Steric tuning of silylacetylenes and chiral phosphine ligands for rhodium-catalyzed asymmetric conjugate alkynylation of enones

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