Ag(I)-Catalyzed Oxidative Cyclization of 1,4-Diynamide-3-ols with N-Oxide for Divergent Synthesis of 2-Substituted Furan-4-carboxamide Derivatives

This work reports Ag(I)-catalyzed oxidative cyclizations of 1,4-diynamide-3-ols with 8-methylquinoline oxide to form 2-substituted furan-4-carboxamides. The reaction chemoselectivity is distinct from that reported in previous work by Hashmi. We performed density functional theory calculations to elucidate our proposed mechanism after evaluation of the energy profiles of two possible pathways. In this Ag(I) catalysis, the calculations suggest that the amide and alkyne groups of the 3,3-dicarbonyl-2-alkyne intermediates tend to chelate with the Ag(I) catalyst, further inducing a formyl attack at the Ag(I)-π-alkyne moiety to deliver the observed products.