Enantiomer最新文献_第2页

Mechanistic aspects of chiral discrimination on an amylose tris(3,5-dimethylphenyl)carbamate. 直链淀粉三(3,5-二甲基苯基)氨基甲酸酯手性鉴别的机理。

Enantiomer Pub Date : 2002-11-01 DOI: 10.1080/10242430215711

Y Bereznitski, R LoBrutto, N Variankaval, R Thompson, K Thompson, P Sajonz, L S Crocker, J Kowal, D Cai, M Journet, T Wang, J Wyvratt, N Grinberg

{"title":"Mechanistic aspects of chiral discrimination on an amylose tris(3,5-dimethylphenyl)carbamate.","authors":"Y Bereznitski, R LoBrutto, N Variankaval, R Thompson, K Thompson, P Sajonz, L S Crocker, J Kowal, D Cai, M Journet, T Wang, J Wyvratt, N Grinberg","doi":"10.1080/10242430215711","DOIUrl":"https://doi.org/10.1080/10242430215711","url":null,"abstract":"The separation of [2R-[2alpha(R*),3alpha]]-5-[[2-[1-[3,5-bis-(trifluoromethyl)phenyl]ethoxy]-3(S)-4-fluorophenyl)4-morpholinyl]-methyl]-N,N-dimethyl-1H-1,2,3-triazole-4-methanamine hydrochloride from its enantiomer was achieved on an amylose tris-3,5-dimethylphenyl carbamate stationary phase. The retention of the enantiomers is dominated by weak hydrogen bonds while the enantioselectivity is governed by other kinds of interactions, e.g., inclusion in the amylose carbamate chains. Van't Hoffplots of 1nalpha vs. reciprocal temperature were non-linear and could be divided into two linear regions. One region at low temperature (5 degrees C- approximately 20 degrees C) and another one between 25 degrees C-70 degrees C with the change in slope occurring between 16 degrees C and 20 degrees C. DSC experiments suggested that the behavior can be attributed to breakage of H-bonds triggering a conformational change. Molecular simulation indicated a correlation between the interaction energies and the elution order obtained experimentally. The most retained enantiomer (R,R,S-enantiomer) interacts with the stationary phase through a hydrogen bond between the triazole proton and the C=O groups of the stationary phase, as well as through an inclusion in the cleft of the stationary phase. The other enantiomer exhibits a bifurcated H-bond between the triazolic proton and the C=O groups of the stationary phase leading to a less stable complex.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22295711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 23

An improved methodology for the synthesis of enantiomerically pure (S)-2,3-O-cyclohexylideneglyceraldehyde. 合成对映体纯(S)-2,3- o -环己基甘油醛的改进方法。

Enantiomer Pub Date : 2002-11-01 DOI: 10.1080/10242430215702

M Benaglia, M Caporale, A Puglisi

引用次数: 4

Generation of chirality by the aggregation of column structures for two-component molecular crystals composed of chloronitrobenzoic acids and p-anisidine. 氯硝基苯甲酸和对茴香胺组成的双组分分子晶体的柱状结构聚集产生手性。

Enantiomer Pub Date : 2002-11-01 DOI: 10.1080/10242430215703

Teruki Sugiyama, Jiben Meng, Teruo Matsuura

引用次数: 6

Determination of absolute configurations of light-atom molecules by means of direct detection of Bijvoet differences. 用直接检测毕氏差的方法测定轻原子分子的绝对构型。

Enantiomer Pub Date : 2002-11-01 DOI: 10.1080/10242430215709

Shoichi Sato, Toshifumi Yoshida, Toshihiko Hori

{"title":"Determination of absolute configurations of light-atom molecules by means of direct detection of Bijvoet differences.","authors":"Shoichi Sato, Toshifumi Yoshida, Toshihiko Hori","doi":"10.1080/10242430215709","DOIUrl":"https://doi.org/10.1080/10242430215709","url":null,"abstract":"The absolute configurations of two light-atom molecules were determined sufficiently well by direct detection of Bijvoet differences. The compounds examined were (I) beta-cytidine C9H13N3O5 and (II) (S)-3-[(R)-4,4,4-Trifluoro-3-[4-methoxyphenyl]butanoyl]-4-(phenylmethyl)oxazolidin-2-one, C21H20NO4F3. Both compounds crystallize in orthorhombic system with the space group P2(1)2(1)2(1) and Z = 4. The crystal structures were carefully refined by the technique of conventional structure analysis. All possible reflections were measured on a laboratory diffractometer with Cu Kalpha radiation. The multiple-diffraction effect was often observed especially as remarkable intensity enhancement in weak reflections. After such unreliable reflections were eliminated by comparisons among the equivalent mates, data were averaged to a set of Bijvoet pairs. Afterwards, additional measurements by the psi-scan technique were tested. Since psi-scan data showed a slight systematic error probably owing to some shape-effect, an artificial absorption correction DIFABS was adopted to remove the error. Small but significant intensity differences could be detected for many Bijvoet pairs, and the absolute configurations were correctly determined without ambiguity in all cases. The R and wR values for separate refinements of enantiomorphs supported the results with slight differences. Flack parameters indicated no contradictions as well.","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/10242430215709","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22294652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

The synthesis and structure of substituted dimenthyl malonate derivatives. 取代丙二酸二甲酯衍生物的合成及结构。

Enantiomer Pub Date : 2002-11-01 DOI: 10.1080/10242430215697

Gregory S Coumbarides, Jason Eames, Majid Motevalli, Yonas Yohannes

引用次数: 0

CD and ACD spectroscopy on anisotropic samples: chirality of oriented molecules and anisotropic phases--a critical analysis. 各向异性样品的CD和ACD光谱:定向分子的手性和各向异性相——一个关键的分析。

Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212880

H. Kuball

引用次数: 16

Circular dichroism spectra of regioregular poly[3 [(S)-2-methylbutyl]-thiophene] and of poly[3,4-di[(S)-2-methylbutyl]-thiophene]. 区域规则聚[3 [(S)-2-甲基丁基]-噻吩]和聚[3,4-二[(S)-2-甲基丁基]-噻吩]的圆二色光谱。

Enantiomer Pub Date : 2002-07-01 DOI: 10.1080/10242430212881

F. Lebon, G. Longhi, S. Abbate, M. Catellani, F. Wang, P. Polavarapu