3-Chloro-W-thiete 1, l-dioxide, prepared by dichlorination of thietane 1, l-dioxide followed by dehydrochlorination, reacts with carbanions, amines, alcohols, and thiols to give 3- substituted thietane or W-thiete 1, l-dioxides. For example, reaction with the anion of dimethyl or diethyl malonate gives 3-[bis (alkoxycarbonyl) methylidene] thietane 1, l-dioxide. 3-Chloro-2H-thiete 1, l-dioxide also undergoes Diels-Alder reactions with butadiene and 1 ...