STEREOCHEMISTRY OF A CARBON-CARBON BOND-FORMING PROCESS

α-硅烷基羧酸酯的热分解生成1，2- 未活化的烷基从硅到碳的迁移 伴随着羧酸盐的反向迁移。这 极其有效的重排发生在温度 在100到250摄氏度之间，这种立体专一性 将对反应进行调查，目的是开发一种 碳-碳形成的综合有用工艺 债券。这样的过程对于准备 生物活性材料。 该反应比其他偶极或非偶极反应有几个优点 硼介导的碳-碳形成方法 债券：1)它发生在极其温和的条件下，没有 强碱或强酸；2)硅原子提供一种方便的， 用于引导烷基中手性形成的一次性手柄 碎片；3)因为两个碳碎片都不一定要经过 转化为高活性物种(如碳负离子)，两者 中心应保持手性(通过反转或保留 构型)，从而允许两个立体地连接 不需要手性助剂的碳原子；4)大 碳-硅键的形成方式有多种 允许将此方法应用于编制 多种多样的系统。 绝对的手性将在迁徙和终点处产生 碳原子和硅原子都是如此。终点站的手性， 含氧碳将通过酰基还原而引入 具有手性硼烷试剂的硅烷。生成的手性 硅基甲醇也将被作为合成前体进行评估 目前无法通过内和手性醇 分子间过程。迁移性碳原子的手性 将通过硅基阴离子与 可利用的手性醇的对甲苯磺酸盐。手性硅烷 硅将通过立体定向转化来制备 ()-α-萘甲基苯基硅烷。

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.