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A. Schmidt 《Fresenius' Journal of Analytical Chemistry》1968,234(4):289-290
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On the Depolymerization of Poly-(R)-3-hydroxy-butanoate (PHB) From cell-free PHB or from dried cells of Alcaligenes eutrophus H 16, which had been grown in an aqueous fructose solution, enantiomerically pure methyl, ethyl, butyl or β-methoxyethyl (R)-3-hydroxy-butanoates are obtained in yields ranging from 75–90% (0.1 to 70 g scale). The depolymerization is achieved by heating the PHB-containing materials to temperatures of 80–160° in the corresponding alcohol with or without the cosolvent dichloroethane in the presence of either sulfuric acid or tetraethoxytitanium catalyst. Since (S)-3-hydroxy-butanoates are also readily obtained (by yeast reduction of aceto-acetates), starting materials derived from 3-hydroxy-butyric acid now belong to the especially useful group of synthetic building blocks which are available in both enantiomeric forms. 相似文献
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Daniel Obrecht Roland Prewo Jost H. Bieri Heinz Heimgartner 《Helvetica chimica acta》1982,65(6):1825-1836
1,3-Dipolar Cycloadditions of 2-(Benzonitrilio)-2-propanide with 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione and Carbon Disulfide Irradiation of 2,2-dimethyl-3-phenyl-2H-azirine ( 11 ) in the presence of 4,4-dimethyl-2-phenyl-2-thiazolin-5-thione ( 7 ) yields a mixture of the three (1:1)-ad-ducts 8 , 12 and 13 (Schemes 3 and 6). The formation of 8 and 12 can be explained by 1,3-dipolar cycloaddition of 2-(benzonitrilio)-2-propanide ( 1b ) to the C, S-double bond of 7. Photochemical isomerization of 12 leads to the third isomer 13 (Schemes 3 and 7). Photolysis of the azirine 11 in the presence of carbon disulfide gives a mixture of two (2:l)-adducts, namely 12 and 13 (Scheme 4). A reaction mechanism via the intermediate formation of the 3-thiazolin-5-thione b is postulated. The structure of the heterocyclic spiro compound 13 has been established by single-crystal X-ray structure determination (cf. Fig. 1 and 2). 相似文献