- Studies Towards the Total Synthesis of Taxoids: An Efficient Formal Total Synthesis of an A-seco Taxane Framework
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Compounds 6 and 19 embodying the whole carbon framework and suitable functionalities of the taxane skeleton have been assembled starting from readily available chemicals.
- Arseniyadis, S.,Wang, Q.,Yashunsky, D. V.,Kaoudi, T.,Alves, R. Brondi,Potier, P.
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- Highly efficient procedure for the synthesis of fructone fragrance using a novel carbon based acid
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The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and β-keto esters make this novel carbon based acid one of the best choices for the reaction.
- Hu, Baowei,Li, Chunqing,Zhao, Sheng-Xian,Rong, Lin-Mei,Lv, Shao-Qin,Liang, Xuezheng,Qi, Chenze
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- Studies towards the total synthesis of taxoids: A rapid entry into bicyclo[6.4.0]dodecane ring system. Part 1
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We report a short and stereocontrolled synthesis of the taxoid BC- subunit (+)-5 embodying the whole carbon framework and most of the required oxygen functionalities for further elaboration. Enantiomeric purity was secured at an early stage by resolution
- Arseniyadis, Simeon,Rico Ferreira, Maria Del Rosario,Del Moral, Jose Quilez,Hernando, Jose Ignacio Martin,Potier, Pierre,Toupet, Loic
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- Synthetic study of yonarolide: Stereoselective construction of the tricyclic core
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Stereoselective construction of the tricyclic core of yonarolide (1), a marine norditerpenoid, was achieved. This synthetic route includes a Diels-Alder reaction and an intramolecular aldol condensation. It also involves efficient epimerization through a retro-Michael reaction-Michael addition and will be applicable to the total synthesis of 1.
- Ueda, Yohei,Abe, Hideki,Iguchi, Kazuo,Ito, Hisanaka
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- Br?nsted acidic cellulose-PO3H: An efficient catalyst for the chemoselective synthesis of fructones and trans-esterification via condensation of acetoacetic esters with alcohols and diols
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Cellulose is the most abundant organic source and has expedient a great deal of interest as renewable and emerged as sustainable feedstock. The functionalization of cellulose as designed catalytic system intriguing furnished to the production of fine chemicals. Herein, we synthesized an environmental friendly solid acid catalyst by functionalizing cellulose with phosphoric acid (PO3H). The successful functionalization of cellulose with PO3H was confirmed by 31P NMR, ICP-OES, FE-SEM, and XPS analysis. ICP-OES revealed the presence of phosphorus content of ~1.0 wt. % on the catalyst's surface while elemental mapping by FESEM and XPS shows a uniform distribution of phosphorus over the material. The synthesized solid acid catalyst was utilized for condensation of diols with acetoacetic esters in solvent-free conditions to synthesize fine chemicals. The present approach not only circumvented the one-step protection and other products but more fascinatingly provided trans-esterification of acetoacetic esters with diols and n-alcohols. The catalyst was successfully used for chemoselective protection on ethyl acetoacetate with 1, 2 diols to essential fructone molecule with ~100% conversion and 99% selectivity. The results suggested that the catalyst has the advantage over commercial solid acid heterogeneous and homogeneous catalysts.
- Naikwadi, Dhanaji R.,Singh, Amravati S.,Biradar, Ankush V.
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- Synthesis of deuterated isopentyl pyrophosphates for chemo-enzymatic labelling methods: GC-EI-MS based 1,2-hydride shift in epicedrol biosynthesis
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A sesquiterpene epicedrol cyclase mechanism was elucidated based on the gas chromatography coupled to electron impact mass spectrometry fragmentation data of deuterated (2H) epicedrol analogues. The chemo-enzymatic method was applied for the specific synthesis of 8-position labelled farnesyl pyrophosphate and epicedrol. EI-MS fragmentation ions compared with non-labelled and isotopic mass shift fragments suggest that the 2H of C6 migrates to the C7 position during the cyclization mechanism.
- Said, Madhukar S.,Navale, Govinda R.,Gajbhiye, Jayant M.,Shinde, Sandip S.
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p. 28258 - 28261
(2019/09/30)
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- A method for the synthesis of the original drug of
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The invention relates to the technical field of pharmaceutical chemical engineering, and discloses a synthetic method of a hymexazol raw pesticide. The synthetic method is characterized by comprising the following steps: adding methyl acetoacetate into a mixed solvent of ethylene glycol and cyclohexane, heating and refluxing, distilling to remove generated water under reduced pressure, after timely separating out the generated water, and distilling out cyclohexane under reduced pressure to obtain a compound A; after adding 8-hydroxyquinoline, ethylenediamine tetraacetic acid and water into hydroxylamine hydrochloride, stirring to completely dissolve the mixture, dropwise adding a sodium hydroxide solution at 5-10 DEG C, controlling PH to below 11-13, dropwise adding the sodium hydroxide solution while dropwise adding A, then heating up to 25-28 DEG C, and reacting to obtain a compound B; rapidly dropwise adding the compound B into concentrated hydrochloric acid while stirring, heating up to 70 DEG C, cooling to room temperature, dropwise adding the sodium hydroxide solution, filtering, cooling filtrate to 10-15 DEG C, adjusting the PH by using strong aqua, crystallizing at 5-10 DEG C, and drying. The synthetic method provided by the invention has the beneficial effects of easiness in synthesis, short reaction period, high yield, stable production, low cost, and high purity of products.
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Paragraph 0017; 0018
(2017/03/14)
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- Acid-labile δ-ketal-β-hydroxy esters by asymmetric hydrogenation of corresponding δ-ketal-β-keto esters in the presence of CaCO 3
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A series of acid-labile, optically pure ε-substituted δ-ketal-β-hydroxy esters were obtained by a Ru-SunPhos catalyzed asymmetric hydrogenation of the corresponding ε-substituted δ-ketal-β-keto esters. CaCO3 played a dual role in the hydrogenation reaction - removing the acid generated during the formation of the catalyst and maintaining the activity of the catalyst.
- Fan, Weizheng,Li, Wanfang,Ma, Xin,Tao, Xiaoming,Li, Xiaoming,Yao, Ying,Xie, Xiaomin,Zhang, Zhaoguo
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supporting information; experimental part
p. 4247 - 4249
(2012/05/05)
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- The effect of fluorine substituents on the polymerization mechanism of 2-methylene-1,3-dioxolane and properties of the polymer products
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Perfluoro-2-methylene-1,3-dioxolane (III) was synthesized and polymerized with an initiator, perfluoro dibenzoyl peroxide, and a white solid product III-P was quantitatively isolated. The polymer was insoluble in organic solvents including fluorinated solvents such as Fluorinert FC 75 and hexafluorobenzene, but dissolved in hexafluorobenzene by heating at around 140 °C in a sealed ampoule. The X-ray measurement showed that III-P was semi-crystalline and melted at 230 °C. The IR spectrum of III-P indicated that the polymer obtained did not show carbonyl peak and it was the vinyl addition product. When the solid product was heated above the melting temperature and pressed under 100-200 kg/cm2, we obtained an amorphous and flexible film, which is transparent from the UV region to the near IR region. The glass transition temperature was 110 °C and refractive indexes were 1.3443, 1.3434 and 1.3373 at 633, 839 and 1544 nm, respectively. The film did not degrade in concentrated sulfuric acid and aqueous sodium hydroxide solutions even heated at 80-90 °C for 2 days. The film was thermally stable and began to decompose at 300 °C under air atmosphere.
- Okamoto,Mike?,Yang,Koike
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p. 202 - 206
(2008/03/13)
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- From dicarbonylallene to 1-aryl-3,6-dimethyl-4-aminoaryl-2-pyridones: a one-pot versatile and uncatalyzed synthesis
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Reaction of amines with an allenic precursor leads to new 1-aryl-3,6-dimethyl-4-aminoaryl-2-pyridones in good yields. These syntheses can be performed in two distinct steps, allowing the possibility to introduce different substituents in the positions 1 a
- Boisse, Thomas,Rigo, Beno?t,Millet, Régis,Hénichart, Jean-Pierre
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p. 10511 - 10520
(2008/02/13)
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- Regio- and diastereoselective synthesis of lissoclinolide analogues by Lewis acid catalyzed cyclization of the first 1,5-bis(trimethylsilyloxy)-1,3,5-hexatrienes with oxalyl chloride
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The Lewis acid catalyzed cyclization of 1,5-bis(trimethylsilyloxy)-1,3,5-hexatrienes with oxalyl chloride resulted in formation of polyunsaturated butenolides.
- Langer,Freifeld
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p. 523 - 525
(2007/10/03)
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- Potentiation of cADPR-induced Ca2+-release by methylxanthine analogues
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Caffeine and other methylxanthines are known to induce Ca2+-release from intracellular stores via the ryanodine receptor. In the present work, a range of caffeine analogues, in which methyl groups at the 1 and 7 positions were replaced with alkyl chains containing different functional groups (oxo, hydroxyl, propargyl, ester, and acids), were synthesized. These compounds were then screened for their ability to potentiate Ca2+-release induced by cADPR (an endogenous modulator of ryanodine receptors) in sea urchin egg homogenates. Two of the synthesized methylxanthines, 1,3-dimethyl-7-(7- hydroxyoctyl)xanthine (37) and 3-methyl-7-(7-oxooctyl)-1-propargylxanthine (66), were shown to be more potent than caffeine in potentiating cADPR- induced Ca2+-release, while 1,3-dimethyl-7-(5-ethylcarboxypentyl)xanthine (14) was shown to be more efficacious. The development of new methylxanthine analogues may lead to a better understanding of ryanodine receptor function and could possibly provide novel therapeutic agents.
- Cavallaro, Rosaria A.,Filocamo, Luigi,Galuppi, Annamaria,Galione, Antony,Brufani, Mario,Genazzani, Armando A.
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p. 2527 - 2534
(2007/10/03)
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- N-(arylmethyl)-2-(or -4)-cyanopyridinium hexafluoroantimonates as new useful catalysts for acetalization of carbonyl compounds
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Carbonyl compounds 1 were converted to the corresponding 1,3-dioxolanes 2 and 1,3-dioxanes 4 with ethylene glycol and 2,2-dimethyl-1,3-propandiol, respectively, in the presence of 1-3 mol% of N-(benzyl, 4-methylbenzyl or 4-methoxybenzyl)-2(or -4)cyanopyridinium hexafluoroantimonates 3. The catalyst 3d was also effective for the tetrahydropyranylation.
- Lee,Lee,Takata,Endo
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p. 368 - 370
(2007/10/02)
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- Preparation of β-Keto Ester Acetals by Reaction of Ortho Esters with Ketene Silyl Acetals in the Presence of Titanium Tetrachloride
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Reaction of 2-ethoxy-2-methyl-1,3-dioxolan (1c) with 1-methoxy-1-trimethylsilyloxyethene (4a) in dichloromethane in the presence of titanium tetrachloride gave 62percent of methyl 2-(2'-methyl-1',3'-dioxolan-2'-yl)acetate (5a).Similarly, reaction of (1c) with 1-methoxy-1-trimethylsilyloxyprop-1-ene (4b) afforded 73percent of methyl 2-(2'-methyl-1',3'-dioxolan-2'-yl)propanoate (5b).
- Collins, David J.,Choo, Gabrielyn Lee Poh,Obrist, Hans
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p. 617 - 622
(2007/10/02)
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- Efficient synthesis of α-(hydroxymethyl) ketones not available through aldol-type processes
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An efficient synthesis of α-(hydroxymethyl) ketones from β-keto esters has been developed, which is experimentally simple, amenable to large scale production and provides products of high purity without resort to chromatography in most cases. The method is a useful alternative and complement to condensation processes.
- Hitchcock,Perron,Martin,Albizati
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p. 1059 - 1061
(2007/10/02)
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