Improvement of proline enantioselective stationary phases by replacing the 9-fluorenylmethoxycarbonyl group

• Published in: Journal of Chromatography A Vol. 1109; no. 2; pp. 307 - 311
• Main Authors: Huang, Junmin, Chen, Hui, Zhang, Peng, Li, Tingyu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.03.2006; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Fluorenes - chemistry; Peptide stationary phase; Proline; Proline - chemistry; Proline chiral stationary phase; Proline enantioselective stationary phase; Stereoisomerism; Proline; Peptide stationary phase; Proline chiral stationary phase; Proline enantioselective stationary phase; Protecting group; Separation; Enantioselectivity; Peptides; Chiral stationary phase; α-Aminoacid; Enantiomer; Property structure relationship; Stationary phase
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2006.01.072

The role of 9-fluorenylmethoxycarbonyl (Fmoc) in previously reported proline enantioselective stationary phases was investigated. Seven stationary phases in which the Fmoc group was replaced by other groups were prepared and evaluated in normal phase mode. The Fmoc group proved nonessential for the broad enantioselectivity observed, as the stationary phase with a trimethylacetyl (Tma) group proved much more effective than the one with the Fmoc group. For the 53 analytes studied, the stationary phase with the Tma group resolved 39, while the one with the Fmoc group resolved 19. Separation factors achieved for the stationary phase with the Tma group are also significantly higher than those for the stationary phase with the Fmoc group. The stationary phase with the (−)-2-(2,4,5,7-tetranitro-9-fluorenylideneaminooxy)propionyl (Tapa) group provides very different selectivity profile when compared to the one with the Tma group. In most of the proline stationary phases studied, pi–pi interaction is not the dominant interaction for the enantioselective recognition.