Studies in Stereochemistry

分子的化学和物理性质不仅取决于它们的元素组成，而且还取决于它们的形状(立体化学)。这些研究将提供有关形状在控制化学性质中的作用的进一步信息。这对于理解分子如何在生物系统中相互作用尤为重要。该项目的具体立体化学研究包括四个方面：(A)构象分析--1，2，3，4-N-甲基四氢喹啉及其盐的研究以及顺式-3-羟基硫亚砜等化合物的旋光度与构象和氢键的关系；(B)核磁共振波谱-核磁共振波谱研究将涉及O-17核磁共振，特别是氢键的影响，在机理研究和糖衍生物光谱中的应用；(C)不对称合成--不对称合成的研究将涉及以前研究过的1，3-恶硫烷体系，还将包括作为立体选择性合成模具的手性1，3-恶杂环的方法学研究。此外，在涉及克拉姆循环规则的这类研究中，将通过停流方法对螯合作用的重要性进行机理研究；以及(D)碳离子化学-碳负离子研究将涉及1，3-恶硫烷和1，3-二氧六环衍生的碳负离子，并将包括通过停流核磁共振研究它们的反转速度。

The chemical and physical properties of molecules are determined not only by their elemental composition, but also by their shape (stereochemistry). These studies will provide further information on the role of shape in controlling chemical properties. This is particularly important in understanding how molecules interact in biological systems. The specific stereochemical studies of this project are in four areas: (A) Conformational Analysis - The conformational behavior of 1,2,3,4-N-methyltetrahydroquinolines and their salts will be studied as well as the relation of optical rotation to conformation and hydrogen bonding in cis-3-hydroxythiane sulfoxide and other compounds; (B) NMR Spectroscopy - NMR spectroscopic studies will deal with O-17 NMR, especially effects of hydrogen bonding, application to mechanistic studies and spectra of sugar derivatives; (C) Asymmetric Synthesis - The studies in asymmetric synthesis will involve the previously investigated 1,3-oxathiane system and will also encompass methodological studies of chiral 1,3-oxazanes as molds for stereoselective syntheses. Further, mechanistic studies of the importance of chelation in such studies involving Cram's cyclic rule will be undertaken by stop-flow methods; and (D) Carbanion Chemistry - The carbanion studies will involve carbanions derived from 1,3-oxathiane and 1,3-dioxane and will encompass efforts to investigate their rate of inversion by stop-flow nmr.