Benzazoles XIII—determination of the E and Z configuration of isomeric 2-(2-benzimidazolyl)-di- and -tetra-hydrothiophenes by IR, 1H and 13C NMR spectroscopy

The configuration of the diastereomeric pairs of 2-(3-hydroxy-3-methyl-5-phenyl-2,3-dihydrothiophen-2-yl)benzimidazole (1a,1b) and 2-(3-hydroxy-3-methyltetrahydrothiophen-2-yl)benzimidazole (2a, 2b), as well as that of the acyl and diacyl derivatives of 2a and 2b, and the structure of the dehydrated products formed by heating 1a or 1b, and 2a or 2b, were determined by IR, ¹H and ¹³C NMR spectroscopy.