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

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 δ′-regioselective
Rauhut–Currier-type reaction with N-methyl
electrophiles by the catalysis of β-isocupreidine, while spirooxindoles
incorporating an aromatic chromene motif were generated with N-MOM acceptors in the presence of α-isocupreine through
different domino transformations.