Ruthenium-Catalyzed Regioselective Reactions of Nitriles and 1,3-Dicarbonyl Compounds with Terminal Alkynes

RuH2(PPh3)(4)-catalyzed reaction of nitriles with terminal alkynes proceeds highly efficiently under neutral conditions to give the corresponding Michael adducts. Furthermore, 1,3-dicarbonyl compounds react with terminal alkynes at the alpha-position to afford the exo-methylene compounds with high regioselectivity under neutral conditions. The regioselectivity depends upon the change of substrates. The precise mechanism is presented.