Study of the reactivity of 2-methyl-3-butenenitrile with Ni(0)-N-heterocyclic carbene complexes

The catalytic isomerization of 2-methyl-3-butenenitrile (2M3BN) was performed in the presence of Ni(0) with N-heterocyclic carbene (NHC) ligands. On using bulky aromatic substituents on the NHC nitrogen atoms, the isomerization reaction proceeded at room temperature within 15 min: a total conversion of such substrate into the E- and Z-isomers of 2-methyl-2-butenenitrile (2M2BN), being confirmed to take place as a result of governing C-H bond activation, at the catalytic proportion of substrates used. The presence of fluorinated substituents on the heterocyclic carbene ligand results in low catalyst stability, resulting in rapid decomposition of the catalysts. The use of stoichiometric amounts of nickel complex in this reaction did show that C-CN bond cleavage is feasible, allowing isolation and characterization of the allyl complex [Ni(NHC)(2)(eta(3)-1Me-allyl)(CN)] (2). (C) 2008 Elsevier B.V. All rights reserved.