Efficient synthesis of butenolide-medium ring ether hybrids by a [3 + 2] cyclization-ring-closing metathesis strategy

A new strategy for the synthesis of bicyclic gamma-alkylidenebutenolides, butenolide-medium ring ether hybrids, is reported which involves Me(3)SiOTf-catalyzed cyclization of 1, 3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride, Mitsunobu reaction, and subsequent ring-closing metathesis.