Efficient Synthesis of γ-Alkylidenetetronic Esters by Sequential Lewis Acid Catalyzed [3 + 2] Cyclizations and Palladium-Catalyzed Cross-Coupling Reactions

Abstract

A new approach for the synthesis of gamma-alkylidenetetronic acids and esters is reported which involves Me3SiOTf-catalyzed, regio- and stereoselective cyclization of 4-alkoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride. The alpha-hydroxy group of the butenolides is efficiently functionalized by palladium-catalyzed cross-coupling reactions via the corresponding enol triflates.