Polymethylation reactions of saturated and unsaturated thiacrown ethers

Abstract

Saturated thiacrown ether 12S4 (1 mmol) reacted with methyl trifluoromethanesulfonate (1 and 2 mmol) in dichloromethane at room temperature to give mono- and dimethylated products. When the reaction of 12S4 with excess methyl trifluoromethanesulfonate was carried out, a tetramethylated product was obtained as a single isomer. The crystal structures of the mono- and dimethylated products were determined by X-ray crystallographic analysis. Unsaturated thiacrown ether 15UT5 also reacted with methyl trifluoromethanesulfonate to give mono- and dimethylated products.