Reactions of prop-2-yne-1-sulphonyl chloride with α-morpholinostyrene

Abstract

The reaction between prop-2-yne-1-sulphonyl chloride and α-morpholinostyrene was performed (a) in the presence of an equimolar amount of triethylamine at 0° to give 4-acetyl-3-phenyl-2H-thiet 1,1-dioxide (7) and 1-morpholino-1-phenyl-3-thiahex-1-en-5-yne 3,3-dioxide (3) or the corresponding 3-thiahex-1-en-5-one dioxide (6), depending on the work-up conditions; and (b) at –30° with triethylamine and sulphonyl chloride in a 3:1 ratio to give 3-morpholino-3-phenyl-2-vinylidenethietan 1,1-dioxide (11) and the open-chain sulphone (6). The origin of the products is discussed. Compound (11) and 1-morpholino-1 -phenyl-3-thiahexa-1,4,5-triene 3,3-dioxide (10) are shown to be the possible precursors of the sulphones (7) and (6), respectively.