ASYMMETRIC SYNTHESIS--STRUCTURE, STEREOCHEMISTRY AND NMR

我们继续研究了 黑根霉（Rhizopus nigricans）在发育过程中产生的酯 制备手性醇的方法 可预测的配置。 早期的研究集中在 形成的醇的构型分配，而最近 工作一直致力于定量预测 对映体过量酒精。 提高 e. e.的可靠性。有必要制定的决定 一种非光学分析方法。 所采用的方法包括 制备非对映体酯，通过 毛细管气相色谱法 同时， 为了解决mg量的一些醇用于药理学 研究，我们还研究了使用基于HPLC的方法， 分离这些非对映体酯。 的洗脱顺序 对映体在手性柱上或非对映体在非手性柱上 柱子已经被用来使试探性的配置 分配任务。 类似的1，2-苯并环烯-3-醇， 研究了 除了酶介导的水解，我们正在研究 羟基化基团的区域和立体选择性 在Beauvaria sulfurescens中的酶。 虽然醇和胺 已经证明是差的底物， 几种醇被羟基化。 然而，对于反应， 羟基化物质的低产率 必须增加。 我们已经研究了提高 水平的羟化酶，并开发了一个成功的 approach. 该方法将用于研究区域和 酶的立体化学偏好。 由以下获得的光二聚体的结构和立体化学： 对硝基肉桂酸甲酯的辐照归属于a 对材料进行详细的NMR研究。

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.