Determination of the Enantiomerization Barrier of the Residual Enantiomers of C3 -Symmetric Tris[3-(1-Methyl-2-Alkyl)Indolyl]Phosphane Oxides: Case Study of a Multitasking HPLC Investigation Based on an Immobilized Polysaccharide Stationary Phase

Simona Rizzo; Sergio Menta; Tiziana Benincori; Rosella Ferretti; Marco Pierini; Roberto Cirilli; Francesco Sannicolò

doi:10.1002/chir.22525

Determination of the Enantiomerization Barrier of the Residual Enantiomers of C3 -Symmetric Tris[3-(1-Methyl-2-Alkyl)Indolyl]Phosphane Oxides: Case Study of a Multitasking HPLC Investigation Based on an Immobilized Polysaccharide Stationary Phase

Chirality. 2015 Dec;27(12):888-99. doi: 10.1002/chir.22525. Epub 2015 Sep 24.

Authors

Simona Rizzo¹, Sergio Menta², Tiziana Benincori³, Rosella Ferretti⁴, Marco Pierini², Roberto Cirilli⁴, Francesco Sannicolò⁵

Affiliations

¹ Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, Milano, Italy.
² Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Roma, Italy.
³ Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell'Insubria, Como, Italy.
⁴ Dipartimento di Chimica del Farmaco, Istituto Superiore di Sanità, Roma, Italy.
⁵ Dipartimento di Chimica, Università degli Studi di Milano, Milano, Italy.

PMID: 26402152
DOI: 10.1002/chir.22525

Abstract

The residual enantiomers of three tris-(3-indolyl)-phosphane oxides bearing different alkyl groups (methyl, ethyl or i-propyl) in position 2 of the indole rings constituting the blades were separated on the immobilized type Chiralpak IC column in polar organic and reversed-phase modes. The good enantioselectivity and versatility of the IC CSP allowed easy isolation of the enantiomerically highly enriched samples suitable for configurational stability studies. The enantiomerization barriers of residual phosphane oxides were evaluated both by off-column techniques (CD signal and enantiomeric purity decay kinetics) and by dynamic enantioselective high-performance liquid chromatography (HPLC).

Keywords: Chiralpak IC; chiral phosphane oxides; circular dichroism; dynamic enantioselective HPLC; enantiomerization barrier; enantioselective HPLC; propellers, residual enantiomers.