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手性邻二醇--(2S,3R)-1,2,3-丁三醇-1-对甲苯磺酸酯的不对称合成 总被引:3,自引:0,他引:3
以(E)-2-丁烯-1-醇为原料经不对称环氧化反应合成2,3-环氧醇(1) 。该环氧醇的对甲苯磺酸酯对映选择性酸水解开环制备手性邻二醇(2)(95%ee)。 相似文献
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新的烯丙型环氧醇重排还原反应研究 总被引:3,自引:3,他引:0
自1980年Sharpless[1]报道烯丙醇制备立体选择性烯丙型环氧醇化合物以来,有关烯丙型环氧醇的反应及其在有机合成中的应用研究日益受到重视,其中路易斯酸催化的反应尤为重要[2].但由路易斯酸催化的反应极少涉及碳骨架的重排或基团的迁移.我们最近在... 相似文献
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锌和锡参与下末端环氧化物的选择性烯丙基化反应 总被引:1,自引:0,他引:1
烯丙基溴和金属辛或锡成功地将末端环氧化合物1一锅法合成高烯丙基醇2和双高烯丙基醇3. 还研究了环氧化合物取代基的影响, 并提出了此烯丙基化的反应途径 . 相似文献
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在不同浓度的三乙胺乙酸乙酯溶液中2-甲基环戊-1,3-二酮与氯代甲基乙烯酮(1b)反应可分别得三酮、α-氯代醇或环氧双酮. α-氯代醇经X射线单晶衍射分析结果推断出环氧双酮的环氧是β构型, 其异构体为α, 用相似的方法制得的同系环氧物也经X射线单晶衍射分析, 结果表明其环氧为β构型. 相似文献
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路易斯酸催化下的环氧醇开环重排反应是极为重要的一类反应[1~3], 但是, 至目前所发现的反应都限于控制2个立体中心. 我们在前文[4]中报道了几个环氧醇在异丙醇铝(AIP)的作用下生成1,3-二醇的例子. 最近我们合成了一系列不同结构的底物, 对该反应进行了系统深入的研究, 得出了一些规律性的结果, 即在某些情况下能控制3个立体中心, 别的情况下至少能控制2个立体中心. 该反应还建立了一个立体控制的季碳中心. 我们认为该反应是一个极好的合成手性1,3-二醇特别是螺环二醇的新方法, 对于研究新的不对称反应催化剂具有重要的理论和应用价值[5], 本文对这一反应的初步结果进行了讨论. 相似文献
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为了克服以往许多烯烃环氧化催化剂发生严重沉积的缺点,我们首次合成了一种苯乙二醇氧钼螯合物(简称M BC,M为MoO_2,B为苯乙二醇,C为螯合物).将其用于丙烯环氧化新反应中,可以免去助溶剂,苯乙二醇配位体原料可重新由该过程获得,各反应指标均较满意,较好地消除了沉积,表明MBC是个良好的环氧化催化剂. 相似文献
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Silyl-proton exchange reactions with ketene methyl trialkylsilyl acetals proceeded rapidly and quantitatively under mild conditions. The preparative silylation of alcohols, carboxylic acids, mercaptans, and amides is described. 相似文献
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A. S. Dzhalmukhanova E. R. Badamshina V. V. Komratova V. P. Lodygina M. P. Garkushina Ya. I. Estrin 《Kinetics and Catalysis》2008,49(1):52-58
The exchange reactions of phenyl-N-phenylurethane with aliphatic alcohols, namely, n-butyl, sec-butyl, and tert-butyl alcohols, in ortho-dichlorobenzene and in the media of the corresponding alcohols were studied. In the absence of a catalyst and proton-donating compounds, the monomolecular cleavage of phenyl-N-phenylurethane to isocyanate and alcohol proceeds at a noticeable rate starting only at 250°C. Between 40 and 80°C, the exchange reactions take place via direct exchange between urethane and the photon-donating compound and are second-order up to high conversions (until the almost complete disappearance of the initial urethane). Activation energies and apparent rate constants have been determined for the exchange reactions of phenyl-N-phenylurethane with butyl alcohols. The rates of the exchange reactions in the alcohol medium are compared with those in ortho-dichlorobenzene. 相似文献
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Elisabetta Ranucci Gloria Spagnoli Paolo Ferruti 《Macromolecular rapid communications》1999,20(1):1-6
A novel activated derivative of methacrylic acid, namely 2‐[(1‐imidazolyl)formyloxy]ethyl methacrylate was synthesized and homopolymerized. The resulting polymer was used in exchange reactions with alcohols and amines, thus showing a potential for the synthesis of multifunctional polymers. All reactions, expecially those carried out in the presence of amines, proceeded under mild conditions. 2‐[(1‐Imidazolyl)formyloxy]ethyl methacrylate can also be regarded as a valuable precursor for the preparation of new and easily polymerizable functional monomers. 相似文献
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Proton exchange and transesterification reactions of acetate enolates with alcohols in the gas phase
Transesterification reactions and proton exchange reactions between acetate enolates and alcohols were studied both separately and together. Kinetic analysis shows that transesterification and proton exchange happen in a single collision event. The transesterification reaction is best viewed as an endothermic proton transfer, followed by an exchange of alkoxide and an exothermic proton transfer. Reaction barriers were modeled by Rice-Ramsperger-Kassel-Marcus theory and compared to quantum calculations. CBS-QB3 achieves good agreement whereas B3LYP and MP2 give slightly higher barriers. Quantum calculations also predict that the transition state for these transesterification reactions is the same as that for direct transesterification reactions between alkoxides and esters. 相似文献
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Dr. Masanori Shigeno Kazutoshi Hayashi Dr. Kanako Nozawa-Kumada Prof. Dr. Yoshinori Kondo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(24):6077-6081
The organic superbase tBu-P4 catalyzes methoxy-alkoxy exchange reactions on (hetero)arenes with alcohols. The catalytic reaction proceeded efficiently with electron-deficient methoxy(hetero)arenes as well as with a variety of alcohols, including 3-amino-1-propanol, β-citronellol, menthol, and cholesterol. An intramolecular version of this reaction furnished six- and seven-membered ring compounds. 相似文献
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More environmentally benign alternatives to current chemical processes, especially large-scale, fundamental reactions such as ester condensations, are highly desirable for many reactions. Bulky diarylammonium pentafluorobenzenesulfonates and tosylates serve as extremely active dehydration catalysts for the ester condensation reaction of carboxylic acids with equimolar amounts of sterically demanding alcohols and acid-sensitive alcohols. Typically, the esterification reaction is performed in heptane by heating at 80 degrees C in the presence of 1 mol % of the catalyst without removing water. Esterification with primary alcohols proceeds without solvents even at room temperature. Furthermore, 4-(N-mesitylamino)polystyrene resin-bound pentafluorobenzenesulfonate can be recycled more than 10 times without activity loss. 相似文献
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Iwasaki M Hayashi S Hirano K Yorimitsu H Oshima K 《Journal of the American Chemical Society》2007,129(14):4463-4469
Allylations of aryl halides take place upon treatment of tertiary homoallyl alcohols with aryl halides in the presence of cesium carbonate and a palladium catalyst. The allylation reaction would consist of the following steps: (1) oxidative addition of aryl halide to palladium, (2) ligand exchange between the halide and the homoallyl alcohol affording aryl(homoallyloxy)palladium, (3) retro-allylation of the palladium alkoxide to generate sigma-allyl(aryl)palladium with concomitant liberation of the relevant ketone, and (4) productive reductive elimination. Since the retro-allylation step proceeds in a concerted fashion via a conformationally regulated six-membered cyclic transition state, the allylation reactions are highly regio- and stereospecific when homoallyl alcohols having a substituted allyl group are used. Whereas triarylphosphine is known to serve as a ligand for the palladium-catalyzed allyl transfer reactions, tricyclohexylphosphine proves to significantly expand the scopes of aryl halides to electron-rich aryl chlorides and of homoallyl alcohols to cyclic homoallyl alcohols. The new arylative ring-opening reactions of cyclic homoallyl alcohols allow for the synthesis of ketones having a branched or linear allylarene moiety at the remote terminus in regio- and stereospecific manners. 相似文献
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ZHANG Jing-wen ZHANG Xiao-long MA Xiu-li LIU Chang-cheng MU Ying SUN Yun-xiu JIANG Wen-pu HUANG Hua-min LI Yao-xian PENG Wan-ru 《高等学校化学研究》1998,14(1):38-41
StudiesonEsterExchangeReactionZHANGJing-wen,ZHANGXiao-long,MAXiu-li,LIUChang-cheng,MUYing,SUNYun-xiu,JIANGWen-pu,HUANGHua-min... 相似文献
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Cumpstey I Agrawal S Borbas KE Martín-Matute B 《Chemical communications (Cambridge, England)》2011,47(27):7827-7829
Primary carbohydrate amines at primary and secondary carbons are alkylated by alcohols in the presence of [Cp*IrCl(2)](2). When primary carbohydrate alcohols are used as the coupling partners and in the presence of Cs(2)CO(3), amine-linked pseudodisaccharides are obtained. Secondary carbohydrate alcohols are unaffected under these conditions, which allows regioselective reactions. 相似文献
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Ahlsten N Bartoszewicz A Martín-Matute B 《Dalton transactions (Cambridge, England : 2003)》2012,41(6):1660-1670
Allylic alcohols can be isomerised into carbonyl compounds by transition metal complexes. In the last few years, catalyst design and development have resulted in highly efficient isomerisations under mild reaction conditions, including enantioselective versions. In addition, the isomerisation of allylic alcohols has been combined with C-C bond forming reactions when electrophiles such as aldehydes or imines were present in the reaction mixture. Also, C-F bonds can be formed when electrophilic fluorinating reagents are used. Thus, allylic alcohols can be treated as latent enol(ate)s. In this article, we highlight the latest developments concerning the isomerisation of allylic alcohols into carbonyl compounds, focusing in particular on tandem isomerisation/C-C or C-heteroatom bond formation processes. Significant attention is given to the mechanistic aspects of the reactions. 相似文献