有机催化β-酮酸酯不对称α-羟基化反应研究进展

手性α-羟基β-酮酸酯是多种天然产物及医药产品的重要中间体,获得这一类结构单元最简单的方法是β-酮酸酯的直接不对称α羟基化,因此该反应在医药工业和精细化工领域具有重要的研究价值。本文针对小分子金鸡纳碱衍生物、二萜类生物碱、芳氧基氨基醇及手性相转移催化剂直接氧化β-酮酸酯不对称α-羟基化反应研究,该反应的催化机理被认为是氢键、π-π键等多种分子间力协同作用,同时还需要适当的位阻基团遮蔽以获得羟基化反应立体选择性。     

Visible Light instead of Transition Metal: Electron Donor Acceptor Complex Enabled Cross-Coupling of Aryl Halides with Active Methylene Compounds

An arylation of anions of active methylene compounds with aryl halides provides an access to synthetically versatile α-arylated 1,3-diketones, β-keto esters, β-keto nitriles, β-cyano esters, etc. Previously, these C−C cross-coupling reactions have been accomplished only using transition metal-based catalysts. Herein, we demonstrate that these arylations can be successfully realized under catalyst-free conditions employing the electron donor-acceptor (EDA) complex photoactivation strategy. The protocol was further optimized for a semi-one pot synthesis of indole derivatives via an intramolecular C−C coupling.     

聚羧酸硅基酯的合成及其可降解性质的研究进展

综述了聚羧酸硅基酯的合成方法和降解性质。用于合成聚羧酸硅基酯的方法主要有AA/BB型硅基转移酯基交换法、AB型硅基转移酯基交换法、AB型硅氢化反应以及交叉去氢偶联反应。对上述方法的特点进行了总结和比较。详细介绍了该类聚合物的降解机理以及影响降解速率的因素,并对其在生物医学以及环境科学领域的应用进行了展望。     

Sulfur dichloride diadducts of unsaturated fatty derivatives. I. preparation and oxidation

Sulfur dichloride diadducts of oleate esters, oleylnitrile, elaidate esters and ethyl linoleate were prepared by addition of the theoretical amount of sulfur dichloride to the fatty derivative. Similar diadducts were also prepared from commercial oleate esters including esters of ADM's monoenoic acid. Several of the resultingβ,β′- dichlorosulfide diesters were then oxidized with peracetic acid to β,β′-dichlorosulfoxide diesters and to β,β′-dichlorosulfone diesters. The latter materials were converted to the divinyl sulfone diacids. Cis andtrans-2-butene were used as model compounds for studying the addition of sulfur dichloride to oleates and elaidates respectively. The results on these systems, which paralleled the results with the fatty materials, indicated that substitution reactions were negligible and that the addition was stereoselective, that is, oleates and elaidates gave stereochemically different products.     

The Reactivity of Azidonitrobenzofuroxans towards 1,3-Dicarbonyl Compounds: Unexpected Formation of Amino Derivative via the Regitz Diazo Transfer and Tautomerism Study

Herein, we report on the reaction of nitro-substituted azidobenzofuroxans with 1,3-dicarbonyl compounds in basic media. The known reactions of benzofuroxans and azidofuroxans with 1,3-dicarbonyl compounds in the presence of bases are the 1,3-dipolar cycloaddition and the Beirut reaction. In contrast with this, azidonitrobenzofuroxan reacts with 1,3-carbonyl compounds through Regitz diazo transfer, which is the first example of this type of reaction for furoxan derivatives. This difference is seemingly due to the strong electron-withdrawing effect of the superelectrophilic azidonitrobenzofuroxan, which serves as the azido transfer agent rather than 1,3-dipole in this case.     

无水氯化镁和三乙胺催化合成β-酮酸酯

以丙二酸二乙酯为原料,在氢氧化钾条件下将其转变为丙二酸单乙醇酯钾盐,研究丙二酸单乙醇酯钾盐在无水氯化镁-三乙胺碱体系作用下,与酰氯反应制备β-酮酸酯的方法。产物结构经1H NMR、质谱、元素分析确证。该方法避免使用格氏试剂、氢化钠、丁基锂等强碱,条件温和,操作简单,成本低,适合在实验室和工业生产中制备β-酮酸酯。     

Synthesen und Eigenschaften Mono- und diphenylsubstituierter Monothio-β-dicarbonylverbindungen und ihrer Nickel(II)chelate

Syntheses and Properties of Mono- and Disubstituted Monothio-β-dicarbonyl Compounds and their Nickel(II) chelates Reaction of phenylacetaldehyde with phosphorous oxichloride and dimethylformamide yielded 3-chloro-2-phenyl-propenal, which was converted into 2-phenyl-monothiomalonic dialdehyde 2 by treating with sodium sulfide nonahydrate. Furthermore the reactions of other mono- and diphenylsubstituted monothio-β-dicarbonyl compounds with aniline on the one side and nickel(II)acetate on the other side have been studied. It was shown, that compounds 1–6 react in different way with aniline yielding either sulfur free products or in case of 1 and 4 enaminothioketones, which are of interest as building blocks for syntheses. In contrast to this the nickel complexes of 1–6 indicates an one another similar, typical chelate structure, which have been elucidated by u.v.-vis-, i.r.- and x-ray photoelectron spectroscopy.     

Simple process for preparation of optically active methacrylates polymer with controlled molecular weight

Novel optically active methacrylates polymer with controlled molecular weight have been prepared simply by opening ring reaction of poly(glycidyl methacrylate) and S-(−)-α-methylbenzylamine. The structure of the novel optically active methacrylates polymer was characterized by FT-IR, and chiroptical properties of the polymer were characterized by polarimeter and circular dichroism spectrum. Thermogravimetry analysis and differential scanning calorimetry were employed to examine the thermal properties of the polymer. This preparation process was simple and the racemization of optically active monomers in preparation can be avoided. The molecular weight of optically active methacrylates polymer could be controlled by molecular weight of poly(glycidyl methacrylate) prepared by atom transfer radical polymerization.     

Synthese,Reaktivität und 1H-NMR-Daten von 14,15-Methylenderivaten der Androstan- und Östratrienreihe

Synthesis, Reactivity and ¹H-NMR-Spectroscopy of 14,15-Methylene Derivatives of the Androstane and Estratriene Series Under the activating and syn-directing effect of the 17-hydroxy group the Simmons Smith cyclopropanation of 14,15-unsaturated 17-hydroxy steroids of the androstane and estratriene series 1a, 5 and 9 affords the 14,15-methylene steroids 2a, 6 and 10 with cis position of the 14,15-methylene and 17-hydroxy groups in a stereospecific reaction. Oxidation of these compounds yields the 17-keto derivatives 3, 7 and 11 , which were reduced to the compounds 4a, 8 and 12 with trans position of the 14,15-methylene and 17-hydroxy groups by complex hydrides or diborane. In a phase transfer catalyzed reaction dichloro- or dibromocarbene was added to 3β, 17β-diacetoxy-5α-androst-14-ene 1b forming the 14β, 15β-dihalogenmethylene steroids 13 and 14 . The 17-keto steroids 7 and 11 were transformed into 17-methyl and 17-ethynyl derivatives 15–20 . Cleavage of the cyclopropane ring of 2a, 2b and 3 by catalytic hydrogenation affords the 14β-methyl derivatives 21–23 , the acid catalyzed ring opening with hydrogen chloride yields the 14β-chloro, 15β-methyl derivatives 24–29 . Structure elucidation has been established by ¹H n.m.r. and mass spectroscopy. The configuration at C17, C14 and C15 was also determined by means of ¹H n.m.r. spectroscopy, using the chemical shifts of the 18-protons, the coupling constants and the chemical shifts of the 17-protons. The configuration of the 17-disubstituted steroids was established with the aid of an europium shift reagent.     

一锅法合成3,4-二氢嘧啶-2-酮及其衍生物

在极少量的盐酸存在下,以聚乙二醇2000为催化剂,将芳香醛、硫脲和β-二羰基化合物放入25 mL圆底烧瓶中加热,使其进行Biginelli反应,催化合成3,4-二氢嘧啶-2-酮及其衍生物。此法高效、绿色、安全,操作便捷,反应耗时短,且产率高,环境友好。     

Reaktionen mit Thio-bis-formamidinen

Reactions with Thio-bis-formamidines N,N,N′-Trisubstituted S-(4-amino-s-triazin-2-yl)-isothioureas 3 are prepared in good yields form trisubstituted thio-bis-formamidine-hydrochlorides 1 and esters of cyanimidocarboxylic acids 2 . In aqueous alkali solutions compounds 1 react with β-dicarbonyl compounds under rearrangement to yield substituted N-(pyrimidin-2-yl)-thioureas 4 and 5 .     

光学活性1,1'-联-2-萘酚类合成受体的应用研究新进展

具有光学活性的1,1'-联-2-萘酚及其衍生物由于其本身具有C2对称轴而具有独特的化学性质和手性诱导功能,且在适合结构基团修饰下能产生很强的荧光,在不对称催化和手性客体的荧光识别等方面得到了广泛的应用.在与手性胺、手性醇、糖类、手性阴离子、手性氨基醇和手性氨基酸等手性化合物作用时,该类受体在不同位点接受客体分子,通过光...     

A facile procedure for transesterification of β-keto esters promoted by ceria-yttria based Lewis acid catalyst

Ceria-yttria based strong Lewis acid efficiently catalyses the transesterification of β-keto esters under environmentally safe, heterogeneous reaction conditions in good to excellent yields.     

ZrOCl2.8H2O/SiO2: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Silica gel supported zirconyl chloride octahydrate was found to be an efficient and recyclable catalyst for the synthesis of a series of biologically important molecules in high turnover numbers and rates. Several substituted coumarins can be prepared in high yield and purity by direct reaction of β-keto esters and phenol derivatives in the presence of a catalytic amount of ZrOCl₂.8H₂O/SiO₂ as Lewis acid and at ambient temperature under solvent-free conditions. This method which is called Pechmann condensation is a very easy and a rapid reaction for the synthesis of coumarin derivatives.     

β-环糊精衍生物模拟酶研究进展

β-环糊精被广泛用于酶模型的设计,大量的文献报道了符合米氏常数的环糊精模拟酶的催化反应。文章综述了近十几年来环糊精模拟酶的研究。     

Reaction Mechanisms of Lean-Burn Hydrocarbon SCR over Zeolite Catalysts

A large number of novel fatty compounds have been synthesized by catalytic C,C-bond forming addition reactions to the C,C-double bond of unsaturated fatty compounds. Radical reactions such as the solvent-free addition of α-halocarboxylic acid esters initiated by electron transfer, e.g., from copper to give fat-derived γ-lactones are described as well as Lewis acid–induced electrophilic addition reactions yielding new oleochemicals such as alkyl-substituted 4-chlorotetrahydropyrans, primary homoallylic alcohols, β-, γ-unsaturated ketocarboxylic acids and Diels–Alder addition products. New catalysts as, e.g., ligand-modified rhodium catalysts for the hydroformylation and heterogeneous boron-modified rhenium catalysts for the olefin metathesis have been developed. The addition of C-nucleophiles such as dimethylmalonate and nitromethane is possible by palladium-(0)catalyzed additions to unsaturated fatty compounds after conversion of the electron-rich to an electron-poor double bond. More than fifty literature articles are reviewed.     

Zur Chemie aktivierter Vinylhalogenide. Synthese und Reaktionsverhalten von 3-(β-Chlor-vinyl)-acrylnitrilen

Chemistry of Activated Vinyl Halogenides. Synthesis and Reaction Behaviour of 3-(β-Chlorovinyl)acrylonitriles Formamide chlorides 2 react with arylmethylketones 8 to give arylsubstituted β-chloro-vinyl-methinimmonium salts 4 which were converted by reaction with cyanoacetic acid derivatives 9 to 3-(β-chlorovinyl)acrylonitriles 7 . These nitriles react with various nucleophiles, such as aliphatic and aromatic amines, sodium sulfide, sodium thiosulfate, ammonium dithiocarbamates or alkali hydroxide to yield 3-(β-aminovinyl)acrylonitriles 10 or 19 , substituted 3-(β-hydroxyvinyl)acrylonitriles 14 , substituted 3-(β-mercaptovinyl)acrylonitriles 24 , 1,2-dihydro-2-imino-pyridines 12 , 2-amino-pyridinium salts 13 , 2-amino-pyrylium salts 15 , 2-pyridones 17 , 2-imino-2H-thiopyranes 26 , and 2-amino-thiopyrylium salts 18 , respectively. From the experimental results it was confirmed that the nitriles 7 have an ambident reactivity which can be interpreted theoretically on the basis of a simple HMO method. Some chemical reactions as well as u.v., i.r. and n.m.r. spectroscopical data confirm the structure of the reported compounds.     

Computer-assisted automated synthesis. III. Synthesis of substituted N-(carboxyalkyl) amino-acid tert-butyl ester derivatives

A versatile automated synthesis apparatus, equipped with a chemical artificial intelligence, was developed to prepare and isolate a wide variety of compounds. The apparatus was to the synthesis of substituted N-(carboxyalkyl)amino-acids. The apparatus [1,2] is composed of units for performing various tasks,for example reagent supply, reaction, purification and separation, each linked to a control system. All synthetic processes, including washing and drying of the apparatus after each synthetic run, were automatically performed from the mixing of the reactants to the isolation of the products as powders or crystals. The reaction of an amino-acid tertbutyl ester acetic acid salt with a 2-keto acid sodium salt produces an unstable intermediate, Schiff base, which is reduced with sodum cyanoborohydride to give a substituted N-(carboxyalkyl)aminoacid tert-butyl ester sodium salt. The equilibrium and the consecutive reactions were controlled by adding sodium cyanoborohydride using the artificial intelligence software, which contained novel kinetic equations [3] and substituent effects [4].Substitued N-(carboxyalkyl)amino-acid tert-butyl esters, 90 derivatives, were automatically synthesized using the computerassisted automated synthesis apparatus. The syntheses were performed unattended 24 hours a day, except for supplying the raw materials, reagents and solvents. The apparatus is extremely valuable for synthesizing many derivatives of a particular compound. The configurations of the products were determined by circular dichroism measurements.     

Synthesis of Functionalized δ-Hydroxy-β-keto Esters and Evaluation of Their Anti-inflammatory Properties

δ-Hydroxy-β-keto esters and δ,β-dihydroxy esters are characteristic structural motifs of statin-type natural products and drug candidates. Here, we describe the synthesis of functionalized δ-hydroxy-β-keto esters in good yields and excellent enantioselectivities using Chan's diene and modified Mukaiyama-aldol reaction conditions. Diastereoselective reduction of δ,β-dihydroxy esters afforded the respective syn- and anti-diols, and saponification yielded the corresponding acids. All products were evaluated for their anti-inflammatory properties, which uncovered a surprising structure-activity relationship.     

Mass spectra of TMS esters of deuterated decanoic acids and of TMS ethers of deuterated decanols

Mass spectra of trimethylsilyl esters of nine specifically deuterated decanoic acids and of trimethylsilyl ethers of the corresponding deuterated decanols and of tri[²H₃] methylsilyl derivatives of most of the acids and of decanol have been measured. The fragmentation patterns have been used to examine the formation of ions m/z 117, 129, 131, 132, 145, 159, 171, 185 and 201 in the spectrum of the TMS ester of decanoic acid. Mechanisms of breakdown of one ion to another have been proposed. Similarities and differences in ion formation between spectra of TMS esters and methyl esters have been examined. It has been shown that ion m/z 132 is produced by the McLafferty rearrangement and that ion m/z 117 is formed from it by loss of a silyl methyl group. Ion m/z 145 is formed by hydrogen transfer from C-5, C-6 or C-7 to the carbonyl oxygen and γ-cleavage. Ion m/z 129 is formed from ion m/z 145 by loss of the previously transferred hydrogen and a silyl methyl group. A mechanism of formation of ions m/z 115, 129, 143 and 157, which contained only one silyl methyl group, observed in the mass spectrum of the TMS ether of decanol, has been proposed. Ions in spectra of the derivatives can be used to locate the position of deuterium, or other substituents, at a number of the carbons of decanoic acid or decanol.