Properties and reactions of 1,3-oxathiolans. Part 6. Chemical equilibration and 1H nuclear magnetic resonance conformational study of 4,5-dimethyl-, 2,4,5-trimethyl-, and 2,2,4,5- and 2,4,4,5-tetramethyl-1,3-oxathiolans

Abstract

The 60 MHz ¹H n.m.r. spectra of nine differently substituted 4,5-dimethyl-1,3-oxathiolans have been recorded and analysed. The n.m.r. data are compared with those previously reported for the 4-methyl- and 5-methyl-1,3-oxa-thiolans. Epimeric derivatives were chemically equilibrated to determine the energy differences between the diastereoisomers in question. The thermodynamic quantities obtained were used to clarify different spatial interactions in these compounds.