NMR Studies of the Conformations of 3-Aryl-1,2,3-oxathiazolidine 2-Oxides

Proton magnetic resonance spectroscopy has been used to investigate the conformations of a series of 3-aryl-1,2,3-oxathiazolidine 2-oxides. Their conformations were assigned on the basis of the vicinal coupling constants between four methylene protons at the C-4 and C-5 positions. The oxathiazolidine 2-oxides prefer twist-envelope forms, and their conformations vary with both the situation and the nature of the ring substituent. Postulated collision complexes based on the data of the observed solvent-shifts can also be explained in terms of the differences in the conformations.