Nucleophilic Dialkylation/Diarylation of Cage B(3,6)-H in 1,2-Dialkenyl-o-carboranes.

A direct and regioselective nucleophilic cage B(3,6) dialkylation/diarylation of 1,2-dialkenyl-o-carboranes has been developed. The site selectivity is governed by both steric and electronic effects of the electron-withdrawing alkenyl substituents on the cage carbons. Natural bond orbital (NBO) analyses confirm that the highly electron-deficient B(3,6)-H vertices serve as the preferential sites for nucleophilic substitution. This transition-metal-free strategy provides a clean, facile, and complementary route to traditional transition-metal-catalyzed cage B-H activation methods for the B(3,6) difunctionalization of o-carboranes.