Amylose tris

Chiralpak AD Amylose tris(3,5-dimethylphenylcarbamate) coated on amino-propyl silica. 

Chiralpak AS Amylose tris[l-(5)-phenylethylcarbamate] coated on silica gel [70] Daicel... 

Chiracel OD CXi-Acid glycoprotein oq-Acid glycoprotein Amylose tris (3,5-dimethyoxy-phenylcarbamate)... 

Okamoto et al [85] performed the optical resolution of primaquine and other racemic drugs by high performance liquid chromatography using cellulose and amylose tris-(phenylcarbamate) derivatives as chiral stationary phases. Primaquine and other compounds were effectively resolved by cellulose and/or amylose derivatives having substituents such as methyl, tertiary butyl, or halogen, on the phenyl groups. 

These polysaccharide-based stationary phases appear to be the most useful in organic, bio-organic and pharmaceutical analysis. Of the above-mentioned derivatives three of them, namely cellulose tris-(3,5-dimethylphenylcarbamate), amylose tris-(3,5-dimethylphenylcarbamate) and cellulose tris-(4-methylbenzoate), have very complementary properties and numerous publications have demonstrated that they have been able to achieve the chiral resolution of more than 80% of the drugs currently available on the market. " These CSPs are known under the commercial names, Chiralcel OD-H , Chiralpak AD and Chiralcel OJ , respectively (Figure 4). Their very broad enantiorecognition range is also the... 

Figure 3.1 Chemical structures of the current most successfully employed derivatised polysaccharide CSPs. (a) CHIRALPAK AD Amylose tris (3,5-dimethylphenylcarbamate) coated onto a silica support, (b) CHIRALPAK AS Amylose tris [(S)-a-methylbenzylcarbamate] coated onto a silica support, (c) CHIRALCEL OD Cellulose tris (3,5-dimethylphenylcarbamate) coated onto a silica support, (d) CHIRALCEL OJ Cellulose tris (4-methylbenzoate) coated onto a silica support.

Emtridtabine Amylose tris [(S)-l-phenylethylcarbamate] (home packed) AcN MeOH (95 05) with 0.02% TEA and 0.02% HAc... 

The progress toward enantiomerically pnre drngs makes the selective and rapid analysis of enantiomers an important issue, both for chiral parity determinations and for enantioselective bioanalysis. Chankvetadze et al. [198] performed enantioseparations within an analysis time of 1 min for each of two chiral compounds (1,2,2,2-tetraphenylethanol and 2,2 -dihydroxy-6,6 -dimethylbiphenyl) by nsing a homemade capillary column containing monolithic silica modified with amylose tris(3,5-dimethylphenylcarbamate) (Figure 17.10). 

FIGURE 17.10 Fast enantioseparation of (A) 1,2,2,2-tetraphenylethanol and (B) 2,2 -dihydroxy-6,6 -dimethylbiphenyl. Stationary phase monolithic silica modified with amylose tris(3,5-dimethylphenylcarbam-ate). Mobile phase n-hexane 2-PrOH (9 1 v/v). The UV detection was conducted at 254 nm. (Reprinted from Chankvetadze, B. et al., J. Chromatogr. A, 1110, 46, 2006. Copyright Elsevier, 2006. With permission.)... 

Musshoff et al. [35] developed a method for the enantiomeric separation of the synthetic opioid agonist tramadol and its desmethyl metabolite using a Chiralpak AD column containing amylose tris-(3,5-dimethylphenylcarbamate) as chiral selector and a n-hexane/ethanol, 97 3 v/v (5mM TEA) mobile phase nnder isocratic conditions (1 mL/min). After atmospheric pressure chemical ionization (APCI), detection was carried out in positive-ion MS-MS SRM mode. The method allowed the confirmation of diagnosis of overdose or intoxication as well as monitoring of patients compliance. 

Using amylose tris-3,5-dimethylphenylcarbamate as the chiral selector in enantioselective high-performance liquid chromatography, micropreparative resolution of the DHA racemate was achieved and the chromatographic behaviour in enantio-GC could be defined by coinjecting these references of definite chirality (Fig. 17.4) [13]. 

A single CSP cannot be used for the chiral resolution of all racemic compounds. Therefore, different CSPs were used for the chiral resolution of different racemates. To make this part easy and clear, Table 1 includes the names of 20 CSPs and their most frequent applications. However, some other interesting applications are possible. Upon screening about 510 racemic compounds described in the literature, we observed that 229 of them resolved completely and 86 partially on cellulose tris(3,5-dimethylphenylcarbamate), and the rest not at all. For amylose tris(3,5-dimethylphenylcarbamate) CSP, we screened 384 racemic compounds and observed that 107 resolved completely and 102 partially. Clearly, cellulose and amylose tris(3,5-diphenylcarbamate) CSPs have the ability to resolve about 80% of the racemic compounds investigated. 

Chiralpak AR Amylose tris(R)-1 -phenylethylcarbamate Alkaloids, tropines, amines ... 

The energies of interaction of ethanol and 2-propanol with amylose tris(3,5-dimethylphenylcarbamate) phases were calculated. The energies of interaction of ethanol, 2-propanol, and their mixtures in different ratios are calculated and presented in Table 3. The energy of interaction G and the energy factor (for ethanol and 2-propanol) F are calculated by the following equations [63]. 

Cass et al. [66] used a polysaccharide-based column on multimodal elution for the separation of the enantiomers of omeprazole in human plasma. Amylose tris (3,5-dimethylphenylcarbamate) coated onto APS-Hypersil (5 /im particle size and 120 A pore size) was used under normal, reversed-phase, and polar-organic conditions for the enantioseparation of six racemates of different classes. The chiral stationary phase was not altered when going from one mobile phase to another. All compounds were enantioresolved within the elution modes with excellent selectivity factor. The separation of the enantiomers of omeprazole in human plasma in the polar-organic mode of elution is described. 

Cass et al. [71] described a direct injection HPLC method, with column-switching, for the determination of omeprazole enantiomers in human plasma. A restricted access media of bovine serum albumin octyl column has been used in the first dimension for separation of the analyte from the biological matrix. The omeprazole enantiomers were eluted from the restricted access media column onto an amylose tris (3,5-dimethylphenylcarbamate) chiral column by the use of a columnswitching valve and the enantioseparation was performed using acetonitrile-water (60 40) as eluent. The analytes were detected by their UV absorbance at 302 nm. The validated method was applied to the analysis of the plasma samples obtained from 10 Brazilian volunteers who received a 40-mg oral dose of racemic omeprazole and was able to quantify the enantiomers of omeprazole in the clinical samples analyzed. 

Figure 4. Optical resolution of. v,2-diphenylcyclopropanccarboxamidc on amylose. tris(3,5-dimethylphenylcarbamate) column 25 x 0.46 (i.d.) cm eluent hexane/2-propanol (90/10) flowrate ...

Okamoto, Y., Aburatani, R., Fukumoto, T., and Hatada, K. (1987) Useful chiral stationary phases for HPLC. amylose tris(3,5-dimethylphenylcarbamate) and tris(3,5-dichlorophenylcarbamate) supported on silica gel, Chem. Lett., 1857-1860. 

Yamamoto, C., Yashima, E., and Okamoto, Y. (2002) Structural analysis of amylose tris(3,5-dimethylphenylcarbamate) by NMR relevant to its chiral recognition mechanism in HPLC, J. Am. Chem. Soc. 124, 12583-12589. 

Y. Okamoto, M. Kawashima, and K. Hatada, Optical resolution of racemic drugs by chiral HPLC on cellulose and amylose tris(phenyl-carbamate) derivative, J. Liquid Chromatogr., 11 2147 (1988). 

Y. Bereznitski, R. Lobrutto, N. Variancaval, R. Thompson, K. Thopmpson, R Sajonz, L. S. Crocker, J. Kowal, D. Cai, M. Journet, T. Wang, J. Wyvratt, and N. Grinberg, Mechanistic aspects of chiral discrimination on an Amylose tris(3,5-dimethylphenyl)carbamate. Enantiomer 1 (2002), 305. 

T. Wang, Y. W. Chen, and A. VaUaya, Enantiomeric separation of some pharma-centical intermediates and reversal of elntion order by high performance liquid chromatography using ceUnlose and amylose tris-3,5-demethylphenylcarbamate) derivatives as stationary phase,/. Chromatogr. A 902 (2000), 345. 

In a broad survey of various analytes about 80 of the compounds tested could be separated on the following four CSPs amylose tris(3,5-dimethylphenyl carbamate) (commercialized as Chiralpak AD), amylose tris[(S)-a-methylbenzyl carbamate] (Chi-ralpak AS), cellulose tris(3,5-dimethylphenyl carbamate) (Chiralcel OD), and cellulose tris(4-methyIbenzoate) (Chiralcel OJ), all coated onto the surface of macroporous y-aminopropyl silica. These columns behave excellently in non-aqueous HPLC mode, but they seem to be also well suitable for SFC separations. Other less widely used, but also commercially available polysaccharide-derived CSPs, e.g. cellulose triacetate, cellulose tribenzoate, and cellulose tricinnamate, or cellulose tris(phenylcarbamate), cellulose tris(4-chlorophenylcarbamate), cellulose tris(4-methylphenylcarbamate) selectors... 

Amylose is another polysaccharide that has been used to create CSPs. Amylose is a D-a-glucose polymer with high helical content. Two amylose-based CSPs are commercially available (Table 2) amylose tris(3,5-dimethylphenylcarbamate), the AD CSP and amylose (S)-a-methyl-benzylcarbamate, the AS CSP... 

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