72151-03-2Relevant articles and documents
Photochemically immobilized 4-methylbenzoyl cellulose as a powerful chiral stationary phase for enantioselective chromatography
Francotte, Eric,Huynh, Dan,Zhang, Tong
, (2016/12/30)
A process to immobilize para-methylbenzoyl cellulose (PMBC) on silica gel has been developed and applied to prepare chiral stationary phases (CSPs) for enantioselective chromatography. The immobilization was achieved by simple irradiation of the polysaccharide derivative with ultraviolet light after coating on a silica gel support. The influence of parameters such as irradiation time and solvent on immobilization effectiveness were investigated. The performance of the prepared immobilized phases were evaluated by injection of a series of racemic compounds onto the packed columns and determination of their chiral recognition ability. By contrast to the classical coated phase, the immobilized CSP can be used under various chromatographic conditions without limitation of organic solvent types as the mobile phase. This extended applicability permits to improve selectivity and to resolve chiral compounds which are not or only poorly soluble in the mobile phases which are compatible with the non-immobilized PMBC stationary phase.
Temperature-triggered switchable helix-helix inversion of poly(phenylacetylene) bearing L-valine ethyl ester pendants and its chiral recognition ability
Zhou, Yanli,Zhang, Chunhong,Qiu, Yuan,Liu, Lijia,Yang, Taotao,Dong, Hongxing,Satoh, Toshifumi,Okamoto, Yoshio
, (2016/12/03)
A phenylacetylene containing the L-valine ethyl ester pendant (PAA-Val) was synthesized and polymerized by an organorhodium catalyst (Rh(nbd)BPh4) to produce the corresponding one-handed helical cis-poly(phenylacetylene) (PPAA-Val). PPAA-Val showed a unique temperature-triggered switchable helix-sense in chloroform, while it was not observed in highly polar solvents, such as N,N′-dimethylformamide (DMF). By heating the solution of PPAA-Val in chloroform, the sign of the CD absorption became reversed, but recovered after cooling the solution to room temperature. Even after six cycles of the heating-cooling treatment, the helix sense of the PPAA-Val's backbone was still switchable without loss of the CD intensity. The PPAA-Val was then coated on silica gel particles to produce novel chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). These novel PPAA-Val based CSPs showed a high chiral recognition ability for racemic mandelonitrile (α = 2.18) and racemic trans-N,N′-diphenylcyclohexane-1,2-dicarboxamide (α = 2.60). Additionally, the one-handed helical cis-polyene backbone of PPAA-Val was irreversibly destroyed to afford PPAA-Val-H by heating in dimethyl sulfoxide (DMSO) accompanied by the complete disappearance of the Cotton effect. Although PPAA-Val-H had the same L-valine ethyl ester pendants as its cis-isomer PPAA-Val, it showed no chiral recognition. It was concluded that the one-handed helical cis-polyene backbone of PPAA-Val plays an important role in the chiral recognition ability.
Synthesis and Enantioseparation Ability of Xylan Bisphenylcarbamate Derivatives as Chiral Stationary Phases in HPLC
Li, Geng,Shen, Jun,Li, Qiang,Okamoto, Yoshio
, p. 518 - 522 (2015/08/03)
Ten novel xylan bisphenylcarbamate derivatives bearing meta- and para-substituents on their phenyl groups were synthesized and their chiral recognition abilities were evaluated as the chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) after coating them on macroporous silica. The chiral recognition abilities of these CSPs depended on the nature, position, and number of the substituents on the phenyl moieties. The introduction of an electron-donating group was more attractive than an electron-withdrawing group to improve the chiral recognition ability of the xylan phenylcarbamate derivatives. Among the CSPs discussed in this study, xylan bis(3,5-dimethylphenylcarbamate)-based CSP seems to possess the highest resolving power for many racemates, and the meta-substituted CSPs showed relatively better chiral recognition than the para-substituted ones. For some racemates, the xylan bis(3,5-dimethylphenylcarbamate) derivative exhibited higher enantioselectivity than the CSP based on cellulose tris(3,5-dimethylphenylcarbamate). Chirality 27:518-522, 2015
Influence of stereoregularity and linkage groups on chiral recognition of poly(phenylacetylene) derivatives bearing L -leucine ethyl ester pendants as chiral stationary phases for HPLC
Zhang, Chunhong,Liu, Fangbin,Li, Yufa,Shen, Xiande,Xu, Xiaodong,Sakai, Ryosuke,Satoh, Toshifumi,Kakuchi, Toyoji,Okamoto, Yoshio
, p. 2271 - 2278 (2013/05/09)
Stereoregular poly(phenylacetylene) derivatives bearing L-leucine ethyl ester pendants, poly-1 and poly-2a, were, respectively, synthesized by the polymerization of N-(4-ethynylphenylcarbamoyl)-L-leucine ethyl ester (1) and N-(4-ethynylphenyl-carbonyl)-L-leucine ethyl ester (2) using Rh(nbd)BPh 4 as a catalyst, while stereoirregular poly-2b was synthesized by solid-state thermal polymerization of 2. Their chiral recognition abilities for nine racemates were evaluated as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) after coating them on silica gel. Both poly-1 and poly-2a with a helical conformation showed their characteristic recognition depending on coating solvents and the linkage groups between poly(phenylacetylene) and L-leucine ethyl ester pendants. Poly-2a with a shorter amide linkage showed higher chiral recognition than poly-1 with a longer urea linkage. Coating solvents played an important role in the chiral recognition of both poly-1 and poly-2a due to the different conformation of the polymer main chains induced by the solvents. A few racemates were effectively resolved on the poly-2a coated with a MeOH/CHCl3 (3/7, v/v) mixture. The separation factors for these racemates were comparable to those obtained on the very popular CSPs derived from polysaccharide phenylcarbamates. Stereoirregular poly-2b exhibited much lower chiral recognition than the corresponding stereoregular, helical poly-2a, suggesting that the regular structure of poly(phenylacetylene) main chains is essential to attain high chiral recognition.
Immobilization and chromatographic evaluation of novel regioselectively substituted amylose-based chiral packing materials for HPLC
Shen, Jun,Li, Pengfei,Liu, Shuangyan,Shen, Xiande,Okamoto, Yoshio
scheme or table, p. 878 - 886 (2012/06/30)
The regioselectively substituted amylose derivatives bearing a 4-tert-butylbenzoate or 4-chlorobenzoate group at 2-position, and 3,5-dichlorophenylcarbamate and a small amount of 3-(triethoxysilyl) propylcarbamate groups at 3- and 6-positions were synthesized by a two-step process based on the esterification of 2-position of a glucose unit. The obtained derivatives were effectively immobilized onto macroporous silica gel by intermolecular polycondensation of triethoxysilyl groups. Their chiral recognition abilities were evaluated as chiral packing materials (CPMs) for high-performance liquid chromatography. These CPMs showed high chiral recognition as well as the conventional coated-type CPM, and can be used with the eluents-containing chloroform and tetrahydrofuran. With the extended use of these eluents, improvement of chiral recognition and reversed elution orders were realized. For some racemates, the immobilized CPM exhibited ability comparable or better to the commercial immobilized amylose- or cellulose-based columns,
Preparation and evaluation of a molecularly imprinted polymer derivatized silica monolithic column for capillary electrochromatography and capillary liquid chromatography
Ou, Junjie,Li, Xin,Feng, Shun,Dong, Jing,Dong, Xiaoli,Kong, Liang,Ye, Mingliang,Zou, Hanfa
, p. 639 - 646 (2007/10/03)
A method for preparation of molecularly imprinted polymer (MIP) derivatized onto the surface of a monolithic silica capillary column was successfully developed. The vinyl groups were first introduced onto the silica monolith by immobilization of γ-methacryloxypropyltrimethoxysilane. Then the MIP coating was copolymerized and anchored onto the surface of the silica monolith. Acetonitrile was selected as porogen (solvent). The other preparation conditions, such as monomer concentration, temperature, and time of polymerization, were systematically studied. The obtained MIP-derivatized silica monolith using L-tetrahydropalmatine (L-THP) and (5S,11S)-(-)-Troeger's base (S-TB) as the imprinted template, respectively, was characterized in terms of the retention behavior of thiourea and toluene. Under the optimized CEC conditions, baseline enantioseparations of THP and TB were achieved in 4 min though the effective length of the columns was 8.5 cm. The result indicates that enough recognition sites were on the surface of silica monolith, resulting in strong recognition ability. Compared with a MIP organic monolith, the MIP-derivatized silica monolith exhibits better column efficiency and stability in CEC. Additionally, the comparison of these two kinds of monolithic columns was performed by capillary liquid chromatography. The separation on MIP-derivatized silica monolith was superior to that on the organic monolith.
Optical Resolution on Regioselectively Carbamoylated Cellulose and Amylose with 3,5-Dimethylphenyl and 3,5-Dichlorophenyl Isocyanates
Kaida, Yuriko,Okamoto, Yoshio
, p. 2225 - 2232 (2007/10/02)
The optical resolving ability of two types of regioselectively carbamoylated cellulose and amylose with 3,5-dimethylphenyl and 3,5-dichlorophenyl isocyanates was evaluated.One had 3,5-dimethylphenylcarbamate groups at the 2 and 3 positions and a 3,5-dichlorophenylcarbamate group at the 6 position; the other had 3,5-dichlorophenylcarbamate groups at the 2 and 3 positions and a 3,5-dimethylphenylcarbamate group at the 6 position.In cellulose derivatives, the side chains at the 2,3, and 6 positions seem to interact complicatedly with racemates.On the other hand, in the amylose derivatives, the side chains at the 2 and 3 positions may mainly influence the chiral recognition ability.The optical resolving abilities of the cellulose and amylose derivatives having irregularly either 3,5-dimethylphenyl- or 3,5-dichlorophenylcarbamate groups at the 2,3 and 6 positions were also examined.
Preparative Optical Resolution of Axial- and Planar-chiral Benzene Derivatives, Metallocenes, and Methanoazaannulenes by Medium Pressure Chromatography on Triacetylcellulose
Schloegl, Karl,Widhalm, Michael
, p. 3042 - 3048 (2007/10/02)
Medium pressure chromatography (at 4 - 6 bar and 6 - 40 deg C) on specially prepared triacetylcellulose in ethanol (or ether) renders possible an efficient preparative optical resolution of chiral benzene derivatives, (benzene)tricarbonylchromium complexes (benchrotrenes), ferrocenes, and azaannulenes.The method is presented for 15 selected examples such as 1,3-diferrocenyl-1,3-diphenylallene (1), 2,2'-spirobiindanes (2,3), biphenyl derivatives (4 - 8) and their tricarbonylchromium complexes (9 - 11), metacyclophanes (12 - 14) and 2,7-methanoazaannulenes (15,16) as well as for Troeger's base.In ten cases a quantitative separation of the enantiomers and in two an appr. 80 percent enantiomeric enrichment was achieved whereas for three compounds only a partial resolution took place.
