K2CO3-Promoted Domino Reactions: Construction of Functionalized 2,3-Dihydrobenzofurans and Clofibrate Analogues

The K2CO3-catalyzed domino reactions (Michael alkylation, Mannich alkylation, and aldol alkylation) of salicylic aldehyde derivatives (2-hydroxyaryl-alpha,beta-unsaturated ketones, 2-hydroxyarylnitroalkenes, 2-hydroxyarylimines, and salicylic aldehydes) and 2-halo-1,3-dicarbonyl compounds (diethyl alpha-bromomalonate, diethyl alpha-chloromalonate, ethyl 2-chloroacetoacetate, and 3-chloropentane-2,4-dione) were carried out under mild conditions to provide a series of functionalized 2,3-dihydrobenzofurans in moderate to excellent yields. The novel transformations simultaneously gave a series of clofibrate analogues, which possess various substitution patterns.