Resolution of 1-[2-carboxy-6-(trifluoromethyl)phenyl]-1 H-pyrrole-2-carboxylic acid with methyl ( R)-2-phenylglycinate, reciprocal resolution and second order asymmetric transformation

Abstract

A novel, highly efficient method has been developed for the separation of the optical isomers of 1-[2-carboxy-6-(trifluoromethyl)phenyl]-1 H-pyrrole-2-carboxylic acid with methyl ( R)-2-phenylglycinate. The structural aspects of chiral discrimination have been discussed via comparison of the molecular structures and the packing energies of the diastereoisomeric salts determined by single crystal X-ray diffraction measurements. Reciprocal resolution and a new, highly efficient second order asymmetric transformation of racemic methyl 2-phenylglycinate with the pure enantiomer of the previously resolved atropisomeric carboxylic acid are also reported.