Divergent Cyclization Reactions of Morita-Baylis-Hillman Carbonates of 2-Cyclohexenone and Isatylidene Malononitriles

摘要

Zwitterionic dienolates generated from Morita-Baylis-Hillman carbonates of cyclohexen-2-one and a phenolic tertiary amine catalyst underwent divergent cyclization reactions with isatylidene malononitriles. A new [4 + 2] stepwise cyclization process was disclosed to deliver complex bridged spirooxindoles after the initial delta'-regioselective Rauhut-Currier-type reaction with N-methyl electrophiles by the catalysis of beta-isocupreidine, while spirooxindoles incorporating an aromatic chromene motif were generated with N-MOM acceptors in the presence of alpha-isocupreine through different domino transformations.