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.

我们继续研究了对映选择性水解 在发育过程中由霉菌Rhizopus nigricans产生的酯 一种手性醇的制备方法 可预测的配置。 早期研究集中于 形成的醇的构型分配，而最近 工作的重点是定量预测 酒精的对映体过量（e.e.）。 为了改善 e.e. 的可靠性有必要制定的决定 一种非光学分析方法。 所采用的方法涉及 非对映酯的制备，其分析如下 毛细管气相色谱法。 因为能够 用于药理学分析某些醇的毫克量 研究中，我们还检验了基于 HPLC 的方法的使用 分离这些非对映酯。 洗脱顺序为 手性柱上的对映异构体或非手性柱上的非对映异构体 列已用于进行暂定配置 作业。 类似的 1,2-苯并环烯-3-醇，正在 调查了。 除了酶介导的水解之外，我们正在研究 羟基化基团的区域选择性和立体选择性 硫磺白僵菌中的酶。 虽然醇和胺 已被证明是不良底物，N-苯基氨基甲酸酯 几种醇被羟基化。 然而，对于反应 具有合成用途 羟基化材料的产率低 必须增加。 我们研究了提高 水平的羟基化酶并成功开发了 方法。 该方法将用于研究区域和 酶的立体化学偏好。 光二聚体的结构和立体化学 对硝基肉桂酸甲酯的照射是从 材料的详细核磁共振研究。