61592-48-1Relevant articles and documents
Lipase mediated enzymatic kinetic resolution of phenylethyl halohydrins acetates: A case of study and rationalization
Fonseca, Thiago de Sousa,Vega, Kimberly Benedetti,da Silva, Marcos Reinaldo,de Oliveira, Maria da Concei??o Ferreira,de Lemos, Telma Leda Gomes,Contente, Martina Letizia,Molinari, Francesco,Cespugli, Marco,Fortuna, Sara,Gardossi, Lucia,de Mattos, Marcos Carlos
, (2020/02/18)
Racemic phenylethyl halohydrins acetates containing several groups attached to the aromatic ring were resolved via hydrolysis reaction in the presence of lipase B from Candida antarctica (Novozym 435). In all cases, the kinetic resolution was highly selective (E > 200) leading to the corresponding (S)-β-halohydrin with ee > 99 %. However, the time required for an ideal 50 % conversion ranged from 15 min for 2,4-dichlorophenyl chlorohydrin acetate to 216 h for 2-chlorophenyl bromohydrin acetate. Six chlorohydrins and five bromohydrins were evaluated, the latter being less reactive. For the β-brominated substrates, steric hindrance on the aromatic ring played a crucial role, which was not observed for the β-chlorinated derivatives. To shed light on the different reaction rates, docking studies were carried out with all the substrates using MD simulations. The computational data obtained for the β-brominated substrates, based on the parameters analysed such as NAC (near attack conformation), distance between Ser-O and carbonyl-C and oxyanion site stabilization were in agreement with the experimental results. On the other hand, the data obtained for β-chlorinated substrates suggested that physical aspects such as high hydrophobicity or induced change in the conformation of the enzymatic active site are more relevant aspects when compared to steric hindrance effects.
Organomagnesium Based Flash Chemistry: Continuous Flow Generation and Utilization of Halomethylmagnesium Intermediates
Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
supporting information, p. 7537 - 7541 (2020/10/12)
The generation of highly unstable chloromethylmagnesium chloride in a continuous flow reactor and its reaction with aldehydes and ketones is reported. With this strategy, chlorohydrins and epoxides were synthesized within a total residence time of only 2.6 s. The outcome of the reaction can be tuned by simply using either a basic or an acidic quench. Very good to excellent isolated yields, up to 97%, have been obtained for most cases (30 examples).
Cascade bio-hydroxylation and dehalogenation for one-pot enantioselective synthesis of optically active β-halohydrins from halohydrocarbons
Cui, Hai-Bo,Xie, Ling-Zhi,Wan, Nan-Wei,He, Qing,Li, Zhi,Chen, Yong-Zheng
supporting information, p. 4324 - 4328 (2019/08/21)
A stereoselective hydroxylation and enantioselective dehalogenation cascade reaction was developed for the synthesis of optically active β-haloalcohols from halohydrocarbons. This cascade system employed P450 and halohydrin dehalogenase as two compatible biocatalysts, allowing a straightforward, greener and efficient access to β-halohydrins with excellent enantioselectivities (98-99%).
Extreme halophilic alcohol dehydrogenase mediated highly efficient syntheses of enantiopure aromatic alcohols
Alsafadi, Diya,Alsalman, Safaa,Paradisi, Francesca
, p. 9169 - 9175 (2017/11/15)
Enzymatic synthesis of enantiopure aromatic secondary alcohols (including substituted, hetero-aromatic and bicyclic structures) was carried out using halophilic alcohol dehydrogenase ADH2 from Haloferax volcanii (HvADH2). This enzyme showed an unprecedented substrate scope and absolute enatioselectivity. The cofactor NADPH was used catalytically and regenerated in situ by the biocatalyst, in the presence of 5% ethanol. The efficiency of HvADH2 for the conversion of aromatic ketones was markedly influenced by the steric and electronic factors as well as the solubility of ketones in the reaction medium. Furthermore, carbonyl stretching band frequencies ν (CO) have been measured for different ketones to understand the effect of electron withdrawing or donating properties of the ketone substituents on the reaction rate catalyzed by HvADH2. Good correlation was observed between ν (CO) of methyl aryl-ketones and the reaction rate catalyzed by HvADH2. The enzyme catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that HvADH2 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest.
Bicyclic nitroimidazole derivatives, preparation method thereof and pharmaceutical composition for prevention or treatment of tuberculosis containing the same as an active ingredient
-
Paragraph 0142; 0143, (2017/03/08)
The present invention relates to a bicyclic nitroimidazole derivative or a pharmaceutically acceptable salt thereof, a method for manufacturing the same, and a pharmaceutical composition comprising the same for preventing or treating tuberculosis. The novel bicyclic nitroimidazole derivative according to the present invention shows a superior antitubercular efficacy for tubercular bacillus in various environments, thereby can be used as a pharmaceutical composition for preventing or treating the tuberculosis.
Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water
Talwar, Dinesh,Wu, Xiaofeng,Saidi, Ourida,Salguero, Noemí Poyatos,Xiao, Jianliang
supporting information, p. 12835 - 12842 (2015/03/30)
Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, β-keto esters and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. Water wonder: Iridicycle catalysts are versatile and allow the highly efficient and chemoselective transfer hydrogenation of a variety of carbonyl compounds, including problematic and challenging ones, with formate in neat water (see scheme).
Efficient synthesis of chlorohydrins using ClCH2MgCl·LiCl
Nishimura, Rodolfo H.V.,Toledo, Fabiano T.,Lopes, Jo?o L.C.,Clososki, Giuliano C.
, p. 287 - 290 (2013/02/23)
The mixed lithium-magnesium carbenoid ClCH2MgCl·LiCl was easily generated in THF through the reaction of chloroiodomethane with i-PrMgCl·LiCl at -78 °C. This reagent reacts well with a number of aldehydes to give the corresponding chlorohydrins in good yields.
Highly efficient route for enantioselective preparation of chlorohydrins via dynamic kinetic resolution
Traeft, Annika,Bogar, Krisztian,Warner, Madeleine,Baeckvall, Jan-E.
supporting information; experimental part, p. 4807 - 4810 (2009/05/31)
(Equation Presented) Dynamic kinetic resolution (DKR) of various aromatic chlorohydrins with the use of Pseudomonas cepacia lipase (PS-C "Amano" II) and ruthenium catalyst 1 afforded chlorohydrin acetates in high yields and high enantiomeric excesses. These optically pure chlorohydrin acetates are useful synthetic intermediates and can be transformed to a range of important chiral compounds.
Thiourea catalysis of NCS in the synthesis of chlorohydrins
Bentley, Paul A.,Mei, Yujiang,Du, Juan
, p. 1425 - 1427 (2008/09/18)
Thiourea catalysis of reactions utilizing N-succinimides is demonstrated with NCS chlorination of olefins in the presence of water to afford chlorohydrins.
Chiral styrene oxides from α-haloacetophenones using NaBH4 and TarB-NO2, a chiral Lewis acid
Cordes, David B.,Kwong, Tracey J.,Morgan, Kellie A.,Singaram, Bakthan
, p. 349 - 351 (2007/10/03)
High enantioselectivities are obtained for the preparation of chiral styrene oxides through reduction of α-haloacetophenones using TarB-NO 2 reagent and the inexpensive and mild reducing agent NaBH 4. The epoxides are easily obtained in up to 95% ee through routine acid-base workup of the product alcohols. Either the (R) or (S) epoxide can be obtained by using the appropriate l- or d-tartaric acid starting material in the TarB-NO2 reagent.
