- A NEW METHOD FOR THE SYNTHESIS OF LEVULINIC ACID
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A two-step method is described for the synthesis of levulinic acid from ethyl acetoacetate and ethyl chloroacetate in 70percent yield.
- Sizov, A. Yu.,Yanovskaya, L. A.,Dombrovskii, V. A.
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- Chemoenzymatic Stereoselective Synthesis of Substituted γ- or δ-lactams with Two Chiral Centers via Transaminase-catalysed Dynamic Kinetic Resolution
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The biocatalytic stereoselective synthesis of lactams with two chiral centers by a dynamic kinetic resolution strategy is demonstrated. Five transaminases were examined for the transamination of chemically synthesized substituted γ- or δ-keto esters. The application of (R)- and (S)-selective enzymes led to the corresponding chiral amines with moderate to high diastereomeric ratios and excellent enantiomeric excess, followed by the formation of γ- or δ-lactams in some cases. Reaction conditions including pH, co-solvent and ratio of amine donor vs. acceptor were optimised. The stereoselective biotransaminations were performed at semi-preparative scale, successfully generating the corresponding lactams or amine in 46–70 % isolated yields, up to 99 : 1 diastereomeric ratios and >99 % ee values. This study represents a promising approach to the biocatalytic synthesis of important γ- and δ-lactams with two chiral centers.
- Dong, Wenyue,Yao, Peiyuan,Wang, Yingang,Wu, Qiaqing,Zhu, Dunming
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- Preparation of coumarin derivative thereof for the application of the major diseases in the brain
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The invention discloses novel coumarin compounds and pharmaceutically acceptable salts thereof, the preparation method of the compounds, pharmaceutical compositions containing the compounds, and application of the compounds to preparation of medicaments for prevention or treatment of cerebral diseases, especially prevention or treatment of diseases related to neuron damage and neuroinflammation, and prevention or treatment of Parkinson's disease, dementia, cerebral ischemia, depression and cerebral apoplexy.
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Paragraph 0019; 0185; 0188
(2018/01/11)
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- Coumarin derivatives protect against ischemic brain injury in rats
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Neuroprotection strategies are of great importance in the treatment of ischemic brain injury. Screening of our in-stock coumarin derivatives identified compound 1 as exhibiting neuroprotective activity. Subsequently, a structural optimization was carried out, which led to the discovery of the potent compound 20. This compound signi ficantly attenuated the damage in a cell line derived from a pheochromocytoma of the rat adrenal medulla induced by oxygen-glucose deprivation in vitro. Furthermore, compound 20 exhibited clear neuroprotection in middle cerebral artery occlusion rats by reducing infarct size and brain-water content, improving neurological function, and suppressing neuronal loss and neuropathological changes in the cortex and hippocampus. Pharmacokinetic evaluation indicated that compound 20 could penetrate the blood-brain barrier of rats.
- Sun, Mingna,Hu, Jinfeng,Song, Xiuyun,Wu, Donghui,Kong, Linglei,Sun, Yupeng,Wang, Dongmei,Wang, Yan,Chen, Naihong,Liu, Gang
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- Copper(II) triflate catalyzed amination and aziridination of 2-Alkyl substituted 1,3-dicarbonyl compounds
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A method to prepare α-acyl-β-amino acid and 2,2-diacyl aziridine derivatives efficiently from Cu(OTf)2 + 1,10-phenanthroline (1,10-phen)-catalyzed amination and aziridination of 2-alkyl substituted 1,3-dicarbonyl compounds with PhI=NTs is described. By taking advantage of the orthogonal modes of reactivity of the substrate through slight modification of the reaction conditions, a divergence in product selectivity was observed. In the presence of 1.2 equiv of the iminoiodane, amination of the allylic C-H bond of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, was found to selectively occur and give the β-aminated adduct. On the other hand, increasing the amount of the nitrogen source from 1.2 to 2-3 equiv was discovered to result in preferential formal aziridination of the C-C bond of the 2-alkyl substituent of the starting material and formation of the aziridine product.
- Ton, Thi My Uyen,Tejo, Ciputra,Tiong, Diane Ling Ying,Chan, Philip Wai Hong
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experimental part
p. 7344 - 7350
(2012/06/16)
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- N-Heterocyclic carbene-catalysed intermolecular Stetter reactions of acetaldehyde
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A facile method for the intermolecular Stetter reaction of various Michael acceptors with acetaldehyde as a biomimetic acylanion source was realized using N-heterocyclic carbene catalysis. This catalytic system has also been applied to the enantioselective Stetter reaction and resulted in moderate to good enantioselectivities for the corresponding Stetter products.
- Kim, Sun Min,Jin, Ming Yu,Kim, Mi Jin,Cui, Yan,Kim, Young Sug,Zhang, Liqiu,Song, Choong Eui,Ryu, Do Hyun,Yang, Jung Woon
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supporting information; experimental part
p. 2069 - 2071
(2011/05/14)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Synthesis of labelled [13C6]testosterone and [13C5]19-nortestosterone
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The condensation of ethyl acetoacetate-13C4 and ethyl bromoacetate-13C2 afforded, in seven steps, (1,2,3,4,5-13C5) 5-(diethylphosphono)-2-pentanone ethylene ketal 9. The reaction of this labelled compound with 7-[[(1,1-dimethylethyl)-dimethylsilyl]oxy]-1,6,6a,7,8, 9, 9a, 9b-octahydro-6a-methyl-[6aS-(6aa,7a,9aβ,9ba)] cyclopenta[f][1]benzopyran-3 (2H)-one 13 gave the benzindenone 14 which was converted to (1,2,3,4,10,19-13C6)testosterone 17 then, into (1,2,3,4,10-13C5)19-nortestosterone 18 by a reductive alkylation method.
- Joubert,Beney,Marsura,Luu-Duc
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p. 745 - 754
(2007/10/02)
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- Surface-mediated Solid-phase Reaction. Part 2. Highly Selective Mono- and Di-C-alkylation of 1,3-Dicarbonyl Compounds on the Surface of Alumina
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Highly selective mono- and di-C-alkylation of 1,3-dicarbonyl compounds with different, structurally varied alkyl halides has been achieved in high yields through a simple solvent-free reaction on the surface of alumina impregnated with sodium or potassium alkoxide.
- Ranu, Brindaban C.,Bhar, Sanjay
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p. 365 - 368
(2007/10/02)
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- SYNTHESIS OF POLYFUNCTIONAL ALIPHATIC CARBONYL COMPOUNDS UNDER PHASE-TRANSFER CONDITIONS
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We have studied mono- and dialkylation of malonic, acetoacetic, and cyanoacetic esters with esters of haloacetic and β-halopropionic acids and addition of the CH acids mentioned and their analogues to methyl and ethyl acrylate under phase-transfer catalysis conditions, and also deethoxycarbonylation of the obtained products.We have demonstrated for the first time the possibility of Dieckmann cyclization under phase-transfer catalysis conditions and have developed a simple method for the synthesis of 2,3-di(ethoxycarbonyl)cyclopentanone, a key intermediate in the synthesis of deoxyprostaglandins, by cyclization of triethyl 1,2,4-butanetricarboxylate.
- Sizov, A. Yu.,Dombrovskii, V. A.,Yanovskaya, L. A.
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p. 955 - 961
(2007/10/02)
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- On Triazoles XIX: The Reaction of 5-Amino-1,2,4-triazoles with Functionalized Acetoacetic Esters
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Different "functionalized" alkyl 3-oxo-butyrates (2) were reacted with 5-amino-3-Q-1H-1,2,4-triazoles (1) to yield 3 and 4 type 1,2,4-triazolopyrimidinones.In case of 2 (R1 = methyl, R2 = 1-ethoxycarbonylethyl, R3 = ethyl) beside the corresponding derivative 4 the unexpected 5,6-dihydro-6,8-dimethyl-7-ethoxycarbonyl-3-methylthio-1,2,4-triazolo-1,3-diazepin-5(9H)-one (7) was isolated, representing a novel ring system.
- Reiter, Jozsef,Pongo, Laszlo,Somorai, Tamas,Pallagi, Istvan
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p. 173 - 187
(2007/10/02)
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- CATALYST DEPENDENT MECHANISTIC PATHS IN THE REACTIONS OF ETHYL DIAZOACETATE WITH β-KETO ESTERS
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The catalyzed decomposition of ethyl diazoacetate in the presence of β-keto esters produces regioisomeric enol ethers and the diester from formal carbenoid insertion into the α-C-H bond.The product distribution is very catalyst dependent.
- Lottes, Andrew C.,Landgrebe, John A.,Larsen, Kristin
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p. 4093 - 4096
(2007/10/02)
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- CONVERSION OF 1,3-DICARBONYLS TO 1,4-DICARBONYLS
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The cyclopropanation of β-trimethylsiloxy α,β-unsaturated esters and ketones, prepared from 1,3-dicarbonyl compounds, with carbenes followed by ring cleavage gave corresponding 1,4-dicarbonyl compounds in moderate yields.
- Saigo, Kazuhiko,Kurihara, Hiroshi,Miura, Hisao,Hongu, Akinori,Kubota, Naomi,et al.
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p. 787 - 796
(2007/10/02)
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