Spiro‐Bicyclic Bisborane Catalysts for Metal‐Free Chemoselective and Enantioselective Hydrogenation of Quinolines

Abstract

Abstract A new series of spiro‐bicyclic bisborane catalysts has been prepared by means of hydroboration reactions of C 2 ‐symmetric spiro‐bicyclic dienes with HB(C 6 F 5 ) 2 and HB( p ‐C 6 F 4 H) 2 . When used for hydrogenation of quinolines, these catalysts give excellent yields and enantiomeric excesses, and show turnover numbers of up to 460. The most attractive feature of these metal‐free hydrogenation reactions was the broad functional‐group tolerance, making this method complementary to existing methods for quinoline hydrogenation.