Chemoselective synthesis of trifluoromethylated γ-butenolide derivatives via phosphine-promoted tandem reaction of allylic carbonates and trifluoromethyl ketones.

A novel chemoselective phosphine-mediated tandem reaction between nonsubstituted MBH carbonates and aryl trifluoromethyl ketones is described. The product selectivity of the reaction is easily tunable by changing the ratios of the two reactants, and mono- or bicyclic bistrifluoromethylated vinyl γ-butenolide products can be prepared with good chemoselectivity in modest-to-good yields and diastereoselectivities. The formation of the bicyclic γ-butenolide structures via a one-pot four-step sequence under phosphine catalysis is unprecedented.