BF3-Promoted, Carbene-like, C-H Insertion Reactions of Benzynes.

Boron trifluoride is observed to promote a variety of C-H insertion reactions of benzynes bearing pendant alkyl groups. Computations and various mechanistic studies indicate that BF3 engages the strained π-bond to confer carbene-like character on the adjacent, noncoordinated benzyne carbon. This represents an unprecedented catalytic role for a non-transition metal such as BF3.