- Levulinic acid esterification with ethanol to ethyl levulinate production over solid acid catalysts
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Levulinic acid is considered as a versatile building block because it can be used for the synthesis of several organic chemicals. In particular, its esterification with ethanol produces ethyl levulinate that can be used as diesel miscible biofuel (DMB), preventing global warming by decreasing atmospheric CO2 generated from the consumption of fossil fuels. This article explores the use of two groups of solid acid catalysts (sulfated oxides and zeolites with different pore structures) in the esterification of levulinc acid with ethanol aiming for ethyl levulinate production. It was found that while there is a correlation between the number of acidic sites and activity for the sulfated oxides, the same is not true for the studied zeolites where the pore channels play a more important role. Among the catalysts tested, Amberlyst-15 and sulfated SnO2 showed a remarkable high yield of ethyl levulinate that was probably due to the strong acidity provided by SO3H functional groups and SO4 species, respectively.
- Fernandes,Rocha,Mai,Mota, Claudio J.A.,Teixeira Da Silva
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- Oxidation of cyclohexanone and/or cyclohexanol catalyzed by Dawson-type polyoxometalates using hydrogen peroxide
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The oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture using as catalyst, Dawson-type polyoxometalates (POMs) of formula, α- and β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 and hydrogen peroxide, carried out at 90 °C with a reaction time of 20 h, led to a high number of mono- and di-acids which were identified by GC-MS. Levulinic, 6-hydroxyhexanoic, adipic, glutaric and succinic acids, major products were evaluated by HPLC. Regardless of the substrate nature, all POMs exhibited high catalytic activity with 94–99% of conversion, whereas the formation of the different products is sensitively related to both the composition and symmetry of the POMs and the substrate nature. The main products are adipic acid in the presence of α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62, levulinic acid in the presence of α1-K7P2Mo5VW12O62 and β-K6P2W18O62 and 6-hydroxyhexanoic acid in the presence of α- and β-K6P2W18O62. Graphical abstract: High catalytic activity was observed with?α- and?β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 Dawson-type for the oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture, in the hydrogen peroxide presence, to several oxygenated products. Adipic, levulinic and 6-hydroxyhexanoic acids are the main products. The peroxo- species formed in situ could be the active sites.[Figure not available: see fulltext.]
- Dermeche, Leila,Idrissou, Yasmina,Mazari, Tassadit,Moudjahed, Mohammed,Rabia, Cherifa
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- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
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The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
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supporting information
p. 10005 - 10013
(2021/07/19)
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- Synthesis method of 4-acetyl butyrate compound
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The invention discloses a synthetic method of a 4-acetyl butyrate compound, and relates to the technical field of chemical synthesis, and the synthetic method comprises the following steps: taking acetone as a reaction solvent and a reactant to react with an acrylate compound under the catalytic action of tetrahydropyrrole; and after the reaction is finished, carrying out post-treatment on the reaction liquid to prepare the 4-acetyl butyrate compound. The method has the advantages of simple reaction system, environment friendliness, cheap and easily available raw materials, simple post-treatment operation, and no need of column chromatography purification, and is beneficial for industrial production.
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Paragraph 0029; 0039
(2021/04/17)
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- MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
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Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
- Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
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p. 6115 - 6125
(2020/10/27)
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- An efficient method for retro-Claisen-type C-C bond cleavage of diketones with tropylium catalyst
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The retro-Claisen reaction is frequently used in organic synthesis to access ester derivatives from 1,3-dicarbonyl precursors. The C-C bond cleavage in this reaction is usually promoted by a number of transition-metal Lewis acid catalysts or organic Br?nsted acids/bases. Herein we report a new convenient and efficient method utilizing the tropylium ion as a mild and environmentally friendly organocatalyst to mediate retro-Claisen-type reactions. Using this method, a range of synthetically valuable substances can be accessed via solvolysis of 1,3-dicarbonyl compounds.
- Hussein,Huynh,Hommelsheim,Koenigs,Nguyen
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supporting information
p. 12970 - 12973
(2018/11/23)
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- Palladium-Catalyzed Long-Range Deconjugative Isomerization of Highly Substituted α,β-Unsaturated Carbonyl Compounds
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The long-range deconjugative isomerization of a broad range of α,β-unsaturated amides, esters, and ketones by an in situ generated palladium hydride catalyst is described. This redox-economical process is triggered by a hydrometalation event and is thermodynamically driven by the refunctionalization of a primary or a secondary alcohol into an aldehyde or a ketone. Di-, tri-, and tetrasubstituted carbon-carbon double bonds react with similar efficiency; the system is tolerant toward a variety of functional groups, and olefin migration can be sustained over 30 carbon atoms. The refunctionalized products are usually isolated in good to excellent yield. Mechanistic investigations are in support of a chain-walking process consisting of repeated migratory insertions and β-H eliminations. The bidirectionality of the isomerization reaction was established by isotopic labeling experiments using a substrate with a double bond isolated from both terminal functions. The palladium hydride was also found to be directly involved in the product-forming tautomerization step. The ambiphilic character of the in situ generated [Pd-H] was demonstrated using isomeric trisubstituted α,β-unsaturated esters. Finally, the high levels of enantioselectivity obtained in the isomerization of a small set of α-substituted α,β-unsaturated ketones augur well for the successful development of an enantioselective version of this unconventional isomerization.
- Lin, Luqing,Romano, Ciro,Mazet, Clément
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supporting information
p. 10344 - 10350
(2016/08/31)
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- Remote ester group leads to efficient kinetic resolution of racemic aliphatic alcohols via asymmetric hydrogenation
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A highly efficient method for kinetic resolution of racemic aliphatic alcohols without conversion of the hydroxyl group has been realized; the method involves hydrogenation mediated by a remote ester group and is catalyzed by a chiral iridium complex. This powerful, environmentally friendly method provides chiral δ-alkyl-δ-hydroxy esters and δ-alkyl-1,5-diols in good yields with high enantioselectivities even at extremely low catalyst loading (0.001 mol %).
- Yang, Xiao-Hui,Wang, Ke,Zhu, Shou-Fei,Xie, Jian-Hua,Zhou, Qi-Lin
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supporting information
p. 17426 - 17429
(2015/02/02)
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- Efficient conversion of levulinic acid into alkyl levulinates catalyzed by sulfonic mesostructured silicas
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Abstract Sulfonic mesoporous silicas have demonstrated an outstanding catalytic performance in the esterification of levulinic acid with different alcohols to produce alkyl levulinates, a family of chemicals considered to be excellent oxygenated fuel extenders for gasoline, diesel and biodiesel. Catalyst screening indicated that propylsulfonic acid-modified SBA-15 material was the most active one, among tested materials, due to a combination of moderately strong sulfonic acid sites with relative high surface hydrophobicity. Under optimized reaction conditions (T = 117°C, ethanol/levulinic acid molar ratio = 4.86/1 and catalyst/levulinic acid = 7 wt%) almost 100% of levulinic acid conversion was achieved after 2 h of reaction, being negligible the presence of levulinic acid by-products or ethers coming from intermolecular dehydration of alcohols. The catalyst has been reused, without any regeneration treatment, up to three times keeping almost the high initial activity. Interestingly, a close catalytic performance to that achieved using ethanol has been obtained with bulkier alcohols.
- Melero,Morales,Iglesias,Paniagua,Hernández,Penedo
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p. 116 - 122
(2013/08/23)
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- Mediating acid-catalyzed conversion of levoglucosan into platform chemicals with various solvents
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Acid-catalyzed conversions of levoglucosan have been investigated in mono-alcohols, poly-alcohols, water, chloroform, toluene, acetone, N,N-dimethyl formamide, dimethyl sulfoxide and some mixed solvents, aiming to mediate conversion of sugars into platform chemicals with solvents. The mono-alcohols can stabilize soluble polymers and thus suppress formation of insoluble polymers. Water does not have such an effect, leading to lower yields of levulinic acid. Chloroform cannot effectively dissolve levoglucosan, leading to dissolving of levoglucosan in the catalyst and the consequent rapid polymerization. Acetone reacted with sugars, forming substantial amounts of polymer. N,N-Dimethyl formamide poisoned the acid resin catalyst, leading to negligible conversion of levoglucosan. Dimethyl sulfoxide (DMSO) mainly catalyzed the conversion of levoglucosan into 5-(hydroxymethyl)furfural (HMF), 2,5-furandicarboxaldehyde, and the sulfur ether of HMF. DMSO has a low ability to transfer protons, which helps to avoid further contact of HMF with catalytic sites and stabilizes HMF.
- Hu, Xun,Wu, Liping,Wang, Yi,Mourant, Daniel,Lievens, Caroline,Gunawan, Richard,Li, Chun-Zhu
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p. 3087 - 3098
(2013/01/15)
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- Michael addition of stannyl ketone enolate to α,β-unsaturated esters catalyzed by tetrabutylammonium bromide and an ab initio theoretical study of the reaction course
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Michael addition of stannyl ketone enolates to α,β-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu4NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl4 or Bu4NF) failed to give the desired products. The bromide anion from Bu4NBr coordinates to the tin center in enolate to accelerate the conjugate addition where a five-coordinated tin species was generated. The coordination of the bromide anion significantly raises the HOMO level of tin enolate and enhances its nucleophilicity. The conjugate addition provides the intermediate Michael adduct, which has an ester enolate moiety, and the adduct immediately transforms to α-stannyl γ-ketoester by keto - enol tautomerization. This step contributes to the stabilization of the product system and leads to a thermodynamically favorable reaction course. An ab initio calculation reveals that the activation energy in the reaction using the bromide anion is lower than that of the reaction without using it. The transition state in either reaction course has a linear structure, not a cyclic one. This system can be applied to a variety of tin enolates and α,β-unsaturated carbonyls involving enoates, enones, and unsaturated amides.
- Yasuda, Makoto,Chiba, Kouji,Ohigashi, Noriyuki,Katoh, Yasuhiro,Baba, Akio
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p. 7291 - 7300
(2007/10/03)
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- Reactions of Grignard reagents with bis- or mono-phosphonium ions in Situ generated from Bu3P and dicarboxylic acid dichlorides or ω-ethoxycarbonyl alkanoyl chlorides as a novel method to obtain diketones and ketoesters
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Reactions of Grignard reagents with bis-phosphonium or mono-phosphonium ions in situ generated from Bu3P and ClCO(CH2)(n)COCl (5) or ClCO(CH2)(n)CO2Et (13) as a tool for preparation of symmetrical diketones or ketoesters were examined. Addition of Bu3P (2.0 eq) to a THF solution of 5 (n=2) at -40°C followed by addition of n-BuMgCl (2.0 eq) gave the corresponding diketone in good yield. When a mixture of Bu3P and the Grignard reagent (2.0 eq each) was added to the dichloride solution at the same temperature, a better result was obtained. The latter method not with PhMgBr but with n-BuMgCl or MeMgBr was shown to be useful for preparation of symmetrical alkanediones and keto alkanoates from various 5 (n=2 - 6) and 13 (n=2 or 3), respectively. For synthesis of α-diketones or α-ketoesters, only PhMgBr entered the reaction, although the yields were not satisfactory. Addition of a mixture of Bu3P (2.0 eq), MeMgBr (1.0 eq) and BuMgCl (1.0 eq) to a THF solution of 5 (n=4) at -40°C afforded a mixture of 2,7-undecanedione and the corresponding two symmetrical diketones, with the yield of the unsymmetrical diketone being 36%.
- Maeda,Hino,Yamauchi,Ohmori
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p. 1196 - 1199
(2007/10/03)
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- Oxidation of 2-alkylcycloalkanones with iodine-cerium(IV) salts in alcohols
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The reaction of 2-alkylcycloalkanones with iodine-cerium(IV) salts in alcohols (methanol, ethanol, propan-1-ol or propan-2-ol) gave the respective oxo ester in 28-98% yields.
- He, Liangyou,Kanamori, Miyuki,Horiuchi, C. Akira
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p. 122 - 123
(2007/10/03)
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- Oxidation of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate in alcohols and acetic acid
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The reaction of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate (CS) in alcohols and acetic acid gave the corresponding alkyl esters of oxo acids (80-96%) and oxo acids (78-96%), respectively, by oxidative cleavage of the C(R).C=O bond. In the case of 2-iodocycloalkanones in methanol, the dimethyl ester was obtained in good yield. A treatment of 5α-cholestan-3-one with CS in methanol produced 2-acetal 3-ester of 2,3-seco derivative in good yield. The effects of cerium(IV) and copper(II) salts are also discussed.
- He, Liangyou,Horiuchi, C. Akira
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p. 2515 - 2521
(2007/10/03)
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- Indium-trichloride catalyzed Michael reaction of silyl enol ethers with α,β-unsaturated carbonyl compounds under neat condition
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In the presence of a catalytic amount of indium (III) trichloride (InCl3) (20 mol%), ketene silyl enol ethers react quickly with α, β- unsaturated ketones and esters to afford the corresponding Michael adducts in moderate to good yields. Indium(III) trichloride can be recovered and reused without decrease in yields.
- Loh, Teck-Peng,Wei, Lin-Li
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p. 7615 - 7624
(2007/10/03)
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- Nucleophilic Substitution Reactions at Chloro-Substituted Ozonides and at a Chlorinated Dimeric Peroxide
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Reactions of substituted 3-chloro- (2a-4a) and 3,5-dichloro-1,2,4-trioxolanes (9a, 10a) with AgBF4 in the presence of LiF gave the corresponding fluoro-substituted ozonides (2b - 4b and 9b and 10b).Substitutions of some of these chlorinated ozonides by the methoxy and by the acetoxy groups, and of 3,6-dichloro-3,6-dimethyl-1,2,4,5-tetroxane (22a) with the acetoxy group have been achieved too.
- Griesbaum, Karl,Schlindwein, Konrad
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p. 8062 - 8066
(2007/10/03)
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- The Michael-type Reaction of B-Iodo-9-BBN/Ethoxyethyne Adduct to α,β-Unsaturated Ketones. A Selective Synthesis of δ-Keto Esters
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The adduct formed from B-iodo-9-borabicyclononane and ethoxyethyne reacts with α,β-unsaturated ketones under mild conditions to give δ-keto esters in excellent yield selectively.
- Kawamura, Fumitoshi,Tayano, Takao,Satoh, Yoshitaka,Hara, Shoji,Suzuki, Akira
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p. 1723 - 1726
(2007/10/02)
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- A New Synthesis of (+/-)-5,6-Dehydrosenedigitalene
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Ethyl 2-carbethoxy-5-oxohexanoate (II) on heating with NaCl in DMSO-water mixture gives the monoester (III) which when submitted to selective Grignard reaction with p-tolylmagnesium bromide furnishes ethyl 5-hydroxy-5-(p-tolyl)hexanoate (IV).The benzylic alcohol (IV) on catalytic hydrogenolysis gives ethyl 5-(p-tolyl)hexanoate (V) which on reduction with LAH provides the alcohol (VI).Oxidation of VI with Corey's reagent furnishes the aldehyde (VII) which on Wittig reaction with methylenetriphenylphosphorane in DMSO yields the title compound (I).
- Vig, O. P.,Sharma, M. L.,Verma, N. K.
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p. 384 - 385
(2007/10/02)
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