Enantio- and Regioselective Ni-Catalyzed Radical Relay 1,4-Arylalkylation of 1,3-Enynes to Access Chiral Tetrasubstituted Allenes

The enantio- and regioselective reductive 1,4-arylalkylation of 1,3-enynes has been successfully accomplished using a nickel catalyst in conjunction with a chiral bulk bis-oxazoline ligand. This method facilitates the efficient synthesis of a wide variety of structurally diverse, enantioenriched tetrasubstituted allenes, which are key structural motifs in numerous pharmacologically active compounds and natural products. The reaction proceeds under mild conditions and is operationally straightforward. Mechanistic investigations indicate that the reaction follows a radical pathway.