Copper-Catalyzed Regiodivergent Silacarboxylation of Allenes with Carbon Dioxide and a Silylborane

A regio­divergent sila­carb­oxyl­ation of allenes under a CO2 atmosphere with PhMe2Si–B­(pin) as a silicon source in the presence of a copper catalyst at 70 °C has been developed. The regio­selectivity of the reaction is successfully reversed by the proper choice of ligand; carboxylated vinylsilanes are obtained with rac-Me-DuPhos as the ligand, whereas the use of PCy3 affords carboxylated allylsilanes. Thus, two different carboxylated silanes can be selectively and regio­divergently synthesized from a single allene substrate.