Steric Tuning of Silylacetylenes and Chiral Phosphine Ligands for Rhodium-Catalyzed Asymmetric Conjugate Alkynylation of Enones

Rhodium-catalyzed asymmetric conjugate alkynylation of α,β-unsaturated ketones giving β-alkynylketones took place in high yields with high enantioselectivity. The reaction was realized by use of (triisopropylsilyl)acetylene combined with (R)-DTBM-segphos as a chiral phosphine ligand, where the sterically bulky substituents on the silicon and phosphorus atoms suppress the alkyne dimerization.