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.