ISSN:0899-0042    

DOI:10.1002/chir.530030302

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530030303

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractInversion of inactive (R)‐ibuprofen to active (S)‐ibuprofen has been suggested to occur presystemically only. In order to investigate the site of inversion in dogs we administered both enantiomers either intravenously or intraduodenally (10 mg/kg) to adult, male beagle dogs (n= 3) in a crossover design. Plasma, urine, and bile were collected for up to 6 h and analyzed stereospecifically by HPLC, according to a previously published method. Pharmacokinetic parameters were calculated using a linear computer program. Absorption after intraduodenal administration occurred rapidly, resulting in maximum plasma concentrations 0.2 h after giving the enantiomer. Approximately 70% of the (R)‐enantiomer (according to AUC) was inverted to the S‐enantiomer independent of route of administration. No R‐ibuprofen could be detected in plasma after (S)‐ibuprofen administration. Mean residence time was found to be 2 to 3 times longer for (S)‐than for (R)‐ibuprofen. Total systemic clearance from plasma was twice as high for (R)‐ than for (S)‐ibuprofen. There were no differences between plasma clearances after intravenous and intraduodenal administration. Between 8 and 17% of dose was recovered in bile [especially as free and conjugated (S)‐ibuprofen] and 3–12% in urine [as (S)‐ibuprofen, hydroxy‐ and carboxyibuprofen, free and conjugated forms]. Small amounts of (R)‐ibuprofen were detected in bile after intraduodenal administration of (R)‐ibuprofen only (1.8% of dose). In short, the unidirectional inversion of R‐ibuprofen appears to occur systemically ra

ISSN:0899-0042    

DOI:10.1002/chir.530030304

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractOptical resolution of β‐(1‐naphthyl)alanine and β‐(2‐naphthyl)alanine have been efficiently carried out through enzymatic hydrolysis of their methyl ester and/orN‐acetyl ester derivatives by immobilized enzymes. Difficulties related to the lipophilic character of these amino acids were overcome by using emulsions ofn‐butyl acetate–water as reaction medium. The use of an automatic recirculating apparatus allowed reproducible and repetitive use of the immobiliz

ISSN:0899-0042    

DOI:10.1002/chir.530030305

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractTheN‐(n‐butylamide) of (S)‐2‐(phenylcarbamoyloxy)propionic acid, easily prepared starting from the inexpensiveL‐ethyl lactate, can be used as convenient chiral solvating agent (CSA) to determine the enantiomeric composition ofN‐(3,5‐dinitrobenzoyl)amino acid

ISSN:0899-0042    

DOI:10.1002/chir.530030306

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

Abstract2,2,2‐Trifluoro‐1‐(9‐anthryl)ethanol (TFAE) has now been widely used as a powerful chiral solvating agent for NMR spectroscopy. In connection with the development of a new general synthesis of halogenoalkylalkanols, starting from the corresponding ketone or aldehyde, we synthesized some halogenoalkyl‐1‐(9‐anthryl)methanol derivatives liable to work as chiral solvating agents. The racemic anthryl derivatives were preparatively resolved into their corresponding enantiomers by chromatography on triacetyl cellulose (CTA I) or onmeta‐methylbenzoyl cellulose beads as chiral stationary phases. Their effectiveness as chiral solvating agents was measured as the magnitude of the splitting induced in the1H‐NMR spectra of 1‐phenylethylamine and of (1‐phenylethyl)methyl ether in comparison with splitting caused by TFAE. While TFAE induced the largest splitting for 1‐phenylethylamine, 2,2,3,3,3‐pentafluoro‐1‐(9‐anthryl)propanol 2 was more effective in the case of (1‐phenylethyl)methyl ether, pointing out that depending on the substrate, other derivatives of the TFAE type can be very

ISSN:0899-0042    

DOI:10.1002/chir.530030307

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA chiral stationary phase (CSP) derived fromN‐(1‐naphthyl) leucine has been prepared. This CSP is conceptually similar to the CSP derived fromN‐(2‐naphthyl)alanine and was expected to separate the enantiomers of the same clientele of analytes as does the latter. The magnitudes of the separation factors observed on the two CSPs may differ markedly for a given analyte, the new CSP often affording much greater enantiosele

ISSN:0899-0042    

DOI:10.1002/chir.530030308

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA Pirkle‐concept chiral stationary phase (CSP) derived fromN‐(1‐naphthyl)leucine was evaluated for developing methods to reduce analysis times and investigating techniques in the rapid screening of a variety of chiral compounds over a given chiral selector. The effects of reduced column lengths and elevated temperatures were studied to shorten analysis

ISSN:0899-0042    

DOI:10.1002/chir.530030309

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractSamples enriched in (−)‐ and (+)‐1,2‐benzocyclononen‐3‐ol were prepared by microbially mediated reactions. An enriched sample of (+)‐1,2‐benzocyclodecen‐3‐ol was prepared by fractional crystallization of the diastereoisomeric camphanates, followed by hydrolysis. The absolute stereochemistry of both alcohols was established by chemical transformations. The elution order of their enantiomers from a chiral Pirkle HPLC column [(R)‐N‐(3,5‐dinitrobenzoyl)phenyl glycine ionically bound to γ‐aminopropyl silanized silica] was determined. The information in conjunction with other data was used to formulate a rule to predict the configuration of an enantiomer of an alkylarylcarbinol from its el

ISSN:0899-0042    

DOI:10.1002/chir.530030310

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractRacemic cyclohexylaminoglutethimide (±ChAG) and its acetylated metabolite (±ChAG) were resolved by a direct chromatographic method using a Chiracel OD column without derivatization. Maximum resolutions (R) of 4.89 and 0.74 were obtained for the enantiomers of cyclohexylaminoglutethimide and its acetylated metabolite, respectivel

ISSN:0899-0042    

DOI:10.1002/chir.530030311

出版商:Alan R. Liss, Inc.    

年代:1991

数据来源: WILEY