34356-83-7Relevant academic research and scientific papers
Modular and Chemoselective Strategy for Accessing (Distinct) α,α-Dihaloketones from Weinreb Amides and Dihalomethyllithiums
Malik, Monika,Pace, Vittorio,Senatore, Raffaele,Touqeer, Saad,Urban, Ernst
supporting information, p. 5056 - 5061 (2020/10/21)
The selective transfer of diversely functionalized dihalomethyllithiums (LiCHBrCl, LiCHClI, LiCHBrI, LiCHCl2, LiCHBr2, LiCHFI) to Weinreb amides for preparing gem-dihaloketones in one synthetic operation is reported. The capability of these amides as acylating agents and, the wide availability of dihalomethanes as pronucleophiles, enable a straightforward route to the title compounds under full chemocontrol. No racemization phenomena were evidenced in the case of optically active materials. Additionally, tolerance to sensitive functional groups (esters, amides, halogens, olefins etc.) was uniformly noticed, thus making this conceptually intuitive strategy flexible and tunable by the operator. (Figure presented.).
Selective Debromination of α,α,α-Tribromomethylketones with HBr–H2O Reductive Catalytic System
Cheng, Zhao,Guo, Hongmei,Huang, Guozheng,Rexit, Abulikemu Abudu,Wang, Hui,Zheng, Meng-Xia
, p. 6455 - 6458 (2020/10/21)
A debromination of α,α,α-tribromomethylketones is developed for chemoselective synthesis of α-mono- and α,α-dibromomethylketones with high selectivity under H2O–HBr reductive conditions. This method offers an efficient and direct way to synthesize α-mono or α,α-dibromomethylketone compounds in high to excellent yields through the process of HBr self-circulation in water.
Method for synthesizing tulobuterol
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Paragraph 0015; 0031-0032, (2020/01/03)
The invention discloses a method for synthesizing tulobuterol. According to the method, 1-(2-chlorophenyl)-2-bromoethanone (compound 3) and 1-(2-chlorophenyl)-2,2-dibromoethanone (compound 10) can besimultaneously utilized to synthesize the tulobuterol. In an original route, the compound 10 is a by-product of synthesis of the compound 3, and about 10-15% of the compound 10 is not fully utilized.The method provided by the invention can improve the synthesis yield of the tulobuterol, is simple to operate, is environmentally friendly, is low in cost and is suitable for industrial production.
A H2O2/HBr system-several directions but one choice: oxidation-bromination of secondary alcohols into mono- or dibromo ketones
Nikishin, Gennady I.,Kapustina, Nadezhda I.,Sokova, Liubov L.,Bityukov, Oleg V.,Terent'ev, Alexander O.
, p. 28632 - 28636 (2018/08/31)
In this work we found that a H2O2-HBr(aq) system allows synthesis of α-monobromo ketones and α,α′-dibromo ketones from aliphatic and secondary benzylic alcohols with yields up to 91%. It is possible to selectively direct the process toward the formation of mono- or dibromo ketones by varying the amount of hydrogen peroxide and hydrobromic acid. The convenience of application, simple equipment, multifaceted reactivity, and compliance with green chemistry principles make the application of the H2O2-HBr(aq) system very attractive in laboratories and industry. The proposed oxidation-bromination process is selective in spite of known properties of ketones to be oxidized by the Baeyer-Villiger reaction or peroxidated with the formation of compounds with the O-O moiety in the presence of hydrogen peroxide and Bronsted acids.
Water-controlled selective preparation of α-mono or α,α′-dihalo ketones: Via catalytic cascade reaction of unactivated alkynes with 1,3-dihalo-5,5-dimethylhydantoin
Wu, Chao,Xin, Xiu,Fu, Zhi-Min,Xie, Long-Yong,Liu, Kai-Jian,Wang, Zheng,Li, Wenyi,Yuan, Zhi-Hui,He, Wei-Min
, p. 1983 - 1989 (2017/06/09)
The control of a reaction that can produce multiple products from the same starting material is a highly attractive and challenging concept in organic synthesis. An efficient protocol for the selective synthesis of α-mono or α,α′-dihalo ketones via a water-controlled three-component thiourea-catalyzed cascade reaction of unactivated alkynes, 1,3-dihalo-5,5-dimethylhydantoin and water has been developed. α-Monohaloketones were obtained in aqueous acetone at 45 °C; conversely, α,α′-dihalo ketones were formed with pure water as the sole solvent at room temperature.
One-pot syntheses of α,α-dibromoacetophenones from aromatic alkenes with 1,3-dibromo-5,5-dimethylhydantoin
Wu, Ping,Xu, Senhan,Xu, Hao,Hu, Haiyan,Zhang, Wei
supporting information, p. 618 - 621 (2017/01/25)
A novel method for the preparation of α,α-dibromoacetophenones from aromatic alkenes was reported. This procedure was mediated by 1,3-dibromo-5,5-dimethylhydantoin, which served as bifunctional reagent, proceeding oxidation and bromination in one-pot.
Substituent effects on the reaction of β-benzoylalanines with Pseudomonas fluorescens kynureninase
Kumar, Sunil,Gawandi, Vijay B.,Capito, Nicholas,Phillips, Robert S.
experimental part, p. 7913 - 7919 (2011/11/06)
Kynureninase is a pyridoxal 5′-phosphate-dependent enzyme that catalyzes the hydrolytic cleavage of l-kynurenine to give l-alanine and anthranilic acid. β-Benzoyl-l-alanine, the analogue of l-kynurenine lacking the aromatic amino group, was shown to a good substrate for kynureninase from Pseudomonas fluorescens, and the rate-determining step changes from release of the second product, l-Ala, to formation of the first product, benzoate [Gawandi, V. B., et al. (2004) Biochemistry 43, 3230-3237]. In this work, a series of aryl-substituted β-benzoyl-dl-alanines was synthesized and evaluated for substrate activity with kynureninase from P. fluorescens. Hammett analysis of kcat and kcat/Km for 4-substituted β-benzoyl-dl-alanines with electron-withdrawing and electron-donating substituents is nonlinear, with a concave downward curvature. This suggests that there is a change in rate-determining step for benzoate formation with different substituents, from gem-diol formation for electron-donating substituents to Cβ-Cγ bond cleavage for electron-withdrawing substituents. Rapid-scanning stopped-flow kinetic experiments demonstrated that substituents have relatively minor effects on formation of the quinonoid and 348 nm intermediates but have a much greater effect on the formation of the aldol product from reaction of benzaldehyde with the 348 nm intermediate. Since there is a kinetic isotope effect on its formation from β,β-dideuterio-β-(4-trifluoromethylbenzoyl)-dl- alanine, the 348 nm intermediate is proposed to be a vinylogous amide derived from abortive β-deprotonation of the ketimine intermediate. These results provide additional evidence for a gem-diol intermediate in the catalytic mechanism of kynureninase.
A facile one-pot synthesis of a?-halo-a?-allyl-aldehydes from a?,a?-Dihaloketoncs Using Allylsamarium Bromide and DMF
Di, Jucai,Zhang, Songlin
experimental part, p. 1491 - 1494 (2009/04/07)
A convenient, one-pot synthesis of a range of a?-halo-a?-allyl aldehydes is described. The protocol involves the reaction of allylsamarium bromide with various a?,a?-dihalo ketones. A possible mechanism of the transformation is proposed.
A convenient synthesis of 2,2-dibromo-1-arylethanones by bromination of 1-arylethanones with the H2O2-HBr system
Terent'ev, Alexander O.,Khodykin, Sergey V.,Krylov, Igor B.,Ogibin, Yuri N.,Nikishin, Gennady I.
, p. 1087 - 1092 (2007/10/03)
1-Arylethanones and related compounds are brominated in dioxane with the H2O2-HBraq system, resulting in the replacement of two hydrogen atoms in the methyl group with bromine. The reaction is also accompanied by bromination of the aromatic ring provided that the latter contains electron-donating substituents. The reaction proceeds rapidly (20 min) and results in complete conversion of ketones to give 2,2-dibromo-1- arylethanones in yields up to 86%. Georg Thieme Verlag Stuttgart.
