Zn(II)/amine-catalyzed coupling reaction of alkylidenemalonates with propargyl alcohol: A one-pot synthesis of methylenetetrahydrofurans

A metal-catalyzed tandem 1,4-addition/cyclization between propargyl alcohol and a Michael acceptor, such as alkylidene malonate, has been developed. In the presence of catalytic amounts of zinc triflate [Zn(OTf)(2)] and triethylamine (Et3N), various 2-alkylidene-1,3-dicarbonyl compounds reacted with propargyl alcohol to give 3- or 4-methylene tetrahydrofurans in excellent yields.