Catalytic alkoxysilylation of C–H bonds with tert-butyl-substituted alkoxysilyldiazenes†

Abstract

Organoalkoxysilanes (e.g. R–SiMe_3−n(OR′)_n, 1 ≤ n ≤ 3 with R = alkyl or aryl) have found various applications in synthetic chemistry and materials science because the silicon-bound alkoxy groups provide unique opportunities for further derivatization and transformations. Among the few catalytic strategies that allow the direct and intermolecular introduction of an alkoxysilyl unit onto an organic substrate, the alkoxysilylation of unactivated C–H bonds has barely been achieved despite its synthetic potential and the atom-economy it conveys. In particular, a catalytic and transition metal-free C–H silylation protocol towards this class of organosilicon compounds has yet to be reported. We herein describe the first general alkoxysilylation of (hetero)arene C(sp²)–H and benzylic C(sp³)–H bonds under ambient, transition metal-free conditions using newly-prepared tert-butyl-substituted alkoxysilyldiazenes (tBu–NN–SiMe_3−n(OR′)_n, 1 ≤ n ≤ 3 with R′ = Et, iPr or tBu) as silylating reagents and tBuOK as catalytic promoter.