The reaction of 3-(p-tolylsulfinyl)-2-butanone with trimethylsilyl trifluoromethanesulfonate in the presence of diisopropylethylamine gave 3-(p-tolylthio)-2-(trimethylsilyloxy)-1,3-butadiene (2) quantitatively. The Diels-Alder reactions of 2 and the related dienes with methyl acrylate were studied.