Synthesis and stereochemical stability of new atropisomeric 1-(substituted phenyl)pyrrole derivatives

Addition of organometallic reagents to optically active methyl 1-(2-methoxycarbonyl-6-trifluoromethylphenyl)pyrrole-2-carboxylate provided the corresponding tetrasubstituted diols and/or pyrrolo[1,2-a]benzoxazepines as pure enantiomers or racemates depending on the organometallic reagents used. Rotational energy barriers around the interconnecting C-N bonds were estimated by molecular modeling calculations and NMR measurements with the aim of clarifying the stereochemical stability order of the new atropisomeric compounds. NMR methods for the determination of the enantiomeric purity of the new compounds are proposed.