- Preparation method of 2-amino-5-bromopyridine
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The invention belongs to the technical field of organic synthesis, and specifically relates to a preparation method of 2-amino-5-bromopyridine. The method comprises the following steps: 2-aminopyridine serves as a raw material, dichloromethane or trichloromethane serves as a solvent, 2-aminopyridine and phenyl trimethyl ammonium tribromide carry out reactions for 1-3 hours at the temperature of 20-50 DEG C, and the molar ratio of 2-aminopyridine to phenyl trimethyl ammonium tribromide is 0.7-1.4. The preparation method provided by the invention has the beneficial effects that (1) the generation of a large number of 3-position byproducts in a traditional preparation method is avoided, and the waste of raw materials and the load of subsequent separation are reduced; and (2) the raw materialnamely 2-aminopyridine is easy to obtain and low in cost, the synthesis route has the advantages of high yield and mild conditions, no 3-position byproduct is generated in the whole process, and the preparation method has an industrialization prospect.
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Paragraph 0016; 0038-0046
(2020/05/05)
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- Novel preparation method D-(-)- tartaric acid
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The invention discloses a new preparation method for D-(-)-tartaric acid, and relates to the preparation method of the resolving agent D-(-)-tartaric acid widely applied in the field of pharmaceuticalsynthesis. The method includes the following steps successively: taking (2R,3R)-2,3-diethyl dihydroxy succinate as a raw material, after hydroxyl protection, substituting with an acetoxyl group, andfinally, carrying out hydrolysis reaction to obtain D-(-)-tartaric acid. The invention provides a new route comprising the steps of directly preparing chiral hydroxyl protected D-(-)-tartaric acid through the selective substitution reaction and then hydrolyzing to obtain the product. The reaction conditions of all the steps are easy to operate, the process is simple, and the reaction of each stepis conventional to operate.
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Paragraph 0016; 0038-0046
(2020/05/05)
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- Decorated single-enantiomer phosphoramide-based silica/magnetic nanocomposites for direct enantioseparation
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The nano-composites Fe3O4SiO2(-O3Si[(CH2)3NH])P(O)(NH-R(+)CH(CH3)(C6H5))2 (Fe3O4SiO2PTA(+)) and Fe3O4SiO2(-O3Si[(CH2)3NH])P(O)(NH-S(-)CH(CH3)(C6H5))2 (Fe3O4SiO2PTA(-)) were prepared and used for the chiral separation of five racemic mixtures (PTA = phosphoric triamide). The separation results show chiral recognition ability of these materials with respect to racemates belonging to different families of compounds (amine, acid, and amino-acid), which show their feasibility to be potential adsorbents in chiral separation. The nano-composites were characterized by FTIR, TEM, SEM, EDX, XRD, and VSM. The VSM curves of nano-composites indicate their superparamagnetic property, which is stable after their use in the separation process. Fe3O4, Fe3O4SiO2, Fe3O4SiO2PTA(+) and Fe3O4SiO2PTA(-) are regularly spherical with uniform shape and the average sizes of 17-20, 18-23, 36-47 and 43-52 nm, respectively.
- Karimi Ahmadabad, Fatemeh,Pourayoubi, Mehrdad,Bakhshi, Hadi
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p. 27147 - 27156
(2019/09/12)
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- Structural insight into the catalytic mechanism of a cis-epoxysuccinate hydrolase producing enantiomerically pure d(-)-tartaric acid
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Crystal structure determination and mutagenesis analysis of a cis-epoxysuccinate hydrolase which produces enantiomerically pure d(-)-tartaric acids revealed a zinc ion and essential residues in the stereoselective mechanism for the catalytic reaction of the small mirror symmetric substrate.
- Dong, Sheng,Liu, Xi,Cui, Gu-Zhen,Cui, Qiu,Wang, Xinquan,Feng, Yingang
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p. 8482 - 8485
(2018/08/04)
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- Preparation method of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol
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The invention discloses a preparation method of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol. According to the preparation method, DL-1-phenyl-2-(1-pyrrolidyl)-1-acetone is taken as a starting material and subjected to resolution, racemization and reduction, and (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol is prepared. The yield of one-time resolution is higher than 35%, a resolving agent is easy to recover, and the recovery rate is higher than 90%; the racemization process is performed under the slightly alkaline condition, and the racemization yield is higher; the yield of (1R,2S)-1-phenyl-2-(1-pyrrolidyl)-1-propanol obtained through reduction is higher than 85%. The preparation method has the advantages of mild reaction conditions, stable process, high product optical purity, low cost, high production safety and the like.
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Paragraph 0037
(2016/10/31)
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- Method D-tartaric acid or a salt thereof
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PROBLEM TO BE SOLVED: To provide a method of high practical usability usable for industrial production, in a method of producing D-tartaric acid or salts thereof at a high yielding amount and a high yielding ratio from 4-keto-D-arabonic acid or salts thereof. SOLUTION: The method of producing the D-tartaric acid or salts produces the D-tartaric acid or salts in a reaction liquid, by bringing a carbonate into aerobic contact with an aqueous solution containing the 4-keto-D-arabonic acid or salts thereof, in the method of producing the D-tartaric acid or salts thereof from the 4-keto-D-arabonic acid or salts thereof. COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0040
(2017/01/02)
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- Sesquiterpene dimers esterified with diverse small organic acids from the seeds of Sarcandra glabra
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11 new sesquiterpene dimers, sarglabolides A-K (1-11), and five known ones were isolated from the seeds of Sarcandra glabra. Their structures were elucidated by spectroscopic data analysis and chemical evidence. Sarglabolide A (1) was verified to exclusively possess a seventeen-membered macrocyclic ester ring formed by the scaffold of the sesquiterpene dimer and small organic acids, different from the eighteen-membered rings of the other reported analogues. The chiral small organic acid moieties were assigned to l-malic acid, d-malic acid, and d-tartaric acid based on the combination of spectroscopy, chemical derivatization and HPLC analysis. Dimers 1, 12 and 13 can significantly inhibit NO production in LPS-induced macrophages with IC50 values at 3.04, 4.65 and 2.33 μmol/L, respectively.
- Wang, Peng,Luo, Jun,Zhang, Yang-Mei,Kong, Ling-Yi
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p. 5362 - 5370
(2015/07/15)
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- Synthesis and properties of crosslinked chiral nanoparticles via RAFT miniemulsion polymerization
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Crosslinked chiral nanoparticles were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization of 6-O-p-vinylbenzyl-1,2:3,4di-O-isopropylidene-D-galactopyranose (VBPG) using linear poly(VBPG) as the macro-RAFT agent. The polymerization of VBPG in the absence of crosslinker was first studied and the kinetic results showed that the molecular weights of the obtained poly(VBPG) increased linearly with the monomer conversion and was in good consistency with the corresponding theoretical ones while there remained a relative narrow polydisperslty. The effect of the amount of crosslinker, divlnylbenzene, on the nanoparticle size and chiral separation properties of the obtained nanoparticles were investigated in detail using four racemates ±-3-Amino-1,2propanediol, D,L-arablnose, D,L-tartaric acid, and D,L-mandelic acid.
- Xu, Wenliang,Cheng, Zhenping,Zhang, Lifen,Zhang, Zhengbiao,Zhu, Jian,Zhou, Nianchen,Zhu, Xiulin
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experimental part
p. 1324 - 1331
(2011/02/26)
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- Magnesium-mediated intramolecular reductive coupling: A stereoselective synthesis of C2-symmetric 3,4-bis-silyl-substituted adipic acid derivatives
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Chiral C2-symmetric 3,4-bis-silyl-substituted adipic acid derivatives have been synthesised by a Mg/trimethylsilyl chloride-mediated intramolecular reductive coupling of symmetrical disiloxanes of β-silylacrylic acid N-oxazolidinone derivatives
- Kundu, Pintu K.,Ghosh, Sunil K.
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experimental part
p. 4611 - 4621
(2009/12/08)
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- Chiral mono boronic acid as fluorescent enantioselective sensor for mono α-hydroxyl carboxylic acids
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(Graph Presented) New mono boronic acid was found to be an enantioselective fluorescent chemosensor for mono α-hydroxyl carboxylic acids, such as mandelic acid and lactic acid. The chiral sensor shows lower background fluorescence, higher fluorescence enh
- Chi, Lina,Zhao, Jianzhang,James, Tony D.
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p. 4684 - 4687
(2008/09/21)
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- Self-healing dental composites and related methods
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Dental restorative composites having self-healing capabilities to repair discontinuities in the composite are provided. Dental restorative composites according to the present invention include a microsphere that encapsulates a monomer. When a fracture occurs, the microsphere is ruptured and the monomer fills the fracture. Depending on the monomer present in the microsphere, it is polymerized by a polymerization initiator or by an olefin metathesis catalyst present in the dental restorative composite. Self-healing dental restorative composites provide increased resistance to fracturing, and thus remain substantially intact for a longer period of time, preserving the remedial integrity of the dental repair or reconstruction.
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- A NOVEL PROCESS FOR THE PREPARATION OF PREGABALIN
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The present invention encompasses novel intermediates of pregabalin, namely 3 -cyano-5 -methyl hexanamide (28) and 3-(amino methyl)-5 methyl hexanamide (29), and processes for their preparation. The invention also encompasses a process for converting the novel pregabalin intermediates into pregabalin, Formula (I): The present invention further provides a cost effective method for the synthesis of (S)-pregabalin, which involves the recovery of mandelic acid and tartaric acid used in the resolution process and recycling them, increasing the yields of the final product formed, which substantially reduced the cost of the production.
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Page/Page column 29
(2009/03/07)
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- Plaster retarding composition
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The present invention is related to a calcium tartrate plaster retarding composition, characterised in that it has a mean particle size lower than 30 μm,The present invention is also related to the plaster comprising said composition and to the preparation process of said composition.
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- Process for the recovery and recycle of D-tartaric acid
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There is provided a process for the recovery of essentially enantiomerically pure D-tartaric acid from aqueous and organic waste streams generated in the resolution of racemic 2-amino-2,3-dimethylbutyronitrile via the formation and isolation of a crystalline monobasic tartrate salt. The recovered optically pure D-tartaric acid may be efficiently recycled to provide a sustainable resolution of racemic 2-amino-2,3-dimethylbutyronitrile.
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Page column 7-8
(2008/06/13)
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- Preferential Cryatallization of 2-Amino-2-phenylethanol and Its Application as a Resolving Agent
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(+/-)-2-Amino-2-phenylethanol (phenylglycinol) prepared from (+/-)-2-amino-2-phenylacetic acid (DL-phenylglycine) by lithium aluminium hydride reduction was efficiently resolved into a pair of optically active forms by preferential crystallization.The optically active amino alcohol was successfully applied as a basic resolving agent to the resolution of tartaric acid, 2-hydroxy-2-phenylpropionic acid, 2-hydroxy-3-phenylpropionic acid, 2-phenylpropionic acid, and 2-phenyl-2-ureidoacetic acid.
- Saigo, Kazuhiko,Miura, Hisao,Ishizaki, Kozi,Nohira, Hiroyuki
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p. 1188 - 1190
(2007/10/02)
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- Optical Resolution of 2-Amino-1,2-diphenylethanol by Preferential Crystallization and Its Utilization in Fractional Crystallization and Enantioselective Reduction of Prochiral Ketones
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(-/+)-erythro-2-Amino-1,2-diphenylethanol prepared from benzoin oxime by catalytic reduction was successfully resolved into pair of optically active forms by preferential crystallization.The optically active amino alcohol was found to be useful as a basic resolving agent for optical resolution of tartaric acid, trans-2,3-oxiranedicarboxylic acid, 2-hydroxy-2-phenylpropionic acid, and 3-endo-benzamido-5-norbornene-2-endo-carboxylic acid.Chiral hydrides prepared from lithium aluminium hydride and optical active threo- and erythro-2-amino-1,2-diphenylethanol derivatives were applied to the enantioface differentiating reduction of prochiral ketones to give the corresponding optically active alcohols in the 26-72percent optical purities.
- Saigo, Kazuhiko,Ogawa, Shigeo,Kikuchi, Shigetoshi,Kasahara, Atsushi,Nohira, Hiroyuki
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p. 1568 - 1573
(2007/10/02)
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