Cobalt/Bisoxazolinephosphine-Catalyzed Asymmetric Alkynylation of Isatins.

A new catalyst system based on Co(OAc)2/bisoxazolinephosphine has been developed to catalyze the direct addition of terminal alkynes to isatins under base-free conditions. Chiral propargyl alcohols with an oxindole skeleton could be prepared in up to 99% yield and 99% ee with the help of the chiral tridentate ligand. A variety of functionalized aliphatic or aromatic alkynes and isatins were utilized in this method, and gram-scale synthesis could be achieved with 1 mol % catalyst.