摘要:

AbstractA modified albumin was prepared by selective reaction of Lys199with acetyl salicylic acid. Protein binding investigation was carried out on native and modified proteins by difference circular dichroism (ΔCD). Acetylation of Lys199reduces significantly the effects of the interaction between drugs in the stereoselective HSA binding at specific binding areas. © 1995 Wiley‐Liss,

ISSN:0899-0042    

DOI:10.1002/chir.530070202

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractChiral symmetry breaking can be realized in stirred crystallization of Na‐ClO3. We present experimental and theoretical studies of the random distribution of crystal enantiomeric excess (cee) for various stirring and solvent evaporation rates. For a fixed solvent evaporation rate, as the stirring RPM is increased, the probability distribution of cee initially broadens and subsequently develops a sharp peak close to cee = 1. On further increase of stirring rate, the probability distribution once again broadens. This broad probability distribution becomes narrow, with a sharp peak near cee = 1, if the solvent evaporation rate is decreased. Thus we show some ways in which the probability distribution of cee can be controlled in stirred crystallization. In particular, our study shows that the stirring rate and the solvent evaporation rate can be adjusted to maximize crystal enantiomeric excess. © 1995 Wiley‐Liss,

ISSN:0899-0042    

DOI:10.1002/chir.530070203

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA method has been presented to evaluate the Ca2+‐dependent binding affinity of ligands to calmodulin (CaM) from their chromatographic retentions obtained on a CaM‐Sepharose column. Enantiomers of benzodiazepines and related compounds could be separated. Among chiral calcium antagonists, verapamil showed stereoselectivity of binding. © 1995 Wiley‐Lis

ISSN:0899-0042    

DOI:10.1002/chir.530070204

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe solubility behaviour of praziquantel enantiomeric system at −15°C, 4°C, and 15°C is presented. This system exhibits both a pseudoracemate behaviour and one which leads to the formation of enantiomerically pure crystals. For solutions with lower enantiomeric purity, the pseudoracemate behaviour is more prominent. Solid solutions are formed when the mixtures of the enantiomers are crystallised. The phase diagram shows a complete absence of a eutetic. For mixtures with higher enantiomeric purity, pure crystals of the excess enantiomer are obtained when the solution is crystallised. Temperature dependency of this polymorphism is not significant. With these phase diagrams, a method is suggested to obtain enantiomerically pure isomers of praziquantel from a partially resolved mixture. © 1995 Wiley‐Li

ISSN:0899-0042    

DOI:10.1002/chir.530070205

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe circular dichroism (CD) spectra of a series of oxygenated 2‐(dipropylamino)tetralin derivatives are reported. On the basis of known absolute configurations and conformational preferences of the compounds, the validity of published correlations between the sign of the1LbCotton effect and the three‐dimensional structure was examined. Contrary to predictions, substitution in position 6 or 7 of the tetralin moiety did not change the sign of the1LbCotton effect. An unexpected sign inversion was, however, observed in some of the compounds containing methyl substituents in the nonaromatic ring. The occurrence of this inversion was not correlated with a change in conformational behaviour and varied depending on the position and nature of the aromatic substituent. No correlations were obvious between the sign of the1LbCotton effect and the absolute configuration and conformational preferences of the compounds. Therefore, at present, CD spectroscopy does not appear to be useful in assignments of the absolute configurations of 2‐(dipropylamino)tetralin derivatives. © 1995 Wiley‐L

ISSN:0899-0042    

DOI:10.1002/chir.530070206

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe stereoisomers of α,α′‐bis[3‐(N,N‐diethylcarbamoyl)‐piperidino]‐p‐xylene (1) were synthesized.Racethyl nipecotate was resolved by diastereomeric (‐)‐D‐ and (+)‐L‐tartrate salt formation. The enantiomeric esters were hydrolyzed to the corresponding nipecotic acids, which were then converted intot‐BOC derivatives. Treatment of the latter with diethylamine/isobutyl chloroformate and removal of thet‐BOC protecting group afforded (R)‐ and (S)‐N,N‐diethylnipecotamides. Condensation of the latter with α,α′‐dibromo‐p‐xylene gave (R,R)‐ and (S,S)‐1. Themeso‐diastereomer was obtained by stereospecific synthesis in addition to our earlier procedure involving fractional crystallization of the diastereomeric mixture obtained by synthesis. The latter was resolved earlier into1A,1B, and1Cusing chiral high‐performance liquid chromatography (HPLC). Based on the stereospecific synthesis now achieved,1Aand1Bare assigned the configurations, (R,R) and (S,S) respectively, and1Cis assigned themesoconfiguration. The (R,S) structure of the latter is also confi

ISSN:0899-0042    

DOI:10.1002/chir.530070207

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe diastereofacial selectivity of both inter‐ and intramolecular Diels‐Alder reactions with dienes having an allylic stereogenic center has been studied by varying the allylic oxygen protective group. Four different hydroxy protective groups were investigated including benzyl,t‐butyldiphenylsilyl, triethylsilyl, andt‐butyldimethylsilyl ethers. For intermolecular reactions, the benzyl ether derivative gave the highest sπ‐facial selectivity through a transition state in which the allylic stereocenter favors the CH eclipsed conformation. For intramolecular cycloadditions, thet‐butyldimethylsilyl group gave a slightly higher selectivity than the benzyl ether derivative through a transition state in which the allylic stereocenter favors the CO eclipsed conformation. The opposite diastereofacial selectivity observed for inter‐ and intramolecular reactions is explained by considering both steric and electronic effects. © 1995

ISSN:0899-0042    

DOI:10.1002/chir.530070208

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA general approach to the synthesis of enantiomerically pure α‐phenyl amino alcohols via the asymmetric reduction of α‐phenyl haloalkyl ketones or α‐phenyl aminoalkyl ketones withB‐chlorodiisopinocampheylborane is described. Using this approach, an improved synthesis of a potential antipsychotic, α‐(4‐fluorophenyl)‐4‐(2‐pyrimidinyl)‐1‐piperazinebutanol in ⩾98% ee, and the broncholdilator 1‐(2‐methoxy‐2‐phenethyl)‐4‐(3‐hydroxy‐3‐phenylpropyl)piperazine (eprozinol) i

ISSN:0899-0042    

DOI:10.1002/chir.530070209

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530070210

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530070201

出版商:Alan R. Liss, Inc.    

年代:1995

数据来源: WILEY