AbstractBenzylsilanes have found increasing applications in organic synthesis as bench‐stable synthetic intermediates, yet are mostly produced by stoichiometric procedures. Catalytic alternatives based on the atom‐economical silylation of benzylic C(sp3)−H bonds remain scarcely available as specialized directing groups and catalytic systems are needed to outcompete the kinetically‐favored silylation of C(sp2)−H bonds. Herein, we describe the first general and catalytic‐in‐metal undirected silylation of benzylic C(sp3)−H bonds under ambient, transition metal‐free conditions using stable tert‐butyl‐substituted silyldiazenes (tBu−N=N−SiR3) as silicon source. The high activity and selectivity of the catalytic system, exemplified by the preparation of various mono‐ or gem‐bis benzyl(di)silanes, originates from the facile generation of organopotassium reagents, including tert‐butylpotassium.
摘要苄基
硅烷作为稳定的合成中间体,在有机合成中的应用日益广泛,但大多是通过
化学计量法生产的。基于苄基 C(sp3)-H 键原子经济
硅烷化的催化替代品仍然很少,因为需要专门的定向基团和催化系统才能与动力学上有利的 C(sp2)-H 键
硅烷化竞争。在本文中,我们首次介绍了以稳定的叔丁基取代的
硅二氮(tBu-N=N-SiR3)为
硅源,在无过渡
金属的环境条件下,对苄基 C(sp3)-H 键进行的通用
金属内催化非定向
硅烷化反应。该催化系统的高活性和高选择性源于
有机钾试剂(包括叔丁基
钾)的简便生成,以制备各种单苄基或双苄基(二)
硅烷为例。