Skeletal transformation of α-pyrones having electron-withdrawing groups at 3,5-positions into ring-fused dihydrofurans

Abstract A skeletal transformation of α-pyrones having electron-withdrawing groups at the 3,5-positions into dihydrofurans was developed. Using dimethylsulfoxonium methylide as the methylene-transfer reagent, the α-pyrones were converted into dihydrofurans as major products and 1-methylthiopyran-1-oxides as minor products. The selectivity of the dihydrofuran formation was improved by optimizing the reaction conditions.