- 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; 0022-0023; 0025
(2019/04/04)
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- Cobalt-bisoxazoline-catalyzed asymmetric kumada cross-coupling of racemic α-bromo esters with aryl grignard reagents
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The first cobalt-catalyzed asymmetric Kumada cross-coupling with high enantioselectivity has been developed. The reaction affords a unique strategy for the enantioselective arylation of α-bromo esters catalyzed by a cobalt-bisoxazoline complex. A variety of chiral α-arylalkanoic esters were prepared in excellent enantioselectivity and yield (up to 97% ee and 96% yield). The arylated products were transformed into α-arylcarboxylic acids and primary alcohols without erosion of ee. The new enantioenriched α-arylpropionic esters synthesized herein are potentially useful in the development of nonsteroidal anti-inflammatory drugs. This method was conducted on gram-scale and applied to the synthesis of highly enantioenriched (S)-fenoprofen and (S)-ar-turmerone.
- Mao, Jianyou,Liu, Feipeng,Wang, Min,Wu, Lin,Zheng, Bing,Liu, Shangzhong,Zhong, Jiangchun,Bian, Qinghua,Walsh, Patrick J.
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supporting information
p. 17662 - 17668
(2015/02/02)
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- Highly selective synthesis of α-bromoesters using molecular bromine catalyzed by phosphorus
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A series of α-bromoesters have been synthesized by applying Hell-Volhard-Zelinsky reaction catalyzed by phosphorus instead of usual phosphorus tribromide. An excellent regioselectivity to good yields are achieved at comparatively mild reaction conditions of an operational simplicity.
- Sun, Zhaoyun,Peng, Xinhua,Dong, Xiongzi,Shi, Wenwen
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scheme or table
p. 929 - 930
(2012/07/30)
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- HETEROCYCLYL-SUBSTITUTED ANTI-HYPERCHOLESTEROLEMIC COMPOUNDS
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This invention provides cholesterol absorption inhibitors of Formula I: and the pharmaceutically acceptable salts thereof, wherein R12 is a hydroxylated alkyl group and R9 contains a heterocyclic ring. The compounds are useful for lowering plasma cholesterol levels, particularly LDL cholesterol, and for treating atherosclerosis and preventing atherosclerotic disease events.
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Page/Page column 38
(2008/12/05)
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- Free radical trapping properties of several ethyl-substituted derivatives of 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO)
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The spin trapping behavior of several ethyl-substituted EMPO derivatives, cis- and trans-5-ethoxycarbonyl-3-ethyl-5-methyl-pyrroline N-oxide (3,5-EEMPO), 5-ethoxycarbonyl-4-ethyl-5-methyl-pyrroline N-oxide (4,5-EEMPO), cis- and trans-5-ethoxycarbonyl-5-ethyl-3-methyl-pyrroline N-oxide (5,3-EEMPO), and 5-ethoxycarbonyl-5-ethyl-4-methyl-pyrroline N-oxide (5,4-EEMPO), toward a series of different oxygen- and carbon-centered radicals, is described. Considerably different stabilities of the superoxide adducts (ranging from about 12 to 55 min) as well as the formation of other radical adducts were observed.
- Stolze, Klaus,Rohr-Udilova, Natascha,Rosenau, Thomas,Hofinger, Andreas,Nohl, Hans
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p. 2827 - 2836
(2007/10/03)
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- SYNTHESES D'ESTERS OU D'ACIDES α-HALOGENES A PARTIR DES GEM DICYANO EPOXIDES.
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α-halogeno esters or α-halogenoacids were easily prepared by selective one pot reaction of gem-dicyano epoxides with halohydric acids in an alcoholic or aqueous media.
- Robert, A.,Jaguelin, S.,Guinamant, J. L.
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p. 2275 - 2282
(2007/10/02)
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- A Simple and Mild Esterification Method for Carboxylic Acids Using Mixed Carboxylic-Carbonic Anhydrides
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A simple and mild esterification method using mixed carboxylic-carbonic anhydrides has been developed.Simple aliphatic carboxylic esters are prepared in high yields by the reaction of acids with equimolar amounts of chloroformates (2,2,2-trichloroethyl chloroformate is an exception) and triethylamine in the presence of a catalytic amount of 4-(dimethylamino)pyridine.Although aromatic acids give a mixture of the ester, the acid anhydride, and the carbonate under normal conditions utilized in this study, it is found that increasing the amount of 4-(dimethylamino)pyridine drastically decreases the formation of the acid anhydride and the carbonate, affording a satisfactory yield of the ester.This method reaches a limit with sterically hindered acids and the formation of the acid anhydride and the carbonate is favored.
- Kim, Sunggak,Lee, Jae In,Kim, Youn Chul
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p. 560 - 565
(2007/10/02)
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- Unnatural nucleosides and nucleotides. III. Preparation of 2-14C and 4-14C labelled 5-alkyluracils and 5-alkyl-2'-deoxyuridines
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2-14C Labelled 5-alkyluracils were prepared by condensation of the diethylacetals of α-formyl-carbonic acid esters with 14C-thiourea. Compounds labelled at 4-C were synthesized by condensation of the labelled carboxylic acid derivatives with thiourea. β-Anomers of 5-alkyl-2'-deoxyuridines were obtained in a fairly good radiochemical yield. Alkyl substituents ranged from methyl to tetradecyl, isopropyl and tert-butyl.
- Szabolcs,Kruppa,Sagi,Otvos
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p. 713 - 726
(2007/10/08)
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