5333-88-0Relevant academic research and scientific papers
Efficient and Divergent Synthesis of α-Halogenated Amides and Esters by Double Electrophilic Activation of Ynamides
Thilmany, Pierre,Evano, Gwilherm
supporting information, p. 242 - 246 (2019/11/26)
An efficient and modular entry to α-halogenated amides and esters is reported. This reaction is based on an underestimated double electrophilic activation of ynamides sequentially involving highly reactive activated keteniminium and iminium ions. Upon simple reaction with HCl and an electrophilic halogenation reagent in the presence of water or an alcohol, a broad range of ynamides can be transformed, in a highly divergent manner, to α-halo amides and esters with high efficiency and under mild conditions.
Highly selective synthesis of α-bromoesters using molecular bromine catalyzed by phosphorus
Sun, Zhaoyun,Peng, Xinhua,Dong, Xiongzi,Shi, Wenwen
, p. 929 - 930 (2012/07/30)
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.
Enantiodiscrimination of racemic electrophiles by diketopiperazine enolates: asymmetric synthesis of methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates
Bull, Steven D.,Davies, Stephen G.,Epstein, Simon W.,Garner, A. Christopher,Mujtaba, Nadeam,Roberts, Paul M.,Savory, Edward D.,Smith, Andrew D.,Tamayo, Juan A.,Watkin, David J.
, p. 7911 - 7925 (2007/10/03)
Enolates of (S)-N,N′-bis-(p-methoxybenzyl)-3-iso-propylpiperazine-2,5-dione exhibit high levels of enantiodiscrimination in alkylations with (RS)-1-aryl-1-bromoethanes and (RS)-2-bromoesters, affording substituted diketopiperazines containing two new stereogenic centres in high de. Deprotection and hydrolysis of the resultant substituted diketopiperazines provides a route to the asymmetric synthesis of homochiral methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates in high de and ee.
Lipase catalysed synthesis of optically enriched α-haloamides
Azim, Abul,Sharma, Sunil K.,Olsen, Carl E.,Parmar, Virinder S.
, p. 1345 - 1348 (2007/10/03)
An efficient lipase catalysed synthesis of optically enriched α-halogenated amides with concomitant optical enrichment of the starting α-haloesters is described. Candida antarctica lipase (CAL) was found to be a better catalyst over porcine pancreatic lipase (PPL) and Candida cylindracea lipase (CCL). The effect of different organic solvents was also studied.
Oxidation of Diols and Ethers by NaBrO3/NaHSO3 Reagent
Sakaguchi, Satoshi,Kikuchi, Daisuke,Ishii, Yasutaka
, p. 2561 - 2566 (2007/10/03)
NaBrO3 combined with NaHSO3 was found to be an excellent oxidizing reagent of alcohols, diols, and ethers under mild conditions. A variety of aliphatic and cyclic diols were selectively oxidized with satisfactory yields to the corresponding hydroxy ketones and/or diketones, which are difficult to selectively prepare due to a concomitant formation of cleaved products. For example, 2-hydroxycyclohexanone and 1,2-cyclohexanedione were selectively formed by allowing 1,2-cyclohexanediol to react with NaBrO3/NaHSO3 reagent in a selected solvent. On the other hand, an alkyl ether, such as dioctyl ether, reacted with NaBrO3/NaHSO3, in water at room temperature to give octyl octanoate in 82% yield. The same oxidation at higher temperature (60°C) produced the α-brominated ester, octyl 2-bromooctanoate, which is considered to be formed through an alkenyl alkyl ether as the intermediate. The treatment of 1-ethoxy-l-heptene with NaBrO3/NaHSO3 afforded ethyl 2-bromoheptanoate and 2-bromoheptanoic acid as the major products.
SOLVOLYSIS OF 1-CHLORO-1-ALKENYL PHENYL SULFIDES. SYNTHESIS OF α-BROMO PHENYL THIOCARBOXYLIC ESTERS, α-BROMO ALKYL CARBOXYLIC ESTERS AND α-PHENYLTHIO METHYL CARBOXYLIC ESTERS
Fortes, C. C.,Chaves, M. H.
, p. 751 - 762 (2007/10/02)
1-Chloro-1-alkenyl phenyl sulfides treated with bromine followed by hydrolysis or methanolysis give α-bromo phenyl thiocarboxylic esters and α-phenylthio methyl carboxylic esters.Direct oxidative solvolysis with bromine and alcohol give α-bromo alkyl carboxylic esters.
Unnatural nucleosides and nucleotides. III. Preparation of 2-14C and 4-14C labelled 5-alkyluracils and 5-alkyl-2'-deoxyuridines
Szabolcs,Kruppa,Sagi,Otvos
, p. 713 - 726 (2007/10/08)
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.
