Cyclization of N-alkenyl-o-chloroanilides with organonickel(0) complexes: conformational analysis of 3-substituted oxindoles

Abstract

3-Substituted oxindoles (1)–(6) have been obtained as the main products of the cyclization reaction of N-alkenyl-o-chloroanilides with the zerovalent complex tetrakis (triphenylphosphine)nickel(0). ¹H N.m.r. spectra of the oxindoles (2)–(6) show an AMX proton system for the CH–CH₂R² fragment. Conformational analyses of this fragment for (2)–(6) are given. Moreover, conformational analysis of the N-β-cyanoethyl chain in oxindole (6) is also given.