Solvent-free copper-catalyzed trisilylation of alkynes: a practical and atom-economical approach for accessing 1,1,1-trisilylalkanes

Abstract

Organosilicon compounds are versatile reagents in chemical synthesis and materials sciences. As an important class of organosilanes, 1,1,1-trisilylalkanes can undergo various organic transformations and serve as core units for silicon-containing hyperbranched polymers. The existing catalytic approaches for accessing 1,1,1-trisilylalkanes via alkyne trisilylation not only requires pre-synthesized moisture- and air-sensitive organocalcium and organolanthanum catalysts but also suffers from limited substrate scope for both alkyne and hydrosilane reagents. For example, only alkyl-substituted alkynes can undergo organocalcium-catalyzed trisilylation with alkyl hydrosilanes to provide the desired 1,1,1-trisilylalkane products. Herein, we report a selective copper-catalyzed trisilylation reaction of both alkyl- and aryl-substituted alkynes with a readily accessible copper catalyst that is generated in situ from Cu(OAc)₂ and tributylphosphine PⁿBu₃. This copper-catalyzed trisilylation reaction features easy catalyst preparation, broad substrate scope, and mild solvent-free reaction conditions. Mechanistic studies reveal that this trisilylation reaction occurs through copper-catalyzed deprotosilylation of alkynes to form alkynylsilanes followed by double hydrosilylation of alkynylsilane.