Annelated furans. V. Selective Wittig synthesis of euparin and dehydrotremetone

Abstract

Three-step syntheses of euparin (5-acetyl-6-hydroxy-2- isopropenylbenzofuran) and dehydrotremetone (5-acetyl-2- isopropenylbenzofuran) are described. The key step involves the selective attack of methylenetriphenylphosphorane on the appropriate 2,5-diacetylbenzofurans.