Palladium-Catalyzed Ring-Opening Reaction of Cyclopropenones with Vinyl Epoxides

Palladium-catalyzed sequential [3+2] cyclization/C-H activation of o-iodostyrenes with cyclopropenones as C2 synthons

Herein, we report a novel palladium-catalyzed synthesis of diverse dihydroindeno[2,1-a]indenes by the reaction of o-iodostyrenes with cyclopropenones. This protocol involves a [3+2] cyclization/C-H activation sequence, forming a C(sp2)-C(sp2) and two C(sp2)-C(sp3) bonds. This procedure represents an innovative method for the assembly of tetracyclic dihydroindeno-indenes utilizing cyclopropenones as a new C2 synthon.

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.

Phosphine-Catalyzed Ring-Opening Regioselective Addition of Cyclopropenones with Amides

A series of amides, including α-bromo hydroxamates, N-alkoxyamides, and N-aryloxyamides, were subjected to phosphine-catalyzed ring-opening O-selective addition with cyclopropenones, producing various special α,β-unsaturated esters containing oxime ether motif, in moderate to excellent yields, with high regioselectivity, and exclusive O-selectivity. The methodology is highly atom-economical, with simple operation procedures, and compatible with a wide substrate scope (more than 44 examples).

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.

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

We developed a phosphine-catalyzed ring-opening reaction of cyclopropenones with dicarbonyl compounds as C-nucleophiles, leading to 1,3,3'-tricarbonyl compounds. During this neutral procedure, C-acylation is more dominant than O-acylation. This transition-metal free procedure features mild and neutral reaction conditions with good atom economy. As such, it represents a facile pathway to access 1,3,3'-tricarbonyl derivatives.