NHC-Catalyzed 1,2-Selective Hydroboration of Quinolines

Abstract

Selective dearomative transformation of readily available N-heteroarenes is a powerful tool accessing useful synthetic building units. Described herein is the NHC-catalyzed 1,2-selective hydroboration of quinolines with high functional group tolerance. Dihydroquinoline products could be isolated as their amide derivatives upon in situ N-protection, thus offering high synthetic utility of the current procedure. Combined experimental and computational studies revealed that the observed regioselectivity can be rationalized by proposing a six-membered transition state that collectively incorporates NHC catalyst, hydroborane reductant, and protonated quinoline substrate.