Pyridine-catalyzed ring-opening reaction of cyclopropenone with bromomethyl carbonyl compounds toward furan-2(5 H )-ones.

We developed a pyridine-catalyzed annulation of diaryl cyclopropenone with bromomethyl carbonyl compounds leading to 5-carbonyl furan-2(5 H )-ones. Pyridinium, derived from the reaction of bromomethyl carbonyl and pyridine, triggered the reaction by the inter-molecular Michael addition to cyclopropenone. This procedure was sensitive neither to air nor moisture and proceeded at room temperature with broad substrate scopes and good functional group tolerance in moderate-to-good yields. As such, it represents a facile and practical pathway leading to 5-carbonyl furan-2(5 H )-one derivatives.