- Catalytic oxidative decarboxylation of malic acid into dimethyl malonate in methanol with dioxygen
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If you've got it, use it: Malic acid is converted into dimethyl malonate by a direct, one-pot process. The process is cyanide- and halide-free. Phosphovanadomolybdates serve as bifunctional catalysts, effecting the oxidative decarboxylation and esterification in a consecutive manner. Oxidative C-C bond cleavage first forms hemiacetals. The results serve as example for the production of valuable chemicals by fully utilizing the oxygen atoms and basic structure inherent to biomass products.
- Liu, Junxia,Du, Zhongtian,Yang, Yanliang,Lu, Tianliang,Lu, Fang,Xu, Jie
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- A stereospecific transannular Diels-Alder approach to the [6.6.7] tricyclic skeleton related to aphidicolin and scopadulan natural products
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Model trans-cis-cis (TCC) macrocyclic triene 7 was synthesized using a convergent approach. Upon heating at 200°C, a 1,5-hydrogen-shift on the diene moiety was found to compete with the transannular Diels-Alder (TADA) reaction, thus leading to a mixture of tricyclic products. However, the diene rearrangement could be avoided by using boron trifluoride-diethyl ether complex as catalyst at reduced temperature (60°C). The exclusive formation of the trans-syn-cis [6.6.7] (TSC) tricyclic product 8 through an endo approach was observed. This result demonstrates the feasibility of a TADA strategy for synthesizing the title compounds and analogs.
- Hall,Caille,Drouin,Lamothe,Muller,Deslongchamps
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- Liquid Phase Carbonylation with Solid Catalyst. Carboxy Methylation of Dihalo Methane with Group VIII Metals Supported on Active Carbon
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It was found that cobalt supported on active carbon showed an excellent catalytic activity for the carbonylation of dibromo methane in the liquid phase.For example, when the reaction was conducted under the conditions of 140 deg C, P (CO) = 31 atm, the yields of dimethyl malonate and bromomethyl acetate were 34.4percent and 22.2percent, respectively.Pd and Rh also showed catalytic activities.
- Yagita, Hiroshi,Kuwahara, Hiroyuki,Omata, Kohji,Fujimoto, Kaoru
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- STRUCTURE OF MONARDAEIN, A BIS-MALONYLATED ANTHOCYANIN ISOLATED FROM GOLDEN BALM, MONARDA DIDYMA
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Structure of monardaein was determined to be 3-O-(6-O-trans-p-coumaryl-β-D-glucopyranosyl)-5-O-(4,6-di-O-malonyl-β-D-glucopyranosyl) pelargonidin (1).
- Kondo, Tadao,Nakane, Yukari,Tamura, Hirotoshi,Goto, Toshio,Eugster, C.H.
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- On the most powerful chemical traps for bis(methoxycarbonyl)carbene (=2-methoxy-1-(methoxycarbonyl)-2-oxoethylidene)
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The efficiency and validity of different chemical substrates for trapping bis(methoxycarbonyl)carbene (=2-methoxy-1-(methoxycarbonyl)-2-oxoethylidene; 1) is dependent on the conditions of carbene generation. On conventional photolysis of dimethyldiazomalonate (=2-diazopropanedioic acid dimethyl ester; 2) by long-wave UV light (through a Pyrex filter, λ > 290 nm), the most powerful trap for carbene 1 in the series of substrates Me2S, MeOH, cyclohexane, and pyridine is Me2S (with an efficiency ratio of ca. 6 :4 : 2 : 1, resp.). When short-wave decomposition of diazomalonate 2 is employed (through a quartz filter, λ > 210 nm), more reliable and useful chemical traps for bis(methoxycarbonyl)carbene (1) are pyridine and cyclohexane, whose adducts with 1 are rather stable under short-wave-irradiation conditions. Application of alcohols for the trapping of 1 proves to be preferential when simultaneous monitoring of carbene and oxoketene formation during photolysis is necessary.
- Shevchenko, Vladimir V.,Zhegalova, Natalya G.,Borzenko, Andey O.,Nikolaev, Valerij A.
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- Synthesis of Alkyl(alkoxycarbonyl)tetracarbonyliron Complexes : the First Evidence of their Relevance to the Catalytic Cycle in the Carbonylation of Organic Halides induced by Pentacarbonyliron
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Reaction of (1-) (1) (R = Me or But) with BrCH2CO2Me produces stable complexes (3) which thermally decompose to yield Fe(CO)5 and malonic esters under a CO atmosphere; these reactions provide the first demonstration of possible key steps in the catalytic cycle of the carbonylation of reactive halides into esters with Fe(CO)5 and an alkoxide anion.
- Laurent, Pascale,Sabo-Etienne, Sylviane,Larsonneur, Anne-Marie,Abbayes, Herve des
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- Esterification by ZrO2 and Mo-ZrO2 eco-friendly solid acid catalysts
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Esterification of mono- and dicarboxylic acids catalysed by single (ZrO2) and mixed oxide (Mo-ZrO2) eco-friendly solid acid catalysts is described. The Mo-ZrO2 catalyst exhibits better catalytic performance than ZrO2.
- Manohar, Basude,Reddy, Vangala R.,Reddy, Benjaram M.
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- 6-O-MALONYL-β-METHYL-D-GLUCOPYRANOSIDE FROM ROOTS OF RUMEX OBTUSIFOLIUS
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From the methanol-soluble acidic fraction of Rumex obtusifolius 6-O-malonyl-β-methyl-D-glucopyranoside and ascorbalamic acid were isolated and identified.The identity of the former compound was confirmed by synthesis.Key Word Index- Rumex obtusifolius; Polygonaceae; roots; 6-O-malonyl-β-methyl-D-glucopyranoside; organic acids.
- Kasai, Takanori,Okuda, Michiko,Sakamura, Sadao
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- VAPOR PHASE CARBONYLATION OF METHYL CHLOROACETATE
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The vapor phase carbonylation of methyl chloroacetate (MCA) with rhodium trichloride supported on active carbon was carried out at 200-300 deg C.Dimethyl malonate (DMM) was obtained in good yield without any side reactions.
- Shinoda, Kiyonori,Yasuda, Kensei
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- Palladium phthalocyaninesulfonate functionalized mesoporous polymer: A highly efficient photocatalyst for degradation of 4-chlorophenol under visible light irradiation
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A novel sulfonated palladium phthalocyanine (PdPcS) modified FDU-15 mesoporous polymer (FDU-PdPcS) has been prepared by rationally chemical modification process. The PdPcS molecules were highly dispersed inside the confined mesopores, and were further stabilized through a π-π interaction with mesopolymer, which may prevent the PdPcS molecules from agglomerating and deactivating in photodegradation reactions. The physicochemical properties of thus prepared FDU-PdPcS material were characterized by XRD, N2 adsorption-desorption, UV-vis and inductively coupled plasma techniques. FDU-PdPcS proved to be highly efficient heterogeneous photocatalyst for the degradation of 4-chlorophenol (4-CP) in the presence of H2O 2 under visible light irradiation. The photodegradation of 4-CP with an initial concentration 0.6 mM was completed within 5 h at pH 11 using a dose of 0.2 g/L of the 0.12 wt% FDU-PdPcS photocatalyst. The photodegradation intermediates were identified by GC-MS. A possible mechanism involved in the photodegradation of 4-CP has also been discussed.
- Xing, Rong,Wu, Lin,Fei, Zhenghao,Wu, Peng
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- Catalytic hydrophosphorylation of dialkyl 2-allylmalonates
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The reaction of dialkyl hydrogen phosphites and diphenylphosphine oxide with dialkyl 2-allylmalonates in the presence of [Pd(Ph3P) 4] is studied. The addition of the hydrophosphoryl compounds to the multiple bond is established to proceed by the Markovnikov rule. The reaction is accompanied by the side process of malonate dealkoxycarbonylation whose contribution to the main process depends on the nature of the reagents.
- Reznikov,Skvortsov
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- Insight into the Claisen condensation of methyl acetate and dimethyl carbonate to dimethyl malonate
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A mechanistic study on the synthesis of dimethyl malonate (DMM) via condensation of methyl acetate (MA) and dimethyl carbonate (DMC), catalyzed by sodium methoxide, has been conducted using gas chromatography-mass spectrometry, liquid chromatography-electrospray ionization-mass spectrometry, X-ray diffraction, solid-state nuclear magnetic resonance spectroscopy and density functional theory calculations. The results indicated that the Claisen condensation of MA and DMC in the presence of methoxide yielded (CH3OCO)2CHNa (DMNa) instead of DMM since DMM is easily deprotonated by the methoxide catalyst. Further protonation after the condensation by adding a proton-donor reagent is essential to obtain DMM. Based on the experimental results, a detailed reaction mechanism for the condensation of MA and DMC into DMM in the presence of methoxide has been proposed and disclosed by computational calculations. Besides, it has been proven that the base strength of the catalyst has a critical effect on the condensation reaction and the DMM yield.
- Zheng, Sainan,Xu, Shiwei,Zhou, Jinghong,Shen, Rongchun,Ji, Yang,Shen, Ming,Li, Wei
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- Method for preparing diacid diester compound under catalysis of deep eutectic solvent
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The invention belongs to the technical field of organic synthesis, and discloses a method for preparing a diacid diester compound through catalysis of a deep eutectic solvent, wherein the deep eutectic solvent takes ammonium salt and ferric salt as hydrogen acceptors, takes p-toluenesulfonic acid as a hydrogen donor, takes diacid or anhydride of the diacid and an alcohol compound as raw materials, and adopts a one-pot method to prepare the diacid diester compound; and under the catalysis of the deep eutectic solvent, the esterification reaction is performed to generate the diester product. The selected deep eutectic solvent has characteristics of environmental protection, easy preparation, cheap components and easy recovery; the preparation method has characteristics of simple operation, simple separation, no water-carrying agent, repeated use of the deep eutectic solvent, and high diester yield.
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Paragraph 0035-0038
(2021/05/19)
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- Modulation of cancer therapy using nano-organometallic compounds: Preparation, spectroscopic characterization and cytotoxic evaluation
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New series of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) organometallic complexes with hydroxyl benzylidene malonohydrazide ligand have much potential as therapeutic and diagnostic agents. The ligand allows the thermodynamic and kinetic reactivity of the metal ion to be controlled and also provide a scaffold for functionalization. The establishment of structure activity relationships and elucidation of the specification of complexes under conditions relevant to drug testing and formulation are crucial for the further development of promising medicinal applications of organometallic complexes. Specific examples involving the design of metal complexes as anticancer agents are discussed. These complexes have been synthesized and characterized by (1H-NMR, mass, IR, UV-VIS and ESR) spectroscopy, as well as magnetic moments, conductance, elemental and thermal analyses. Molar conductance in DMF solution indicates that, the complexes are non-electrolytes. The ESR spectra of solid Cu(II) complexes (7) and (8) showed isotropic and anisotropic types indicating an octahedral geometry with covalent bond character. However, Co(II) complexes (3) and (4) showed anisotropic type where, g g >2.0023, indicating compressed tetragonal distortion around Co(II) ion. Cytotoxic evolution of the ligand and its complexes have been carried out. Complexes showed enhanced activity in comparison to the parent ligand or standard drug applied.
- El-Tabl, Abdou S.,Wahed, Moshira M. Abd-El,Mohamed, Eman A,Abu-Setta, Mohammed H. H.
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p. 3873 - 3887
(2021/07/17)
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- FLOW CHEMISTRY SYNTHESIS OF ISOCYANATES
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The disclosure provides, inter alia, safe and environmentally-friendly methods, such as flow chemistry, to synthesize isocyanates, such as methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and tetramethylxylene diisocyanate.
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Paragraph 0175; 0186-0187
(2021/06/22)
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- Tailorable carbazolyl cyanobenzene-based photocatalysts for visible light-induced reduction of aryl halides
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Herein, a series of carbazolyl cyanobenzene (CCB)-based organic photocatalysts with a broad range of photoredox capabilities were designed and synthesized, allowing precise control of the photocatalytic reactivity for the controllable reduction of aryl halides via a metal-free process. The screened-out CCB (5CzBN), a metal-free, low-cost, scalable and sustainable photocatalyst with both strong oxidative and reductive ability, exhibits superior performance for both dehalogenation and C[sbnd]C bond-forming arylation reactions.
- Ou, Wei,Zou, Ru,Han, Mengting,Yu, Lei,Su, Chenliang
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supporting information
p. 1899 - 1902
(2019/12/27)
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- A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
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A Br?nsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids.
- Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
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supporting information
p. 4438 - 4444
(2020/08/10)
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- Efficient synthesis of esters through oxone-catalyzed dehydrogenation of carboxylic acids and alcohols
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Since esters are important organic synthesis intermediates, an environmentally friendly oxone catalyzed-esterification of carboxylic acids with alcohols has been developed. A series of carboxylic acid esters are obtained in high yield. This strategy requires mild reaction conditions, providing an attractive alternative for the construction of valuable carbonyl esters. Electron-rich and electron-deficient groups are compatible with the standard conditions and a variety of substrates are demonstrated. Moreover, the reaction could easily be adapted to typical prodrugs, drugs and gram-scale synthesis.
- Hou, Fei,Wang, Xi-Cun,Quan, Zheng-Jun
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supporting information
p. 9472 - 9476
(2019/01/03)
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- Preparation method of malonic ester
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The invention provides a preparation method of malonic ester. Malonic ester is obtained by using 70-80 wt% of cyanoacetic acid, hydrogen chloride-alcoholic solution and corresponding alcohol as raw materials, and is subjected to the process of esterification, dealcoholic water, alcoholysis esterification, dealcoholization, neutralization and distillation. The preparation method chooses the cyanoacetic acid of reasonable concentration, reduces the heat-sensitive reaction of distillation dehydration when obtaining high concentration cyanoacetic acid, and reduces the difficulty of dehydration ofthe cyanoacetic acid raw materials; the method is high in operability, reasonable and economy, reduces the discharge of three wastes greatly, and has good social benefit.
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Paragraph 0033-0044
(2018/04/01)
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- Efficient flow fischer esterification of carboxylic acids with alcohols using sulfonic acid-functionalized silica as supported catalyst
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Flow Fischer esterification of carboxylic acids using hydroxy-substituted sulfonic acid-functionalized silica (HOSAS) packed into a stainless steel column reactor was investigated. HO-SAS well catalyzed flow esterification of long chain carboxylic acids with methanol within 3min of residence time at 110°C, and the methyl esters were quantitatively obtained. The flow esterification protocol was applied to the synthesis of a variety of esters (19 examples) and scalable synthesis was also successful.
- Furuta, Akihiro,Fukuyama, Takahide,Ryu, Ilhyong
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p. 607 - 612
(2017/06/19)
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- 1,5-Diketones Synthesis via Three-Component Cascade Reaction
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A mild and efficient cascade synthesis of 1,5-diketones from readily available N,N-dicyclohexylmethylamine, 1,3-dicarbonyl compounds, and trifluoromethyl β-diketones has been developed. This cascade reaction occurs via an oxidation/Mannich reaction/Cope elimination/Michael addition/retro-Claisen reaction sequence, and provides multiple C-C bond formations in one pot. In addition, exquisite chemoselectivity is achieved in the reaction between 1,3-dicarbonyl compounds and trifluoromethyl β-diketones.
- Xing, Li-Juan,Lu, Tao,Fu, Wei-Li,Lou, Mei-Mei,Chen, Bo,Wang, Zhi-Shen,Jin, Yang,Li, Dan,Wang, Bin
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supporting information
p. 3076 - 3080
(2015/11/03)
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- Acid-catalyzed oxidation of levulinate derivatives to succinates under mild conditions
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Levulinate derivatives are an attractive platform for the production of renewable chemicals. Here we report on the oxidation of methyl levulinate into dimethyl succinate with peroxides under mild conditions using Br?nsted and Lewis acid catalysts. Selectivities to succinate and acetate derivatives of approximately 60 and 40 %, respectively, were obtained with strong Br?nsted acids in methanol. Although the molecular structure (i.e., carbon-chain length and branching around the C=O group) and the oxidant type affect the product distribution, solvent choice has the strongest impact on changing the location of oxygen insertion into the carbon backbone. Specifically, switching the solvent from methanol to heptane resulted in a decrease in the succinate/acetate ratio from 1.6 to 0.3. In contrast to Br?nsted acids, we demonstrate that the nature of the metal cation is responsible for changing the reaction selectivity of water-tolerant Lewis acidic triflate salts.
- Wang, Yuran,Vogelgsang, Ferdinand,Román-Leshkov, Yuriy
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p. 916 - 920
(2015/03/18)
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- Synthesis of coumarin-3-carboxylic esters via FeCl3-catalyzed multicomponent reaction of salicylaldehydes, Meldrum's acid and alcohols
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A FeCl3-catalyzed multicomponent reaction was developed for the facile synthesis of coumarin-3-carboxylic ester derivatives in a highly atom-economic and environmentally friendly way. Using simple and cheaply available salicylaldehydes, Meldrum's acid and alcohols as the starting materials, the method needs no extra additives and features wide substrate scope, good functional group tolerance and mild reaction conditions.
- He, Xinwei,Shang, Yongjia,Zhou, Yao,Yu, Zhiyu,Han, Guang,Jin, Wenjing,Chen, Jiaojiao
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p. 863 - 868
(2015/01/30)
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- On the synthesis, characterization and reactivity of n-heteroaryl-boryl radicals, a new radical class based on five-membered ring ligands
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The synthesis and physical characterization of a new class of N-heterocycle-boryl radicals is presented, based on five membered ring ligands with a N(sp2) complexation site. These pyrazole-boranes and pyrazaboles exhibit a low bond dissociation energy (BDE; B-H) and accordingly excellent hydrogen transfer properties. Most importantly, a high modulation of the BDE(B-H) by the fine tuning of the N-heterocyclic ligand was obtained in this series and could be correlated with the spin density on the boron atom of the corresponding radical. The reactivity of the latter for small molecule chemistry has been studied through the determination of several reaction rate constants corresponding to addition to alkenes and alkynes, addition to O 2, oxidation by iodonium salts and halogen abstraction from alkyl halides. Two selected applications of N-heterocycle-boryl radicals are also proposed herein, for radical polymerization and for radical dehalogenation reactions.
- Tehfe, Mohamad-Ali,Schweizer, Stephane,Chany, Anne-Caroline,Ysacco, Cedric,Clement, Jean-Louis,Gigmes, Didier,Morlet-Savary, Fabrice,Fouassier, Jean-Pierre,Neuburger, Markus,Tschamber, Theophile,Blanchard, Nicolas,Lalevee, Jacques
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supporting information
p. 5054 - 5063
(2014/05/06)
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- Promoted role of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran over VOSO4
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The promoted effect of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) catalyzed by VOSO4 in acetonitrile was intensively investigated. It was revealed that Cu(NO3)2 facilitated the activation of VOSO 4 to generate active V5+ species via the generation of NOx gas. The high DFF selectivity is ascribed to Cu2+ cation which can effectively prohibit oxidative CC bond cleavage reaction of HMF and prevent radical reaction of DFF to humins. In addition, the polarity of solvent plays a great role on high selectivity of DFF.
- Jia, Xiuquan,Ma, Jiping,Wang, Min,Du, Zhongtian,Lu, Fang,Wang, Feng,Xu, Jie
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p. 231 - 236
(2014/07/08)
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- One-by-one hydrogenation, cross-coupling reaction, and Knoevenagel condensations catalyzed by PdCl2 and the downstream palladium residue
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A novel catalyst-economic strategy with a recovered palladium catalyst was successfully applied for multi-task and maximum reuse in different types of one-by-one downstream reactions, from catalytic hydrogenation to Suzuki and Sonogashira-type cross-coupling reactions, Knoevenagel condensations, and trans-Knoevenagel-like condensations.
- Wang, Hu,Li, Li,Bai, Xing-Feng,Deng, Wen-Hui,Zheng, Zhan-Jiang,Yang, Ke-Fang,Xu, Li-Wen
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supporting information
p. 2349 - 2355
(2013/09/12)
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- Visible light-mediated atom transfer radical addition via oxidative and reductive quenching of photocatalysts
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Herein, the development of visible light-mediated atom transfer radical addition (ATRA) of haloalkanes onto alkenes and alkynes using the reductive and oxidative quenching of [Ir{dF(CF3)ppy}2(dtbbpy)]PF 6 and [Ru(bpy)3]Cl2 is presented. Initial investigations indicated that the oxidative quenching of photocatalysts could effectively be utilized for ATRA, and since that report, the protocol has been expanded by broadening the scope of the reaction in terms of the photocatalysts, substrates, and solvents. In addition, further modifications of the reaction conditions allowed for the efficient ATRA of perfluoroalkyl iodides onto alkenes and alkynes utilizing the reductive quenching cycle of [Ru(bpy) 3]Cl2 with sodium ascorbate as the sacrificial electron donor. These results signify the complementary nature of the oxidative and reductive quenching pathways of photocatalysts and the ability to predictably direct reaction outcome through modification of the reaction conditions.
- Wallentin, Carl-Johan,Nguyen, John D.,Finkbeiner, Peter,Stephenson, Corey R. J.
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scheme or table
p. 8875 - 8884
(2012/07/02)
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- Alkyl sulfonate functionalized ionic liquids: Synthesis, properties, and their application in esterification
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Ionic liquids based on alkyl sulfate anions and alkyl sulfonate functionalized cations were prepared from commercially available and cheap materials and their thermal-instability properties were studied in detail. These ionic liquids were active catalysts for esterification and they gave moderate to high yields. The catalytic performance was found to be much better than that of conventional non-cation functionalized ionic liquids and close to sulfonic acid functionalized ionic liquids. The catalytic process in this reaction was investigated by electrospray ionization mass spectrometry and a plausible reaction mechanism is suggested.
- Zhao, Yingwei,Li, Zhen,Xia, Chungu
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experimental part
p. 440 - 445
(2012/05/04)
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- Catalytic asymmetric conjugate allylation of coumarins
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A catalytic asymmetric conjugate allylation was successfully developed to synthesize potential pharmacologically active 4-allyl-2-oxochroman skeletons. A dual activation strategy was employed by using N,N′-dioxide-Yb(OTf) 3 to activate coumarins and using (CuOTf)2?C 7H8 to activate tetraallyltin via transmetalation, respectively. Good yields and enantioselectivities were obtained under mild conditions.
- Kuang, Yulong,Liu, Xiaohua,Chang, Lu,Wang, Min,Lin, Lili,Feng, Xiaoming
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supporting information; experimental part
p. 3814 - 3817
(2011/09/15)
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- Study on the Pd/C-catalyzed (retro-)Michael addition reaction of activated methylene compounds to electron-poor styrenes
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Palladium on carbon (10 % Pd/C) efficiently catalyzes the (retro-)Michael addition of activated methylene compounds 2a-d, such as malononitrile (2b), to mono- and doubly activated styrenes 1a-h to give the adducts 3a-l. The scope and limitations are described. The Knoevenagel condensation reaction of benzaldehyde and 2b or ethyl cyanoacetate (2c) is also catalyzed by 10 % Pd/C. In these cases the Michael adducts can even be prepared in a three-component reaction. A mechanism, with as first step the oxidative addition of 2a-d to Pd0, is proposed. Palladium on carbon (10 % Pd catalyzes the (retro-)Michael addition of activated methylene compounds 2a-d to mono- anddoubly activated styrenes. The scope and limitations of the reaction are described. A mechanism is proposed. Copyright
- Nikishkin, Nicolai I.,Huskens, Jurriaan,Verboom, Willem
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body text
p. 6820 - 6823
(2011/02/26)
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- Modulation of carbene spin state population through precursor photophysics
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Dicarbomethoxycarbene can be generated by photolysis of S-C sulfonium ylides derived from thiophene. By manipulating the thiophene (leaving group) portion of the ylide, the initial spin distribution of the carbenes can be strongly influenced. With certain carbene traps, product distributions from dicarbomethoxycarbene depend on the initial spin state distribution in which the carbene is generated and this is used as a means to report on the initial spin state distributions. This approach should be general for other carbenes generated from analogous precursors.
- Jenks, William S.,Heying, Melanie J.,Rockafellow, Erin M.
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supporting information; experimental part
p. 955 - 958
(2009/07/11)
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- A Simple, efficient, green, cost effective and chemoselective process for the esterification of carboxylic acids
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Carboxylic acids have been esterified under mild and solvent-free conditions in high yield and purity using the green reagents, dimethyl carbonate and diethyl carbonate, under acid catalysis. The present methodology is free of the disadvantages of base catalysis described earlier, such as high temperatures, use of autoclaves, use of the expensive DBU as base in stoichiometric amounts and the carbonate as solvent. High chemoselectivity is observed in the case of hydroxybenzoic acids.
- Rekha,Ramani, Modukuri V.,Ratnamala,Rupakalpana, Vempati,Subbaraju, Gottumukkala V.,Satyanarayana, Chava,Rao, C. Someswara
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experimental part
p. 769 - 773
(2010/04/22)
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- Synthesis of functionalized dialkyl cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-chloro-α,β-unsaturated diesters and ketoesters
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Michael-induced ring closure (MIRC) of dimethyl 2-(3-chloro-2,2- dimethylpropylidene)malonate, upon treatment with sodium tert-butylthiolate, sodium methoxide or sodium cyanide in methanol, provided a short and efficient synthesis of new 2-functionalized cyclobutane-1,1-dicarboxylic esters. Under similar conditions, methyl 2-acetyl-5-chloro-4,4-dimethylpent-2-enoate afforded 4-functionalized methyl 5,6-dihydro-4H-pyran-3-carboxylates as the MIRC products.
- Mangelinckx, Sven,Vermaut, Brano,Verhé, Roland,De Kimpe, Norbert
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scheme or table
p. 2697 - 2701
(2009/04/16)
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- S,C-sulfonium ylides from thiophenes: Potential carbene precursors
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Photolysis of S,C-sulfonium ylides derived from thioanisol, thiophene, benzothiophene, or dibenzothiophene provides products deriving from dicarbomethoxycarbene. In methanol, no rearrangement of the carbene to the ketene derivative is observed. Formation of dibenzothiophene and benzothiophene is quantitative. For the thiophene-based ylide, insertion of the carbene into the α-CH bond of thiophene is observed. Evidence is presented that supports formation of both singlet and triplet carbene. Copyright
- Stoffregen, Stacey A.,Heying, Melanie,Jenks, William S.
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p. 15746 - 15747
(2008/09/19)
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- Selective monoesterification of malonic acid catalyzed by boric acid
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Boric acid catalyzes the monoesterification of malonic acid, likely through a chelation mechanism that is not available to the monoester product. Under more forcing conditions, diesters form to some extent, but conditions can be optimized to favour the monoester product (56?80%). With the easily handled solid acid catalyst, these reactions can be run with excess alcohol as solvent or with stoichiometric amounts of alcohol in acetonitrile with moderate heating. CSIRO 2007.
- Levonis, Stephan M.,Bornaghi, Laurent F.,Houston, Todd A.
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p. 821 - 823
(2008/03/12)
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- Biodiesel additive and method of preparation thereof
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Fuel oxygenates comprised of fatty acid or fatty acid ester derivatives which have been reacted with ozone; a base; and a lower alkanol (1 to 8 carbon atoms) are described. The oxygenates comprise ester groups at a point of cleavage by the ozone which provide oxygen in the oxygenate.
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Page/Page column 4-5
(2008/06/13)
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- Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or hydroxyl groups. 1. Method development
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In this study, a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g., methanol, 1-butanol) in the presence of a relatively strong Lewis acid (BF3) as a catalyst. This esterification reaction quicldy and quantitatively converts carboxylic acids to their ester forms. The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent. For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups, a third step was used based on PFBHA derivatization of the carbonyls. Different parameters including temperature, reaction time, and effect due to artifacts were optimized. A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds. The new approach was tested on a number of multifunctional compounds. The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds. For example, when derivatized only with BF3-methanol, their mass spectra comprise primary ions at m/z M .+ + 1, M.+ + 29, and M.- - 31 for compounds bearing only carboxylic groups and M.- + 1, M.+ + 29, M.+ - 31, and M+. - 17 for those bearing hydroxyl and carboxylic groups. However, when a second derivatization (BSTFA) was used, compounds bearing hydroxyl and carboxylic groups simultaneously show, in addition to the ions observed before, ions at m/z M.+ + 73, M .+ - 15, M.+ - 59, M.+ - 75, M.+ - 89, and 73. To the best of our knowledge, this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.
- Jaoui,Kleindienst,Lewandowski,Edney
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p. 4765 - 4778
(2007/10/03)
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- Borontrifluoride etherate promoted one-pot conversion of nitriles to esters
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One-pot borontrifluoride etherate promoted transformation of nitriles to esters was achieved by heating in corresponding alcohol as a reactant and solvent.
- Jayachitra,Yasmeen,Srinivasa Rao,Ralte, Samuel L.,Srinivasan,Singh
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p. 3461 - 3466
(2007/10/03)
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- Malonic acid and esters thereof
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A process for preparing malonic acid from the hydrolysis of cyanoacetic acid in the presence of aqueous hydrochloric acid, the process conditions being such that they allow high yields in malonic acid product. The product of said acid hydrolysis is a mixture of malonic acid and ammonium chloride by-product; the mixture is concentrated, the ammonium chloride by-product is separated by dissolution with an oxygen solvent and isolated. Alternatively, said concentrated mixture is dissolved with a primary or secondary esterifying alcohol in C1-C10, the resulting mixture being esterified, while the ester product is purified by distillation under reduced pressure, the molar yields and purity of the ester product being high.
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- Process for preparing malonate derivatives or beta -keto esters from epoxide derivatives
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A process for preparing a malonic acid monoester or β-ketoester from an epoxide includes the steps of reacting an epoxide with carbon monoxide and an alcohol in the presence of a catalytic amount of a cobalt compound and at least one promoter to produce a β-hydroxyester, separating the β-hydroxyester from the cobalt compound and the promoter, and oxidizing the β-hydroxyester to produce a malonic acid monoester or β-ketoester.
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- Process for preparing malonic esters
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Malonic esters of the general formula where R is C1-10-alkyl, C3-10-alkenyl or aryl-C1-4-alkyl, are prepared by reacting an alkali metal salt of malonic acid with a halide of the general formula R—X (II), where R is as defined above and X is chlorine, bromine or iodine, in the presence of water and a phase-transfer catalyst.
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- A mild and efficient method for esterification and transesterification catalyzed by iodine
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Iodine, was found to be a practical and useful Lewis acid catalyst for the esterification of carboxylic acids with alcohols. The high catalytic activity of iodine can be used for the transesterification of esters by different alcohols including tertiary alcohols and sterically hindered primary and secondary alcohols. The method presented is especially effective for simultaneous esterification and transesterification reactions.
- Ramalinga,Vijayalakshmi,Kaimal
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p. 879 - 882
(2007/10/03)
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- Efficient methylation of carboxylic acids with potassium hydroxide/methyl sulfoxide and iodomethane
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Methylation of several carboxylic acids was promoted by potassium hydroxide in methyl sulfoxide and iodomethane to produce corresponding methyl esters in good yield. This method has advantage over other described methods because it uses inexpensive reagents and the reaction is carried out under mild and favorable conditions.
- Avila-Zarraga,Martinez
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p. 2177 - 2183
(2007/10/03)
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- One-Pot synthesis of 5-Alkylthio-3H-1,2-dithiole-3-thiones: Advantages and scopes
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The reaction of dialkyl malonate esters with P2S5/S8 in boiling xylene in the presence of 2-mercaptobenzothiazole/ZnO as catalyst produces 5-alkylthio-3H-1,2-dithiole-3-thiones as major identifiable product. Moderate yields were obtained with malonate esters of primary alcohols. The reaction fails with malonate esters of secondary alcohols. Regarding the substituent in position two, dialkyl malonates with groups such as CH3, Ph, CH2Ph, OCH3 and Cl afford the corresponding 4-substituted derivatives whereas with Br and NO2 do not give the expected products. Some mechanistic evidences are described.
- Aimar,De Rossi
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p. 1749 - 1755
(2007/10/03)
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- Process for the synthesis of α-substituted acrylic acids and their application
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Process for the synthesis of a-substituted acrylic acids and their application. Process for the synthesis of a-substituted acrylic acids of general formula (I) and their application to the synthesis of N- (mercaptoacyl) aminoacid derivatives of formula (II). STR1
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- Radical cyclization of allyl α-bromocarboxylates into γ-butyrolactones. Effect of the ester structure on the cyclization
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Allyl dibromoacetate, allyl α-bromopropionate, and allyl phenylbromoacetate undergo cyclization in benzene in the presence of increased concentration of Fe(CO)5 - DMF as the initiating system to give the corresponding bromo-substituted butyrolactones.
- Terent'ev,Vasil'eva,Kuz'mina,Ikonnikov,Orlova,Mysov,Belokon'
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p. 2096 - 2098
(2007/10/03)
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- Synthesis and characterization of N,N'-aliphatic dicarboxylbis(hydrazones)
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N,N'-Malonylbis-, N,N'-adipinylbis- and N,N'-sebacoylbis(hydrazones) 1 of various aldehydes and ketones have been prepared and characterized by elemental analyses, melting points, and 1H NMR and IR spectral data.
- Amanulla, S.,Jain, S. R.
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p. 687 - 690
(2007/10/03)
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- Efficient Dimethyl Malonate Synthesis by Methoxycarbonylation of Dichloromethane catalysed by Electrogenerated - Species
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Electrochemistry is used for the synthesis of - complex in a methanol-methyl formate medium, which catalyses the alkoxycarbonylation of dichloromethane to dimethyl malonate in up to 75percent yield.
- Suisse, P.,Pellegrini, S.,Castanet, Y.,Mortreux, A.,Lecolier, S.
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p. 847 - 848
(2007/10/02)
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- CHEMISTRY OF NITRO ESTERS XVII. METHOD FOR THE PRODUCTION OF MESOXALIC ESTERS
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A new preparative method was developed for the production of mesoxalic esters from bromomalonic esters and silver nitrate
- Kochergin, P. M.,Titkova, R. M.
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p. 1042 - 1044
(2007/10/02)
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- Michael addition of N-isobutylidene-t-butylamine to dimethyl methoxymethylenemalonate and a new synthesis of some fused pyrazole derivatives from the adduct
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N-Isobutylidenemethylamine reacted with dimethyl methoxymethylenemalonate to afford the N-alkylation product 3a exclusively. Exchanging the N- substituent of the Schiff's base from methyl to t-butyl altered the course of the reaction, allowing Michael addition to take place predominantly. The Michael adduct 4c on reaction with hydrazinoalkanols 6a,b, 6c,d and 6e gave tetrahydropyrazolo[5,1-b]oxazoles 9a,b, tetrahydropyrazolo[5,1- b][1,3]oxazines 9c,d and hexahydropyrazolo[5,1-b][1,3]oxazepine 9e, respectively.
- Ito,Ihara,Miyajima
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p. 1529 - 1532
(2007/10/02)
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- Flash vacuum pyrolysis of tert-butyl β-ketoesters: Sterically protected α-oxoketenes
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Infrared spectroscopic analysis of the products showed that flash vacuum pyrolyses (FVP) of dimethyl tert-butylmalonate (1b) and methyl tert-butyl(pivaloyl)acetate (1d) at ca. 550°C afforded the corresponding tert-butyl(carbomethoxy)ketene (4b) and tert-butyl(pivaloyl)ketene (4d), respectively, with loss of methanol, together with unreacted 1b and 1d (Ar matrix, 12 K or neat at 77 K; 10-5 mbar). Monitoring by IR spectroscopy showed that 4b reacted with methanol at ca. -50°C to give 1b. Ketene 4d does not react with methanol at room temperature, but afforded ester 1d on refluxing for 8 h. FVP of 1b and 1d at temperatures above 650°C gave the α-oxoketenes 4b and 4d, respectively, unsubstituted dimethyl malonate (1a) and methyl 4,4-dimethyl-3-oxo-pentanoate (1c), respectively, due to retro-ene reactions with elimination of isobutene, as well as pyrolysis products derived from 1a and 1c, respectively. FVP of α-unsubstituted β-ketoesters 1a and 1c at ca. 500°C (10-5 mbar) with argon matrix isolation of the products at 12 K afforded the ketenes 4a and 4c as mixtures of s-Z and s-E conformers together with mixtures of unreacted keto (1a, c) and enol forms (2a, c). On warming to temperatures between -90 and -50°C, back-reaction of ketenes 4a, c with methanol resulted in the re-generation of enols 2a, c without increasing the amounts of the keto forms 1a, c.
- Leung-Toung,Wentrup
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p. 7641 - 7654
(2007/10/02)
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- Vapor Phase Carbonylation of Organic Halo Compounds
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RCH2X, s-C4H9X and C6H5X were methoxy-carbonylated with carbon monoxide and methanol into methyl carboxylates in the presence of rhodium trichloride/potassium iodide supported on activated charcoal.The reactivity decreased in the order: X=I above Br above Cl.
- Yasuda, Kensei,Shinoda, Kiyonori
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p. 289 - 291
(2007/10/02)
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- A CONVENIENT METHOD FOR ENZYMATIC BENZYL-ALKYL TRANSESTERIFICATION UNDER MILD NEUTRAL CONDITIONS
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Lipases from Candida cylindracea and from Pseudomonas fluorescens efficiently catalyse the benzyl to alkyl transesterification in organic solvents under mild conditions in nearly quantitative yields.
- Gutman, Arie L.,Shkolnik, Eleonora,Shapira, Michal
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p. 8775 - 8780
(2007/10/02)
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- Intrinsic Reactivities of Some Carbanions in ?-Adduct Forming Reactions
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Kinetic and equilibrium data are reported for nucleophilic attack in methanol at unsubstituted ringpositions of 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene and 1-chloro-2,4,6-trinitrobenzene by carbanions derived from dimethyl malonate, ethyl cyanoacetate and 4-nitro-, 4-cyano- and 2-cyanobenzyl cyanides.The results are used to determine intrinsic reactivities for the carbanions in these ?-adduct forming reactions and are discussed in terms of the electronic and solvent reorganisation occurring during reaction.
- Crampton, Michael R.,Stevens, Andrew J.
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p. 1715 - 1720
(2007/10/02)
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