Palladium-Catalyzed Cyanation of Propargylic Carbonates with Trimethylsilyl Cyanide

[reaction: see text]An equimolar mixture of propargylic carbonate (1) and trimethylsilyl cyanide (2) in THF under reflux affords cyanoallene (3) in the presence of a catalytic amount (5 mol %) of Pd(PPh3)4. In the reaction, the trimethylsilyl moiety of 2 effectively traps the leaving group of 1. The use of 2 in excess (6 equiv) provides dicyanated products (7 or 8) in high yields.