2.6- diisopropylphenylcarbamoyl-quinine

A number of nonnatural amino acids were resolved into individual enantiomers on 0-9-(2,6-diisopropylphenylcarbamoyl)quinine-based CSPby Peter and coworkers [48,90,113,114] after derivatization with Sanger s reagent, chloroformates (DNZ-Cl, FMOC-Cl, Z-Cl), Boc-anhydride, or acyl chlorides (DNB-Cl, Ac-Cl, Bz-Cl). For example, the four stereoisomers of P-methylphenylalanine, P-methyltyrosine, P-methyltryptophan, and P-methyl-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid could be conveniently resolved as various A-derivatives [113]. The applicability spectrum of cinchonan carbamate CSPs comprises also P-amino carboxylic acid derivatives, which were, for example, investigated by Peter et al. [114]. A common trend in terms of elution order of DNP-derivatized P-amino acids was obeyed in the latter study On the utilized quinine carbamate-based CSP, the elution order was S before R for 2-aminobutyric acid, while it was R before S for the 3-amino acids having branched R substituents such as wo-butyl, iec-butyl, tert-butyl, cyclohexyl, or phenyl residues. 

In a recent study, chiral separations for pyrethroic acids, which are the chiral building blocks of synthetic pyrethroids and the primary metabolites of the acid part of these potent ester insecticides, have been developed [62], For example, a polar-organic mobile phase allowed the complete baseline resolution of all four stereoisomers of chrysanthemic acid (2,2-dimethyl-3-(2-methylprop-l-enyl)-cyclopropanecarboxylic acid) on a 0-9-(tcrt-butylcarbamoyl)quinine-based CSP(acjj = 1.20, oLtrans = 1-35, critical Rs = 3.03) (Figure 1,32a). This chiral acid is the precursor of pyrethroids like allethrin, phenothrin, resmethrin, and tetramethrin but not excreted as metabolite. The primary acid metabolite of these pyrethroids is chrysanthemum dicarboxylic acid (3-[(l )-2-carboxyprop-l-enyl]-2,2-dimethylcyclopropanecarboxylic acid) the stereoisomers of which could also be resolved with a reversed-phase eluent (acetonitrile— 30-mM ammonium acetate buffer 90 10, v/v pHa = 6.0) and employing an O-9-(2,6-diisopropylphenylcarbamoyl)quinine-based CSP ads = 1-09, atrans = 1-50,... 

FIGURE 1.32 Stereoisomer separations of chrysanthemic acid (a) and fenvaleric acid (b) employing an 0-9-(tert-bntylcarbamoyl)qninine-based CSP in the polar-organic mode (a) and an 0-9-(2,6-diisopropylphenylcarbamoyl)quinine based CSP (b). Experimental conditions Column dimensions, 150 mm x 4mmID eluents(a)0.06%aceticacidin acetonitrile-methanol (95 5 v/v) (b) acetonitrile-0.3 M ammoninm acetate buffer (90 10 v/v) (pHa 6.0) flow rate, 0.65 mLmin temperature, 25°C detection, UV at 230 nm. (Reproduced from W. Bicker et al., J. Chromatogr. A, 1035 37 (2004). With permission.)... 

O-tert-Butylcarbamoylquinine (t-BuCQN) and 2,6-diisopropylphenylcarbamoyl-quinine (DIPPCQN) type CSPs have been evaluated for the enantiomer separation of a set of isoindolin-l-one fluorescent derivatives of a-amino adds obtained by their reaction with the ortho-phthalaldehydc, naphthalene-2,3-dicarboxaldehyde, or anthracene-2,3-dicarboxaldehyde. The latter reagent afforded the derivatives of the... 

QN, quinine QD, quinidine DIPPCQN, diisopropylphenylcarbamoyl quinine DIPPCQD, diisopropylphenylcarbamoyl quinidine tBuCQN, tert-butylcarbamoyl quinine tBuCQD, tert-butylcarbamoyl quinidine DNB-Leu, (3,5)-dinitrobenzoyl-leucine nd, not determined np, no preference. 

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