Intermolecular Pauson-Khand reactions of &ITN&IT-substituted maleimides

Co-2(CO)(8)-mediated intermolecular Pauson-Khand reactions of N-substituted maleimides with terminal alkynes are described, producing maleimide-fused cyclopentenones. The transformation differs from other intermolecular Pauson-Khand-type reactions of electron-deficient olefins, which react with Co-2(CO)(8) and alkynes to produce conjugated dienes, or generally require terminal, monosubstituted olefins to generate cyclopentenones. The reaction works well for N-benzyl, N-aryl, and N-alkyl substituted maleimides, and tolerates branching at the 3-position of the terminal alkyne. N-H maleimide, N-CO2Me maleimide, and maleicanhydride do not take part in the transformation. (C) 2017 Elsevier Ltd. All rights reserved.