Cyclization of N-acetyl-N-(ortho-chlorophenyl)-4-aminobut-2-enenitrile with zerovalent nickel complexes: conformational analysis of the N-3-cyano-prop-2-enyl chain

Abstract

Cyclization of N-acetyl-N-(ortho-chlorophenyl)-4-aminobut-2-enenitrile with zerovalent nickel complexes, prepared from bis(acetylacetonate)nickel(II), with either pyridine or triphenylphosphine as ligands, and triethylaluminium as reducing agent has been carried out. The α-methylene protons show a diastereotopic effect which could be explained by a rigid bridged hydrogen bound through the oxygen atom of the acetanilide group to one of the α-methylene protons and partially hindered rotation around the N-phenyl bond, due to the ortho-substitution. Conformational analysis of the fragments of the N-3-cyanoprop-2-enyl chain has been carried out using the Sternhell treatment.