Synthesis of Furo[3,2-c]pyridinones via an Aza-Oxy-Carbanion Relay Strategy

Significance

Reported is the synthesis of furo-[3,2-c]pyridinones 3 from 1-cinnamoylcyclopropanecarboxamides 1 with aldehydes 2, which proceeds via a proposed aza-oxy-carbanion relay process. Both electron-rich and -poor aromatic groups are tolerated in reactant 1. Aromatic and alkenyl aldehydes 2 participate equally well, although aliphatic aldehydes lead to decomposition. Chalcones were also shown to be efficient electrophiles, giving rise to compounds 4 in excellent yield. However, the use of simpler electrophiles (BnBr, MeI, TMSCl) proved unsuccessful. A mechanism is proposed involving a Michael addition/cyclopropane ring opening/anion migration/electrophile quench cascade.