Conformational energy analysis of substituted diphenylethanes: Part VIII. Conformations of some hydroxy and amino 1-monosubstituted and 1,3-disubstituted 1,2-diphenylpropanes

Abstract

Experimental estimates (NMR and IR) of the conformational preferences of some 1-monosubstituted and 1,3-disubstituted 1,2-diphenylpropanes are compared with those calculated by means of Momany's empirical force field (EFF). Except for the erythro 1,3-diol, the NMR J-constants indicate varying degrees of preference for conformations with antiperiplanar hydrogen atoms for both isomers. The EFF calculations agree well for the erythro 1,3-diol, although for the other compounds they tend to exaggerate the strains in the more congested conformations. The orders of preference and the equilibrium shifts, however, correlate satisfactorily with the EFF conformational energies.