Synthesis of poly(phenylacetylene)s containing chiral phenylethyl carbamate residues as coated‐type CSPs with high solvent tolerability

Abstract

Two novel helical poly(phenylacetylene) derivatives containing chiral phenylethyl carbamate residues in the end of each side chain (PPA-S and PPA-R) were synthesized by polymerization of the corresponding phenylacetylene monomers using Rh(nbd)BPh 4 as a catalyst in DMF. The enantioseparation properties of the polymers were evaluated as coated-type chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). Under the same chromatographic conditions, PPA-S and PPA-R showed different enantioseparation properties, indicating that the different interactions between the analytes and the polymers, which result from the different chiral phenylethyl carbamate groups in the end of each side chains.Racemates 1, 7, and 8 could be better resolved on PPA-S, while racemate 6 was separated on PPA-R more efficiently. In addition, the coated-type CSPs showed good solvent tolerability and could work without any damage by introducing the polar solvents, such as CHCl 3 and THF, in eluent. Moreover, some racemates could be better resolved on these coated-type CSPs with the addition of THF to the eluent. K E Y W O R D S chiral phenylethyl carbamate, CSP, enantioseparation, helical poly(phenylacetylene), HPLC, solvent tolerability

Strategies for Preparation of Chiral Stationary Phases: Progress on Coating and Immobilization Methods

“…Recently, two polymeric-coated CSPs based on helical poly(phenylacetylene) derivatives were prepared by Okamoto et col. [ 36 ] ( Figure 2 A). The solvent for the coating procedure was a mixture of trifluoroacetic acid and tetrahydrofuran being the derivatives coated on aminopropyl-silanized silica gel.…”

“…The new CSPs presented a noteworthy solvent tolerability being compatible with chloroform and tetrahydrofuran, which are solvents typically not tolerate by coated-type CSPs. Nuclear magnetic resonance (NMR) was applied for the characterization of the obtained CSPs [ 36 ].…”

Recent progress in the development of chiral stationary phases for high‐performance liquid chromatography

“…Recently, a series of stereoregular helical polyacetylene derivatives bearing amino acids, amino alcohols, and their phenylcarbamate residues as side chains were synthesized for use as CSPs in HPLC [170][171][172][173][174]., Their structures are presented in Figure 8. The chiral side chain was found to have an important influence on the formation of the main chain helical structure and the chiral recognition capability of the polymer.…”

Macromolecular helicity induction and static helicity memory of poly(biphenylylacetylene)s bearing aromatic pendant groups and their use as chiral stationary phases for high‐performance liquid chromatography

“…1982 as the first practical helical polymer-based CSP. Since then, a variety of CSPs consisting of one-handed helical polymers, including polyacetylenes [26][27][28][29][30][31][32][33][34] and polyisocyanides, [35][36][37][38] have been developed. 25,39,40 Among the helical polymers, the helical polysaccharide derivatives (e.g., cellulose and amylose derivatives) 25,[41][42][43][44] developed by Okamoto et al are recognized as the most used commercially available CSPs in the world.…”

“…Okamoto et al achieved the first asymmetric synthesis of a one‐handed helical poly(triphenylmethyl methacrylate) (PTrMA) 20–25 by the helix‐sense‐selective polymerization of an achiral bulky vinyl monomer with a chiral catalyst in 1979 and discovered its remarkable chiral separation ability when used as a CSP for HPLC, which was then commercialized in 1982 as the first practical helical polymer‐based CSP. Since then, a variety of CSPs consisting of one‐handed helical polymers, including polyacetylenes 26–34 and polyisocyanides, 35–38 have been developed 25,39,40 . Among the helical polymers, the helical polysaccharide derivatives (e.g., cellulose and amylose derivatives) 25,41–44 developed by Okamoto et al are recognized as the most used commercially available CSPs in the world.…”