Chiral phases derived from

Lammerhofer, M., Tobler, E., Zarbl, E., Lindner, W., Svec, E, and Frechet, J. M. J. (2003). Macroporous monolithic chiral stationary phases for capillary electrochromatography new chiral monomer derived from cinchona alkaloid with enhanced enantioselectivity. Electrophoresis 24, 2986-2999. 

Dabashi, Y. and Hara, S., Direct resolution of enantiomers by liquid chromatography with the novel chiral stationary phase derived from (R,R)-tartramide, Tetrahedron Lett., 26, 4217, 1985. 

Y. Dobashi and S. Hara, A chiral stationary phase derived from (R,R)-tartramide with broaden scope of application to the liquid chromatographic resolution of enantiomers, /. Org. Chem. 52 (1987), 2490. 

M. Caude, A. Tambute, and L. Siret, Chiral stationary phase derived from tyrosine, J. Chromatogr. 550 (1991), 357. 

Machida,Y, Nishi, H., Nakamura, K. Nuclear magnetic resonance studies for the chiral recognition of the novel chiral stationary phase derived from 18-crown-6 tetracarboxylic acid, J. Chromatogr. A, 1998, 810, 33-41. 

To avoid the P-elimination-promoted rearrangements observed when the promising indolooxazaphosphorine approach was applied to solid phase synthesis of PS-oligos, Just developed a set of chiral auxiliaries, derived from d- and L-tryptophan, that could be removed by direct displacement of the primary... 

However, more remarkable was the discovery that in alkane solvents, large, orrfiometallated macrocyclic complexes of palladium shown in Figure 92 would form lyotropic columnar phases [171], These remarkable materials have been shown to form columnar hexagonal phases and, in suitable solvents, lyotropic nematic phases derived from columnar organization. Further, in certain non-mesomorphic examples, mesophases can be induced by the addition of an electron acceptor such as trinitrofluorenone chiral phases are introduced when the acceptor is resolved 2 -(2,4,5,7-tetranitro-9-fluorenylideneaminoxy)propionic acid (know as TAPA). 

Direct determination of the enantiomeric purity of an enantiomeric mixture is usually achieved by GC or HPLC on a chiral stationary phase derived from chiral materials such as cellulose and cyclodextrin. NMR analysis in the presence of a chiral shift reagent is also applicable, although with less accuracy than the chromatographic methods. 

The use of chiral H-bonding components yields stable chiral phases by molecular association [35-37]. For example, a ferroelectric phase derived from a chiral smectic C phase can be induced by the self-assembly of nonferro-electric molecules [35-37]. Complex 11 (n = 8) exhibits a chiral smectic phase from 109 to 123 °C [35]. In this case, the H-bonded mesogen consists of nonmesomorphic chiral benzoic acid and a stilhazole that shows a very narrow temperature range of ordered smectic phases. The value of spontaneous polarization for 11 at 115 °C is 33.0 nC/cm. When the oxygen in the alkoxy... 

Chiral oxazaphosphorinanes, derived from (-)-8-amino menthol are alkylated with good to excellent diastereoselectivities. The regioselectivity in the alkylation is dependent on the base used for protonation.Both enantiomers of the major diastereoisomer of 2-(l-phenyl)ethylamino-4-thioxo-4-phenoxy-l,3,4-thiazaphos-phol-2-ine were obtained in optically pure form by the reaction of 0-phenyl(chloro-methyljisothiophosphonate with (i )-(-l-)- and (5)-(—)-(l-phenyl)ethylamine. Phase-transfer 7V-allylation and A7-propargylation of (bicyclo[1.1.0]butylmethyl)-amines initiate diastereoselective pericyclic cascade reactions that culminate in novel spirocyclic (206) and tricyclic pyrrolidine (207) heterocycles through formal ene or [2 + 2] pathways (Scheme 76). ... 

The direct resolution of underivatised enantiomers has been effected with the aid of some metal-containing chiral stationary phases. Particular attention has been paid to the resolution of chiral alkenes and epoxides using stationary phases derived from chiral metal chelate complexes. The rhodium dicarbonyl P-diketonate complex (5), when dissolved in squalene and coated onto a capillary column, permitted the quantitative enantiomer resolution of 3-methylcyclopentene while methyl oxirane was similarly resolved... 

Cellulose and its derivatives can form liquid crystalline solutions in a variety of organic solvents. Most of the lyotropic liquid crystalline phases derived from these compoxmds are cholesteric. Since the flow occurs in a shear field, the chiral nematic structure is transformed into a nematic phase. Nevertheless, shear phase orientation can be destroyed when the applied force is removed. This phenomenon is caused by the driving force that makes the liquid crystal form a supramolecular helical structure with thermodynamic stability [70]. The mesophase has a supramolecular helical structure, whose cellulose molecules are inclined at a small angle, which varies from one layer to another. 

Hyun, M.H. Han, S.C. Cho, Y.J. Jin, J.S. Lee, W. Liquid chromatographic resolution of gemifloxacin mesylate on a chiral stationary phase derived from crown ether, Biomed.Chromatogr., 2002, 16,... 

Machida Y, Nishi H, Nakamura K, Nakai H, Sato T (1998) Enantiomer separation of amino compounds by a novel chiral stationary phase derived from crown ether. J Chromatogr A 805 85-92... 

Hyun, M.H., Na, M.S., and Jin, J.S., Chiral recognition models for the liquid chromatographic resolution of pi-acidic racemates on a chiral stationary phase derived from iV-phenyl-Al-alkylamide of (5-naproxen), J. Chromatogr. A, 752, 77, 1996. 

Liquid Crystalline Structures. In certain ceUular organeUes, deoxyribonucleic acid (DNA) occurs in a concentrated form. Striking similarities between the optical properties derived from the underlying supramolecular organization of the concentrated DNA phases and those observed in chiral nematic textures have been described (36). Concentrated aqueous solutions of nucleic acids exhibit a chiral nematic texture in vitro (29,37). 

Licjuid Crystals. Ferroelectric Hquid crystals have been appHed to LCD (Uquid crystal display) because of their quick response (239). Ferroelectric Hquid crystals have chiral components in their molecules, some of which are derived from amino acids (240). Concentrated solutions (10—30%) of a-helix poly(amino acid)s show a lyotropic cholesteric Hquid crystalline phase, and poly(glutamic acid ester) films display a thermotropic phase (241). Their practical appHcations have not been deterrnined. 

The enantioselectivity a is defined as the distribution ratio of one single enantiomer over the two chiral phases and has been determined experimentally for a variety of compounds (Table 5-1). It has been known from work by Prelog [66, 67] that tartaric acid derivatives show selectivities towards a-hydroxyamines and amino acids. However, from Table 5-1 it is obvious that tartaric acid derivatives show selectivity for many other compounds, including various amino bases (e.g. mirtazapine (10)) and acids (e.g. ibuprofen (11)). The use of other chiral selectors (e.g. PLA)... 

Arai and co-workers have used chiral ammonium salts 89 and 90 (Scheme 1.25) derived from cinchona alkaloids as phase-transfer catalysts for asymmetric Dar-zens reactions (Table 1.12). They obtained moderate enantioselectivities for the addition of cyclic 92 (Entries 4—6) [43] and acyclic 91 (Entries 1-3) chloroketones [44] to a range of alkyl and aromatic aldehydes [45] and also obtained moderate selectivities on treatment of chlorosulfone 93 with aromatic aldehydes (Entries 7-9) [46, 47]. Treatment of chlorosulfone 93 with ketones resulted in low enantioselectivities. 

More recently, the same group has used a simpler and more easily prepared chiral ammonium phase-transfer catalyst 99 derived from BINOL in asymmetric Darzens reactions with a-halo amides 97 to generate glycidic tertiary amides 98 (Table 1.13). Unfortunately the selectivities were only moderate to low [48]. As mentioned in Section 1.2.3.1, tertiary amides can be converted to ketones. 

Walsh and coworkers oxidized ethyl p-tolyl sulfide on an analytical scale to the S-sulfoxide of 64% enantiomeric purity using a bacterial flavoenzyme cyclohexanone monooxygenase derived from Adnetobacter . Using a flavin adenine dinucleotide containing monooxygenase purified from hog liver microsomes yielded the R-sulfoxide of 90% enantiomeric purity. HPLC on a column containing a 3,5-dinitrobenzoyl-D-phenylglycine chiral stationary phase was used to determine the optical purity of the sulfoxides. 

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