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

TL;DR

A new method for adding alkoxysilyl groups to organic molecules using tert-butyl-substituted alkoxysilyldiazenes under metal-free conditions is introduced.

Contribution

The first catalytic, transition metal-free alkoxysilylation of C–H bonds using novel tert-butyl-substituted alkoxysilyldiazenes.

Findings

Tert-butyl-substituted alkoxysilyldiazenes enable efficient alkoxysilylation of (hetero)arene and benzylic C–H bonds.

The reaction proceeds under ambient conditions without transition metals.

This method provides a general and atom-economic route to organoalkoxysilanes.

Abstract

Organoalkoxysilanes (e.g. R–SiMe3−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–N

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N–SiMe3−n(OR′)n, 1 ≤ n ≤ 3 with R′ = Et, iPr or tBu) as silylating reagents and tBuOK as catalytic promoter.

This work introduces the synthesis and use of novel tert-butyl-substituted alkoxysilyldiazenes (tBu–NN–SiMe3−n(OR′)n, 1 ≤ n ≤ 3 with R′ = alkyl) to expedite the assembly of various organoalkoxysilanes under catalytic transition metal-free conditions.

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