2-Halogeno-3-morpholinothietan 1,1-dioxides. Kinetics of base catalysed cis–trans-isomerization and hydrogen–deuterium exchange

Abstract

The kinetics of base catalysed H–D exchange at position 2 and cis–trans-isomerization have been measured in CD₃CN–D₂O for a series of 2-halogeno-3-morpholinothietan 1,1-dioxides (1)–(6). The isomerization and exchange rates depend upon the nature of the halogen and are in the order I > Br > CI. The results are rationalized in terms of electrostatic and/or steric effects. The values of the ratio K_ex/K_is are ca. 1 for compounds (1)–(3) and further support the known configurational instability of strained α-sulphonyl carbanions.