Photocatalytic C–H Aminoalkylation of Hydrosilanes with Retention of Si–H Bond

Abstract

Hydrosilanes, important reagents in synthesis, typically undergo Si–H bond reactions, with selective functionalization of adjacent C–H bonds in the presence of Si–H remaining a major challenge. In this work, we present a dual-metal photocatalytic strategy that achieves a long-standing selectivity goal: the direct radical C–H functionalization of hydrosilanes while completely preserving the reactive Si–H bond. Unlike classical transformations where hydrosilanes act solely as reductants, our method leverages their inherent β-silicon effect to activate adjacent C(sp³)–H bonds. By employing a cooperative system of an Fe(III) chloride/tetrabutylammonium decatungstate photocatalyst and a Cu(I) cocatalyst under light, we facilitate a chemoselective hydrogen atom transfer (HAT) and radical cross-coupling with α-imino esters. The reaction demonstrates broad scope, accommodating a wide range of α-imino esters bearing diverse electronic and steric properties, as well as various alkyl-, aryl-, and heterocycle-substituted silanes. Remarkably, the process exhibits excellent selectivity for the β-C–H bond even in substrates containing multiple Si–H bonds, with no detectable hydrosilylation byproducts. The retained Si–H functionality serves as a versatile handle for further derivatization, as demonstrated through one-pot etherification and catalytic hydrosilylation of alkenes and alkynes. Mechanistic studies, including light-switching experiments, radical trapping and the isolation of self-coupling side product from the α-imino ester substrate, support a pathway involving ligand-to-metal charge transfer (LMCT) from photoexcited Fe(III) to generate chlorine radicals, subsequent hydrogen abstraction to form β-silyl carbon radicals, and their ultimate cross-coupling with imine-derived α-amino radicals. This work establishes a platform for the modular editing of hydrosilane frameworks, introducing a valuable disconnection for synthesizing functionally dense organosilicon molecules.

Keywords

Si–H bond retention / Site-selectivity / Aminoalkylation / C–H bond functionalization / Photocatalysis / Radical chemistry / Dual-metal catalysis / Hydrogen atom transfer

RIGHTS & PERMISSIONS

2026 SIOC, CAS, Shanghai, & WILEY-VCH GmbH