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1.
烯烃的催化不对称氨羟基化反应是Sharpless继手性钛络合物催化的烯丙醇的不对称环氧化反应和烯烃的催化不对称双羟基化反应这后发现的又一极为重要的催化不对称反应。本文对这一新反应作一综述。 相似文献
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作为一类重要的有机化学反应,烯烃的双官能团化反应不仅可以经济有效地一步合成多位点反应产物,而且可以将起始原料转化为多种含有生物活性或药物活性的化合物,同时还为构建化学结构的多样性提供了更多的方法,所以发展烯烃的双官能团化反应十分重要.对近十二年来各类烯烃的双官能团化反应进行了综述.主要分为:铜催化的烯烃的双官能团化反应、其它过渡金属催化的烯烃的双官能团化反应以及非金属催化的烯烃的双官能团化反应.同时对该类反应的发展前景进行了展望. 相似文献
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烯烃的双官能化反应在有机合成中占有十分重要的地位, 如锇催化烯烃的双羟化反应被广泛应用于天然产物和药物合成中. 近年来, 钯催化烯烃的双官能化反应引起了有机化学家的重视, 在文献上报道的有: 钯催化烯烃的双氨化反应、氨基乙酰氧基化反应和羟基乙酰氧基化反应. 这些反应共同的特点都是以PhI(OAc)2作为氧化剂, 而以环境友好的氧气(O2)作为氧化剂的烯烃双官能化反应却鲜有报道. 华南理工大学江焕峰等以O2作为单一氧化剂, 醋酸钯为催化剂, 成功实现了烯烃的双乙酰氧基化反应. 这一方法以1,2-二取代的烯烃为底物时, 得到的1,2-二乙酰氧基产物以顺式为主(syn∶anti>95∶5). 该催化反应体系为合成1,2-二乙酰氧基化合物开辟了一条新的绿色化途径. 相似文献
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本文介绍近年来国外金属有机化学家报道的烷基及芳基三氧合铼(14e,Ⅶ)络合物RReO3的合成和反应,以及利用该类络合物催化的烯烃歧化、烯烃环氧化和醛与重氮化合物烯烃化反应。 相似文献
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烯胺作为许多药物的关键结构单元,在有机合成,特别是天然产物的合成和含氮杂环化合物的合成中有很重要的应用。为了更好地发展适用性广的合成新方法,本文综述合成烯胺的最新研究进展。首先总结了传统合成烯胺的相关工作,随后综述了催化合成烯胺的相关工作,包括烯烃的催化胺化和炔烃氢胺化反应,详细介绍了过渡金属(主要是Cu(Ⅰ或Ⅱ)或Pd(0或Ⅱ))催化的Buchwald-Harwig反应中,使用多种取代烯烃(包括卤代烯烃及拟卤代烯烃与烯基硼酸)作为底物的研究进展,同时,对通过C(sp2)-H直接活化来构筑与不同胺相连的C-N键的Aza-Wacker氧化偶合反应也进行了介绍。希望对发展合成烯胺的新方法有所裨益。 相似文献
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A highly productive synthesis of phenylthio glycoside 33 is described which constitutes a fully functional surrogate for the hikosamine core of hikizimycin 1, a complex nucleoside antibiotic endowed with promising anthelmintic properties. The chosen approach to this undecose derivative starts from mannofuranose 7 which was one-carbon homologated to alkyne 8 in one step on treatment with lithio (trimethylsilyl)diazomethane. Alkynyl iodide 12 derived from 8 was combined with the tartrate-derived aldehyde 17 by a Nozaki-Hiyama-Kishi reaction that can either be performed using overstoichiometric amounts of CrCl2 or by means of a catalytic manifold based on the turnover of a cat. CrCl2/chlorosilane/manganese redox couple. Semi-hydrogenation of the resulting alkyne 18 to (Z)-olefin 19 required the use of Pd/C as the catalyst, whereas conventional Lindlar reduction was unsatisfactory. Attempted cis-dihydroxylation of alkene 22 (formed from 19 by a Mitsunobu reaction with phthalimide) by using catalytic amounts of OsO4 and NMO as the stoichiometric oxidant essentially failed, whereas a stoichiometric osmylation afforded the stable osmate ester 26 a as a single diastereomer. Since the use of OsO4 in stoichiometric amounts deemed inappropriate for a total synthesis project, recourse was taken to catalytic "Blitz dihydroxylation" with RuO4 in the presence of FeCl2.4H2O as co-catalyst. Application of these conditions to alkene 30 bearing a free aldehyde function at the terminus of the "higher sugar" chain furnished pyranose 32 in good yield and excellent diastereoselectivity, which was converted into the targeted thioglycoside 33 on treatment with PhSSPh/Et3P. It is particularly noteworthy that the conformational constraints of the acyclic substrate 30 enforce the dihydroxylation to violate Kishi's empirical rule for transformations of this type. 相似文献
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Majid M. Heravi Vahideh Zadsirjan Maryam Esfandyari Tahmineh Baie Lashaki 《Tetrahedron: Asymmetry》2017,28(8):987-1043
Sharpless asymmetric dihydroxylation involves the reaction of an alkene with osmium tetroxide in the presence of a chiral quinine ligand to form an optically active vicinal diol. This reaction was primarily developed by Sharpless based on the already known racemic Upjohn dihydroxylation. The chiral diols obtained by Sharpless asymmetric dihydroxylation are important intermediates in organic synthesis. Herein, we emphasise the applications of Sharpless asymmetric dihydroxylation in the total synthesis of natural products. 相似文献
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《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):76-89
A highly productive synthesis of phenylthio glycoside 33 is described which constitutes a fully functional surrogate for the hikosamine core of hikizimycin 1 , a complex nucleoside antibiotic endowed with promising anthelmintic properties. The chosen approach to this undecose derivative starts from mannofuranose 7 which was one‐carbon homologated to alkyne 8 in one step on treatment with lithio (trimethylsilyl)diazomethane. Alkynyl iodide 12 derived from 8 was combined with the tartrate‐derived aldehyde 17 by a Nozaki–Hiyama–Kishi reaction that can either be performed using overstoichiometric amounts of CrCl2 or by means of a catalytic manifold based on the turnover of a cat. CrCl2/chlorosilane/manganese redox couple. Semi‐hydrogenation of the resulting alkyne 18 to (Z)‐olefin 19 required the use of Pd/C as the catalyst, whereas conventional Lindlar reduction was unsatisfactory. Attempted cis‐dihydroxylation of alkene 22 (formed from 19 by a Mitsunobu reaction with phthalimide) by using catalytic amounts of OsO4 and NMO as the stoichiometric oxidant essentially failed, whereas a stoichiometric osmylation afforded the stable osmate ester 26 a as a single diastereomer. Since the use of OsO4 in stoichiometric amounts deemed inappropriate for a total synthesis project, recourse was taken to catalytic “Blitz dihydroxylation” with RuO4 in the presence of FeCl2 ? 4 H2O as co‐catalyst. Application of these conditions to alkene 30 bearing a free aldehyde function at the terminus of the “higher sugar” chain furnished pyranose 32 in good yield and excellent diastereoselectivity, which was converted into the targeted thioglycoside 33 on treatment with PhSSPh/Et3P. It is particularly noteworthy that the conformational constraints of the acyclic substrate 30 enforce the dihydroxylation to violate Kishi's empirical rule for transformations of this type. 相似文献
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Cyclobutane malonoyl peroxide (7), prepared in a single step from the commercially available diacid 6, is an effective reagent for the dihydroxylation of alkenes. Reaction of a chloroform solution of 7 with an alkene in the presence of 1 equiv of water at 40 °C followed by alkaline hydrolysis leads to the corresponding diol (30-84%). With 1,2-disubstituted alkenes, the reaction proceeds with syn-selectivity (3:1 → 50:1). A mechanism consistent with experimental findings is proposed, which is supported by deuterium and oxygen labeling studies and explains the stereoselectivity observed. Alternative reaction pathways that are dependent on the structure of the starting alkene are also described leading to the synthesis of allylic alcohols and γ-lactones. 相似文献
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Effect of some tert-amines on the catalytic osmium tetroxide dihydroxylation of cyclohexene in aqueous tert-butyl alcohol has been investigated All amines have been found to retard the catalysis greatly and beyond a definite concentration of amine, the rate reaches a minimal and remains constant. The oxidation of cyclohexene is inhibited by pyridine, 2.2′-bipyridyl and DABCO with an inverse first-order dependence whereas inhibition by triphenylamine NN-diethylaniline, picoline pyrazine hexamethylenetetraamine and TMEDA shows an inverse partial order dependence. The inolvement of dioxomonoglycolatoosmium(VI) esters and their monoamine adducts in the rate determining oxidation step was established by the linear plots of 1/Δk2 vs. 1/[L] where Δk2 is the decrease in the second-order rate constant in the presence of [L] concentration of tert-amine. The ligand-accelerated or ligand-decelerated catalysis of tert-amines in the catalytic osmium tetraoxide dihydroxylation of alkenes may vary depending on the secondary oxidant on the alkene and on the structure and concentration of the tert-amine. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 359–366, 1997 相似文献
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[reaction: see text] Two short synthetic approaches toward cryptophycin unit A comprise a catalytic asymmetric dihydroxylation as the sole source of chirality, while all further stereogenic centers are introduced under substrate control. The key step of the first route is a vinylogous Mukaiyama aldol addition, which introduces the alpha,beta-unsaturated ester moiety with defined configuration at the delta-carbon atom. Likewise, allylation with allyltributylstannane diastereoselectively gives the homoallylic alcohol that can be converted by a metathesis reaction to a unit A precursor. 相似文献
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[reaction: see text] The catalytic dihydroxylation of olefins represents a unique synthetic tool for the generation of two C,O-bonds with defined relative configuration. Whereas OsO(4) has been established as a very general dihydroxylation catalyst within the past 30 years, the less expensive and toxic isoelectronic RuO(4) has found only limited use for this type of oxygen-transfer reaction. High catalyst loading and undesired side reactions were severe drawbacks in RuO(4)-catalyzed oxidations of C,C-double bonds. Recently, we were able to improve the RuO(4)-catalyzed dihydroxylation by addition of Bronsted acids to the reaction mixture. This protocol proved to be of general applicability, however, certain limitations were observed. To address these problematic functional groups a new Lewis acid accelerated oxidation was developed. The use of only 10 mol % of CeCl(3) allowed a further decrease in the catalyst concentration down to 0.25 mol % while broadening the scope of the reaction. Silyl ethers and nitrogen containing functional groups are now tolerated in this optimized protocol. Furthermore, competing scission reactions are supressed in the presence of Lewis acid allowing longer reaction times and the successful oxidation of electron-deficient tetrasubstituted double bonds that cannot be oxidized using known dihydroxylation protocols. 相似文献
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[reaction: see text] The synthesis of the C9-C26 portion of amphidinolide B1 is described. A Fleming allylation followed by elimination was employed for the construction of the C13-C15 diene portion. Sharpless asymmetric dihydroxylation was utilized for regioselective functionalization of a styrene-derived alkene, in the presence of the C13-C15 diene functionality. A highly diastereoselective aldol reaction was developed to establish the C18 stereochemistry. 相似文献
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A mild, palladium(II)-catalyzed ring-forming aminoacetoxylation of alkenes is described. Treatment of a range of nitrogen nucleophiles with catalytic palladium(II) in the presence of PhI(OAc)2 as oxidant resulted in alkene aminoacetoxylation, affording a variety of nitrogen-containing heterocycles. Our studies indicate the possibility for high levels of reaction regio- and stereocontrol. It appears that this is a stereoselective trans alkene difunctionalization and thus a useful alternative to related cis-selective, metal-catalyzed alkene aminohydroxylation processes. 相似文献
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[formula: see text] Using the Sharpless catalytic asymmetric dihydroxylation reaction on 5-aryl-2-vinylfurans, diols are produced in high enantioexcess. The resulting diols can be efficiently transformed into the spiroketal ring precursor of the antifungal compound papulacandin D. Stereoselective reduction of this precursor followed by a diastereoselective dihydroxylation completes the synthesis of a mannopyranoside isomer of a papulacandin derivative. 相似文献