关键词： Mixtures   Arylation   Kinetic resolution   Stereoselectivity   Conjugate acid-base pairs  

摘要： A catalytic asymmetric conjugate arylation of racemic 5-(trimethylsilyl)cyclohex-2-enone with arylboronic acids was catalyzed by 3 mol % chiral amidophosphane- or BINAP-Rh(l) in dioxane-water (10:1) to afford trans- and cis-3-aryl-5-(trimethylsilyl)cyclohexanones in high enantioselectivity. Dehydrosilylation of the product mixture with cupric chloride in DMF gave 5-arylcyclohex-2-enones with up to 93% ee in good yield. Enantiofacial selectivity with chiral phosphane-Rh(l) exceeds the trans-diastereoselectivity that is maintained in the achiral or racemic phosphane-Rh(l)-catalyzed conjugate arylation of 5-(trimethylsilyl)cyclohexenone.

关键词： asymmetric synthesis   nucleoside analogues   hydrazones   organocerium reagents   diastereoselective reduction  

摘要： An efficient diastereo- and enantioselective synthesis of 4'-quaternary 2'-deoxy-3'-epi-beta-C-nucleosides is described employing the RAMP-hydrazone methodology to establish the first stereocentre. Further key steps include diastereoselective nucleophilic 1,2-additions with Grignard and organocerium reagents.

关键词： chiral   cyclopolymerization   metal-organic catalysts/organometallic   polysulfides   ring-opening polymerization  

摘要： The polymerizations of the diepisulfides 1,2:5,6-diepithio-3,4-di-O-methyl-D-mannitol (1a), 1,2:5,6-diepithio-3,4-di-O-methyl-L-iditol (1b), and 1,2:5,6-diepithio-3,4-di-0-methyl-allitol (1c) were carried out with ZnEt2/H2O, ZnEt2/alcohol, and ZnEt2/(S or R)-1,1'-bi-2-naphthol (BN) as the initiator systems. All the polymerizations proceeded without any gel formation and gave white, powdery products. The number-average molecular weights of the obtained polymers were changed in the range of 5300-33,600. The polymerization of la using the ZnEt2/H2O (1/1) catalyst in tetrahydrofuran proceeded through a regio- and stereoselective cyclopolymerization mechanism to produce thiosugar polymers mainly consisting of 2,5-anhydro-1,5dithio-D-glucitol as the five-membered ring units. The polymers obtained from 1b and 1c with ZnEt2/H2O exhibited lower stereoregularities than that from la. For the polymers obtained from la with the ZnEt2/alcohol systems, the molar fraction of the five-membered ring units depended on the alcohol used as a ligand. On the other hand, the polymerization of le using ZnEt2/(R or S)-BN asymmetrically proceeded, and optically active polymers consisting of desulfurized acyclic units were obtained. When ZnEt2/(R)-BN (1/1) was used in toluene, the polymer with [alpha](D)(23) = +56.9 degrees was obtained in an 88.6% yield. The resulting polymer had an isotactic-rich structure consisting of about 90% (R)-configurational units and about 10% (S)-units. (c) 2005 Wiley Periodicals, Inc.

关键词： ENANTIOSELECTIVE catalysis   HETEROGENEOUS catalysis   NUCLEOPHILIC reactions   CHIRALITY   PHOSPHINE   CATALYSTS   PHYSICAL & theoretical chemistry  

摘要： For several years,we have been pursuing the development of enantioselectivenucleophile-catalyzed *** now,our efforts have focused on the use of chiral derivativesof 4-(di-methylamino)pyridine (DMAP),due to the remarkable versatility of DMAP as a *** past decade,tertiary phosphines have emerged as effective nucleophilic catalysts for animpressive range of transformations;unfortunately,there has been only very limited progress inachieving high levels of asymmetric induction with chiral *** this,we recentlydecided to broaden our program in enantioselective nucleophilic catalysis to include studies ofchiral tertiary phosphines.

关键词： asymmetric synthesis   chiral resolution   helical structures   total spontaneous resolution  

摘要： Helical complexes formed between aluminum tris(2,6-diphenylphenoxide) (ATPH) and five different aldehydes have been prepared and structurally characterized by X-ray diffraction. It was found that [Al(OC6H3Ph2),PhCHO] (2), [Al(OC6H3Ph2),(4-CH3C6H4CHO)] (3), [Al(OC6H3Ph2)(3)(4-tBUC(6)H(4)CHO)] (4), and [Al(OC6H4Ph,)3(p-CH3OC6H4-CHO)] (5) all crystallize as conglomerates, while crystals of [Al(OC6H3Ph2)3(o-CH3OC6H4CHO)] (6) are racemic. Supramolecular CH/pi interactions between molecules in crys- tals of 2-5 that enable stereochemical information to be mediated in three dimensions have been identified and explain the high frequency of conglomerate formation among ATPH helicates. Since 2 -5 are stereochemically labile and thus enantiomerize rapidly in solution, the conglomerates can be resolved by crystallization-induced asymmetric transformation. The determination of the enantiomeric excess (ee) in solid samples of stereochemically labile molecules is not trivial, but solid-state CD spectroscopic data, anomalous dispersion data, and the ee values in alkylation reactions all indicate that preferential crystallization of 2-5 yields an essentially enantiopure product. Thus the preparation of 2-5 constitute new examples of absolute asymmetric synthesis. The helical chirality can be transferred (and thus trapped) to alcohols (with ee values of up to 16%) in crystal-to-crystal reactions with achiral organometallic reagents.

关键词： HIGHLY DIASTEREOSELECTIVE HYDROCYANATION   METAL ALPHA-CYANOCARBANIONS   CHIRALTI(IV) COMPLEX   LITHIATED PHENYLACETONITRILE   AROMATIC-ALDEHYDES   L-DAUNOSAMINE   NITRILES   CARBANIONS   SILYLCYANATION   STEREOCENTERS  

摘要： [GRAPHICS] Optically pure functionalized cyanohydrins derived from 1[2-(p-tolylsulfinyl)phenyl] ethanone can be obtained by the reaction of 2-p-tolylsulfinyl benzaldehyde derived cyanohydrins with bases and further treatment with suitable electrophiles. High yields and excellent stereoselectivities (up to de > 98%) were obtained for these remote 1,4-asymmetric induction processes controlled by a sulfinyl chiral inductor.

关键词： TERT-BUTANESULFINYL IMINES   DIASTEREOSELECTIVE SYNTHESIS   ENANTIOSELECTIVESYNTHESIS   ALKALOIDS   SULFINIMINES   CONDENSATION   ALDIMINES   REAGENTS   ALCOHOLS   KETONES  

摘要： [GRAPHICS] The first examples of conjugate additions of N-tert-butanesulfinyl metalloenamines are reported. Highly stereoselective conjugate additions (97:3 to 99:1 dr) were observed between metalloenamines derived from N-sulfinyl ketimines and alpha,beta-unsaturated ketones bearing either alkyl or aryl substituents. The conjugate addition products could rapidly be converted with high diastereoselectivity to 2,4,6-trisubstituted piperidines, which are difficult to access by other methods.

关键词： 手性化合物   拆分工艺   不对称合成   酒石酸   苯丙胺  

摘要： 技术类型：精细化工与中间体 项目简介：手性化合物的拆分多年来一直困扰着制药及农药的生产，特别是一些精细化工中间体经拆分后可获得几倍乃至十几倍的经济效益，多年来手性化合物规模拆分始终不能满意，近年来经过一系列的努力后，我单位在手性化合物的大规模拆分方面建立一整套理论和实践的基础，先后在上海等地建立了年产100吨L-酒石酸及年产10吨L-苯丙胺装置。

关键词： 手性镓铟   金属有机配合物   不对称合成   手性催化剂   结构表征  

摘要： 本论文的工作主要分为四个方面：一、用手性 Salen 配体、Salan 配体与二甲基氯化铟、三甲基铟反应，合成了一系列手性铟金属有机配合物，通过多种手段对配合物结构进行了表征；二、用手性 Salen 配体与三甲基镓反应，合成了一系列手性镓金属有机配合物，通过多种手段对配合物结构进行了表征；三、以这些配合物为手性催化剂，催化不对称反应，表征催化剂的催化性能；四、合成了一系列2，6－二亚胺苯氧基二甲基镓配合物，通过多种手段对配合物结构进行了表征。这些工作包括：\n 1、手性Salen－铟配合物的合成、表征及晶体结构\n 以（1R，2R）－1，2－环己二胺和（1R,2R）－1，2－二苯基乙二胺为手性源分别与水杨醛、3－甲氧基水杨醛、5－氯水杨醛、3，5－二叔丁基水杨醛和3，5－二氯水杨醛反应合成了10个手性 Salen 配体（L<,1>～L<,10>）。这些手性 Salen 配体与二甲基氯化铟反应制得8个手性 Salen－InCl 配合物（1～8），与三甲基铟反应制得10个手性 Salen－InMe 配合物（9～18）。这些配合物均为关环单核铟配合物。对得到的配合物用 H－NMR、IR、MS 和元素分析进行了表征，并对配合物3、7、13进行了 X-ray 晶体结构解析。配合物3、7、13均为单体结构，其中铟原子都是五配位的，配位几何为四方锥型。\n 合成了两个手性 Salan 配体，其中一个 Salan 配体与三甲基铟的反应产物19进行了 X-ray 晶体结构解析。配合物19以二聚体的形式存在。\n 2、手性Salen－镓配合物的合成、表征及晶体结构\n 8个手性Salen配体与三甲基镓反应制得8个手性Salen－Ga配合物（20~27），反应中均放出甲烷气体，生成开环双镓配合物。对得到的配合物用<’1>H—NMR、IR、MS和元素分析进行了表征，并对配合物21和27进行了X-ray晶体结构解析。配合物21和27均为单体结构，其中镓原子都是四配位的，配位几何为四面体型。\n 3、苯硫酚、苄基硫醇对内消旋环氧化物的不对称开环反应\n 以8个手性Salen—InCl配合物（1~8）不对称催化苯硫酚、苄基硫醇对内消旋环氧化物的开环反应，所得产物产率中等，ee值不超过10％。但在手性Salen－InCl配合物和NaBPh4的共同作用下，ee值有所提高，最高为37％。研究表明：1）最佳反应条件是－10℃，20mol％Salen－InCl配合物3、20m01％NaBPh<,4>、以乙腈为溶剂。4A分子筛的加入对反应无影响；2）催化剂结构中的取代基对催化剂的活性有影响，大取代基（t-Bu）能得到相对高的ee值。\n 4、2－吡啶基甲基锂对环氧化物的不对称开环反应\n 首次以手性Salen镓、铟配合物不对称催化2－吡啶基甲基锂对环氧化物的开环反应，发现：（1）手性配体与三甲基镓以1：1摩尔比生成的手性单镓配合物的催化效果明显好于双镓配合物；（2）Salen配体的催化效果好于Salan配体的催化效果；（3）两个t-Bu取代的配体L<,4>的单镓配合物催化能力相对最高；（4）-50℃、20mol％配体L<,4>的单镓配合物、乙醚为溶剂，是最佳反应条件。\n 5、手性Salen镓、铟配合物不对称催化Biginelli反应的研究\n 以手性Salen镓、铟配合物不对称催化Biginelli反应，发现（1）手性Salen镓配合物的催化活性高于手性Salen铟配合物：（2）催化反应的最佳条件是：0℃，20mol％配合物20，乙醇为溶剂；（3）水杨醛环上无取代基时配合物的ee值高于有取代基的，空间位阻越大越不利于提高ee值。\n 6、2，6-二亚胺苯氧基二甲基镓的合成、表征和晶体结构\n 以5-甲基-2-羟基-1，3-苯二醛（1）、5－叔丁基-2-羟基-1，3-苯\n 二醛（2）分别与苯胺、4－甲基苯胺、2－氯苯胺和1－萘胺反应合成了8个5－烷基－2，6－二亚胺苯酚类化合物（3～10），这8个化合物与三甲基镓反应合成了8个2，6－二亚胺苯氧基二甲基镓配合物（11～18），对其中的11、12、18进行了晶体结构分析，这三个配合物的晶体结构有着共同的特征：配合物分子是单体结构。镓原子与一个亚胺氮原子、一个氧原子、两个碳原子配位，配位几何为扭曲的四面体构型。

关键词： 1,1’-联二萘酚   对映体拆分   不对称合成   不对称氧化反应   不对称还原反应  

摘要： 综述了催化氧化偶联2-萘酚合成外消旋体1,1′-联二萘酚(B INOL)的方法。介绍了制备对映体B INOL的化学拆分法、酶拆分法、不对称催化合成法和酶催化合成法的新进展。介绍了对映体B INOL作为手性试剂在不对称还原前手性羰基化合物为手性醇、不对称还原亚胺为手性氨基化合物、不对称环氧化合成α,β-不饱和化合物以及不对称氧化硫化物反应中的应用。