ISSN:0899-0042    

DOI:10.1002/chir.530040502

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe broken wedge, broken line, solid bar, and broken bar are either not reasonable or can be replaced by only one type of solid wedge in the stereochemical formulation. A convention based on a one‐wedge symbolization is proposed, whereaorbis used instead ofc, d, e, f, g, orh. © 1992 Wiley‐Liss,

ISSN:0899-0042    

DOI:10.1002/chir.530040503

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe hepatic α1‐adrenergic receptor mediates a variety of hepatic functions including respiration, glycogenolysis, gluconeogenesis, and growth. We have utilized a rat primary hepatocyte culture system to show that the α1‐adrenergic receptor can be activated in a stereoselective manner by a series of phenethylamines and catecholimidazolines resulting in the stimulation of DNA synthesis as determined by [3H]thymidine incorporation. The phenethylamines adhered to the Easson–Stedman hypothesis with a rank order of potency of (–)‐(R)‐norepinephrine (NE)>(+)‐(S)‐NE>the desoxy analog dopamine (DA) for the stimulation of DNA synthesis. However, the 2‐substituted catecholimidazolines did not follow this trend and demonstrated an order of potency of the desoxy analog 3,4‐dihydroxybenzyl imidazoline (DHT) ≥ (–)‐(R)‐2‐(3,4,α‐trihydroxybenzyl)imidazoline (TBI)>(+)‐(S)‐TBI. 4‐Substituted catecholimidazolines were less potent as inducers of DNA synthesis than the corresponding 2‐substituted analogs with an order of potency of (+)‐(R)‐4‐(3,4‐dihydroxybenzyl)imidazoline (DBI)>(+, –)‐(R,S)‐DBI>(–)‐(S)‐DBI. When the β‐hydroxyl moiety of NE is replaced with an amino group as in 3,4‐dihydroxyphenylethylenediamine, the isomers are less active than the β‐hydroxylated analogs and also demonstrate no stereoselectivity for the stimulation of DNA synthesis. These results demonstrate that the hepatic α1‐adrenergic receptor can recognize various isomeric forms of these compounds and that hepatocellular growth can be modulated in a stereosel

ISSN:0899-0042    

DOI:10.1002/chir.530040504

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractBoth (R)‐ and (S)‐4‐hydroxypentylaminoacetamide have been synthesized by reductive amination of glycinamide on the γ‐valerolactols corresponding to (R)‐ and (S)‐γ‐valerolactone, respectively. These enantiomeric lactones were readily obtained in high enantiomeric excess (ee) by enzymic porcine pancreatic lipase (PPL) kinetic resolution ofrac‐methyl γ‐hydroxyvalerate. ©

ISSN:0899-0042    

DOI:10.1002/chir.530040505

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe asymmetric synthesis polymerization or “enantiogenic” polymerization of some meso oxiranes,cis‐dimethyloxirane (cis‐DMO) and cyclohexene oxide (CHO), and thiiranes,cis‐dimethylthiirane (cis‐DMT) and cyclohexene sulfide (CHS), initiated with different chiral systems was examined. Strong differences in behaviour were observed between oxiranes and thiiranes depending on the initiator used. The initiators based on ZnEt2or CdMe2and a chiral diol give optically active polymers from meso thiiranes but fail to induce an asymmetric polymer synthesis with meso oxiranes. A new chiral initiator based on ZnEt2and (1S,2R)‐ephedrine allowed us to prepare optically active poly CHOs, which can be fractionated into fractions exhibiting opposite optical activities. © 1992 W

ISSN:0899-0042    

DOI:10.1002/chir.530040506

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe chiral biphenyl‐containing diamine1complexed with OsO4oxidizedtrans‐stilbene at –80°C to (+)‐(1R;2R)‐1,2‐diphenyl‐1,2‐ethanediol in high enantiomeric excess. On the other hand, (R)‐ or (S)‐2,2'‐bis(dimethylamino)‐6,6'‐dimethylbiphenyl proved to be ineffective in promoting oxidati

ISSN:0899-0042    

DOI:10.1002/chir.530040507

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractRacemic 5,5‐dialkyl hydantoins derived from ketones are resolved by preparative liquid chromatography as the diastereomeric 1‐carboxamide derivatives afforded by the reaction with optically pure configurationally known α‐phenylethyl isocyanate. Hydrolysis of the resolved diastereomers affords α‐substituted α‐amino acids of high enantiomeric purity. The synthetic route is short, overall yields are high, and the absolute configuration of the amino acid enantiomers may be deduced from the chromatographic and NMR properties of the diastereomers. © 1992 Wi

ISSN:0899-0042    

DOI:10.1002/chir.530040508

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractAntibody‐mediated extraction followed by chiral high‐performance liquid chromatography (HPLC) was applied to stereoselective determination in human and rat plasma of the active metabolite [(2S,1]R,2[S)‐trans‐alcohol] with three chiral centers of Loxoprofen, a 2‐arylpropionic acid antiinflammatory agent after oral administration. Antiserum against the (1'R,2'S)‐cyclopentanol moiety was obtained from a rabbit immunized with bovine serum albumin conjugate linked to the propionic acid moiety, in which another chiral center is located. Then, the immunoglobulin G purified by a protein A column was coupled to BrCN‐activated Sepharose 4B. Plasma samples were applied to the immobilized antibody column. After washing the column to remove unrequired stereoisomers, a mixture of two diastereomers whose configurations were 1'R,2'S in the cyclopentanol moiety was extracted with 95% methanol. The solvent was evaporated and the residue was derivatized with (+)‐(R)‐1‐(1‐naphthyl)ethylamine as a chiral reagent to separate the diastereomers by HPLC. This combined analytical method showed the stereoselective metabolism of Loxoprofen in human, that is, 64% of the total amount of fourtrans‐alcohol stereoisomers was in the 2S, 1'R,2'S form, which is the active metabolite. This phenomenon was also observed in rats given Loxoprofen and its (2S)‐ and (2R)‐isomers, and is explained by stereoselective ketone reduction of Loxoprofen to the (1'R,2'S)‐trans‐alcohol and inversion from 2R to 2S in the propionic acid moiety. Antibody‐mediated extraction should be a selective and simple clean‐up method for determining haptens with complicated structures, combined with an appropriate analyt

ISSN:0899-0042    

DOI:10.1002/chir.530040509

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe application of a central composite design to the enantiomeric separation of the antifungal drug tioconazole is investigated. The design involves application of a mathematical model to the data to model the response in regions of the factor space not investigated in the experimental design. The significance of the variable terms in the model is assessed statistically and those terms declared not significant are removed from the model. The statistical adequacy of these reduced models is discussed, together with an examination of the prediction errors of the models. Three‐dimensional predicted response surfaces for the complete models are presented and the predictive performance assessed. © 1992 Wiley‐Liss,

ISSN:0899-0042    

DOI:10.1002/chir.530040510

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe application of porous graphitic carbon as adsorbing phase for direct separation of enantiomeric acids and amines using chiral ion‐pair chromatography is described. The enantiomeric amines were separated as diastereomeric ion pairs withN‐benzyloxycarbonylglycyl‐L‐proline,N‐benzyloxycarbonylglycylglycyl‐L‐proline, or captopril as the chiral counterion. High enantioselectivities were obtained for amines having a hydrogen bonding function in the vicinity of the asymmetrical carbon atom. Quinine was the chiral counterion used to separate the enantiomeric acids. The strongly UV‐absorbing quinine improved detection of solutes having low UV‐absorbing properties, e.g., (R,S)‐2‐chloropropionic acid, by “indirect detection.” Retention and stereoselectivity of enanticmeric acids were regulated by the quinine concentration and by the addition of carboxylic acids as well as polar modifiers, e.g., methanol and 2‐propanol, to the mobile ph

ISSN:0899-0042    

DOI:10.1002/chir.530040511

出版商:Alan R. Liss, Inc.    

年代:1992

数据来源: WILEY