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罗库溴铵(Rocuronium Bromide)是新的手术前的甾醇类肌松药,其安全性和有效性已得到临床研究和应用的证实.雄甾-3,17-二醇(1)是合成罗库溴铵的关键中间体.用硼氢化钠还原(2α,3α,5α,16β)-2,3-环氧基-16-(1-吡咯)-17-氧代雄甾烷(2),然后在吗啉和水中回流使环氧开环得到雄甾-3,17-二醇(1).高分辨TOF-MS质谱和1H NMR,13C NMR,1H-1H COSY,HSQC,DEPT,HMBC,2D NOESY等核磁共振谱表征确认其分子构造,并且制备和测定了雄甾-3,17-二醇1的单晶结构,确认了它的立体构型.雄甾-3,17-二醇(1)的样品的X粉末衍射分析研究表明其衍射谱与根据单晶数据计算的理论谱一致,因此,合成的雄甾-3,17-二醇(1)的分子结构是(2β,3α,5α,16β,17β)-2-(4-吗啉基)-16-(1-吡咯)雄甾-3,17-二醇,其立体构型与罗库溴铵的立体构型一致. 相似文献
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通过硼烷对三级有机膦的配位保护,避开了甲基化试剂对膦官能团的季膦化作用,以甘露糖环氧物为原料经4步反应以55%总产率制得甲基2-O-甲基-3-脱氧-3-二苯膦基-4,6-O-苯次甲基-α-D-吡喃阿糖苷(5).制得的含碳水化合物单元的新手性膦5分别与cis-[Pt(DMSO)2Cl2]和trans-[Pt(NCMe)2Cl2]反应制得相应的cis-和trans-[Pt(5)2Cl2](6和7).实验中发现:(1)在烷氧根负离子存在时,硼烷优先与三级膦配位形成膦硼烷加合物;(2)室温下四氢呋喃中糖环上二级醇形成的烷氧根锂盐不能有效地与碘甲烷发生反应,而相应的钠盐顺利地形成目标产物;(3)有机碱是有效的脱硼烷试剂,而乙醇则有更好的反应结果,后处理简便且可几乎定量地得到产物;(4)偶合常数1JPt-P可作为指认这类含碳水化合物单元的手性膦配位的Pt(II)络合物几何构型的可靠参数. 相似文献
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一类新型的双β-氨基醇的合成及催化硼烷对芳酮的不对称还原反应 总被引:7,自引:0,他引:7
以L-半胱氨酸盐酸盐出发,经与二卤代烷偶联,成酯和格氏反应制得三种双手性β-氨基醇,1,2-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]乙烷(4a),1,3-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]丙烷(4b),1,4-双[R-2-氨基-3-羟基-3,3-二苯基丙硫基]丁烷(4c)。将此类双手性β-氨基醇与硼烷在THF溶液中反应,in situ制备双手性恶唑硼烷催化硼烷对芳酮的不对称还原,产物苯乙醇的光学收率达72.8%、α-溴代苯乙醇的光学收率达91.4%。 相似文献
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对手性唑硼烷催化3,3-二甲基丁酮-2不对称还原反应机理进行了从头算研究.结果表明,该不对称还原反应是放热的.反应经历了催化剂-硼烷加合物、催化剂-硼烷-酮加合物、含B-O-B-N四元环的催化剂-烷氧基硼烷加合物的生成,以及催化剂-烷氧基硼烷加合物的离解并再生催化剂等过程.在催化剂-硼烷-酮加合物经氢转移而生成催化剂-烷氧基硼烷加合物的过程中,氢转移与B-O-B-N四元环的形成是协同进行的.氢转移是还原反应的控制步骤.氢转移过渡态具有扭曲的椅式结构,所决定的还原产物是与实验相吻合的R手性醇. 相似文献
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A regioselective and stereospecific substitution reaction of 1-(phenylthio)-2,3-epoxyalkanes was achieved by using organoaluminum reagents as a nucleophile. Under the influence of trimethyl- or triethylaluminum, a 1-(phenylthio)-2,3-epoxyalkane underwent substitution at the C2 position to give a product with retention of the configuration. The reaction proceeds through an episulfonium ion intermediate, which gives rise to the C2-substitution products with double inversion of the configuration. Introduction of an alkynyl group was also accomplished by the reaction with dimethyl[2-(trimethylsilyl)ethynyl]aluminum in dichloromethane. 相似文献
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1,9-Bis(methylthio)dibenzothiophene (1a) was treated with one equivalent of bromine and pyridine in the presence of l-menthol and then with aqueous sodium hydroxide to give optically active 1-(methylsulfinyl)-9-(methylthio)dibenzothiophene (2a) enriched by the S isomer (ee: 57%). The configuration of optically pure sulfoxide (2a) was determined by X-ray crystallographic analysis to be the S configuration at the sulfinyl sulfur atom. On the other hand, 1-(methyl-l-menthoxysulfonio)-9-(methylthio)dibenzothiophene tetrafluoroborate (4a) was isolated as an intermediate of this asymmetric oxidation in an optically pure form, as yellow crystals. The absolute configuration of this sulfonium salt (4a) was verified by X-ray crystallographic analysis as the R configuration. Optically pure sulfonium salt (4a) also gave partially optically active sulfoxide (2a) with net inversion on its hydrolysis. It was suggested that the hydrolysis reaction of the sulfonium salt (4a) accordingly proceeds, not only via a sulfurane having a simple SN2 type of geometry but also by a front side attack ofhydroxide anion, with respect to the l-menthoxy group, on sulfur, and the sequential elimination of the l-menthoxy group from the tetracoordinated intermediate. © 1996 John Wiley & Sons, Inc. 相似文献
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A C2 hexadentate diester derived from (5-hydroxymethyl)pyridine-2-aldehyde 2'-pyridylhydrazone (5-HOCH2PAPHY) and an enantiomerically pure (aS)-spirane dicarboxylic acid diastereoselectively reacts with iron(II) benzenesulfonate in methanol to furnish a 20% diastereomeric excess (de) of a two-bladed propeller, octahedral iron complex in which the P configuration of the newly created (+/-)-[Fe(PAPHY)2](2+) stereocenter predominates; when the reaction mixture is heated under reflux for 12 h, however, the excess of the diastereomer having the P configuration at iron increases to 80%, as determined by (1)H NMR spectroscopy. The configuration at iron in the major diastereomer of the complex was determined by comparison of the circular dichroism spectrum of the deprotonated complex with that of a related complex of known configuration. Repositioning of the hydroxymethyl group of the pyridine-2-aldehyde from the 5- to the 6-position produced a C2-spirane ligand that generates a double-stranded diiron(II) helicate in >99% de. Single crystal X-ray structure determinations of the racemates of the protonated and deprotonated helicates revealed that the complexes crystallize diastereoselectively, that is, two ligand strands of a S configuration generate two octahedral iron(II) stereocenters of P configuration to give a dinuclear metal helicate of P configuration and vice versa for the ligand of a R configuration. 相似文献
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García Ruano JL Alemán J Alonso I Parra A Marcos V Aguirre J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(21):6179-6195
N-Arylarylideneamines react with sulfinylbenzyl carbanions derived from 2-(p-tolylsulfinyl)toluenes (S)-1 and (S)-2, affording epimeric mixtures at C1 of 1,2-diarylethyl- and 1,2-diarylpropylamine derivatives. The sulfinyl group completely controls the configuration at C2 in the reactions of (S)-2. The configuration at C1 depends on the electron density of the ring adjacent to the iminic carbon atom which is modulated by pi-pi stacking interactions with the ring joined to the carbanionic centre. The stereoselectivity was controlled by modifying the acceptor character of the arylideneamine ring with appropriate substituents, the formation of the highly selective (R) configuration at C1 being made possible by electron-donating groups. N-(2,4,6-Trimethoxyphenyl)arylideneamines have been shown to be suitable starting materials for the preparation of (R)-1,2-diarylethyl- and (1R,2S)-1,2-diarylpropylamines (syn epimers) in a highly stereoselective manner. 相似文献
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The prediction of the absolute configuration of alpha-chiral carboxylic acids from the 1H NMR spectra of their esters with (R)- and (S)-ethyl 2-hydroxy-2-(9-anthryl) acetate [(R)- and (S)-9-AHA, 5] is discussed. Low-temperature NMR experiments, MM, semiempirical, and aromatic shielding effect calculations allowed the identification of the main conformers and showed that, in all esters studied, conformer ap is the most stable. A simple model for the assignment of the absolute configuration from NMR data is presented, and its reliability is corroborated with acids 6-31 of known absolute configuration. In addition to 5, other auxiliary reagents with open (32-38) and cyclic (39-42) structures have also been studied. trans-(+)- and (-)-2-phenyl-1-cyclohexanol (41) was found to be particularly efficient and produced delta delta RS values similar to those of 5. 相似文献
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Mechanistic studies on the intramolecular nucleophilic substitution with allylic rearrangement (SNi' reaction) and a new stereoselective access to substituted cyclobutanones are reported. 4,4-Dialkyl-5-oxohex-2E-en-1-yl methanesulfonates 4 were converted to 2,2-dialkyl-3-vinylcyclobutanones 6 by SNi' ring closure. The stereochemical analysis of the reaction was achieved through ring closure of (6S)-6-chloro-3,3-diethylhept-4E-en-2-one (S)-17, defined by the absolute configuration of C(6), leading to (3S)-2,2-diethyl-3-(prop-1E-en-1-yl)cyclobutanone (S)-(E)-18 and (3R)-2,2-diethyl-3-(prop-1Z-en-1-yl)cyclobutanone (R)-(Z)-18, in a ratio of 85:15, with almost complete transfer of chirality (>97%). The absolute configuration of (S)-17 was determined by X-ray diffraction analysis of the camphanoate derivative 16. The absolute configuration of the cyclobutanone products (S)-(E)-18 and (R)-(Z)-18 was determined by Raman optical activity spectroscopy. Comparison of the absolute configuration of (S)-17 and the resulting (E)- and (Z)-cyclobutanones 18 allowed the conclusion that the SNi' reaction proceeds with syn geometry relative to the leaving group. 相似文献
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The structure of rogioldiol A ((?)- 1 ), isolated from the red seaweed Laurencia microcladia, was determined. Employing the exciton-coupling technique for rogioldiol A p-bromobenzoate ( 2 ), the absolute configuration at C(9) of (?)- 1 was assigned, and, together with extensive NMR experiments, the absolute configuration at C(10) and preferred conformations of (?)- 1 were determined. The absolute configuration of the hetero-substituted cyclohexane ring was deduced in analogy from the X-ray structure of 4 , a derivative of the aldehyde 3 , which was isolated from the same seaweed and is believed to be a degradation product of (?)- 1 . 相似文献
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旋光活性O-乙基-O-苯基硫代磷酰胺酯在4.7mol/LHCl-MeOH溶液中进行酸性甲醇解时得到P-N键断裂的构型翻转产物,与MeONa-MeOH的碱性甲醇解得到以PhO基为离去基的构型翻转产物.两种甲醇解反应的机理均可用三角双锥(TBP)中间体概念完满地解释. 相似文献
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By capitalizing on a highly selective Claisen rearrangement, ent-galbanic acid 1 and (+)-marneral 2 have been synthesized. The relative configurations of (+)- 1 and (+)- 2 were unambiguously established by X-ray crystallographic analysis of the precursors 11a and 20, with the absolute configuration ensuing from their derivation from R-pulegone. In this way, the controversial issue of the configuration of galbanic acid was unequivocally settled. 相似文献
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A 1:1 mixture of the racemic trans- and cis-1-p-menthene-3,8-diols ((±)- 3 and (±)- 4 , resp.) was readily prepared in 3 steps starting from 3-methyl-2-cyclohexen-1-one. The relative configuration of the diols, purified via the corresponding cyclocarbonates, was assigned by 1H-NMR spectroscopy and found to be at variance with tentative claims in the literature. Optically active samples of 3 and 4 were prepared by resolution of the racemates with (R)-1-phenylethylamine. The absolute configuration of the resulting diols was determined by chemical correlation with standards of known absolute configuration. 相似文献