Phosphine-catalyzed ring-opening reaction of cyclopropenones with dicarbonyl compounds

Phosphine-catalyzed reaction of cyclopropenones with water: divergent synthesis of highly functionalized γ-butenolides, trisubstituted α,β-unsaturated acids and anhydride

The reaction between cyclopropenones and water catalyzed by different phosphines has been thoroughly investigated. Under the catalysis of trimethylphosphine, highly functionalized γ-butenolides were successfully synthesized from the simple starting material, cyclopropenones, and water in 35%-81% yields with excellent diastereoselectivities. Under the catalysis of triphenylphosphine, cyclopropenones were transferred to trisubstituted α,β-unsaturated acids with sufficient water in 78%-99% yields, while α,β-unsaturated acid anhydrides were obtained with trace water.

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

We developed a pyridine-catalyzed annulation of diaryl cyclopropenone with bromomethyl carbonyl compounds leading to 5-carbonyl furan-2(5H)-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(5H)-one derivatives.