Efficient synthesis of optically active 1-(2-carboxymethyl-6-ethylphenyl)- 1H-pyrrole-2-carboxylic acid: a novel atropisomeric 1-arylpyrrole derivative

• Published in: Tetrahedron: asymmetry Vol. 20; no. 1; pp. 98 - 103
• Main Authors: Faigl, Ferenc, Vas-Feldhoffer, Bernadett, Kubinyi, Miklós, Pál, Krisztina, Tárkányi, Gábor, Czugler, Mátyás
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2009
• ISSN: 0957-4166; 1362-511X
• DOI: 10.1016/j.tetasy.2009.01.010

An efficient synthesis and resolution of (±)-1-(2-carboxymethyl-6-ethylphenyl)-
1H-pyrrole-2-carboxylic acid has been developed for the preparation of novel optically active atropisomers. The ee values were measured by a
1H NMR spectroscopic method using quinidine as the chiral complexing agent. Absolute configurations of the separated enantiomers were determined using single crystal X-ray diffraction measurements of both the disodium salt and the (
R)-1-phenylethylamine salt of the enantiomerically pure dicarboxylic acid, separately. The analysis of the CD spectra with the aid of TD-DFT quantum chemical calculations confirmed the assignment of configurations.