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A protocol was developed for the solution‐phase synthesis of multigram amounts of two 9‐fluorenylmethoxycarbonyl (Fmoc)‐protected tetraproline peptides. These tetraproline peptides were then attached to amino derivatized silica gel. The replacement of the Fmoc group with the trimethylacetyl group lead to two tetraproline chiral stationary phases (CSPs). A comparison of the chromatographic behavior...
A chiral capillary electrophoresis method has been developed for the quantification of 0.1% of the enantiomeric impurity (dextrocetirizine) in levocetirizine and determination of both in pharmaceuticals using sulfated‐β‐cyclodextrins (CDs) as chiral selector. Several parameters affecting the separation were studied such as the type and concentration of chiral selectors, buffer composition and pH,...
Hexaconazole [(RS)‐2‐(2,4‐dichlorophenyl)‐1‐(1H‐1,2,4‐triazol‐1‐yl) hexan‐2‐ol] is a potent triazole fungicide and consists of a pair of enantiomers. Enantioselective degradation of hexaconazole was investigated in rat hepatic microsomes in vitro. Concentrations of (−)‐ and (+)‐hexaconazole and enantiomer fraction were determined by high performance liquid chromatography with a cellulose‐tris‐(3,5‐dimethylphenylcarbamate)‐based...
Nine novel (+)‐camphor‐derived thioureas have been prepared. 3‐((Dimethylamino)methylene)camphor (2) served as the common precursor for the preparation of both, 2‐thiourea 15, 16, 17, 18, 19, 20 and 3‐thiourea functionalized camphor derivatives 6, 7/7', respectively. Starting from 2, the latter were prepared in two or three steps whereas the former in five steps, respectively. Configuration of all...
(R)‐(−)‐α‐Methoxy phenyl acetic acid, (S)‐(−)‐1,1′‐(2‐naphthol), and (R)‐(+)‐α‐methoxy‐α‐trifluoromethyl phenyl acetic acid were evaluated as chiral shift reagents (CSRs) for 1H NMR spectroscopic resolution and determination of R and S enantiomers of modafinil (MDL) in bulk drugs and formulations. Effects of the nature of CSR and the weight ratio of substrate to shift reagent on enantiomeric discrimination...
Several pyrrolidine–camphor derived organocatalysts were designed and synthesized. These organocatalysts were used for direct Michael reaction of aldehydes with nitroalkenes to give the desired γ‐nitrocarbonyl compounds in high yields (up to 99%), high diastereoselectivities (syn:anti up to 92:8), and good to excellent enantioselectivities (up to 94% ee). Possible transition‐state model was also proposed...
Quinines phosphorylated at the C‐9 hydroxyl group (diphenyl and diethyl phosphates) were synthesized and validated as novel effective chiral solvating agents in two alternative methods based on 1H and 31P NMR spectroscopy. Tested with a representative set of racemic analytes, the title compounds induced shift nonequivalence effects in 1H NMR signals with values up to 0.1–0.2 ppm for 3,5‐dinitrobenzoyl‐substituted...
(1R, 3R)‐1‐(1, 3‐Benzodioxol‐5‐yl)‐2‐(chloroacetyl)‐2, 3, 4, 9‐tetrahydro‐1H‐pyrido[3, 4‐b]indole‐3‐carboxylic acid methyl ester ((1R, 3R)‐Cpe) is a key intermediate used in the synthesis of tadalafil, a highly selective phosphodiesterase type‐5 inhibitor. In the present study, a chiral high‐performance liquid chromatography method was developed for the simultaneous determination of diastereoisomeric...
A simple chiral high‐performance liquid chromatography method with diode array detector was developed and validated for stereoselective determination of tetraconazole enantiomers in cucumber, muskmelon, and soils. Good separation was achieved at 20°C using cellulose tris‐(4‐methylbenzoate) as chiral stationary phase, a mixture of n‐hexane and ethanol (90:10) as mobile phase at a flow rate of 0.8 ml/min...
This work reports the result of the enantioselective disposition of pantoprazole, omeprazole, and lansoprazole in a same group of Brazilian health subjects. Ten nongenotyped healthy subjects were used for this study. Each subject received a single oral dose of 80 mg of pantoprazole, 40 mg of omeprazole, and 30 mg of lansoprazole, and the plasma concentrations of the enantiomers were measured for 8...
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