- O-to-S Substitution Enables Dovetailing Conflicting Cyclizability, Polymerizability, and Recyclability: Dithiolactone vs. Dilactone
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Developing chemically recyclable polymers represents a greener alternative to landfill and incineration and offers a closed-loop strategy toward a circular materials economy. However, the synthesis of chemically recyclable polymers is still plagued with certain fundamental limitations, including trade-offs between the monomer's cyclizability and polymerizability, as well as between polymer's depolymerizability and properties. Here we describe the subtle O-to-S substitution, dithiolactone monomers derived from abundant feedstock α-amino acids can demonstrate appealing chemical properties different from those of dilactone, including accelerated ring closure, augmented kinetics polymerizability, high depolymerizability and selectivity, and thus constitute a unique class of polythioester materials exhibiting controlled molecular weight (up to 100.5 kDa), atactic yet high crystallinity, structurally diversity, and chemical recyclability. These polythioesters well addresses the formidable challenges of developing chemically recyclable polymers by having an unusual set of desired properties, including easy-to-make monomer from ubiquitous feedstock, and high polymerizability, crystallinity and precise tunability of physicochemical performance, as well as high depolymerizability and selectivity. Computational studies explain why O-to-S modification of polymer backbone enables dovetailing desirable, but conflicting, performance into one polymer structure.
- Chen, Jinlong,Li, Maosheng,Tao, Youhua,Wang, Xianhong,Wang, Yanchao
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supporting information
p. 22547 - 22553
(2021/09/09)
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- Method for preparing alpha-bromo fatty acid ester
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The invention provides a method for preparing alpha-bromo fatty acid ester. The method comprises the steps of bromination and esterification, wherein the bromination comprises the step of subjecting fatty acid and bromine to a bromination reaction in a manner of taking bromosuccinimide as a catalyst so as to produce alpha-bromo fatty acid, and the esterification comprises the step of subjecting the alpha-bromo fatty acid and lower alcohol to an esterification reaction in a manner of taking bisulfate as a catalyst, so as to produce the alpha-bromo fatty acid ester. According to the method provided by the invention, the bisulfate is used as the catalyst during esterification, so that combustible red phosphorus with strong feeding odors is avoided, and the whole reaction process is environmentally friendly and is free of equipment corrosion and a phenomenon of carbonization of part of the product; the catalyst can be recycled, and the yield is relatively high and can reach 98%.
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Paragraph 0020-0021; 0023-0024
(2019/04/04)
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- Reaction of Lithium Acylate α-Carbanions with Carbon Tetrabromide
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Lithium acylate α-carbanions generated by metalation of acetic, butanoic, and 2-methylpropanoic acids with lithium diisopropylamide in THF under argon reacted with carbon tetrabromide at 20-25°C (2 h) to produce butanedioic acid or its 2,3-diethyl and 2,2,3,3-tetramethyl derivatives, as well as the corresponding 2-bromocarboxylic acids and bromoform. The effect of the halogen nature in carbon tetrahalide (CCl4, CBr4) on the reaction selectivity is discussed.
- Zorin,Zaynashev,Zorin
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p. 1527 - 1531
(2019/12/28)
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- Catalytic Asymmetric Conjugate Addition and Sulfenylation of Diarylthiazolidin-2,4-diones
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This work reports the first application of diarylthiazolidin-2,4-diones as nucleophiles in asymmetric catalysis. By utilizing chiral amino acid-based (thio)urea-tertiary amines as the catalysts, we successively established asymmetric conjugate addition to nitroolefins and sulfenylation to N-(sulfanyl)-succinimides of diarylthiazolidin-2,4-diones. Two series of biologically important 5-aryl-5-substituted thiazolidin-2,4-diones were obtained with high enantio- and diastereoselectivities (up to >99% ee and >19:1 dr). The enantioenriched adducts were found to show satisfactory anticancer activities against three different cancer cell lines using the MTT assay. All of these successes depended on the development of a general and expedient synthetic strategy to provide diverse 5H-thiazolidin-2,4-diones.
- Jiao, Lihui,Bu, Liwei,Ye, Xinyi,Zhao, Xiaowei,Jiang, Zhiyong
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p. 9620 - 9629
(2016/11/02)
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- Reactions of α-carbanions of lithium acylates with N,N-diethyl-N-chloro- and N,N-diethyl-N-bromoamines
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The interaction of α-carbanions of lithium acylates (prepared via metalation of acetic, butyric, or isobutyric acid with lithium diisopropylamide in tetrahydrofuran under argon atmosphere) with N,N-diethyl-N-chloro- or N,N-diethyl-N-bromoamine has resulte
- Zorin,Zainashev,Zorin
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p. 2469 - 2472
(2016/12/24)
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- Enoate reductase-mediated preparation of methyl (S)-2-bromobutanoate, a useful key intermediate for the synthesis of chiral active pharmaceutical ingredients
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Enoate reductases belonging to the Old Yellow Enzyme (OYE) family were employed to develop a biocatalysed approach to methyl (S)-2-bromobutanoate, a key intermediate for the introduction of a particular stereogenic unit into the molecular skeleton of a certain class of chiral drugs. Methyl (Z)-2-bromocrotonate afforded, respectively, (S)-2-bromobutanoic acid (ee = 97%) and methyl (S)-2-bromobutanoate (ee = 97%) by baker's yeast fermentation and by OYE1-3 biotransformations. The bioreductions of other methyl 2-haloalkenoates were also considered. It was observed that the (Z)- and (E)-diastereoisomers of α-bromo unsaturated esters afforded the same enantiomer of the corresponding reduced product.
- Brenna, Elisabetta,Gatti, Francesco G.,Manfredi, Alessia,Monti, Daniela,Parmeggiani, Fabio
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experimental part
p. 262 - 268
(2012/06/18)
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- Discovery of a peroxisome proliferator activated receptor γ (PPARγ) modulator with balanced PPARα activity for the treatment of type 2 diabetes and dyslipidemia
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A series of 3-acylindole-1-benzylcarboxylic acids were designed and synthesized while searching for a PPARγ modulator with additional moderate intrinsic PPARα agonistic activity. 2-[3-[[3-(4-Chlorobenzoyl)-2-methyl- 6-(trifluoromethoxy)-1H-indol-1-yl]methyl]phenoxy]-(2R)-butanoic acid (12d) was identified as such an agent which demonstrated potent efficacy in lowering both glucose and lipids in multiple animal models with significantly attenuated side effects such as fluid retention and heart weight gain associated with PPARγ full agonists. The moderate PPARα activity of 12d not only contributed to the agent's ability to manage lipid profiles but also appears to have potentiated its PPARγ efficacy in lowering glucose levels in preclinical diabetic animal models.
- Liu, Weiguo,Liu, Kun,Wood, Harold B.,McCann, Margaret E.,Doebber, Thomas W.,Chang, Ching H.,Akiyama, Taro E.,Einstein, Monica,Berger, Joel P.,Meinke, Peter T.
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supporting information; experimental part
p. 4443 - 4453
(2010/03/02)
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- Investigation of the synthetic and mechanistic aspects of the highly stereoselective transformation of α-thioamides to α-thio-β- chloroacrylamides
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Treatment of a series of α-thioamides with N-chlorosuccinimide results in efficient transformation to the analogous α-thio-β- chloroacrylamides. The mechanistic pathway has been established through isolation and characterisation of intermediate compounds. The scope of the transformation has been explored - aryl and alkylthio substituents, primary, secondary and tertiary amides can be employed. In most instances, the chloroacrylamides are formed exclusively as the Z-stereoisomer; however, with tertiary propanamides or with amides derived from butanoic or pentanoic acid a mixture of E- and Z-stereoisomers is formed. The Royal Society of Chemistry.
- Murphy, Maureen,Lynch, Denis,Schaeffer, Marcel,Kissane, Marie,Chopra, Jay,O'Brien, Elisabeth,Ford, Alan,Ferguson, George,Maguire, Anita R.
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p. 1228 - 1241
(2008/02/03)
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- A synthesis of levetiracetam based on (S)-N-phenylpantolactam as a chiral auxiliary
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The synthesis of levetiracetam and its enantiomer by deracemization of (±)-2-bromobutyric acid using either (S)- or (R)-N-phenylpantolactam as chiral auxiliaries, followed by SN2 substitution of the bromine atom by a 2-oxopyrrolidin-1-yl group and amidation of the carboxylic acid, is described.
- Boschi, Francesca,Camps, Pelayo,Comes-Franchini, Mauro,Munoz-Torrero, Diego,Ricci, Alfredo,Sanchez, Laura
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p. 3739 - 3745
(2007/10/03)
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- Mesoionic 5-alkyl-1,3-dithiolium-4-thiolates: Synthesis and brine shrimp toxicity
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A series of twelve 1,3-dithiolium-4-thiolate mesoionic compounds were synthesized and characterized. The synthetical approach starting from α-bromoalkanoic acids to obtain the corresponding 2-N-morpholino-dithiocarbamoyl-carboxylic acids that by on-pot reaction with carbon disulfide and acetic anhydride in triethylamine formed not isolate intermediates, 1,3-dithiolium-4-olates. After, the 2-N-morpholino-5-alkyl-1,3-dithiolium-4-thiolates were obtained by retro 1,3-dipolar addition reactions. The alkyl moiety linked to C-5 of heterocyclic ring permitted the increase of the hydrophobic character and this effect was evaluated on Artemia salina lethality. The results indicated a bell-shaped relationship between the number of carbon of side chain in mesoionic derivatives and LD50 in brine shrimp toxicity assays.
- De Almeida, Paulo Afonso,Da Silva, Tania Maria Sarmento,Echevarria, Aurea
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p. 593 - 600
(2007/10/03)
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- The autoxidation of aliphatic esters. Part 3. The reactions of alkoxyl and methyl radicals, from the thermolysis and photolysis of peroxides, with neopentyl esters
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This paper reports a study of the dimerisation of ester radicals arising from the thermolysis and photolysis of di-tert-butyl peroxide (DTBPO) and dicumyl peroxide [DCPO, bis(α,α-dimethylbenzyl) peroxide] in neopentyl butanoate and a selection of structurally related neopentyl esters, in the temperature range 298 to 438 K. The acyl moieties of these esters were chosen to incorporate a variety of structural types to provide mechanistic information about the reactions. At 438 K, the thermolyses of DTBPO and DCPO in neopentyl butanoate give six ester radical dimers (three pairs of diastereoisomers). The two major diastereoisomers threo- and meso-dineopentyl 2,3-diethylbutane-dioate have been prepared and the crystal structure of the meso compound determined. Interestingly, the dimer product distribution is independent of the peroxide used. By contrast, at 298 K more than twice as many dimers are observed and the product distributions from the two peroxides are no longer the same. Similar results are also observed for the other neopentyl esters. Evidence is presented to show that the ester radicals arise from hydrogen atom abstraction from the esters by alkoxyl and methyl radicals; the latter being formed by the fragmentation of the alkoxyls. At 438 K the dimer product distributions are determined predominantly by a thermodynamically controlled equilibrium of ester radicals prior to dimerisation. Lowering the temperature leads to the increased importance of kinetic effects in determining the product distribution.
- Lindsay Smith,Nagatomi,Stead,Waddington
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p. 1527 - 1533
(2007/10/03)
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- N-hdroxy-2-(alkyl, aryl, or heteroaryl, sulfanyl, sulfinyl or sulfonyl)-3-substituted alkyl, aryl or heteroarylamides as matrix metalloproteinase inhibitors
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Matrix metalloproteinases (MMPs) are a group of enzymes that have been implicated in the pathological destruction of connective tissue and basement membranes. These zinc containing endopeptidases consist of several subsets of enzymes including collagenases, stromelysins and gelatinases. TNF-α converting enzyme (TACE), a pro-inflammatory cytokine, catalyzes the formation of TNF-α from membrane bound TNF-α precursor protein. It is expected that small molecule inhibitors of MMPs and TACE therefore have the potential for treating a variety of disease states. The present invention provides low molecular weight, non-peptide inhibitors of matrix metalloproteinases (MMPs) and TNF-α converting enzyme (TACE) for the treatment of arthritis, tumor metastasis, tissue ulceration, abnormal wound healing, periodontal disease, bone disease, diabetes (insulin resistance) and HIV infection having the formula wherein R2and R3form a heterocyclic ring and A is S, S(O), or S(O)2, and R1and R4are defined herein.
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- Enantioselective synthesis of α-bromo acid derivatives and bromohydrins from tartrate derived bromoacetals
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Bromination of the acetals 4 derived from aryl alkyl ketones, ArCOR, and (2R,3R)-tartaric acid results in bromoacetals 5 with 78-90% de. Hydrolysis of those compounds with Ar = 4-methoxyphenyl or 3-bromo-4-methoxyphenyl results, after recrystallisation, in α-bromoketones 8 with 66-98% ee which are shown to undergo the Baeyer-Villiger oxidation to α-bromoesters 9 with minimal racemisation, α-Bromoketone 8d is shown to undergo carbonyl reduction to threo-bromohydrin 15 with retention of stereochemistry.
- Boyes, Scott A.,Hewson, Alan T.
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p. 2759 - 2765
(2007/10/03)
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- A simple and efficient method of preparing α-bromo carboxylic acids
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A new and convenient method for α-bromination of aliphatic carboxylic acids is reported. Heating carboxylic acids for 16 hours at 85 °C in trifluoroacetic acid with 1.5 equivalents of N-bromosuccinimide and a catalytic amount of concentrated H2SO4 leads to good yields of the respective α-bromocarboxylic acids.
- Zhang, Lian Hao,Duan, Jianxin,Xu, Yuelian,Dolbier Jr., William R.
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p. 9621 - 9622
(2007/10/03)
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- Isosteres of chiral clofibric acid analogs: Synthesis, resolution, absolute configuration and HPLC detection of the optical purity
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Both racemic and enantiomeric forms of some isosteres of chiral clofibric acid analogs have been synthesized. Also, the absolute configuration has been established by chemical correlation and the optical purity determined by a simple HPLC procedure. Moreover, these studies show that the isosteric substitution of the ether oxygen atom of α-aryloxy- alkanoic acids with sulfur, amino and methylene groups lead to compounds in which both biological activity and stereoselectivity regarding chloride channel are highly reduced.
- Ferorelli,Loiodice,Tortorella,Amoroso,Bettoni,Conte- Camerino,De Luca
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p. 367 - 374
(2007/10/03)
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- Preparation of optically active α-(hydroxyphenoxy)alkanecarboxylic acids and derivatives thereof
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Optically active α-(hydroxyphenoxy)-alkanecarboxylic acids or derivatives thereof, for example D-2-(4-hydroxyphenoxy)propionic acid or lower alkyl ester thereof, are prepared by (a) saponifying an alkyl ester of an optically active α-halogeno-alkanecarboxylic acid, in an alcoholic solvent medium, by reacting same with an aqueous solution of an alkali metal hydroxide, thereby providing a solution of an alkali metal salt of an optically active α-halogeno-alkanecarboxylic acid, (b) next reacting the step (a) solution thus provided with a dihydroxybenzene or salt thereof, in the presence of an alkali metal hydroxide and in an alcoholic solvent medium, and thence (c) recovering the optically active α-(hydroxyphenoxy)-alkanecarboxylic acid or derivative thereof from the medium of reaction.
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- Specific esterase activity of subtilisin toward esters of α-haloacids
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Esters of α-haloacids are specific substrates for subtilisin which catalyses their hydrolysis in aqueous media. The same esters undergo transesterifications in organic solvents in the presence of subtilisin immobilized on an alumina-phosphate complex.
- Pugniere,Juan, C. San,Previero
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p. 4883 - 4886
(2007/10/02)
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- FERROELECTRIC SC* PHASE IN SOME BENZOATE SERIES
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Several homologous benzoate series which exhibit ferroelectric smectic SC* phases have been synthesized.The used chiral acid chains were prepared from commercially available α-amino acids.The series allow us to determine the influence of the size of the substituent of the chiral carbon on the existence and the stability of the SC* phase.They also give some compounds or mixtures which display high spontaneous polarization.
- Tinh, Nguyen Huu,Salleneuve, C.,Babeau, A.,Galvan, J. M.,Destrade, C.
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p. 147 - 154
(2007/10/02)
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- Chirospecific Synthesis of (+)-Pilocarpine
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An efficient chirospecific synthesis for (+)-pilocarpine (1a) using D-methionine or D-2-aminobutanol as chiral educt is described.Formation of the C3-C4 carbon bond at an early stage gave the key intermediate diethyl phosphonate.Wittig coupling of this phosphonate with 1-methyl-5-imidazolecarboxaldehyde introduced the imidazole moiety of the pilocarpine skeleton.Selective reduction of an α,β-unsaturated nitrile to the corresponding allylic alcohol, stereocontrolled hydrogenation of the olefin, and epimerization of (+)-isopilocarpine to (+)-pilocarpine via kinetic protonation led to formation of the natural alkaloid.This methodology allows chirospecific syntheses of the four possible stereoisomers of pilocarpine.A short and convenient route to (+/-)-pilocarpine based on the key intermediate phosphonate is also described.
- Compagnone, Reinaldo S.,Rapoport, Henry
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p. 1713 - 1719
(2007/10/02)
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- Preparation of α-Bromo- and α-Chlorocarboxylic Acids from α-Amino Acids
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Diazotization of α-amino acids in 48:52 (w/w) hydrogen fluoride/pyridine along with excess of potassium halide results in the corresponding α-halocarboxylic acids in good to excellent yields (Table 1 and 2).
- Olah, George A.,Shih, Joseph,Prakash, G. K. Surya
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p. 1028 - 1030
(2007/10/02)
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- Microbiological transformation of terpenes. XIX. Pathway of degradation of 3 p menthene in a soil pseudomonad (PL strain)
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The acidic metabolites such as 1 hydroxy 3 p menthen 7 oic acid and 1 hydroxy 3 p menthen 9 oic acid which accumulated during the fermentation of 3 p menthene are found to be incapable of supporting the growth or respiration of bacteria. On the other hand, α ethylsuccinic acid, an acidic metabolite, and 3 p menthen 1 ol, a neutral metabolite, are freely metabolized by 3 p menthene grown cells. From these data an attempt was made to establish an energy yielding pathway for 3 p menthene.
- Pujar,Rangachari,Bhattacharyya
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p. 173 - 175
(2007/10/05)
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