ASYMMETRIC SYNTHESIS--STRUCTURE, STEREOCHEMISTRY AND NMR

不对称合成——结构、立体化学和核磁共振

• 批准号: 3940611
• 负责人: H ZIFFER
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3940611
• 关键词: X ray crystallography; acetates; alcohols; chemical synthesis; cis trans isomerization; cyclic compound; diol; high performance liquid chromatography; hydrolysis; ketones; lithium; nuclear magnetic resonance spectroscopy; photochemistry; racemization; stereochemistry; stereoisomer

We have continued to examine the enantioselective hydrolysis of esters by the mold Rhizopus nigricans in the course of developing methodologies for the preparation of chiral alcohols of a predictable configuration. Early studies focused on configurational assignments of the alcohols formed, while recent work has been directed toward quantitative predictions of the enantiomeric excess (e.e.) of the alcohol. To improve the reliability of the e.e. determinations it was necessary to develop an analytical non-optical method. The method adopted involves preparation of a diastereomeric ester which is analyzed by capillary gas chromatography. As it was also important to be able to resolve mg quantities of some alcohols for pharmacological studies, we also examined the use of an HPLC based method of separating these diastereomeric esters. The elution order of enantiomers on a chiral column or diastereomers on achiral columns have been used to make tentative configurational assignments. Similar 1,2-benzocycloalken-3-ols, are being investigated. In addition to enzymically mediated hydrolyses, we are studying the regio- and stereo-selectivity of a hydroxylating group of enzymes in Beauvaria sulfurescens. Although alcohols and amines have proved to be poor substrates, the N-phenyl carbamates of several alcohols are hydroxylated. However, for the reaction to be of synthetic utility the low yields of hydroxylated materials had to be increased. We have examined ways of elevating the level of the hydroxylating enzyme and developed a successful approach. This method will be used to study the regio- and stereo-chemical preferences of the enzyme. The structure and stereochemistry of a photodimer obtained from the irradiation of methyl P-nitrocinnamate was assigned from a detailed nmr study of the material.

我们继续研究的对映选择性水解