Cyclization-Carbonylation-Cyclization Coupling Reactions of Propargyl Acetates and Amides with Palladium(II)-Bisoxazoline Catalysts

摘要

3(2H)-Furanones and oxazoles are common structures in a range of important pharmaceuticals. Diaryl ketones are also frequently found in natural products and pharmaceuticals, and they are good precursors for nonsteroidal antiestrogen drugs, such as tamoxifen, and diarylmethyl compounds, such as histamine H4 antagonists, antitubercular compounds, and inhibitors of tubulin polymerization. A variety of carbo- and heterocycles can be synthesized by transition-metal-catalyzed reactions of unsaturated systems. Among the available coupling methods, three-component carbon-ylation reactions, such as the carbonylative Suzuki reaction, the carbonylative Sonogashira reaction, and the carbonylative Heck reaction, create interesting building blocks. The vinyl and aryl palladium intermediates are formed by the oxidative addition of a carbon-halogen bond to palladium(0). In this context, we propose a CCC coupling reaction: a cyclization-carbonylation-cyclization coupling reaction of propargylic compounds should afford symmetrical ketones with two heterocyclic groups (Scheme 1).