{"title":"用直接检测毕氏差的方法测定轻原子分子的绝对构型。","authors":"Shoichi Sato, Toshifumi Yoshida, Toshihiko Hori","doi":"10.1080/10242430215709","DOIUrl":null,"url":null,"abstract":"<p><p>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.</p>","PeriodicalId":11752,"journal":{"name":"Enantiomer","volume":"7 6","pages":"271-81"},"PeriodicalIF":0.0000,"publicationDate":"2002-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/10242430215709","citationCount":"4","resultStr":"{\"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\":null,\"url\":null,\"abstract\":\"<p><p>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.</p>\",\"PeriodicalId\":11752,\"journal\":{\"name\":\"Enantiomer\",\"volume\":\"7 6\",\"pages\":\"271-81\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2002-11-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1080/10242430215709\",\"citationCount\":\"4\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Enantiomer\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1080/10242430215709\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Enantiomer","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1080/10242430215709","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 4
摘要
两个轻原子分子的绝对构型是通过直接检测Bijvoet差来确定的。所检测的化合物为(I) β -胞苷C9H13N3O5和(II) (S)-3-[(R)-4,4,4-三氟-3-[4-甲氧基苯基]丁基]-4-(苯基甲基)恶唑烷-2-one, C21H20NO4F3。两种化合物均为正交晶系,空间群为P2(1)2(1)2(1), Z = 4。用常规结构分析技术对晶体结构进行了细致的细化。所有可能的反射都在实验室用Cu - Kalpha辐射衍射仪上测量。多次衍射效应经常被观察到,特别是在弱反射中显著的强度增强。在通过比较相等的配偶来消除这种不可靠的反射之后,数据被平均为一组Bijvoet对。之后,通过psi扫描技术进行了额外的测量测试。由于psi扫描数据可能由于某些形状效应而出现轻微的系统误差,因此采用人工吸收校正DIFABS来消除误差。在许多Bijvoet对中可以检测到微小但显著的强度差异,并且在所有情况下都正确确定了绝对构型,没有歧义。对映纯的不同细化的R和wR值与结果一致,但差异不大。高射炮参数也没有显示出矛盾。
Determination of absolute configurations of light-atom molecules by means of direct detection of Bijvoet differences.
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.