Configurational Control of Benzyl Carbanion-Copper Complexes by Sulfinyl Groups: Synthesis of Optically Pure Allenes with Central and Axial Chirality

Lean, mean, chiral allene: Optically pure complexes 2 react with propargyl bromides and mesylates 1 to afford the title products (see scheme; LG=leaving group). The regioselectivity and the configuration of the chiral axis are completely controlled, and the stereoselectivity at the benzylic position is high. Kinetic resolution of racemic propargyl mesylates can also be achieved with these reagents.