离子氢化不饱和膦和胺硼烷的机理变化。

Mechanistic variations in ionic hydrogenation of unsaturated phosphine and amine boranes.

机构信息

Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.

出版信息

Org Lett. 2012 Feb 3;14(3):688-91. doi: 10.1021/ol2031203. Epub 2012 Jan 17.

DOI:10.1021/ol2031203

Abstract

Internal hydride transfer occurs when tethered carbocations are generated from unsaturated phosphine or phosphinite boranes. 3-Methylenecyclohexyl-derived boranes 12 or 18 react with MsOH to give ionic hydrogenation products with high syn-selectivity. With unsaturated amine boranes, initial hydrogen evolution gives BH(2)(OMs) complexes, but IH occurs using excess MsOH in a slower second stage. A diastereoselective reaction occurs from 26b using camphorsulfonic acid (first stage) and MsOH (second stage), affording 33 (68% ee) after hydrolysis.

摘要

当不饱和膦或亚膦硼烷生成桥连碳正离子时，就会发生内氢化物转移。3-亚甲基环己基衍生的硼烷 12 或 18 与 MsOH 反应，得到具有高 syn-选择性的离子氢化产物。对于不饱和胺硼烷，初始氢的释放生成 BH(2)(OMs)配合物，但在过量 MsOH 的存在下，在较慢的第二阶段发生 IH。使用樟脑磺酸（第一阶段）和 MsOH（第二阶段），从 26b 发生非对映选择性反应，水解后得到 33（68%ee）。