Cobalt-Catalyzed Enantioselective Hydroboration/Cyclization of 1,7-Enynes: Asymmetric Synthesis of Chiral Quinolinones Containing Quaternary Stereogenic Centers.

An asymmetric cobalt-catalyzed hydroboration/cyclization of 1,7-enynes to synthesize chiral six-membered N-heterocyclic compounds was developed. A variety of aniline-tethered 1,7-enynes react with pinacolborane to afford the corresponding chiral boryl-functionalized quinoline derivatives in high yields with high enantioselectivity. This cobalt-catalyzed asymmetric cyclization of 1,7-enyens provides a general approach to access a series of chiral quinoline derivatives containing quaternary stereocenters.