Thin-layer chromatography on silica gel as a method for assigning the relative configurations to some aliphatic diastereomeric compounds

Abstract

Separation of 37 diastereomeric pairs of compounds from the group ArCH(X)CH(Y)Ar′ (X and Y are polar groups; Ar and Ar′ are phenyl or m-, p-alkoxy substituted phenyl groups) is achieved by thin-layer chromatography on silica gel. In all cases the erythro-isomers have higher R F values than do the corresponding threo-isomers, irrespective of the polarity of the developing solvents as well as of the formation of an intramolecular hydrogen bond between X and Y. The phenomena are explained on the basis of the preferred conformations of the diastereomers. Thin-layer chromatography on silica gel is proposed as a method for assigning the relative configurations of diastereomeric pairs of compounds of the above type.