- Acylation of methylfuran with Br?nsted and Lewis acid zeolites
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The acylation of methylfuran has been investigated using Br?nsted and Lewis acid zeolite catalysts. The highest reaction rate for acylation on a per gram basis is found on zeolite Beta with high aluminum content (Si/Al = 23) and the highest turnover frequency on a per metal site basis is found on zeolite Beta with low aluminum content (Si/Al = 138). Among Lewis acid zeolites, [Sn]-Beta shows higher turnover frequency than [Hf]-, [Zr]- or [Ti]-Beta. Similar apparent activation energies were found for [Al]-Beta with different Si/Al ratios and a lower apparent activation energy was found for [Sn]-Beta. Electronic structure calculations reveal that on both [Al]- and [Sn]-Beta the most favorable pathway follows the classic addition-elimination aromatic electrophilic substitution mechanism. The calculations also reveal that, on both [Al]- and [Sn]-Beta, the rate of methylfuran acylation is controlled by the dissociation of the C–O–C linkage of the anhydride while hydrogen elimination is the rate-determining step in the acylation of furan. The latter is in complete agreement with measured primary kinetic isotope effects. One remarkable and unexpected finding from our calculations is that the most favorable catalytic pathway in [Sn]-Beta involves Br?nsted acid catalysis by the silanol group of the hydrolyzed “open” site and not Lewis acid catalysis by the Sn metal center.
- Koehle, Maura,Zhang, Zhiqiang,Goulas, Konstantinos A.,Caratzoulas, Stavros,Vlachos, Dionisios G.,Lobo, Raul F.
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- Synthesis, and antitubercular and antimicrobial activity of 1′-(4-chlorophenyl)pyrazole containing 3,5-disubstituted pyrazoline derivatives
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A new series of 1′-(4-chlorophenyl)-5-(substituted aryl)-3′-(substituted aryl)-3,4-dihydro-2H,1′H-[3,4′]bipyrazolyl derivatives (6a-e, 8a-e, 10a-e) have been synthesized, characterized and screened for antimicrobial and antitubercular activity. Among the synthesized compounds, the minimum inhibition concentration of 10e was found to be as low as 1.56 μg ml-1 and that of 10c was 6.25 μg ml-1 as compared to the standard anti-tb drugs pyrazinamide and streptomycin.
- Harikrishna,Isloor, Arun M.,Ananda,Obaid, Abdulrahman,Fun, Hoong-Kun
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- Optimization for catalytic performances of Hβ zeolite in the acylation of 2-methylfuran by surface modification and solvents effect
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The liquid phase acylation of 2-methylfuran with acetic anhydride over modified Hβ zeolite was first conducted in a continuous flow reactor. The deactivation of Hβ zeolites was attributed to strong adsorption of reactants or products and was verified by GC–MS and 13C MAS NMR. Deactivated zeolites can be regenerated to their original state by calcination. The acidic properties was adjusted by surface modification on Hβ, the maximum yield of 89.5?mol% and selectivity of 100?% were obtained over tartaric acid modified by Hβ. The deposition of tetraethoxysilane to silica on Hβ contributed to enhancing the catalytic stability. Combined with the results of NH3-TPD and Py-FTIR, the amount of Broensted acids played a major role on catalytic activity. A close relationship between the catalytic stability and the ratio of the amount of strong to weak acids at 1:1 was highlighted here. The solvents' effect on the catalytic performances was examined, and 1,2-dichloroethane with moderate polarity exerted a positive effect on catalytic stability.
- Xiong, Yuannan,Chen, Wenqi,Zeng, Aiwu
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- Photo-on-Demand Synthesis of Vilsmeier Reagents with Chloroform and Their Applications to One-Pot Organic Syntheses
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The Vilsmeier reagent (VR), first reported a century ago, is a versatile reagent in a variety of organic reactions. It is used extensively in formylation reactions. However, the synthesis of VR generally requires highly toxic and corrosive reagents such as POCl3, SOCl2, or COCl2. In this study, we found that VR is readily obtained from a CHCl3 solution containing N,N-dimethylformamide or N,N-dimethylacetamide upon photo-irradiation under O2 bubbling. The corresponding Vilsmeier reagents were obtained in high yields with the generation of gaseous HCl and CO2 as byproducts to allow their isolations as crystalline solid products amenable to analysis by X-ray crystallography. With the advantage of using CHCl3, which bifunctionally serves as a reactant and a solvent, this photo-on-demand VR synthesis is available for one-pot syntheses of aldehydes, acid chlorides, formates, ketones, esters, and amides.
- Liang, Fengying,Eda, Kazuo,Okazoe, Takashi,Wada, Akihiro,Mori, Nobuaki,Konishi, Katsuhiko,Tsuda, Akihiko
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p. 6504 - 6517
(2021/05/06)
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- Method for producing furandicarboxylic acid and derivatives thereof from furfural
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The invention discloses a method for producing furandicarboxylic acid and derivatives thereof from furfural. The method comprises the following steps: furfural is reduced to 2-methylfuran under the hydrogen condition; acetylation reaction is carried out on 2-methylfuran to obtain 5-methyl-2-acetylfuran; 5-methyl-2-acety furan reacts with ester to obtain methyl 5-methyl-2-furanformate, methyl 5-methyl-2-furanformate is oxidized into monomethyl 2,5-furandicarboxylate under the oxygen condition, and monomethyl 2,5-furandicarboxylate is hydrolyzed into monomethyl 2,5-furandicarboxylate or furtheresterified with methyl alcohol to generate dimethyl 2,5-furandicarboxylate. The cheap five-carbon furan compound furfural is used as a raw material, and the 2 5-furandicarboxylic acid and the derivatives thereof are prepared by a strategy of increasing a carbon chain, so that the cost of the raw material is greatly reduced. The product provided by the invention has high purity and can be directlyused as a polymerization monomer of PET polyester.
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- Synthesis method of 2,5-furandicarboxylic acid
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The invention discloses a synthesis method of 2,5-furandicarboxylic acid. The synthesis method comprises the following steps: 1, hydrogenation of furfural into methyl furan; 2, acetylation of methyl furan; 3, hydrogenation of 5-methyl-2-acetylfuran; and 4, oxidation of 2-methyl-5-ethylfuran. According to the invention, a green renewable bio-based platform compound furfural is used as a raw material; and compared with a process for preparing 2,5-furandicarboxylic acid by using 5-hydroxymethylfurfural as a raw material, the method disclosed by the invention has the advantages that the source ofthe used raw material is wider, the raw material is easy to produce, productivity is higher, the cost of the raw material is lower, the cost of a used oxidation catalyst is low, and large-scale production is facilitated. Compared with a noble metal complex catalyst used in a process adopting CO carbonylation for carbon chain growth, a carbon chain growth strategy catalyst used in the invention issolid acid, so cost is greatly reduced.
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- Cobalt-Catalyzed Oxygenation/Dearomatization of Furans
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The dearomatization of aromatic compounds using cobalt(II) acetylacetonate with triplet oxygen and triethylsilane converts furans, benzofurans, pyrroles, and thiophenes to a variety of products, including lactones, silyl peroxides, and ketones.
- Oswald, Jonathan P.,Woerpel
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p. 9067 - 9075
(2018/05/29)
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- Biocatalysis with the milk protein β-lactoglobulin: Promoting retroaldol cleavage of α,β-unsaturated aldehydes
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Enzymes with a hydrophobic binding site and an active site lysine have been suggested to be promiscuous in their catalytic activity. β-Lactoglobulin (BLG), the principle whey protein found in milk, possesses a central calyx that binds non-polar molecules. Here, we report that BLG can catalyze the retro-aldol cleavage of α,β-unsaturated aldehydes making it a naturally occurring protein capable of catalyzing retro-aldol reactions on hydrophobic substrates. Retroaldolase activity was seen to be most effective on substrates with phenyl or naphthyl side-chains. Use of a brominated substrate analogue inhibitor increases the product yield by a factor of three. BLG's catalytic activity and its ready availability make it a prime candidate for the development of commercial biocatalysts.
- Gowda, Vishruth,Foley, Brendan,Du, Jasmine,Esteb, Megan,Watanabe, Coran M. H.
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supporting information
p. 2210 - 2213
(2018/04/05)
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- Production of p-Methylstyrene and p-Divinylbenzene from Furanic Compounds
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A four-step catalytic process was developed to produce p-methylstyrene from methylfuran, a biomass-derived species. First, methylfuran was acylated over zeolite H-Beta with acetic anhydride. Second, the acetyl group was reduced to an ethyl group with hydrogen over copper chromite. Third, p-ethyltoluene was formed through Diels–Alder cycloaddition and dehydration of 2-ethyl-5-methyl-furan with ethylene over zeolite H-Beta. Dehydrogenation of p-ethyltoluene to yield p-methylstyrene completes the synthesis but was not investigated because it is a known process. The first two steps were accomplished in high yield (>88 %) and the Diels–Alder step resulted in a 67 % yield of p-ethyltoluene with a 99.5 % selectivity to the para isomer (final yield of 53.5 %). The methodology was also used for the preparation of p-divinylbenzene. It is shown that acylation of furans over H-Beta zeolites is a highly selective and high-yield reaction that could be used to produce other valuable molecules from biomass-derived furans.
- Koehle, Maura,Sara?i, Erisa,Dauenhauer, Paul,Lobo, Raul F.
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- A salen-Co3+ catalyst for the hydration of terminal alkynes and in tandem catalysis with Ru-TsDPEN for the one-pot transformation of alkynes into chiral alcohols
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The cobalt-salen complex (C1:[(salen)Co3+(OAc)]; salen= N,N'-bis(salicylidene)ethylenediamine, OAc=acetate) was found to efficiently promote the hydration of terminal alkynes to give methyl ketones in the presence of the H2SO4 cocatalyst. In addition, the one-pot transformation of alkynes into chiral alcohols through tandem catalysis by catalyst C1 coupled with a ruthenium-TsDPEN complex (C3: [(R,R-TsDPEN)Ru 2+(cymene)]; TsDPEN=(1R,2R)-N-(p-toluenesulfonyl)-1,2- diphenylethylenediamine, cymene=1-methyl-4-(1-methylethyl)benzene) catalyst was realized with excellent yields and enantioselectivities. Stay hydrated: The salen-Co3+ (1) complex is found to efficiently promote the hydration of terminal alkynes to give methyl ketones in the presence of the H 2SO4 cocatalyst. In addition, the one-pot transformation of alkynes into chiral alcohols through tandem catalysis of 1 with the ruthenium catalyst 2 is realized in excellent yields and enantioselectivities.
- Wang, Shoufeng,Miao, Chengxia,Wang, Wenfang,Lei, Ziqiang,Sun, Wei
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p. 1612 - 1616
(2014/06/24)
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- Hydration of terminal alkynes catalyzed by a water-soluble salen-Co(III) complex
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A water-soluble salen-Co(III) complex was studied as catalyst for hydration of terminal alkynes to methyl ketones in the presence of H2SO4 as a co-catalyst. The products were obtained with excellent yields using relatively low catalyst loadings and a simple protocol. Notably, the products were easily separated from the catalyst after reaction by extraction, and the catalyst could be recovered and reused with only a slight loss of activity.
- Wang, Shoufeng,Miao, Chengxia,Wang, Wenfang,Lei, Ziqiang,Sun, Wei
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p. 1695 - 1700
(2015/09/28)
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- General synthetic approach towards annelated 3a,6-epoxyisoindoles by tandem acylation/IMDAF reaction of furylazaheterocycles. Scope and limitations
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An efficient and versatile one-pot synthesis of 3,6a-epoxyisoindoles annelated with oxazine, oxazole, thiazine, thiazole, pyrimidine fragments and with their benzoannelated analogues is presented. The method is based on tandem N-acylation/intramolecular cycloaddition (the intramolecular Diels-Alder reaction of furan, IMDAF) reaction between α,β-unsaturated acid anhydrides and α-furyl substituted azaheterocycles. The latter can be easily prepared by condensation of diverse furfurals and 1,2- or 1,3-N,X-binucleophiles (aminoalcohols, aminothiols, diamines). The observed IMDAF reaction is stereoselective: exo-adducts are formed exclusively with large prevalence of one of the diastereoisomers. In most cases, the condensation/N-acylation/IMDAF reaction sequence may be carried out via a one-pot domino protocol. The scope and limitations of the proposed approach are thoroughly investigated. The obtained Diels-Alder adducts are attractive and useful substrates for further transformations. Fused isoindoles can be prepared from them in one-step by aromatization of the 7-oxabicyclo[2.2.1]heptene ring. Other transformations, including halogenation, ring cleavage, and Wagner-Meerwein skeletal rearrangement, are also demonstrated. The spatial structures of the obtained compounds have been established by X-ray diffraction analyses.
- Zubkov, Fedor I.,Nikitina, Eugenia V.,Galeev, Timur R.,Zaytsev, Vladimir P.,Khrustalev, Victor N.,Novikov, Roman A.,Orlova, Daria N.,Varlamov, Alexey V.
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p. 1659 - 1690
(2014/02/14)
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- Synthesis and some transformations of 5-(N-tosylaminomethyl)furfuryl alcohols
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Preparative methods were developed for the synthesis of 5-(N-tosylaminomethyl)furfuryl alcohols, and their behavior during the action of acidic catalysts was studied. It was established that the furan ring of these compounds is stable in the presence of o
- Stroganova,Butin
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experimental part
p. 524 - 530
(2010/03/01)
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- Synthesis of 5-acetoxymethyl- and 5-hydroxymethyl-2-vinylfuran
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5-Acetoxymethyl- and 5-hydroxymethyl-2-vinylfuran were synthesized by two routes. The first route starts from 2-methylfuran and the second from furfuryl acetate. The latter route, involving successive Vilsmeier-Haack and Wittig reactions, is suitable for producing 5-acetoxymethyl-2-vinylfuran and 5-hydroxymethyl-2 vinylfuran in 68% and 60% yields, respectively.
- Mehner, Alexander,Montero, Ana L.,Martinez, Ricardo,Spange, Stefan
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p. 634 - 640
(2008/02/01)
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- Reactions of Some Cyclic Ethers in Superacids
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The reactions of some epoxides and tetrahydrofuran derivatives in superacidic media have been studied.The tetrahydrofurans decompose only at 0 deg C or above, yielding, in some cases, unsaturated carbocations which react to give carbocyclic products, though many yield only tar.Cyclohexene oxides decompose more readily; unsubstituted, they slowly form an allylic ion; with one carbon at the epoxide link substituted they yield the ketone, and with both carbons substituted they give the ring-contracted aldehyde.Limonene 1,2-oxide behaves in a similar manner, though yielding small amounts of the ring-contracted protonated aldehyde (10).Reaction of geraniol 2,3-oxide is initially similar but the intermediate is intercepted intramolecularly to yield the hydroxy-iridoid ethers, 3,3,6β-trimethyl-cis-perhydrocyclopentafuran and 3,3,6α-trimethyl-cis-perhydrocyclopentafuran.Protonation of cyclohexene oxide or norbornene oxide yields onium salts, stable at -70 deg C, which show the addition to be either unsymmetrical (i.e. edge protonation) or to take place in two different positions.
- Baig, Mirza Azam,Banthorpe, Derek V.,Carr, Graham,Whittaker, David
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p. 1981 - 1986
(2007/10/02)
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- A Novel Access to Ionone-Type Compounds: (E)-4-Oxo-β-ionone and (E)-4-Oxo-β-irone via Metal-Catalyzed, Intramolecular Reactions of α-Diazo Ketones with Furans
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(E)-5-Demethyl-4-oxo-β-ionone (2), (E)-4-oxo-β-ionone (3), (E)-4-oxo-β-irone (4), and the five-membered ring analogs 36-41 were synthesized by a novel, convergent route starting from 2-methylfuran (1).A recently discovered, intramolecular reaction of 2-(diazoacyl)furans, catalyzed by dirhodium tetraacetate, leading to diene-diones served as key step, thereby testing its utility in natural-product synthesis for the first time.
- Wenkert, Ernest,Decorzant, Rene,Naef, Ferdinand
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p. 756 - 766
(2007/10/02)
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- Friedel-Crafts Reaction of 2-Methylfuran with Saturated and α,β-Unsaturated Acid Anhydrides
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2-Methylfuran (5) reacts with the saturated acid anhydrides 16 - 26 in the presence of SnCl4 to give the 2-acyl-5-methylfurans 37 - 47 selectively.The unsaturated anhydrides 27 - 32, however, yield mixtures which only in the case of senecioic acid anhydride (29) contain the respective primary product 48.Subsequent reactions lead to the addition products 55 (from 27) and 56 (from 29), and to (E,Z)-mixtures of their enol esters 57 - 62 which could partially be separated and assigned. - The olfactory properties of 2, 37 - 48, 50, 52, and 53 were investigated.
- Scholz, Stefan,Marschall-Weyerstahl, Helga,Weyerstahl, Peter
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p. 1935 - 1950
(2007/10/02)
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- Photochemistry of 4-Hydroxypyrylium Cations in Aqueous Sulfuric Acid
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4-Hydroxypyrylium cations that are known to undergo phototransposition to 2-hydroxypyrylium cations in concentrated sulfuric acid were observed to undergo photo-ring contraction in 50percent sulfuric acid.The initial products observed when the irradiations are carried out at 0 deg C are 4,5-dihydroxycyclopent-2-enones that can be isolated.At higher temperatures these initial products undergo secondary acid catalyzed thermal reactions to yield substituted acetylfurans.
- Pavlik, James W.,Spada, Alfred P.,Snead, Thomas E.
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p. 3046 - 3050
(2007/10/02)
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- Photoisomerization of 4-Hydroxypyrylium Cations in Concentrated Sulfuric Acid
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Irradiation of di-, tri-, and tetraalkyl-4-hydroxypyrylium cations in concentrated sulfuric acid leads to the formation of 2-hydroxypyrylium cations as phototransposition products and, in certain cases, to furyl cations by a photo-ring-contraction reaction.Product analysis by spectroscopic techniques, deuterium labeling, and unambiguous synthesis reveals that 2-hydroxypyrylium cations are formed by two distinct transposition patterns and accordingly, by two distinct mechanistic pathways.The bond-forming and -breaking requirements of the major transposition pattern, which constitutes approximately 95percent of the reaction, are consistent with a mechanism initiated by 2,6-bridging in the first excited state of the 4-hydroxypyrylium cation.Similarly, the bond-formation and -breaking requirements of the minor pattern are consistent with a mechanism involving 2,5-bridging in the first excited state of the starting cation.
- Pavlik, James W.,Patten, Arthur D.,Bolin, David R.,Bradford, Kenneth C.,Clennan, Edward L.
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p. 4523 - 4531
(2007/10/02)
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