137-43-9Relevant articles and documents
A mild method for the replacement of a hydroxyl group by halogen: 2. unified procedure and stereochemical studies
Gati, Wafa,Munyemana, Fran?ois,Colens, Alain,Srour, Aladdin,Dufour, Mathilde,Vardhan Reddy, K. Harsha,Téchy, Brigitte,Rosse, Gérard,Schweiger, Ed,Qiao, Qi,Ghosez, Léon
, (2020/08/19)
N,N-Dimethyl- and N,N-diisopropyl-1-halo-2-methyl-l-propenylamines are readily available reagents for the mild deoxyhalogenation of alcohols and hydroxyacids. In this study we showed that the reactivity of the reagents can be tuned by varying the size of the alkyl groups on the reagents: the replacement of methyl by isopropyl groups led to a significant increase of reactivity. We then described a unified procedure for all deoxyhalogenations using the readily available α-chloroenamines as reagents with (bromination, iodination) or without (chlorination) an alkaline bromide or iodide. Finally, we showed that deoxyhalogenation reactions of secondary alcohols were highly stereospecific and generally occurred with inversion of configuration.
Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
, p. 4729 - 4737 (2018/10/23)
The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
Preparation method of alkane brominated material
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Paragraph 0043-0044, (2018/09/08)
The invention relates to a preparation method of an alkane brominated material. The preparation method comprises the following steps: adding alkane, a bromine-containing compound or elemental bromine,a catalyst and acid into a solvent; adding the solvent into a light-transmission reaction container under air or oxygen atmosphere; sealing; performing stirring reaction under constant pressure and light illumination conditions; then analyzing a nuclear magnetic yield, and performing extraction, drying, filtration, distillation under reduced pressure and column separation to obtain the alkane brominated material. Compared with the prior art, the preparation method disclosed by the invention has the advantages that by using low-cost and safe bromic salt as a bromine source, the air as an oxidizing agent and a nitrogen-containing reagent as the catalyst, reaction is carried out under the conditions of constant temperature and constant pressure, so that energy conservation and economy are realized, and the preparation method is convenient and safe to operate and is environmentally friendly.
Catalytic Bromination of Alkyl sp3C-H Bonds with KBr/Air under Visible Light
Zhao, Mengdi,Lu, Wenjun
supporting information, p. 5264 - 5267 (2018/09/12)
Alkyl sp3C-H bonds of cycloalkanes and functional branch/linear alkanes have been successfully brominated with KBr using air or O2 as an oxidant at room temperature to 40 °C. The reactions are carried out in the presence of catalytic NaNO2 in 37% HCl (aq)/solvent under visible light, combining aerobic oxidations and photochemical radical processes. For various alkane substrates, CF3CH2OH, CHCl3, or CH2Cl2 is employed as an organic solvent, respectively, to enhance the efficiency of bromination.
Reliably Regioselective Dialkyl Ether Cleavage with Mixed Boron Trihalides
Atienza, Bren Jordan P.,Truong, Nam,Williams, Florence J.
supporting information, p. 6332 - 6335 (2018/10/09)
A protocol for the regioselective cleavage of unsymmetrical alkyl ethers to generate alkyl alcohol and alkyl bromide products is described. A mixture of trihaloboranes triggers this conversion and exhibits improved reactivity profiles (regioselectivity and yield) compared with BBr3 alone. Additionally, this procedure allows the efficient synthesis of (B-Cl) dialkyl boronate esters. There are limited methods to generate acyclic dialkoxyboryl chlorides, and these intermediates constitute important synthons in main-group chemistry.
Selective C-H halogenation over hydroxylation by non-heme iron(iv)-oxo
Rana, Sujoy,Biswas, Jyoti Prasad,Sen, Asmita,Clémancey, Martin,Blondin, Geneviève,Latour, Jean-Marc,Rajaraman, Gopalan,Maiti, Debabrata
, p. 7843 - 7858 (2018/10/31)
Non-heme iron based halogenase enzymes promote selective halogenation of the sp3-C-H bond through iron(iv)-oxo-halide active species. During halogenation, competitive hydroxylation can be prevented completely in enzymatic systems. However, synthetic iron(iv)-oxo-halide intermediates often result in a mixture of halogenation and hydroxylation products. In this report, we have developed a new synthetic strategy by employing non-heme iron based complexes for selective sp3-C-H halogenation by overriding hydroxylation. A room temperature stable, iron(iv)-oxo complex, [Fe(2PyN2Q)(O)]2+ was directed for hydrogen atom abstraction (HAA) from aliphatic substrates and the iron(ii)-halide [FeII(2PyN2Q)(X)]+ (X, halogen) was exploited in conjunction to deliver the halogen atom to the ensuing carbon centered radical. Despite iron(iv)-oxo being an effective promoter of hydroxylation of aliphatic substrates, the perfect interplay of HAA and halogen atom transfer in this work leads to the halogenation product selectively by diverting the hydroxylation pathway. Experimental studies outline the mechanistic details of the iron(iv)-oxo mediated halogenation reactions. A kinetic isotope study between PhCH3 and C6D5CD3 showed a value of 13.5 that supports the initial HAA step as the RDS during halogenation. Successful implementation of this new strategy led to the establishment of a functional mimic of non-heme halogenase enzymes with an excellent selectivity for halogenation over hydroxylation. Detailed theoretical studies based on density functional methods reveal how the small difference in the ligand design leads to a large difference in the electronic structure of the [Fe(2PyN2Q)(O)]2+ species. Both experimental and computational studies suggest that the halide rebound process of the cage escaped radical with iron(iii)-halide is energetically favorable compared to iron(iii)-hydroxide and it brings in selective formation of halogenation products over hydroxylation.
A base-resistant metalloporphyrin metal-organic framework for C-H bond halogenation
Lv, Xiu-Liang,Wang, Kecheng,Wang, Bin,Su, Jie,Zou, Xiaodong,Xie, Yabo,Li, Jian-Rong,Zhou, Hong-Cai
supporting information, p. 211 - 217 (2017/05/16)
A base-resistant porphyrin metal-organic framework (MOF), namely PCN-602 has been constructed with 12-connected LNi8(OH)4(H2O)2Pz12] (Pz = pyrazolate) cluster and a newly designed Pyrazolate-based porphyrin ligand, 5, 10, 15, 20-tetrakis(4-(pyrazolate-4-yl)-phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F-, CO,2-, and PO43- ions. Interestingly, the Mn3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C-H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOF was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.
A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
, p. 420 - 430 (2015/12/31)
α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
A novel route for the synthesis of alkanes from glycerol in a two step process using a Pd/SBA-15 catalyst
Udayakumar,Pandurangan
, p. 78719 - 78727 (2015/10/05)
Glycerol is produced as a valuable by-product in the transesterification of fatty acids, but it cannot be used directly as a fuel additive. In this study, we developed a systematic conversion for glycerol, which proceeds via synthesizing the key intermediate, 1,2,3-tribromopropane and using the Suzuki coupling reaction to introduce the alkyl group. A series of Pd/SBA-15 catalysts with different wt% of Pd (10%, 15% and 20%) was prepared by a one step sol-gel method. The structure and composition of the catalysts were characterized by X-ray diffraction analysis (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The metallic state of dispersed palladium in SBA-15 is confirmed with X-ray photoelectron spectroscopy (XPS). Pd/SBA-15 with a Pd loading of 20 wt% shows good catalytic activity at 90 °C with methylboronic acid, allowing the complete conversion of 1,2,3-tribromopropane and 64% selectivity of 3-methylpentane. The optimized catalysts were also employed in coupling reactions between various alkylhalides and methylboronic acid, which obtained the desired product with an excellent selectivity. The catalyst can be successfully recycled five times. After the first cycle, we observed a drop in activity with 20% Pd/SBA-15, which was due to the leaching of palladium but in the later cycles, there was no significant decrease in activity.
Site-selective aliphatic C-H bromination using N -bromoamides and visible light
Schmidt, Valerie A.,Quinn, Ryan K.,Brusoe, Andrew T.,Alexanian, Erik J.
supporting information, p. 14389 - 14392 (2014/12/10)
Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations proceed in useful chemical yields, with substrate as the limiting reagent. The site selectivities of these radical-mediated C-H functionalizations are comparable (or superior) to the most selective intermolecular C-H functionalizations known. With the broad utility of alkyl bromides as synthetic intermediates, this convenient approach will find general use in chemical synthesis.
