36808-12-5Relevant articles and documents
By nucleophilic substitution reaction to degrade lignin and lignin model compounds (by machine translation)
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Paragraph 0070; 0071, (2018/04/03)
The invention through the nucleophilic substitution reaction to degrade lignin and lignin model compound method relates to biomass energy chemical technical field. In order to lignin model compounds and organic solvent-soluble lignin as substrate, to halogenated compound B BX3 As nucleophiles, through the nucleophilic substitution reaction, in - 78 °C to 60 °C conditions, reaction 0.5 h - 36 h, at the same time realize lignin model compound, lignin degradation, and the connection of the X substituent. The operation of the invention the method is simple, mild reaction conditions, not only high conversion and high selectivity (>99% conversion rate, close to 99% [...] selective) realizes the lignin and the degradation of lignin model compound, and obtained the degradation product, is a very high can be modified with the nature contains the bromine compound, can be used as an important organic synthetic intermediates. (by machine translation)
Method for synthesizing alpha,beta-dibromide
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Paragraph 0044; 0045; 0046, (2018/04/01)
The invention discloses a method for synthesizing alpha,beta-dibromide. The method is characterized in that a styrene compound as shown in the formula I is taken as a raw material, Zn-Al hydrotalciteZnAl-BrO3-LDHs of a bromate intercalation is taken as
BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
Li, Xuan,He, Jianghua,Zhang, Yuetao
, p. 11019 - 11027 (2018/09/06)
For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
Dibromination of alkenes with LiBr and H2O2 under mild conditions
Martins, Nayara Silva,Alberto, Eduardo E.
supporting information, p. 161 - 167 (2017/12/28)
Electron-rich and electron-poor alkenes, and alkenes bearing protecting groups can be efficiently and stereoselectively converted to trans-dibromides using LiBr/H2O2 and AcOH as a proton source in 1,4-dioxane. For most substrates addition of 0.1 mol% of PhTeTePh enhances the reaction rate and the yield of the products. Experimental data suggest that the brominating agent prepared in situ is molecular bromine and that LiBr assists the activation of H2O2 allowing bromination to occur using AcOH as a mild proton source in uncatalyzed experiments. Scale-up is feasible: 10.0 mmol of 1-octene was quantitatively converted to 1,2-dibromooctene in one hour of reaction at room temperature.
Multicomponent Synthesis of Structurally Diverse Imidazoles Featuring Azirines, Amines and Aldehydes
Rossa, Thaís A.,Fantinel, Mariane,Bortoluzzi, Adailton J.,Sá, Marcus M.
supporting information, p. 4171 - 4177 (2018/08/21)
A novel and efficient method for the synthesis of structurally diverse imidazoles through a multicomponent reaction involving an azirine, an amine, and an aldehyde is described. The method is simple and environmentally benign, producing multifunctionalized imidazoles in moderate-to-good yields and in a regioselective manner, which was demonstrated by NMR experiments and X-ray analysis. A mechanism is proposed in which the amine participates not only as a reactant, but also as a nucleophilic reaction promoter.
Catalytic asymmetric bromochlorination of aromatic allylic alcohols promoted by multifunctional Schiff base ligands
Huang, Wei-Sheng,Chen, Li,Zheng, Zhan-Jiang,Yang, Ke-Fang,Xu, Zheng,Cui, Yu-Ming,Xu, Li-Wen
, p. 7927 - 7932 (2016/08/30)
It was found that the tridentate O,N,O-type Schiff base ligand bearing suitable substituents was a highly effective promoter in the catalytic asymmetric bromochlorination reaction, in which the corresponding aromatic bromochloroalcohols with vicinal halogen-bearing stereocenters were formed with perfect regioselectivity, with moderate to excellent enantioselectivities (up to 93% ee), and with good yields and chemoselectivities.
Catalytic Enantioselective Dihalogenation and the Selective Synthesis of (-)-Deschloromytilipin A and (-)-Danicalipin A
Landry, Matthew L.,Hu, Dennis X.,McKenna, Grace M.,Burns, Noah Z.
supporting information, p. 5150 - 5158 (2016/05/19)
A titanium-based catalytic enantioselective dichlorination of simple allylic alcohols is described. This dichlorination reaction provides stereoselective access to all common dichloroalcohol building blocks used in syntheses of chlorosulfolipid natural products. An enantioselective synthesis of ent-(-)-deschloromytilipin A and a concise, eight-step synthesis of ent-(-)-danicalipin A are executed and employ the dichlorination reaction as the first step. Extension of this system to enantioselective dibromination and its use in the synthesis of pentabromide stereoarrays relevant to bromosulfolipids is reported. The described dichlorination and dibromination reactions are capable of exerting diastereocontrol in complex settings allowing X-ray crystal structure analysis of natural and unnatural diastereomers of polyhalogenated stereohexads.
Stereoselective synthesis of (E)-3,3-diaryl and (E)-3-aryl-3-aryloxy allylamines and allylalcohols from trans-cinnamyl chloride and alcohol
Limberger, Jones,Claudino, Thiago S.,Monteiro, Adriano L.
, p. 45558 - 45565 (2015/02/19)
In this work we describe the regio and stereoselective synthesis of (E)-3,3-diaryl and (E)-3-aryl-3-aryloxy allylamines and allylalcohols. The starting materials are the non-expensive commercially available cinnamyl alcohol and chloride. The bromination/dehydrobromination sequence furnished the (E)-3-bromo-3-phenylallyl amines and alcohol as single regioisomers and with high stereoselectivity (>98%). These vinyl bromides were used as substrates in cross-coupling reactions furnishing the arylated products with good to excellent yields and total E-configuration retention. With this protocol, we were able to produce regio and stereospecifically trisubstituted olefins and vinyl ethers by Suzuki cross-coupling and Ullmann vinylation.
Halocarbocyclization versus dihalogenation: Substituent directed iodine(iii) catalyzed halogenations
Stodulski, Maciej,Goetzinger, Alissa,Kohlhepp, Stefanie V.,Gulder, Tanja
supporting information, p. 3435 - 3438 (2014/03/21)
The nucleophilicity of the substituents in iodobenzene pre-catalysts have a huge impact on product selectivity in iodine(iii) triggered halogenations, steering the reactivity from solely carbocyclizations towards dihalogenations. Utilizing this catalyst-dependent reactivity a diastereo- and chemoselective dihalogenation method was established allowing the conversion of structurally and electronically diverse unsaturated compounds in excellent yields.
Catalytic enantioselective dibromination of allylic alcohols
Hu, Dennis X.,Shibuya, Grant M.,Burns, Noah Z.
supporting information, p. 12960 - 12963 (2013/09/24)
A new dibromination reaction involving the combination of dibromomalonate as the bromonium source and a titanium bromide species as the bromide source has been developed. Enantioselective catalysis has been achieved through apparent ligand acceleration by a tartaric acid-derived diol.
