- Furoic acid and derivatives as atypical dienes in Diels-Alder reactions
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The furan Diels-Alder (DA) cycloaddition reaction has become an important tool in green chemistry, being central to the sustainable synthesis of many chemical building blocks. The restriction to electron-rich furans is a significant limitation of the scope of suitable dienes, in particular hampering the use of the furans most readily obtained from biomass, furfurals and their oxidized variants, furoic acids. Herein, it is shown that despite their electron-withdrawing substituents, 2-furoic acids and derivatives (esters, amides) are in fact reactive dienes in Diels-Alder couplings with maleimide dienophiles. The reactions benefit from a substantial rate-enhancement when water is used as solvent, and from activation of the 2-furoic acids by conversion to the corresponding carboxylate salts. This approach enables Diels-Alder reactions to be performed under very mild conditions, even with highly unreactive dienes such as 2,5-furandicarboxylic acid. The obtained DA adducts of furoic acids are shown to be versatile synthons in the conversion to various saturated and aromatic carbocyclic products.
- Bruijnincx, Pieter C. A.,Cioc, Rǎzvan C.,Crockatt, Marc,Smak, Tom J.,Van Der Waal, Jan C.
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- Photo-induced deep aerobic oxidation of alkyl aromatics
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Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry. Presently, the industrial manufacture of benzoic acids and benzene polycarboxylic acids (BPCAs) is mainly based on the deep oxidation of polyalkyl benzene, which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting MeBr and corrosion hazards of production equipment. In this report, photo-induced deep aerobic oxidation of (poly)alkyl benzene to benzene (poly)carboxylic acids was developed. CeCl3 was proved to be an efficient HAT (hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen (O2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying large-scale implementation advantages. The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks. [Figure not available: see fulltext.].
- Wang, Chang-Cheng,Zhang, Guo-Xiang,Zuo, Zhi-Wei,Zeng, Rong,Zhai, Dan-Dan,Liu, Feng,Shi, Zhang-Jie
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p. 1487 - 1492
(2021/07/10)
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- Preparation method of hemimellitic acid
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The invention relates to a preparation method of hemimellitic acid, wherein the method comprises the following steps: stirring hemimellitene in a strong alkali solution with a certain concentration, heating to about 95 DEG C, adding a certain amount of potassium permanganate in batches, and continuing reflux reaction for 6 hours to finish the reaction; and cooling to room temperature, adding a sulfuric acid solution with a certain concentration, controlling the temperature to be 45 DEG C or less, carrying out reaction for 2 hours, slowly adding a certain amount of oxalic acid, stirring until the purple color of the system is completely faded, extracting with ethyl acetate, filtering, concentrating, adding a certain amount of petroleum ether, pulping, carrying out suction filtration, and drying to obtain a finished product. The method has the advantages of simple and easily available reaction raw materials, rapid reaction, avoidance of recrystallization by using a hydrochloric acid solution in post-treatment, simplicity in operation, less emission of three wastes, good product yield and high product purity.
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Paragraph 0029; 0031-0036
(2020/05/01)
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- AROMATIC COMPOUNDS FROM FURANICS
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Described are methods for preparing phenols, benzene carboxylic acids, esters and anhydrides thereof from furanic compounds by reaction with a dienophile, wherein the furanic compounds are reacted with a hydrazine and/or oxime and then reacted with a dienophile.
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Page/Page column 37
(2017/09/21)
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- Inclusion complex containing epoxy resin composition for semiconductor encapsulation
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The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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- PROCESS FOR THE PREPARATION OF A BENZENE DERIVATIVE
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A substituted benzene derivative is prepared in a process, which comprises reacting a furan derivative of formula (I): wherein R is an alkyl group, with an olefin of formula (II): wherein R1 and R2 are the same or different and independently are selected from the group consisting of hydrogen, -CN, -CHO and -COOR3, wherein R3 is selected from hydrogen or an alkyl group, or R1 and R2 together form a -C(0)-0-(0)C- group, with the proviso that R1 and R2 are not both hydrogen, to produce a bicyclic ether; and dehydrating the bicyclic ether to obtain a benzene derivative. The benzene derivative thus obtained can suitably be converted to a benzene carboxylic acid compound by oxidation.
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Page/Page column 9
(2013/04/13)
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- Aerobic oxidation of trimethylbenzenes catalyzed by N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst
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The oxidation of trimethylbenzenes was examined with air or O2 using N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst. Thus, 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes under air (20 atm) in the presence of THICA (5 mol %), Co(OAc)2 (0.5 mol %), Mn(OAc)2, and ZrO(OAc)2 at 150 °C were oxidized to the corresponding benzenetricarboxylic acids in good yields (81-97%). In the aerobic oxidation of 1,2,4-trimethylbenzene by the THICA/Co(II)/Mn(II) system, remarkable acceleration was observed by adding a very small amount of ZrO(OAc)2 to the reaction system to form 1,2,4-benzenetricarboxylic acid in excellent yield (97%). In contrast, no considerable addition effect was observed in the oxidation of 1,3,5-trimethylbenzene. This aerobic oxidation by the present catalytic system provides an economical and environmentally benign direct method to benzenetricarboxylic acids, which are very important polymer materials.
- Hirai, Naruhisa,Tatsukawa, Yoshinobu,Kameda, Michiko,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 6695 - 6699
(2007/10/03)
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- Multivalent neuraminidase inhibitor conjugates
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The invention relates to a multimeric compound or a pharmaceutically acceptable salt or derivative thereof which comprises three or more neuraminidase-binding groups attached to a spacer or linking group, in which the neuraminidase-binding group is a compound which binds to the active site of influenza virus neuraminidase, but is not cleaved by the neuraminidase. The invention also relates to processes for the preparation of the multimeric compound defined above, pharmaceutical compositions containing them or methods for the treatment and/or prophylaxis of a viral infection involving them.
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- INTERACTION OF 5-AZIDO-1,2,3-BENZENETRICARBOXYLIC ACID WITH THE MITOCHONDRIAL TRICARBOXYLATE CARRIER
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5-azido-1,2,3-benzenetricarboxylic acid (5-N3-BTA), a new derivative of 1,2,3-benzenetricarboxylic acid (BTA) has been synthesised in satisfactory overall yields (25percent).This azido compound inhibits the transport of citrate either in mitochondria or in reconstituted partially purified tricarboxylate carrier, both in the dark and upon irradiation.However, the inhibition is nearly completely supressed after washing the mitochondria, indicating that upon irradiation 5-N3-BTA does not form a covalent bond with the citrate-binding site of the tricarboxylate transport system.
- Capassso, Renato,Randazzo, Giacomino,Stipani, Italo,Zara, Vincenzo,Palmieri, Ferdinando
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p. 449 - 452
(2007/10/02)
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- Dehydration of 1-Substituted Secondary and Tertiary Bicyclononan-9-ols. A Substituent-Driven Rearrangement to 4-Substituted and/or Angularly Substituted Hexahydroindenes
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The acid-catalyzed dehydration of substituted bicyclononan-9-ols (1-9) has been studied as a route to substituted hexahydroindenes via skeletal rearrangement.The nature of the substituent at C1 strongly affects the rearrangement.Thus 1-substituted secondary alcohols 1-3 (R = Ph, CH3, H) afford 4-substituted 2,3,4,5,6,7-hexahydroindenes 1b-3b, while a mixture of 3a-carbethoxyhexahydroindenes (4a,b) is produced from 4 (R = CO2Et).Tertiary alcohols 5-9 afford cis-3a-substituted 2,3,3a,6,7,7a-hexahydroindenes 1a-9a.These processes are discussed in terms of relative stabilities of the intermediate carbonium ions.
- Balata, Fabrizio,Jacono, Anna R. Dello,Gambacorta, Augusto
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p. 566 - 570
(2007/10/02)
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- A Fresh Look at the Pechmann Condensation and Duff Rection with β-Naphthol
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Pechmann condensation of β-naphthol with ethyl acetoacetate in the presence of anhydrous aluminium chloride gives, besides two known compounds, 4-methyl-6,7-benzocoumarin and 3-methyl-9-hydroxyphenalen-1-one (I).The Duff reaction of β-naphthol gives the new compounds 1,3-diformyl-2-naphthol and 2-formyl-2,3-dihydro-1H-naphth-oxazine (II) and the known 2,2'-dihydroxy-1,1'-binaphthylmethane.Compound (II) exists as a mixture of rotamers.
- Kostova, I. N.,Pardeshi, N.,Rangaswami, S.,Lee, Yue-Wei
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p. 859 - 862
(2007/10/02)
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