A general route to the synthesis of 3-alkylidene derivatives of 4-thiochromanone 1,1-dioxide

Abstract

The reactions of the trimethylsilyl enol ethers of both 4-thiochromanone and 4-thiochromanone 1,1-dioxide with various carbonyl compounds complexed with titanium tetrachloride give moderate yields of the previously unknown 3-alkylidene condensation products under mild conditions. Other Lewis acids, with the exception of boron trifluoride, were found to be ineffective in this transformation.