Phosphine-Catalyzed Reaction of Cyanohydrins with Activated Alkynes

A new method for preparing a-cyanoacrylates and a-cy- anoenones is described. The procedure uses a phosphine-catalyzed a-C addition of cyanide ion, generated in situ from cyanohydrins, to activated alkynes. An unexpected tandem reaction producing ben- zylidenecyclopentanones is also described.