Pd-Catalyzed Enantioselective Enyne Cyclization

The first enantioselective Pd-catalyzed cyclization of 1,6-enynes containing silyloxy-substituted olefins is demonstrated using two chiral Pd complexes. Catalyst A required higher catalyst loading and longer reaction times compared to catalyst B. Catalyst B was highly active and selective for a wider scope of substrates, including O-silyl ketene aminals and indoles. Good to excellent yields and enantioselectivities were seen for both catalysts. The reaction’s synthetic utility was shown by the synthesis of the sesqui­terpene (-)-laurebiphenyl.