Phosphine-Catalyzed Stereoselective Ring-Opening Addition of Cyclopropenones with Nucleophiles

Abstract

A phosphine-catalyzed ring-opening addition reaction of cyclopropenones with a variety of nucleophiles (NuH), including oxygen-, nitrogen-, sulfur-, and carbon-based ones, has been investigated, which produces potentially useful α,βunsaturated carbonyl derivatives in high yields (up to 99%), high regioselectivity, and exclusive E-selectivity. The reaction proceeds in high efficiency under very mild conditions using only 1 mol % PPh 3 as the catalyst at room temperature. The method is also amenable for the synthesis of deuterated alkenes when deuterated nucleophiles (NuD) are employed. The mechanism is investigated by experiments and DFT calculations, which suggests an α-ketenyl phosphorus ylide as a key intermediate in the catalytic cycle that captures the nucleophiles in a stereoselective manner.

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

“…Based on the aforementioned experimental results and literature reports, 6–9 a tentative mechanism was proposed as shown in Scheme 3. First, the addition of phosphine to the vinyl group of cyclopropenone produces the zwitterionic phosphine/cyclopropenone adduct A as an α-ketenyl ylide intermediate via ring cleavage.…”

“…8 However, such a system involving active methenyl compounds as C -nucleophiles served as C -nucleophiles toward 1,3,3-tricarbonyl derivatives has never been reported before (eqn (4), Scheme 1). 9…”

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

“…In 2014, Shi and coworkers reported the PPh 3 -catalyzed ring-opening reactions of cyclopropenones with isatin derivatives to afford carboxylated 1H-indoles in good yields. Recently, Xu reported the development of the phosphine-catalyzed ring-opening addition reaction of cyclopropenones with various nucleophil e s such as amines, phenols, alcohols, and malononitriles.…”

Expedient access to polysubstituted acrylamides via strain-release-driven dual phosphine and palladium catalysis

“…Cyclopropenones (CpOs), the highly reactive and smallest aromatic rings, have been established as versatile building blocks for the synthesis of complicated scaffolds through the thermodynamically favored strain release of cyclopropane rings. 9–12 We recently developed a dual phosphine/rhodium catalytic system to achieve multicomponent reactions (MCRs) of readily available CpOs, water and aryl halides, furnishing a wide array of polysubstituted acrylic acids (Scheme 1b). 13 In the presence of condensation reagents EDCI and HOBt, the obtained acrylic acids can be easily converted into ( Z )-polysubstituted acrylamides, which exhibit AIE properties.…”