1,3-Azaprotio cyclotransfer. Nitrone-forming oxime–alkyne cyclisations

Abstract

δ-Alkynyl oximes undergo a concerted 2n + 2π+ 2σ 1,3-azaprotio cyclotransfer (APT) reactiongenerating cyclic N-vinyl nitrones which have been trapped in cycloaddition reactions; MNDO and AM1 calculations and transition-state modelling provide support for the observed greater facility of oxime–alkyne reactions compared to oxime–alkene reactions.