Metal-catalysed synthesis of nitroenaminones from alpha-nitroketones or -esters and nitriles

Transition metal(II) carbonylnitronates or acetates selectively catalyse th e carbon-carbon bond formation reaction between benzoylnitromethane and met hyl (or ethyl) nitroacetate with electrophilically activated nitriles to fo rm the nitroenaminones O2N(RCO)C=C(R')NH2 3a-d in high to medium yields (73 -50%; a: R = Ph, R'= CCl3; b: R = MeO, R'= CCl3; c: R = EtO, R'= CCl3; d: R = MeO, R' = EtOCO). The use of metal catalysts permits of avoiding the bas ic conditions in which compounds 3 are unstable. The proposed mechanism, wh ich implies coordination of the O2NCHCOR- moiety and nucleophilic attack of the metal-chelate to the nitrile carbon atom, is supported by the successf ul synthesis of the intermediate complex [Ni{O2N(MeOCO)CC(CCl3)NH}(2)(H2O)( 2)]. (C) 1999 Elsevier Science B.V. All rights reserved.