STEREOCHEMISTRY OF A CARBON-CARBON BOND-FORMING PROCESS

碳-碳键形成过程的立体化学

• 批准号: 3296519
• 负责人: JOHN D BUYNAK
• 金额: $ 5.16万
• 依托单位: SOUTHERN METHODIST UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1991-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3296519
• 关键词: alkyl group; carbon; carboxylate; catalyst; chemical bond; drug design /synthesis /production; silanes; silicon; stereochemistry

The thermolysis of alpha-silylalkyl carboxylates results in the 1,2- migration of an unactivated alkyl group from silicon to carbon accompanied by a reverse migration of carboxylate. This extremely efficient rearrangement occurs at temperatures between 100 and 250 degrees C. The stereospecificity of this reaction will be investigated with the goal of developing a synthetically useful process for the formation of carbon-carbon bonds. Such processes are crucial to the preparation of biologically active materials. The reaction possesses several advantages over other dipolar or boron-mediated methods for the formation of carbon-carbon bonds: 1) It occurs under extremely mild conditions, without strong bases or acids; 2) The silicon atom provides a convenient, disposable handle to direct the formation of chirality in the alkyl fragments; 3) Since neither carbon fragment must undergo conversion to a highly reactive species (such as a carbanion), both centers should remain chiral (through either inversion or retention of configuration), thus allowing the stereospecific joining of two carbon atoms without the need for a chiral auxiliary; 4) The large number of ways for the formation of carbon-silicon bonds will permit the application of this methodology to the preparation of a variety of systems. Absolute chirality will be created at the migratory and terminal carbon atoms as well as at silicon. Chirality at the terminal, oxygen-bearing, carbon will be introduced by the reduction of acyl silanes with chiral borolane reagents. The resultant chiral silylcarbinols will also be evaluated as synthetic precursors to currently inaccessible chiral alcohols via both intra- and intermolecular processes. Chirality at the migratory carbon atom will be introduced by the reaction of silyl anions with the tosylates of available chiral alcohols. Silanes which are chiral at silicon will be prepared through stereospecific transformations of (+)-alpha-naphthylmethylphenylsilane.

α-甲氨基烷基羧酸盐的热解会导致1,2-- 未活化的烷基从硅迁移到碳 伴随着羧酸盐的反向迁移。 这 在温度下发生极有效的重排 在100至250度之间。 反应将进行研究，目的是开发 形成碳碳的合成有用的过程 债券。 这样的过程对于准备 生物活性材料。 该反应具有比其他偶性或 硼介导的碳碳的形成方法 债券：1）它发生在极度温和的条件下，没有 强碱或酸； 2）硅原子提供了方便的， 一次性手柄指导烷基手性形成 碎片； 3）由于没有碳碎片必须经历 转换为高反应性物种（例如碳纤维），两者都 中心应保持手性（通过反转或保留 配置），因此允许两者的立体特定连接 碳原子无需手性辅助； 4）大 形成碳硅键的方式的数量将 允许将此方法应用于准备 多种系统。 绝对手性将在迁移和终端创建 碳原子以及硅。 终端的手性 含氧，碳将通过还原酰基引入碳 带手性硼烷试剂的硅烷。 由此产生的手性 甲硅烷基甲醇也将作为合成前体进行评估 目前通过内部和 分子间过程。 迁移碳原子的手性 将会由水莲阴离子的反应引入 可用手性醇的甲基酸盐。 硅烷是手性的 硅将通过立体特定的转换来制备 （+） - α-萘基甲基苯基硅烷。