Cu(I)-Catalyzed Asymmetric Cross-Coupling of N-Tosylhydrazones and Trialkylsilylethynes: Enantioselective Construction of C(sp)C(sp3) Bonds

The first catalytic enantioselective C(sp)?C(sp(3)) cross-coupling reaction between N-tosylhydrazones and trialkylsilylethynes in the presence of Cu(I) salts and chiral phosphoramidite ligands was developed. A series of synthetically interesting, functionalized alkynes were obtained with moderate to good enantioselectivities (up to 83% ee). Cu(II) carbene migratory insertion is proposed to be the enantio-determining step.