Conformational analysis of 3-arylpropanoic acids and their methyl esters by 1H nuclear magnetic resonance spectroscopy

Abstract

The gauche–trans conformational equilibria for a series of substituted ethanes of the type ArCH₂CH₂CO₂R have been studied on the basis of their ¹H n.m.r. spectra. A correlation has been found between the population of the favoured trans-form and the inductive effect of the substituent in the aryl ring. It is suggested that polar interactions between the carbonyl oxygen and the ortho-aryl carbons (with respect to the side-chain) might be important for the conformational distribution in such compounds.