MICHAEL REACTION OF STABILIZED CARBON NUCLEOPHILES CATALYZED BY [RUH2(PPH(3))(4)]

The Michael reaction of active methylene compounds lacking cyano group s such as malonates, beta-ketoesters, 1,3-diketones, 1,1-disulfones, n itrocompounds, Meldrum acid, and anthrone with common accepters procee ds in acetonitrile solution in the presence of [RuH2(PPh(3))(4)] as th e catalyst. Cyano acetates, more acidic than malonates in organic solv ents, are also excellent substrates for this reaction, In a number of cases, intramolecular aldol reactions catalyzed by [RuH2(PPh(3))(4)] w ere also observed as side reactions. Catalysis by other ruthenium and rhodium complexes has been examined. Selectivity studies performed wit h malonate and disulfone donors indicate that the catalyst selectively activates Michael donors that can coordinate with ruthenium(II). Addi tionally, it has been shown that the reaction requires the presence of free phosphine. Therefore, the Michael reaction of stabilized enolate s appears to be a ruthenium- and phosphine-catalyzed reaction. From a practical point of view, the use of readily prepared [RuH2(PPh(3))(4)] as the catalyst in acetonitrile provided the best solution for the Mi chael reaction of active methylene compounds.