Catalyst-Controlled 1,2- and 1,1-Arylboration of α-Alkyl Alkenyl Arenes.

Two methods are reported for the 1,2- and 1,1-arylboration of α-methyl vinyl arenes. In the case of 1,2-arylboration, the formation of a quaternary center occurred through a rare cross-coupling reaction of a tertiary organometallic complex. 1,1-Arylboration was enabled by catalyst optimization and occurred through a β-hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations.