim of our investigation is the reduction of energy and resin consumption by enzymatic modification of wood chips and the enzymatic activation of the inherent bonding strength of the material. The first industrial use of fungi for the modification of wood was in the production of “Myco wood”. Pleurothus ostreatus and Trametes versicolor were applied for nonsterile delignification of beech wood. The present investigation of the authors deals with the mycological pre-treatment of wood chips in order to reduce the energy consumption during wood pulping. The screening results favour the brown rotter Gleophyllum trabeum for pinewood (Pinus silvestris) and the white rotter Trametes hirsuta for beech (Fagus silvatica). Both species show resistance against mould fungi. The use of submerged inoculum of these fungi has the advantage over wheat inoculum that the lag phase is less than 12 hours and that the addition of nutrients or fungicides is not necessary. Short-time wood chip incubation results in a 40% decrease of energy consumption during thermo-mechanical pulping and in improved fibreboard properties. Lignin reduction could not be determined by gravimetrical and x-ray microanalysis.Comparative investigations of fibre incubation using laccase, a submerged culture of Trametes versicolor and rape straw fibres show a high increase in bending and tensile strength and an improvement in the hygroscopic properties of glue-free fibre boards for the last two incubation kinds. Similar effects have been obtained incubating pine wood fibres for the production of fibre sheets with enzyme medium of Trichoderma reseei.
    Additional Material: 4 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 335-350 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the 20th century, important relationships developed between the oil industry and both microbiological and biotechnological research. Basic microbiological research has played an important role in both the exploration and production sectors of the oil industry, but as the maturity of the industry has progressed, such contributions have been relegated with respect to their importance. With respect to refining and petrochemicals manufacture, process routes have been extensively researched, but only rarely have the biotechnological solutions developed satisfied the economic criteria that resulted in major investment. In fact, situations exist where investment has occurred, but project life was unrealistically short, suggesting a need for extreme caution when evaluating biotechnological processes for the oil industry. However, as far as engineered processes for both biotreatment and bioremediation are concerned, the fundamental research that has underpinned other areas of hydrocarbon microbiology will finally prove to be of both technical and economic value, in ensuring that the essential needs of treatment, rather than disposal, and restoration, rather than environmental destruction, can be satisfied by the oil and other industries involved in both geochemical manipulation and natural resource exploitation.
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  • 31
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of different growth-limiting factors - namely the sources of carbon, nitrogen and phosphorus and the dilution (growth) rate - on the ice-nucleation activity of Pseudomonas syringe CCM 4073 was studied. A higher ice-nucleation activity was observed at a lower dilution (growth) rate (D = 0.1 h-1) than at a higher dilution (growth) rate (D = 0.3 h-1). Remarkable differences in ice-nucleation activity were found in its dependence on the growth-limiting factor. The highest ice-nucleation activity was observed under carbon limitation (T90 = -2.7°C), a medium activity under nitrogen limitation (T90 = -5°C) and lowest activity under phosphorus limitation (T90 = -12.3°C). After the addition of excess nitrogen or phosphorus to steady-state cultures, the ice-nucleation activity was restored.
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  • 32
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 33
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 65-65 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 34
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 35
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 41-52 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies were carried out to evaluate the feasibility of using coffee industry residues, viz. coffee husk, coffee leaves and spent coffee ground as substrates in solid state fermentation (SSF) to cultivate edible mushrooms Pleurotus. Eight strains of Pleurotus ostreatus and two strains of Pleurotus sajor-caju were screened on a medium prepared from aqueous extract of coffee husk and agar. Based on best mycelial growth (9.68 mm/day) and biomass production (43.4 mg/plate in 9 days at 24°C), the strain P. ostreatus LPB 09 was selected for detailed studies. SSF was carried out using these substrates under different moisture conditions (45-75%) and spawn rates (2.5-25%). In general, although a 25% spawn rate appeared superior, the 10% spawn rate was recommended for all the three substrates in view of the process economics, as there was not any significant difference in the increase with 10 to 15%. The ideal moisture content for mycelial growth was 60-65% for coffee husk and spent coffee ground, and 60-70% for coffee leaves. The biological efficiency (BE), which is defined as the ratio of the weight of fresh fruiting bodies to the weight of dry substrate, multiplied by 100, and which indicates the fructification ability of the fungus for utilizing the substrate, was best with coffee husk. With coffee husk as the substrate, the first fructification occurred after 20 days of inoculation, and the biological efficiency reached about 97% after 60 days. When coffee leaves were used as the substrate, no fructification was observed even upon prolonged cultivation. With spent ground as the substrate, the first fructification occurred 23 days after inoculation and the biological efficiency reached about 90% in 50 days. There was a significant decrease in the caffeine and tannin contents (61 and 79%, respectively) of coffee husk after 60 days. It was remarkable to observe that caffeine was adsorbed onto the fruiting body (0.157%), indicating that it was not completely degraded by the fungal culture. However, no tannins were found in the fruiting body, indicating that the fungal strain was capable of degrading them. The results showed the feasibility of using coffee husk and spent coffee ground as substrates without any pre-treatment for the cultivation of edible fungi in SSF, and provided one of the first steps towards an economical utilization of these otherwise unutilized or poorly utilized residues.
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  • 36
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 75-81 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Serratia marcescens biovar A2/A6 is able to produce a red pigment as a secondary metabolite which has antimicrobial activity. This paper describes its growth and biopigment formation in batch cultures, in media containing different concentrations of lactic acid and beef extract as carbon and nitrogen sources, respectively. An unstructured model has also been developed to describe its growth, lactic acid uptake and biopigment formation. The comparison of simulated and experimental data shows that the proposed model predicts reasonably well the system behaviour over a range of conditions.
    Additional Material: 2 Ill.
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  • 37
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 97-98 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 38
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 39
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 334-334 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 40
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The impact of hydrocarbon remediation on several enzyme activities (catalase, dehydrogenase, lipase, protease, urease, alkaline phosphomonoesterase, fluorescein diacetate hydrolysis) and microbial properties (biomass-C, respiration, N-mineralization, qCO2, microbial counts) was evaluated in a laboratory study over a period of 10 weeks. A pristine soil was contaminated with diesel oil (10 mg/g soil) or with a mixture of phenanthrene and naphthalene (total amount 1 mg/g soil) and supplemented with inorganic nutrients to give a C:N ratio of 20:1. The corresponding controls consisted of uncontaminated nutrient-supplemented soil. Oil contamination caused a significant initial increase of all biological parameters measured. In the presence of PAHs, biomass-C, respiration, protease activity and heterotrophic counts were significantly enhanced, while urease activity was depressed. N-mineralization was initially, however, reversibly inhibited in the presence of oil and PAHs.The measured parameters behaved differently over time: Biomass-C, respiration and alkaline phosphomonoesterase activity reached a maximum activity after about 2-5 weeks, corresponding to the period during which the majority of hydrocarbons disappeared, and declined thereafter to the background level. Activities of catalase and dehydrogenase also followed this pattern, however, were characterized by fluctuations. Activities of lipase, protease, urease and fluorescein diacetate hydrolysis increased and remained almost constant throughout the incubation period.
    Additional Material: 10 Ill.
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  • 41
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 20 (2000), S. 351-368 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The action resonance theory (ART), a hypothesis based on a logical extension of EINSTEIN's theory of Brownian movement, suggests that the genotype × environment interaction can be modelled as forceful encounters of the gene-products of an organism with its environment. This model has implications for molecular and cell biology, morphogenesis, evolutionary development via mutation, the mechanism of natural selection and overall function of ecosystems, extending SCHRÖDINGER's programme for molecular biology. Action, a thermodynamic property with the same physical dimensions as angular momentum and PLANCK's quantum of action, is proposed to be reversibly generated as a result of the molecular exchange of quanta, which become resonant at equilibrium, corresponding to an optimum degree of entropy and action for living systems. Because the theory can potentially predict solutions to unsolved problems such as the folding of proteins it has strong implications for successful genetic modification of organisms and for biotechnology in general; the design of a programme of research to test this theory is proposed. A key element in this research programme, improving productivity and sustainability, would be the need to select genetically modified strains in the ecological environment or niche in which they are required to function.
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  • 42
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
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  • 43
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous counter-current chromatographic processes have been successfully used in the petrochemical and sugar industry over the last 30 years. Only recently has simulated moving bed (SMB)-technology attracted widespread interest in the pharmaceutical industry, mainly as a very efficient system for chromatographic enantioseparation. The application of this technique to the downstream processing of biotechnological products requires some specific changes to meet the special demands of bioproduct isolation. Production processes are set up on an multi-ton scale, for example, for the purification of fructose with both yield and purity higher than 90%. Examples for other mono- and oligosaccharides are reported. In the purification of fatty acids or fat soluble vitamins, SMB technology under supercritical fluid conditions gives additional benefits and increases the productivity by a factor of four when a pressure gradient is applied. Another field of operation is the isolation of drug compounds from natural sources where different batch- and SMB-chromatographic steps could be successfully combined. First examples are reported for cyclosporine A and paclitaxel isolation. Finally, step-gradient elution modes can be used continuously, as demonstrated for the isolation of monoclonal antibodies.
    Additional Material: 6 Ill.
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  • 44
    ISSN: 0009-2940
    Keywords: Norpinanes, preparation ; Carbocations, classical and nonclassical ; Neighbouring group participation ; Halonium ions ; Migratory aptitudes in carbocations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrophilic Additions to the Bicyclo[1.1.0]butane System of Tricyclo[4.1.0.02,7]heptane Derivatives: Halogen ElectrophilesThe known reactions of 8,8-dibromotetracyclo[5.1.0.02,4.03,5]octane (3a) and homobenzvalene (7) with pyridinium bromide perbromide and iodine, respectively, were carried out in the presence of tetra-n-butylammonium chloride. The formation of the chloro-substituted norpinane derivatives 6a and 9 is evidence for cationic intermediates. The same mechanism is operative in the reaction of pyridinium bromide perbromide with the dichlorotetracyclooctane 3b, which was prepared from 7 and dichlorocarbene. On exposure of tricyclo[4.1.0.02,7]heptane (1) to N-bromosuccinimide in acetone/water/triethylamine, the bromonorpinanol 22, the bromonorcaranols 23, and cyclohex-1-ene-1-carboxaldehyde (24) were obtained. On the basis of the steric course and thermodynamic considerations, the cationic intermediates generated in the above reactions by attack of the electrophiles at the bicyclobutane systems are assigned the halonium ion structure 38 and the nonclassical structures 34 and 35, respectively. Elemental bromine and iodine converted the phenyltricycloheptane 10 into the respective diastereomeric norpinanes 11 and 12, which were transformed smoothly into the diastereomeric methyl ethers 13 and 14 by treatment with sodium methoxide in methanol. The reactions of 10 with pyridinium bromide perbromide in pyridine, cyanogen bromide in the presence of aluminium trichloride, and N-bromosuccinimide in acetone/water gave rise to norpinane derivatives, i.e. the pyridinium salt 15, the nitrile 16, and the alcohol 18, respectively. In the case of cyanogen iodide in acetonitrile, the solvent participated in the process to yield the 2-(norpinylimino)propionitriles 17. Corresponding to the configurations of the products, the attack of a halogen electrophile at 10 leads to classical 6-phenyl-6-norpinyl cations 41, which may be approached by nucleophiles from the two possible faces. As origin for the low tendency of the cations 33-35 and 41 to rearrange to norcaryl cations, the electronegativity of the halogen atoms is suggested. The reduced migratory aptitude of a CHHal relative to a CH2 group results from its electron deficiency and from the decreased stability of 7-halo-2-norcaryl relative to the parent 2-norcaryl cations. The chlorophenyltricycloheptane 25 was prepared from 10 and treated with aqueous sulfuric acid to give the norpinanol 27. Formed by protonation of the bicyclobutane system of 25, the cationic precursor of 27 shows a behaviour similar to that of cations 41.
    Additional Material: 2 Tab.
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  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 433-436 
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl- ; Benzofuran epoxides ; Quinone methides ; Photoisomerization ; Chromenes ; 3-Benzofuranones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimethyldioxirane oxidation of the 3-substituted 2-methylbenzofurans 1 [1a: 3(E)-styryl, 1b: 3-acetoxy, 1c: 3-(tert-butyldimethylsilyloxy)] is reported. Only quinone methide 3a, none of the benzofuran epoxides 2a-c, could be detected by 1H- and 13C-NMR spectroscopy at low temperature (-30°C), which on photoisomerization led to chromene 7a. The benzofuran-3-ones 5b, c and the α-diketone 6c are presumably formed by thermal isomerization of the transient benzofuran epoxides 2b, c and quinone methide 3c.
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  • 46
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 581-584 
    ISSN: 0009-2940
    Keywords: Fullerenes ; [3 + 2] Cycloadditions ; Nitrile oxides ; Isoxazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalization of C60 with Nitrile Oxides to 4,5-Dihydroisoxazoles and Their Structure DeterminationCycloadducts 3 of nitrile oxides 2 with C60 (1) are synthesized and isolated. The cycloadducts are characterized by 13C-NMR spectroscopy and high-resolution FAB mass spectrometry. X-ray structure determination of the 3-(9-anthryl)-4,5-dihydroisoxazole derivative 3a of C60 with CS2 included in the crystals is achieved at 173 K without disorder problems.
    Additional Material: 3 Ill.
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  • 47
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 565-579 
    ISSN: 0009-2940
    Keywords: Li enolates, of 6-trifluoromethyl-1,3-dioxan-4-one ; Alkylation, of Li enolates ; Michael additions, to 1,3-dioxin-4-ones, to nitroolefins ; Benzylation, abnormal products ; Methyl 3-hydroxy-3-trifluoromethyl propionates ; 1,3-Dioxanones, 2,5,6-trisubstituted ; Conformation, of 1,3-dioxan-4-ones ; Twist-boat conformation, of cis,cis- and trans,trans-2.5,6-trisubstituted 1,3-dioxan-4-ones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Enantiomerically Pure 4,4,4-Trifluoro-3-hydroxy-butanoic Acid Derivatives, Branched in the 2- or 3-Position, from 6-Trifluoromethyl-1,3-dioxan- and -dioxin-4-onesEnantiomerically pure 3-hydroxy-3-trifluoromethyl-propionic acid and esters, substituted in the 2- or 3-position, are prepared (13 examples) from (R)- or (S)-4,4,4-trifluoro-3-hydroxy-butanoic acid. Key intermediates are the 2-t-butyl-6-trifluoromethyl-1,3-dioxan- and -dioxin-4-ones. The Li enolate of the cis-dioxanone is generated with t-BuLi and reacts with electrophiles (alkyl halides, aldehydes, imines, nitroolefins, Br2, I2) with predominant formation of trans,trans-2,5,6-trisubstituted dioxanones (9 examples). Elimination of HBr from the 5-Br-substituted dioxanone gives the (R)- or (S)-dioxinone, a chiral derivative of 4,4,4-trifluoro-3-oxo-butanoic acid (trifluoro-acetoacetate). Michael additions of cuprates or of CuCl-doped Grignard reagents to the dioxinone produce 6,6-disubstituted dioxanones (10 examples) bearing a CF3 group in the 6-position. In most cases this addition is highly diastereoselective, with the new substituent winding up in the trans position. There are, however, surprising exceptions, such as the product formed with benzylmagnesium chloride which is an abnormal adduct with a p-quinoid structure (26) and with the newly introduced group in the cis position with respect to the t-Bu group. The structures of four trisubstituted dioxanones bearing CF3 groups are determined by X-ray crystal structure analysis (Figure 1, Table 1), one of them including the absolute configuration (by anomalous diffraction). Besides the well-known sofa, a twist-boat conformation of dioxanones appears to be favorable. The solution conformations of the different types of CF3-substituted dioxanones are derived from Nuclear Overhauser NMR measurements and compared with the crystal structures (Figure 3).
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  • 48
    ISSN: 0009-2940
    Keywords: Isocyanide-bridged metal complexes ; Metal complexes as ligands ; N-Protonation (alkylation, metalation) ; Heteropentanuclear metal complexes ; Diisocyanide bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination Chemistry with the Complex Chelating Ligands [{Fe2Cp2(CO)3)2{CN[CH2]n NC}] (n = 2, 3). Heteropentanuclear “Supercomplexes” with μ5-Diisocyanide BridgesHerrn Professor Dr. O. J. Scherer zum 60. Geburtstag gewidmet.The tetranuclear complexes [(Fe2Cp2(CO)2(μ-CO)}2(μ4-CN[CH2]nNC}] [n = 2 (2), 3 (3)] act as bidentate chelating ligands towards the Lewis-acidic metal halides MnCl2, MnBr2, FeCl2, CoCl2, NiCl2, NiBr2, CuCl2, CuBr2, ZnCl2, ZnI2, CdCl2, CdI2, HgCl2, the chloro complexes [MCl2-(NCPh)2] (M = Pd, Pt), Zn(OAc)2 · H2O, and [Mo(CO)4(η-NBD)] (NBD = 2,5-norbornadiene) to give a total of 22 pentanuclear “supercomplexes” ,6-21, which have been characterized by elemental analyses and IR and NMR (1H, 13C) spectra. Reaction of 2 with [Ni(COD)2] in CH2Cl2 gave only rise to the dichloronickel(II) species 9a. Very remarkably, the pentairon complex [(Fe2Cp2(CO)2(μ-CO)2(μ5-CN(CH2)2-NC)}]FeCl2 (7) also formed spontaneously (!) when 2 was refluxed in chloroform for several hours. The X-ray structure analysis of [{Fe2Cp2(CO)2(μ-CO))2{μ5-CN(CH2)2NC}]CdI2 (14b) confirms the twofold μ3-(C,C,N) bridging mode of a diisocyanide ligand in a cis/cis-anti-configurated [Fe2]2Cd pentanuclear system of crystallographic C2 symmetry.
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  • 49
    ISSN: 0009-2940
    Keywords: Germane, optically active ; Biotransformation, stereoselective ; Transesterification, enzymatic ; Porcine liver esterase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)germane [( - )-MePhGe(CH2OAc)(CH2OH)] by an Esterase-Catalyzed Transesterification: the First Enzymatic Synthesis of an Optically Active GermaneThe prochiral germane MePhGe(CH2OH)2 (1) was synthesized by a six-step synthesis starting from GeCl4 (3) [3 → Cl2Ge(CH2Cl)2 (4) → Ph2Ge(CH2Cl)2 (5) → (CF3S(O)2O)PhGe(CH2Cl)2 (6) → MePhGe(CH2Cl)2 (7) → MePhGe(CH2OAc)2 (8) → 1]. Reaction of 1 with Ac2O/NEt3 (molar ratio 1: Ac2O = 1:1) gave the racemic germane rac-MePhGe(CH2OAc)(CH2OH) (rac-2). Stereoselective transesterification of 1 with vinyl acetate (acetate source and solvent), catalyzed by immobilized porcine liver esterase (PLE; E.C.-3.1.1.1), yielded the optically active germane ( - )-MePhGe(CH2OAc)(CH2OH) [( - )-2] (yield 57%, enantiomeric purity 50% ee).
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  • 50
    ISSN: 0009-2940
    Keywords: Platinum complexes, five-coordinate ; Nitrosyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title complex has been prepared in 36% yield by reaction of [NBu4]2[trans-Pt(C6Cl5)2Cl2] with NOClO4 (1:1) in CH2Cl2. The anion exhibits an almost tetragonal-pyramidal geometry (X-ray analysis), the platinum atom being virtually located in the basal plane and the NO ligand occupying the apical position. The Pt—N—O unit is bent [119.5(8)°].
    Additional Material: 1 Ill.
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  • 51
    ISSN: 0009-2940
    Keywords: Dimethyldioxirane ; 3-Phenyl-2-phenylsulfonyloxaziridine ; Titanium enolates ; Enantioselective hydroxylation ; α-Hydroxy carbonyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselective oxidation of the optically active titanium enolate complexes 2 of propiophenone by dimethyldioxirane (3) (as acetone solution) and 3-Phenyl-2-phenylsulfonyloxaziridine (4) has been investigated. The chiral titanium enolates 2 were synthesized by the reaction of the lithium enolate of propiophenone and the respective optically active chlorotitanate complexes 1. For 3 as oxidant, the stereoselectivity of the α hydroxylation strongly depends on the substitution pattern at the central titanium atom and reached for the best case, namely 2e, an enantiomeric excess (ee) of 63%. Solvent and temperature exhibited only small effects on the stereoselectivity. Compound 4 as oxidant gave lower enantiomeric excesses than 3.
    Additional Material: 1 Tab.
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  • 52
    ISSN: 0009-2940
    Keywords: C—C Bond cleavage, kinetics of ; Heats of formation ; Radicals, stability of ; Capto-dative effect ; Geminal substituents, energetic interaction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects on the Strength of C—C Bonds, 14[1].  -  Kinetic and Thermodynamic Stability of 2,3-Bis(dialkylamino)-1,4-diketones  -  Energy of Stabilization of α-Dialkylamino α-Carbonylalkyl Radicals with Capto-dative SubstituentsProf. Dr. H.-G. Viehe zum 65. Geburtstag gewidmet.The equilibrium constants and rate constants for the dissociation of the 2,3-bis(dialkylamino)-1,4-diketone diastereomers meso- and DL-7a and 7b were measured over a temperature range of 40°C. From the enthalpies of dissociation ΔHDiss and enthalpies of activation ΔH≠ and the strain enthalpies of 7 the bond dissociation enthalpies BDE(C—C) of 7 were determined. By comparison with the dissociation enthalpies of Ct-Ct alkanes[21] the change of these BDEs(C—C) by the cap-to-dative substitution was determined to be 85.4 kJ mol-1 (20.4 kcal mol-1). The heats of formation ΔHof (g) of a series of amino ketones 8 were determined from their heats of combustion and their heats of evaporation. From the ΔHof(g) values in combination with MM2 calculations of their strain enthalpies strain-free increments CHn[N, CO, C2 - n] with n With n = 0, 1, 2 were derived and geminal interaction enthalpies in the ground states were obtained thereof. The radical stabilization enthalpy RSE of 6 was deduced from the ΔBDE(C—C) values and the ground state effect to be 73.6 kJ mol-1 (17.6 kcal mol-1). From these data and the radical stabilization enthalpies RSE of α-aminoalkyl radicals (4.2 kJ mol-1) and α-carbonyl radicals (28.9 kJ mol-1) a synergetic radical stabilization enthalpy of 40.5 kJ mol-1 (9.7 kcal mol-1) is deduced. This number combines “extra” resonance stabilization and general inductive or anomeric geminal substituent interaction in the radicals. The crystal structure of meso-7a has been determined by X-ray diffraction methods.
    Additional Material: 2 Ill.
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  • 53
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 739-742 
    ISSN: 0009-2940
    Keywords: C—H Activation ; Palladium catalysis ; Domino coupling processes ; Palladium(IV) intermediates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By palladium catalysis substituted ortho-iodoanisoles (5, 8, 10, 13) are transformed either to annulated pyran (6) or furan derivatives (7, 9, 11, 14, 15), depending on the reactivity of additional substituents. The regiochemistry of the domino coupling processes is analyzed and a mechanistic rationale developed. Key step is the C—H activation at methoxy groups.
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  • 54
    ISSN: 0009-2940
    Keywords: Fullerenes ; Azirines ; Photochemistry ; [3 + 2] Cycloadditions ; Electron transfer reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreactions with C60-Fullerene. [3 + 2] Photocycloaddition of 2,3-Diphenyl-2H-azirineUpon irradiation 2,3-Diphenyl-2H-azirine (2) is added to C60 1 with formation of mono and oligo adducts. 1,9-(3,4-Dihydro-2,5-diphenyl-2H-pyrrolo)fulleren-60 (3) has been isolated and identified by standard spectroscopic methods. Mechanistic studies revealed two reaction paths leading to 3, i.e. the classic 1,3-dipolar cycloaddition via the nitrile ylide 4 (direct irradiation) or a route via 2-azaallenyl radical cations 5 (sensitization by photoinduced electron transfer).
    Additional Material: 1 Tab.
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  • 55
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 805-811 
    ISSN: 0009-2940
    Keywords: Bent metallocene complexes ; Heterodimetallic zirconium-aluminium compounds ; Hydrocarbyl-bridging ligands ; “π-Agostic” interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (s-trans/s-cis-η4-butadiene)zirconocene reagent adds dimethylaluminium chloride to yield the heterodimetallacyclic main group/transition-metal system 2b, containing a seven-membered metallacyclic framework that exhibits a “π-agostic” s̰-allyl zirconium interaction. Similar compounds (2c-f, 5a, 6) are obtained upon reaction of (butadiene)zirconocene with Et2All and (butadiene)hafnocene with Me2AlCl or Et2AlI. Addition of Me2AlCl or Et2AlI to (isoprene)zirconocene proceeds regioselectively to yield the corresponding heterodimetallacycles bearing the methyl substituent at C-3 (i.e. near to the attached aluminium center). The iodide-bridged heterodimetallacycles exhibit dynamic NMR spectra that indicate a rapid enantiomerization process on the NMR time scale (ΔG±ent ≈ 11-12 kcal mol-1). It is assumed that this automerization reaction proceeds by rate-limiting aluminium-halogen bond cleavage leading to an acyclic mixed metal heterodimetallic intermediate. This process is markedly inhibited by the presence of excess diethylaluminium iodide.
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  • 56
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 829-833 
    ISSN: 0009-2940
    Keywords: N-Isocyandialkylamine complexes ; Cyanamide complexes ; Guanidine complexes ; Reactions at the coordinated ligand ; N—N bond breakage ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Functional Isocyanides, XXIV.  -  Reactions of N-Isocyanodialkylamine Complexes with Secondary AminesReactions of pentacarbonyl(N-isocyanodialkylamine) group 6-metal complexes [M(CO)5CNNR2] [M = Cr, W; R = Et, iPr; 2R = -{MeCH(CH2)3CHMe}-] with secondary amines proceed with cleavage of the N—N bond and C→N migration of the metal to give the corresponding N-cyanamide complexes [M(CO)5NCNR′2] (1a-2g) [R′ = Me, Et, nPr, nBu; 2R′ = —(CH2)4—, —(CH2)5—, —(CH2)2O(CH2)2—]. However, when diiodobis(N-isocyanodialkylamine)platinum(II) was allowed to react with an excess of the amine amine(guanidine)platinum(II) complexes [PtI2(HNR′2){HN=C(NR′2)2}] (3a-c) [R′ = Et; 2R′ = —(CH2)5—, —(CH2)2O(CH2)2—] were obtained. Structural assignments are made on the basis of IR, NMR (1H, 13C), and mass spectroscopy as well as of an X-ray structure analysis of trans-[PtI2(HNEt2){HN=C(NEt2)2}] (3a).
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  • 57
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 849-851 
    ISSN: 0009-2940
    Keywords: Selenium iodides ; Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Derivatives, IX.  -  Stabilisation of Selenium Diiodide by ComplexationHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.Stable selenium diiodide complexes 2 are obtained by the reaction of the 2-selenoxoimidazolines 1 with iodine. An X-ray structure analysis of 2c reveals its monomeric nature. In the trigonal bipyramid, the iodo substituents are situated in axial positions forming elongated iodine bonds [Se-I(1) 2.854(1), Se—I(2) 2.768(1) Å; I(1)—Se—I(2) 175.4(0)°].
    Additional Material: 1 Ill.
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  • 58
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 881-885 
    ISSN: 0009-2940
    Keywords: Fiscellanes, doubly-bridged ; Semibullvalenes, doubly-bridged ; Cyclopropanes ; SEM-protective groups ; Annulenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of the First Doubly-Bridged FiscellanesThe synthesis of the novel hexacycle 2 containing a fiscellane framework is described. Starting from Weiss' tetraester 6, the fiscellane 2 is build up in six steps by successive chemical transformation of the methoxycarbonyl functions using SEM protecting groups. The behaviour of the novel diol 2 towards introduction of several leaving groups is examined. Upon treatment with methanesulfonyl chloride the highly strained hexacycle 2 undergoes a skeletal rearrangement with formation of the triene 4. Instead of reacting to a doubly-bridged semibullvalene 3, the diol 2 gives rise to a new heterocyclic π perimeter 5 when the trifluoroacetyl derivative 12 is treated with sodium iodide in acetone.
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  • 59
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 905-909 
    ISSN: 0009-2940
    Keywords: Allyltributylstannane ; Trimethylsilyl cyanide ; α,β-Epoxy aldehydes ; Chelation-controlled addition ; Diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chelate-Controlled Diastereoselective Addition to α,β-Epoxy AldehydesLiClO4-mediated reaction of trans-substituted α,β-epoxy aldehydes 1 with allyltributyltin (2) or trimethylsilyl cyanide provides a general method for the synthesis of the corresponding syn-alcohols 3 with high selectivity. In the case of cis-substituted α,β-epoxy aldehydes the selectivity depends on the size of the substituents.
    Additional Material: 2 Tab.
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  • 60
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 947-953 
    ISSN: 0009-2940
    Keywords: 1-Aza-2-azoniaallene cations ; Isocyanates ; 4,5-Dihydro-5-oxo-1,2,4-triazolium salts ; Cinnolinium salts ; Cycloadditions ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aza-2-azoniaallene salts 3, prepared in situ from geminal chloroalkylazo compounds 2 with Lewis acids, react with isocyanates 4 to give 4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 6 and 4,5-dihydro-5-oxo-1H-1,2,4-triazolium salts 7, respectively. The intramolecular cyclization of 3u opens a new route to cinnolinium salts 11. Allenes 3 react with isobutene to give pyrazolium salts 8. According to AM1 calculations the cycloadditions of 3 to isocyanates proceed in two steps via acylium salts 5 as intermediates. Mechanistically, the rearrangements 6 → 7 resemble Wagner-Meerwein rearrangements rather than pericyclic [1,5]-sigmatropic shifts.
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  • 61
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 965-966 
    ISSN: 0009-2940
    Keywords: Cyclophanes ; Photochemistry ; Triplet states ; Enolization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When ethanolic solutions of 4-(1-naphthoyl)[2.2]paracyclophane (3) and 4-(2-naphthoyl)[2.2]paracyclophane (4) are subjected to UV irradiation at low temperature, 1,5-hydrogen migration of the 2-H bridge proton to the carbonyl group takes place, leading to the enol of type 2. In the context of mechanistic considerations the triplet spectroscopic properties of 3 and 4 are discussed.
    Additional Material: 1 Ill.
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  • 62
    ISSN: 0009-2940
    Keywords: Cyclophosphahydrazides ; Dinitrogen-bridged ; Conformation ; Chair and Boat forms ; Dinuclear Mo(0) complexes ; 1,2,4,5,3,6-Tetrazadiphosphorinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of methylhydrazine with RPC12 (R = Et, tBu, and Ph) produced the cyclic phosphorus (III) hydrazides (1,2,4,5,3,6-tetrazadiphosphorinanes) [RPN(Me)N(H)2 (R = Et, 1; (Ph, 2; tBu, 3) in good yields. The 1H-and 31P-NMR spectroscopic analysis indicated that 1 exists in chair and boat conformations. However, it crystallizes in the chair conformation exclusively. The X-ray crystallographic investigation of all the three cyclo-phosphorus hydrazides 1-3 confirms the existence of these compounds in the chair conformations in the solid state. The reaction of Mo(CO)4-(NHC5H10)2 with 1 and 2 gives the dinuclear Mo(0) complexes [{Mo(CO)4(NHC5H10)}2(μ-[RPN(Me)N(H)]2}] (R = Et, 5; Ph, 6). Based on 1H- and 31P-NMR spectroscopic data, a bridging dinuclear dimetallic formulation is proposed for 5 and 6. The IR spectra indicate that the carbonyls are disposed in cis-geometry around the Mo(0) center.
    Additional Material: 6 Ill.
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  • 63
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2373-2379 
    ISSN: 0009-2940
    Keywords: Chelating ligands ; Molybdenum complexes ; Peroxo complexes ; Catalysis ; Olefine epoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N-Chelate Ligands - Applications in Molybdenum-Catalyzed Epoxidation of Olefins*Oxodiperoxomolybdenum complexes 4 of substituted 2-[3(5)-pyrazolyl]pyridines (2a-g) were synthesized in order to control the solubility of these complexes in organic solvents. Alkyl side chains (butyl, octyl, octadecyl) increase the solubility of the complexes and enable spectroscopic investigations in solution. Due to the symmetry of the ligands the peroxo complexes 4 appear in two isomeric forms, with the terminal oxo ligand in the trans position either to pyridine or to pyrazole. The latter isomer of (C5H4NC3H2N2CH2COOEt)MoO(O2)2 (4f) was characterized by an X-ray structure analysis. The alkyl-substituted peroxo complexes are active catalysts for the epoxidation of olefins with tert-butyl hydroperoxide.
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  • 64
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2397-2401 
    ISSN: 0009-2940
    Keywords: [Amino(imino)phosphane]gallium trichloride adduct ; 1,3-Diaza-2λ2-phosphonia-4λ4-gallatacyclobutanes ; Nickel tricarbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Diaza-2λ2-phosphonia-4λ4-gallatacyclobutanesReaction of amino(imino)phosphanes 1a-c with gallium trichloride results in the formation of 1,3-diaza-2λ2-phosphonia-4λ4-gallatacyclobutanes 3a, b with elimination of chlorotrimethylsilane (1a) or tert-butyl chloride (1b, c). The intermediately formed amino(imino)phosphane/Lewis acid adducts R(Me3Si)NPN(GaCl3)R′ (2, R,R′ = tBu, Me3Si) can be isolated in the case of compound 2a (R = R′ = SiMe3). A diazaphosphasilacyclobutane - gallium trichloride adduct 4 is formed in a side reaction by isomerization of 2a. Reaction of compound 3b with Ni(CO)4 gives the corresponding transition metal complex 5. The NMR data and X-ray structures of compounds 2a, 4, and 5 are reported.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2393-2396 
    ISSN: 0009-2940
    Keywords: 1,4-Diborafulvenes, 1,4-dihydro- ; Slipped triple-decker ; Nickel complexes ; platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of 1,4-Dihydro-1,4-diborafulvenes with Ni(cod) and Pt(cod) Fragments*Reactions of the 1,4-diborapentafulvene derivatives 1 and 2a, b with M(cod)2 (M = Ni, Pt) yield the complexes [(η5-1)Ni-(cod)] (8), [(μ,η2η5-2a){Ni(cod)}2] (9a), [(μ,η2,η5-2b){Ni(cod)}2] (9b), and [(μ,η2,η5-2a){Pt(cod)}2] (10). Compounds 9 and 10 are the first examples of complexes with 2a, b as a μ,η2,η5-ligand. The X-ray structure analyses of 9b and 10 are described.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2511-2518 
    ISSN: 0009-2940
    Keywords: Allylboration, stereoselective ; Erythronolide building blocks ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral pentenylboronate 3 was the key reagent in the stereoselective construction of two erythronolide building blocks 6 and 7. Addition of 3 to achiral aldehydes furnished homoallylic alcohols 21 and 26 with 〉98% e.e. Addition of 3 to chiral aldehydes 8 or 11 generated homoallylic alcohols with 〉95% d.e. In the mismatched case of addition to the aldehyde 29 diastereoselectivity reached merely 80%.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2535-2537 
    ISSN: 0009-2940
    Keywords: Cobalt complexes, (η3-allyl)(η5-pentamethylcyclopentadienyl)- ; Pyridine synthesis ; Catalytic activity ; Chemoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - a Selective Catalyst for the Pyridine Synthesis(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt (1) catalyses the synthesis of various pyridines from alkynes and nitriles under mild conditions. Only small amounts of benzenes are formed in this selective reaction.
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1317-1322 
    ISSN: 0009-2940
    Keywords: Cyclization of a hydroxy triketone ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A protected hydroxy triketone 22 has been generated by direct Swern oxidation of a δ-trimethylsilyloxy alcohol 11, avoiding the formation of a δ-hydroxy ketone as an intermediate. Conditions have been worked out, which allow the deprotection of a tert-butyldimethylsilyl group and the spontaneous tricyclization of the resulting hydroxy triketone 4 to an acid-sensitive hydroxytrioxaadamantane 5.
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1327-1329 
    ISSN: 0009-2940
    Keywords: Macrocyclic thioethers ; Adamantane as a building block ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4,6:12,14-Di(1,3-adamantano)-1,9-dithiacyclohexadecane (1), 4,6:12,14:20,22-tri(1,3-adamantano)-1,9,17-trithiacyclotetracosane (2), and 5,7:14,16-di(1,3-adamantano)-1,2,10,11-tetrathiacyclooctadecane (3) have been obtained by intermolecular cyclization of 1,3-bis(2-bromoethyl)adamantane (4) with thioacetamide using a high-dilution technique. The reaction is concentration-dependent. The crystal structures of 1, 2, and 3 have been determined by single-crystal X-ray diffraction.
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  • 70
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    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 71
    ISSN: 0009-2940
    Keywords: Dipyrrolo[1,2a:1′,2′-d]pyrazine, (5aS,10aS)-octahydro-1H,5H- ; 1,2-Addition, enantioselective ; Grignard reagents ; Chiral solvent ; Cryoscopic measurements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (5aS,10aS)-Octahydro-1H,5H-dipyrrolo[1,2-a:1′,2′-d]pyrazine «DPP» as Auxiliary Reagent for Enantioselective Alkylations of Prochiral Carbonyl CompoundsIn the presence of one equivalent of the title compound «DPP» (1) prochiral carbonyl compounds 2 react with Grignard reagents 3 in THF to form enantioselectively alcohols 4 with up to 98% ee, whereas the addition of one equivalent of triethylamine yields the opposite enantiomers with up to 97% ee. The optimal molar ratio of 1 and magnesium reagent 3 was determined by cryoscopic measurements. Asymmetric induction is supposed to arise from transition states involving monomeric octahedral complexes of Grignard reagent, chiral solvent, and carbonyl compound. DPP (1) also catalyses Grignard alkylations, because a tenth of its stochiometric amount gives an enantiomeric eccess four times more than as expected. Prepared from (S)-proline, only the boat conformation of 1 induces the observed selectivity as detected by 13C-NMR spectroscopy.
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1331-1332 
    ISSN: 0009-2940
    Keywords: Primary enamines ; Borylation ; 9-BBN ; Amino-polyene ; Enamines, borylation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stable conjugated primary enamine 1,6-diamino-1,6-diphenyl-1,3,5-hexatriene (2a) was treated with 9-borabicyclo-[3.3.1]nonane. At 40°C in dichloromethane solution (18 h) only borylation at nitrogen was observed. With loss of dihydrogen a 9-BBN substituent became attached to each enamine nitrogen. The N,N′-diborylated diaminohexatriene product 3 was characterized by X-ray diffraction.
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1349-1353 
    ISSN: 0009-2940
    Keywords: Isophosphaalkynes ; Transition metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XXI.  -  Isophosphaalkynes as μ3-Ligands in Transition Metal ComplexesReaction of the μ-isophosphaalkyne complex (η5-C5H5)2 (CO)2(μ-CO)Fe2(μ-CPMes) (Mes = 2,4,6-Me3C6H2) (2a) with [(Z)-Cyclooctene]Cr(CO)5 or Fe2(CO)9 gives rise to the μ3-isophosphaalkyne complexes (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[M(CO)n]Mes} 3a [M(CO)n = Cr(CO)5] and 4a [M(CO)n = Fe(CO)4]. Similarly (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[Cr (CO)5]C6H2(CF3)3-2,4,6} (3d) is obtained. The metal carbonyl fragments are attached to 2 in a η1-fashion by the lone-pair at the phosphorus. In contrast to this the treatment of 2a with (Ph3P)2Pt(η2-C2H4) affords complex 5a in which 2a serves as an η3-3e ligand towards the PtPPh3 moiety. The molecular structures of 3a and 5a are determined by single-crystal X-ray analysis.
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  • 74
    ISSN: 0009-2940
    Keywords: Ruthenium compounds ; Osmium compounds ; Alkynes, activated ; Cyclotrimerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a-g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2-C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet-ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru-thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4-halogeno-2-butynes 2c-e yields the bicyclic heterocycles 4c-e. The esters of 2-butyne-1,4-diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a-g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium-catalyzed cyclotrimerization of electron-poor alkynes. If, instead of 1, (η2-C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4-C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.
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  • 75
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1335-1342 
    ISSN: 0009-2940
    Keywords: Fulvalenes ; Bismuth complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bismuth Compounds with Crowded Multiply Alkylated Cyclopentadienyl LigandsHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.Bismuth complexes of alkylated cyclopentadienyl ligands are obtained in good yield on treating bismuth(III) halides with tetraisopropylcyclopentadienylsodium or 1,2,4-tri-tert-butyl-cyclopentadienyllithium. A 1:1 stoichiometric ratio gives the complexes [Cp4iBiCl2] (1), [Cp3tBiCl2] (2), and [Cp4iBiI2] (3) (Cp4i = C5iPr4H, Cp3t = C5H2tBu3-1,2,4). According to X-ray crystal structure analyses, 1 and 3 display dimeric structures with two bridging and two terminal halogeno ligands and η3-coordination of the cyclopentadienyl rings. With half an equivalent of tetraisopropylcyclopentadienylsodium BiCl3 forms [Cp4iBi2Cl5] (4). An X-ray crystal structure analysis of 3 reveals a central Bi2Cl10 core of two edge-sharing BiCl6 octahedra coordinated to two Bi(η5-Cp4i) fragments generating a framework of two face-sharing cubes. Reaction of two equivalents of 1,2,4-tri-tert-butylcyclopentadienyllithium with BiCl3 yields deep purple [Cp3t2BiCl] (5), a bent sandwich complex with an η3,η2-bonding mode of the cyclopentadienyl ligands. Attempted formation of the octaisopropyl analogue of 5 from BiCl3 and two equivalents of tetraisopropylcyclo-pentadienylsodium with elimination of propene gives [Cp4iCp3iBiCl] (6) (Cp3i = C5H2iPr3). Use of monodeuterated tetraisopropylcyclopentadienylsodium in the second substitution step gave pure [Cp4i([D1]Cp3i)BiCl] ([D1]6) proving the absence of ring exchange reactions under the reaction conditions employed and elimination of propene from the second incoming sterically crowded tetraisopropylcyclopentadienyl ring system. The importance of proper choice of solvent and reaction conditions on the formation of alkylated cyclopentadienyl bismuth derivatives is demonstrated by extensive formation of 1,1′,3,3′,5,5′-hexa-tert-butyldihydrofulvalene (7) from 1,2,4-tri-tert-butylcyclopentadienylsodium and BiCl3.
    Additional Material: 8 Ill.
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  • 76
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1355-1357 
    ISSN: 0009-2940
    Keywords: Diphosphanylhydrazides ; Diphosphanes, dinitrogen-bridged ; Cycloplatinaphosphahydrazides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While the transition metal complexes of bis(phosphanyl)amines (PII-N-PIII) have been known for over three decades, the ligating properties of the next homologue PIII-N-N-PIII have been unprecedented so far. The X-ray structures of cycloplatinaphosphanehydrazides, [(OR)2PN(Me)N(Me)P(OR)2-PtCl2], reveal short distances for the P-N [1.639(5) Å] bonds.
    Additional Material: 2 Ill.
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  • 77
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1359-1362 
    ISSN: 0009-2940
    Keywords: Silanes ; Siloxanes ; Si - C bond, selective cleavage ; Arylsilylmethanes ; Si,C,O single-source CVD precursor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic route to partly silylated tetra(silyl)methanes (ArH2Si)nC(SiH3)4  -  n′ to their precursors (TfH2Si)nC-(SiH2Ar)4  -  n (Ar = p-tolyl, phenyl; Tf = CF3SO3; n = 3, 2, 1), and to 1,3-bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O (9) is reported. Starting from symmetrical tetrakis(arylsilyl)-methanes (aryl = p-tolyl, phenyl), we have obtained the selectively dearylated (arylsilyl)silylmethanes (ArH2Si)nC(SiH3)4  -  n (Ar = p-tolyl, phenyl; n = 3, 2, 1) by Si - Ar cleavage with equivalent quantities of trifluoromethanesulfonic acid (triflic acid) and hydrogenation of the corresponding silyl triflates (TfH2Si)nC(SiH2Ar)4  -  n (n = 3, 2, 1) with LiAlH4. The synthesis of 9 has been accomplished by treating trisilyl(p-tolylsilyl)methane p-TolH2SiC(SiH3)3 (7) with stoichiometric amounts of triflic acid to give (trisilylmethyl)silyl triflate TfH2SiC(SiH3)3 (8) and hydrolysing the latter with water.
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  • 78
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1363-1368 
    ISSN: 0009-2940
    Keywords: 1,2-Diboroles, 2,5-dihydro- ; 1,3-Diboroles, 2,3-dihydro- ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Approach to 1,2- and 1,3-DiboroleHerrn Prof. Dr. Joachim Knappe zum 65. Geburtstag gewidmet.Diaminoborylation of 1,3-dilithiopropenes leads to the (Z)-1,3-bis(diaminoboryl)propenes 4a, b, which are transformed by an amine/chlorine exchange to the (Z)-1,3-bis(aminochloroboryl)propenes 5a, b. These react with sodium to yield the 2,5-dihydro-1H-1,2-diboroles 2c, d, whereas the reaction with potassium leads to the 2,3-dihydro-1H-1,3-diboroles 6a, b by rearrangement of the C3B2 skeleton. The constitutions of the heterocycles 2c, d and 6a, b are established by X-ray structure analyses. Reaction of the 1,2-diboroles 2c, d with (C5H5)Co(C2H4)2 leads to the red (1-borabutadiene)cobalt complexes 3c, d. In 3c a sigmatropic rearrangement is studied by NMR spectroscopy.
    Additional Material: 3 Ill.
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  • 79
    ISSN: 0009-2940
    Keywords: Tungsten complexes ; Rhenium complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; Cobalt complexes ; Vinyl ; Cyclohexadienyl ; Cycloheptadienyl ; Cyclooctatrienyl ; Hydrocarbon-bridged complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Complexes, XXX.  -  Nucleophilic Addition of Carbonylmetallates to Cationic Vinyl, Diene, Dienyl and Triene Complexes of Iron, Ruthenium and Cobalt: Di-, Tri-, Tetra- and Pentametallic Complexes with σ,σ- and σ,π-Hydrocarbon BridgesHerrn Professor Ekkehard Lindner zum 60. Geburtstag gewidmet.The reactions of [Re(CO)5]-, [Ru(CO)2Cp]-, and [Os(CO)4]2- with [Cp2(OC)2Fe2(μ-CO)(μ-η1:η2-CH=CH2)]+, [Cp*Ru(η2:η4-1,3,7-octatriene)]+, [(OC)Fe(η4-diene)(η5-cycloheptadienyl)]+, and [CpCo(η5-cyclodienyl)]+ give the nucleophilic adducts whereas with [Mn(CO)5]-, [W(CO)3Cp]-, and [Fe(CO)2Cp]- formation of the corresponding C-C coupling products and of the metal-metal-bonded dimers is observed. The structures of Cp*Ru(μ-η1:η2:η3-1,5-octadienyl)Re(CO)5 (4), [Cp* Ru(μ-η1:η2:η3-1,5-octadienyl)]2Os(CO)4 (6), and of (OC)-Fe(η4-1,3-cyclohexadiene) (μ-η1:η4-1,3-cycloheptadiene)Re(CO)5 (9) have been determined by X-ray diffraction.
    Additional Material: 3 Ill.
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  • 80
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1379-1385 
    ISSN: 0009-2940
    Keywords: Hydrotris(triazolyl)borate ; metal complexes ; Chelate ligands ; Clathrates ; Magnetochemistry ; Spin crossover ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bis[hydrotris(1,2,4-triazolyl)borate]metal complexes [M{HB(C2H2N3)3}2] with M = Fe (5), Co (6), Cu (7), Zn (8) are obtained from MX2 and K[HB(C2H2N3)3] (9). The complexes are characterized by IR, UV/Vis, and MS. Temperature-variable magnetic measurements show a Curie-Weiss behavior for the paramagnetic complexes 6 and 7 with a temperature-dependent magnetic moment for 6. The iron complex 5 exhibits a spin crossover from diamagnetic to paramagnetic, starting at around 270 K. Single-crystal X-ray structures of the solvates 7 · 4 CH3OH and 9 · 2 H2O have been determined. The structure of 7 · 4 CH3OH shows the Jahn-Teller distorted copper complex 7 surrounded by methanol molecules through hydrogen bonding to exocyclic nitrogen atoms of the tris(1,2,4-triazolyl)borate ligand. The crystal system for 7 · 4 CH3OH is monoclinic, space group P21/n. Compound 9 · 2 H2O is a one-dimensional coordination polymer with the potassium atom bridged by the water molecules and the tris(1,2,4-triazolyl)borate ligand and crystallizes in the orthorhombic space group Ccm21.
    Additional Material: 5 Ill.
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  • 81
    ISSN: 0009-2940
    Keywords: 2-Azapropenylium salts, 1,3-dialkoxy- and 1,1,3,3-tetraalkoxy- ; Enamines of N-methyl-4-piperidone ; 4-Aminopyridines ; 3,7-Diazabicyclo[3.3.1]non-2-en-9-ones ; Retro-Mannich reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dialkoxy-2-azapropenylium salts 1 react with enamines 2 of N-methyl-4-piperidone at room temperature to give 2,6-disubstituted 4-aminopyridines 4, 5 in low to moderate yield after hydrolysis. Intermediates of the reaction of 1a with 2 are the bicyclic iminium salts 6 and 7, which may be detected 1H-NMR spectroscopically prior to hydrolysis. Hydrolysis of the mixture obtained from the reaction of 1a with 2a under basic conditions furnishes the bicyclic ketone 3 as the major product. A “retro-Mannich”-type reaction is suggested to explain the degradation of the bicyclic intermediates 6, 7 with the formation of the pyridines 4, 5.
    Additional Material: 1 Tab.
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  • 82
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1441-1445 
    ISSN: 0009-2940
    Keywords: Vinylstannanes ; Photooxygenation ; Schenck reaction ; Hydroxy epoxidation ; Stannyl epoxy alcohols ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct synthesis of stannyl epoxy alcohols 3 from vinylstannanes 1 is described. The procedure involves the photooxygenation of Vinylstannanes 1, which proceeds in a highly regioselective manner with predominant hydrogen abstraction geminal to the stannyl group. Subsequent reaction of the resulting hydroperoxides 2 with Ti(OiPr)4 afforded in a one-pot procedure the epoxy alcohols 3 in high diastereomeric excess, which ranged from 81:19 to greater than 95:5. This convenient and effective method was applied to acyclic and cyclic vinylstannanes as well as to γ-trydroxyvinylstannane 1e, which was converted into the stannyl epoxy diol 3e. In this novel hydroxy epoxidation of vinylstannanes the regioselectivity of the singlet oxygen ene reaction (Schenck reaction) is controlled by the stannyl group.
    Additional Material: 1 Tab.
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  • 83
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1447-1457 
    ISSN: 0009-2940
    Keywords: Addition Stereoselective, nonchelation-controlled ; Reagent, organozinc ; Stereodifferentiation, double ; Oligo(tetrahydrofuran) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The additions of the enantiomerically pure organozinc reagents 17 and 33 to the THF-aldehyde 1 in the presence of the monodentate Lewis acid boron trifluoride - ether give the nonchelation-controlled addition products 7 and 36, respectively (stereoselectivity 95:5, 86:14). These results provide a route to oligo(tetrahydrofuran)s with the relative stereochemistry trans-syn-cis. A stereodirecting effect of the chiral center in the organozinc reagent 17 is found, leading to simple diastereoselectivies in the reaction with achiral aldehydes and to a matched-mismatched case in the reaction with the chiral aldehyde 1.
    Additional Material: 1 Tab.
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  • 84
    ISSN: 0009-2940
    Keywords: Cyclopropenes, 3,3-dimethyl, 1-substituted ; Cyclopropenylzinc chlorides, coupling reactions of ; Palladium catalysis ; Cyclopropenylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [3,3-Dimethyl-2-(trimethylsilyl)-1-cyclopropen-1-yl]zinc chloride (4) reacts with haloarenes and -alkenes as well as 1-bromo-acetylenes under Pd(0) catalysis to give the corresponding 1-phenyl-, 1-ethenyl-, and 1-ethynyl-1-cyclopropenes 6 in isolated yields ranging from 47 to 99%. The corresponding 1-cyclopropen-1-ylstannane 5 reacts with haloarenes only at higher temperatures, and the yields range from 10 to 98%, depending on the substrate and reaction conditions.
    Additional Material: 1 Tab.
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  • 85
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1747-1753 
    ISSN: 0009-2940
    Keywords: Isomerization, thermal ; Radicals ; D-Labeling ; 1,5-Hexadiyne ; Pentafulvene ; Rearrangement, homoallyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal Rearrangements, XXIII[1].  -  The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°CThe thermal isomerization of 1,5-hexadiyne (1) and its [1,6-D2]-labeled derivative (1a) was studied in the temperature range 450-730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
    Additional Material: 2 Ill.
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  • 86
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1765-1779 
    ISSN: 0009-2940
    Keywords: Diradicals ; NO and O2 trapping ; Heat of formation ; Energy well ; Rearrangments ; Bergman cyclisation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Energy Well of Diradicals, V[1].  -  1,3,5-Cyclohexatriene-1,4-diyl and 2,4-Cyclohexadiene-1,4-diylThe energy profile of the Bergman rearrangement of (Z)-3-hexene-1,5-diyne (4) has been established from the NO and oxygen dependance of the trapping rate of the intermediate diradical 1 which leads to a heat of formation for 1,4-didehy-drobenzene (1) of δHOf= 138.0 ± 1.0 kcal . morl-1. By the same technique the heat of formation of 1,2,4-cyclohexatriene (2), generated by thermolysis of (Z)-1,3-hexadien-5-yne (10), gives δHOf = 105.1 ± 1.0 kcal . mol-1 which indicates a high diradical character for 2.
    Additional Material: 4 Ill.
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1797-1798 
    ISSN: 0009-2940
    Keywords: Titanocenes ; Fulvenes ; Solvent effect ; Ketyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Bis(trimethylphosphane)titanocene with KetonesFulvenes are the products of the reaction of aliphatic and aromatic ketones with bis(trimethylphosphane)titanocene in nonpolar solvents, but no formation of pinacols is observed. The mechanism is discussed.
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  • 88
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1781-1795 
    ISSN: 0009-2940
    Keywords: Resonance energy ; Stabilisation energy ; Propargyl resonance ; Force field calculation ; Intrinsic rotational barrier ; Single pulse shock tube ; Gasphase kinetics ; Heats of hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propargyl Stabilisation EnergyFor the alkynyl-substituted olefines 1-14 activation parameters for the geometrical isomerisation have been determined in the gasphase by the single-pulse shoke-tube technique. By comparison of these barriers with the corresponding one of the isolated double bonds, each corrected by the steric energy contribution of the ground and transition state, a value of 7.8 ± 1.3 kcal · mol-1 for the propargyl stabilisation energy (PrSE) has been derived.
    Additional Material: 11 Tab.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1799-1802 
    ISSN: 0009-2940
    Keywords: as-Triazinium salt, fused ; Ring opening ; Ring transformation Heteroaromaticity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring transformation of the tricyclic furo-fused as-triazinium salt 1 in the presence of nucleophilic reagents (e.g. sodium hydrogensulfide, sodium salts of malonic ester, ethyl cyanoacetate, acetylacetone, dimedone, or malononitrile) leads to the two new heteroaromatic ring systems thieno[2,3-e]pyrido[1,2-b]-as-triazinium salt (5) and differently substituted cyclopenta[e]pyrido[1,2-b]-as-triazine compounds (8, 9, 10, 11, and 13).
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  • 90
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1803-1806 
    ISSN: 0009-2940
    Keywords: Singlet carbenes ; [4 + 1] Cycloadditions ; 1,2,4,5-Tetrazines ; SEAr reactions, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wanzlick Carbenes in the [4 + 1] Cycloaddition Reaction with Bis(methylthio)- and Bis(trifluoromethyl)-1,2,4,5-tetrazineThe 3,6-disubstituted 1,2,4,5-tetrazines 3 and 4 have been submitted to a [4 + 1] cycloaddition reaction with the nucleophilic singlet carbenes (Wanzlick carbenes) 2a-d, which are generated from the precursors 1a-d. With 3 as diazadiene the expected spiro compounds 6a-d are formed. In contrast to this presumed two-step reaction sequence of 3, with the tetrazine 4 the cascade cycloaddition/cycloelimination is surprisingly followed by an intramolecular electrophilic aromatic substitution to yield the chiral tetracyclic compounds of type 8 with high diastereoselectivity. The crystal structure of 8d has been determined by X-ray diffraction methods.
    Additional Material: 1 Ill.
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  • 91
    ISSN: 0009-2940
    Keywords: Stannanes, α-(alkylthio) ; Wittig rearrangement ; Configurational stability ; α-Lithio sulfides ; [2,3] Rearrangement ; Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nBuLi-induced tin/lithium exchange reactions of the di-astereomeric γ-[(methoxyethoxy)methoxy]-]α-(tributylstannyl) sulfides anti- and syn-8 delivered the α-(lithioalkyl) benzyl sulfides anti- and syn-11, respectively. Within 1 h at -78°C, these species underwent [2,3]-thia-Wittig rearrangements in THF via the de-aromatized cyclohexadiene intermediates syn- and anti-12. Tautomerization and protonation yielded 81:19 (85%) and 19:81 mixtures (96%) of the ortho-functionalized toluenes syn- and anti-13. Probably, both Wittig rearrangements proceeded with 100% inversion of configuration at the carbanionic stereocenter, and the overall loss of stereoselectivity is due to an epimerization anti-11 ⇌ syn-11 of the lithio sulfide intermediates at a rate which is 3.3 times slower than the rearrangement.
    Additional Material: 2 Tab.
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  • 92
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1959-1968 
    ISSN: 0009-2940
    Keywords: Aldol reaction ; Chiral etiolate ; Mandelic acid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The propionates (R)-5 and (R)-6 which are derived from the readily available chiral auxiliary reagent (R)-triphenylglycol (4) have been applied in stereoselective aldol reactions. Whereas the enolate 7 and the silyl ketene acetal 12, both generated from the ester (R)-6, display only moderate diastereoselectivity when treated with benzaldehyde, ß-hydroxyesters 8b and 16a, b are formed in diastereomeric ratios up to 95:5 (ratio of the main product to the sum of all other stereoisomers) when the propionate (R)-5 is subsequently deprotonated, transmetalated into the zirconium enolate and allowed to react with aldehydes. Alkaline hydrolysis or reduction with LiAlH4 enables the conversion of the adducts 8a and 16a
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  • 93
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1933-1947 
    ISSN: 0009-2940
    Keywords: 7-Oxonorbornane-2,3-dicarboximides ; Reductive amination ; 4,7-Methanoisoindoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonizations of several 7-isopropylidenenorbornane-2,3-dicarboximides (2, 10) yield 7,7-dihydroxynorbornane-2,3-dicarboximides (3, 11) and/or 7-oxonorbornane-2,3-dicarboxi-mides (4, 12). Dehydration of the dihydroxy derivatives to the corresponding carbonyl compounds can be carried out by reaction with P2O5 in an aprotic solvent. Reaction of hydrates 3 with methanol gives mixtures of the stereoisomeric hemiacetals 13 and 14, whereas reaction with other nucleophiles give only the stereoisomer derived from attack by the less hindered carbonyl face. Thus NaBH4 or Al(iPRO)3 reduction of 3 or 4 yields alcohols 15 and LiAlH4 reduction of 3 or 4 amino alcohols 16. Reaction of 4b with phenylmagnesium bromide gives alcohol 22 and a direaction product (rac-26) that easily dehydrates to a tetracyclic compound (rac-30). Reductive aminations of 3 or 4 lead to amines 19 directly or via imines rac-20 and amines 23. LiAIH4 reduction of amine 23b affords tricyclic compounds (rac-27) and (rac-28). The last one was converted to diamine 24 by reduction with NaBH3CN. Similarly, amine 21 was converted into diamine 25, partially via aminal 29 as intermediate. The structures of compounds 3b, 19a, rac-27, and rac-30 have been established by X-ray diffraction analysis.
    Additional Material: 5 Ill.
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  • 94
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1969-1980 
    ISSN: 0009-2940
    Keywords: Protonation ; Enantioselectivity ; Lactone enolates ; Chiral proton sources ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Protonation of Carbanions, 4[1].  -  Enantioselective Protonation of Lactone Enolates[2]The prochiral lithium enolates derived from the five-membered lactones rac-1 and rac-2 were protonated by 37 OH-and 21 NH-chiral proton sources in THF at  -  78°C. The enantioselectivities, determined directly from the reaction mixture by chiral HPLC, are always higher for system 1, probably due to restricted rotation of the phenyl group in 1Li at low temperature (NMR) and range from 0-54% ee. The strongest stereodifferentiation is observed if the OH or NH acids carry an adjacent O- or N-containing group (structures G-J) which allows complexation with the lithium ion. A plausible transition state involving the dimeric lithium enolate is proposed.
    Additional Material: 1 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2009-2012 
    ISSN: 0009-2940
    Keywords: Phthalocyanines, unsymmetrical, soluble ; Boron complex ; Phthalonitrile derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclotrimerization of 4,5-bis(hexylthio)phthalodinitrile (1) in 1-chloronaphthalene in the presence of BCl3 leads to the subphthalocyanine 4. Unsymmetrical phthalocyanines (5, 6) with six alkylthio substituents on three of the benzenoid units are synthesized by the reaction of 4 with an diiminoisoindoline derivative (R′ = H or NO2). These extremely soluble compounds are characterized by IR, 1H- and 13C-NMR as well as UV/Vis spectra.
    Additional Material: 3 Ill.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1989-1992 
    ISSN: 0009-2940
    Keywords: Enantioselectivity ; Protonation ; Ester enolates ; Lactones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Protonation of Carbanions, 6[1].  -  Enantioselective Protonation of γ-Butyrolactone Enolates*The lithium enolates 3Li-7Li, produced from 3-7 by LDA or LiHMDS in THF, are protonated with eleven chiral proton sources at -78°C in THF which produced high enantioselectivities with 1Li and 2Li[5]. Although the enolates (3Li, 6Li, 7Li) are not deuterated quantitatively[1], 1H- and 13C-NMR spectra in THF at -78°C reveal not only quantitative deprotonation (3Li, 6Li) but also aggregation (dimerisation) and hindered rotation of the phenyl group in 3Li. From comparison of the enantioselectivities produced by five chiral proton sources with 1Li-6Li (Tab. 4) definite structure/selectivity correlations can not be derived both for the enolates and the proton sources.
    Additional Material: 4 Tab.
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  • 97
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1981-1988 
    ISSN: 0009-2940
    Keywords: Enantioselectivity ; Protonation ; Solvent effects ; Lewis acids ; Lithium salts ; Deuteration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective Protonation of Carbanions, 5[1].  -  Effects of Reaction Conditions on the Enantioselective Protonation of Lactone Enolates[2]Protonation of the enolates 1Li and 2Li by using standard conditions yields enantioselectivities up to 54 and 50% ee, respectively, depending on the chiral proton source[1]. These values may change dramatically by the following variations (standard ee's in parenthesis): (i) In Et2O/THF (90:10) (S)-2 with 72% ee (44%) is formed with (R)-pantolactone (3) but only 48% ee (39%) with (R,R)-tartaric ester 4 (Figure 1). (ii) Lewis acids may produce rac-2 (SnCl2, MgBr2) or definitely increase the enantioselectivity: With lactone 3: 46% ee (44%); with esters 4: 48% ee (39%); with bissulfonamide 7: 67% ee (47%) (Table 1, 2). (iii) Lithium chloride (2-4 equiv.) in THF yields (S)-1 with 68% ee (47%) and (S)-2 with 77% ee (39%) but only if ester 4 ist employed as chiral proton source (Figure 2). (iv) Chiral Lewis bases create (S)-2 with up to 30% ee on protonation with achiral acids (Table 3, 4). (v) Deuteration of 2Li ranges from 16 to 95% depending on the nature of the base as well as the deuteron source. The degrees of deuteration and enantioselectivity are not correlated. All results demonstrate the complexity of enantioselective protonation of enolates which still needs empirical optimization.
    Additional Material: 2 Ill.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1993-2008 
    ISSN: 0009-2940
    Keywords: Electron donor-acceptor cyclophanes ; Charge-transfer compounds ; Crown ethers ; Oligooxaparacyclophane metal complexes, charge-transfer absorption of, crystal structures of ; Cyclophanes, electron donor-acceptor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intramolecular oligooxa[3n.3]paracyclophane quinhy-drones 2-5 (with n = 3 to 6) were synthesized and their interactions with alkali and alkaline earth metal and mercury(II) ions were studied by electron absorption and NMR spectroscopy. Remarkable enhancements of the CT absorptions were observed by complexation with metal ions of the pentaoxa[15.3]paracyclophane quinhydrone 4 and the hexaoxa[18.3]paracyclophane quinhydrone 5 to the corresponding complexes 6a-e and 7, respectively. The various donor-acceptor orientations and the crown ether-like complexation in the calcium complex 6d, the mercury complex 6e and the barium complex 7 were determined by X-ray analysis. Moreover, the X-ray structures of the tetramethoxy-2,5,8-trioxa[9.3]paracyclophane 8a, a precursor of the quinhydrone 2, and of the pentaoxa[15.3](2,5)-p-benzoquinonophane 20, the product of oxidative demethylation of the quinhydrone 4, are given. For comparison with the cyclic quinhydrones acyclic analogs are also described.
    Additional Material: 7 Ill.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2013-2022 
    ISSN: 0009-2940
    Keywords: Methyleniminium salts, preparation, mechanisms of formation ; (Dialkylamino)trimethylsilanes ; Ethers, α-chloro ; Viehe salts, vinylogous ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Syntheses of Methyleniminium Salts from Carbonyl Compounds and from α-Chloro Ethers; an Access to Vinylogous Viehe Salts*Two methods for the synthesis of isolable methyleniminium salts and amidinium salts are presented. In the first case carbonyl compounds A are treated with a mixture of (dialkyl-amino)trimethylsilane (12) and chlorotrimethylsilane (13) or 12 and trimethylsilyl triflate (14) leading to the iminium chlorides F or iminium triflates G, respectively. With 12/13 the preparation of F is limited to non-enolizable aldehydes and dimethylformamide (10), while 12/14 enables the preparation of G, e.g. 23a-25a, 27a, also with ketones and with substituted amides. The second procedure is based on the treatment of α-chloro ethers L with 12. Both methods afford the Mannich reagent 16a in high yields. By reaction of the α-chloro ether 35 with 12 in diethyl ether the vinylogous Viehe salts 36a-c, e become available for the first time. The reaction pathways are discussed.
    Additional Material: 1 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2035-2041 
    ISSN: 0009-2940
    Keywords: Alkynes ; Cycloalkynes ; Strain, steric ; Cycloaddition reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enthalpies of formation ΔHf and the ring strain energies Eg were calculated for the nine isomeric dithiacyclooctynes 1--9 by applying the MNDO method. Reaction Scheme 2 shows the synthesis of 1,4-dithia-2-cyclooctyne (1), which was the highest Eg value in this series. It dimerizes to 13 in the absence of reaction partners. Scheme 4 summarizes the preparation of 1,5-dithia-2-cyclooctyne (2) and its homologue 1,5-dithia-2-cyclononyne (23) and Scheme 6 the preparation of 1,4-dithia-6-cyclooctyne (6) and its homologue 1,5-dithia-7-cyclononyne (29). Depending on the position of the sulfur atoms, all three reaction sequences contain different steps for the introduction of the triple bonds.
    Additional Material: 2 Tab.
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