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. Keep your options open: Methods were developed for both the 1,2‐ and 1,1‐arylboration of α‐alkyl alkenyl arenes, including enantioselective variants. The formation of quaternary centers by 1,2‐arylboration occurred through a rare cross‐coupling of a tertiary organometallic complex (see scheme). 1,1‐Arylboration was enabled by catalyst optimization and occurred through a β‐hydride elimination/reinsertion cascade.