Enantioselective Alkynylation of Isatins: A Combination of Metal Catalysis and Organocatalysis

An efficient and catalytic asymmetric alkynylation of isatins has been developed using a bifunctional amidophosphine-urea/AgBF₄ complex as the catalyst. By a combination of metal catalysis and organocatalysis, excellent enantioselectivities (up to 99 % ee) and good yields are achieved. A wide range of both terminal alkynes and isatins are tolerated by this new catalyst system, providing access to structurally diverse propargylic alcohols with tetrasubstituted stereogenic centers in high efficiency.