A conformational study of the 3-p-tolylsulphonylbutan-2-ol and 1,2-diphenyl-2-p-tolylsulphonylethanol diastereoisomeric pairs

Abstract

Solvent and temperature effects upon the conformation of erythro- and threo-3-p-tolylsulphonylbutan-2-ol (I) and (III), and of erythro- and threo-1,2-diphenyl-2-p-tolylsulphonylethanol (II) and (IV) have been studied by i.r. and ¹H n.m.r. spectroscopic techniques. All compounds form an intramolecular hydrogen bond in chloroform and carbon tetrachloride solutions, whereas in dimethyl sulphoxide, pyridine, and acetone hydrogen bond formation with the solvent occurs. Steric requirements control the conformational preference of (II) and (IV) in all solvents. The conformation of (I) and (III) in polar solvents may be determined primarily by a gauche attractive interaction between oxygen and sulphur atoms. In low polarity solvents the conformations which facilitate intra-molecular hydrogen bonding are preferred.