578-57-4Relevant articles and documents
Chain-Breaking Phenolic 2,3-Dihydrobenzo[b]selenophene Antioxidants: Proximity Effects and Regeneration Studies
Singh, Vijay P.,Yan, Jiajie,Poon, Jia-Fei,Gates, Paul J.,Butcher, Ray J.,Engman, Lars
, p. 15080 - 15088 (2017)
Phenolic 2,3-dihydrobenzo[b]selenophene antioxidants bearing an OH-group ortho (9), meta (10, 11) and para (8) to the Se were prepared by seleno-Claisen rearrangement/intramolecular hydroselenation. meta-Isomer (11) was studied by X-ray crystallography. The radical-trapping activity and regenerability of compounds 8–11 were evaluated using a two-phase system in which linoleic acid was undergoing peroxidation in the lipid phase while regeneration of the antioxidant by co-antioxidants (N-acetylcysteine, glutathione, dithiothreitol, ascorbic acid, tris(carboxyethyl)phosphine hydrochloride) was ongoing in the aqueous layer. Compound 9 quenched peroxyl radicals more efficiently than α-tocopherol. It also provided the most long-lasting antioxidant protection. With thiol co-antioxidants it could inhibit peroxidation for more than five-fold longer than the natural product. Regeneration was more efficient when the aqueous phase pH was slightly acidic. Since calculated O?H bond dissociation energies for 8–11 were substantially larger than for α-tocopherol, an antioxidant mechanism involving O-atom transfer from peroxyl to selenium was proposed. The resulting phenolic selenoxide/alkoxyl radical would then exchange a hydrogen atom in a solvent cage before antioxidant regeneration at the aqueous lipid interphase.
Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
supporting information, p. 20391 - 20399 (2021/08/13)
Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
Direct bromodeboronation of arylboronic acids with CuBr2 in water
Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
, (2021/01/05)
An efficient and practical method has been developed for the preparation of aryl bromides via the direct bromodeboronation of arylboronic acids with CuBr2 in water. This strategy provides several advantages, such as being ligand-free, base-free, high yielding, and functional group tolerant.
Chiral secondary phosphine oxide pre-ligand and application thereof
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Paragraph 0033-0036, (2021/10/20)
The invention discloses a chiral secondary phosphine oxide pre-ligand and application thereof. The structure of the ligand is as shown in Formula I, where R. 1 . R2 , R3 And R4 Hydrogen, benzyl, substituted alkyl, substituted or unsubstituted aryl. The more preferred structural formula comprises 4 structural general formulas shown in the general formula I in the following formula: I-d, and the formula is shown in the general formula. Based on the designed asymmetric catalytic reaction system, the stability and the easy preparation of the comprehensive test ligand under the hydrocarbon activation condition are synthesized, and finally the chiral secondary oxidation phosphorus precursor with the double functional groups in the oxidation and heating environment is selected. The catalyst formed by the front ligand and the active metal compound has high activity and high selectivity in the reaction of constructing a chiral center, and has the stability.
Orthogonal Stability and Reactivity of Aryl Germanes Enables Rapid and Selective (Multi)Halogenations
Deckers, Kristina,Fricke, Christoph,Schoenebeck, Franziska
supporting information, p. 18717 - 18722 (2020/08/25)
While halogenation is of key importance in synthesis and radioimaging, the currently available repertoire is largely designed to introduce a single halogen per molecule. This report makes the selective introduction of several different halogens accessible. Showcased here is the privileged stability of nontoxic aryl germanes under harsh fluorination conditions (that allow selective fluorination in their presence), while displaying superior reactivity and functional-group tolerance in electrophilic iodinations and brominations, outcompeting silanes or boronic esters under rapid and additive-free conditions. Mechanistic experiments and computational studies suggest a concerted electrophilic aromatic substitution as the underlying mechanism.
Dehydroxyalkylative halogenation of C(aryl)-C bonds of aryl alcohols
Liu, Mingyang,Zhang, Zhanrong,Liu, Huizhen,Wu, Tianbin,Han, Buxing
supporting information, p. 7120 - 7123 (2020/07/14)
We herein report Cu mediated side-directed dehydroxyalkylative halogenation of aryl alcohols. C(aryl)-C bonds of aryl alcohols were effectively cleaved, affording the corresponding aryl chlorides, bromides and iodides in excellent yields. Aryl alcohols could serve as both aromatic electrophilic and radical synthetic equivalents during the reaction.
Mild and Regioselective Bromination of Phenols with TMSBr
Ma, Xiantao,Yu, Jing,Jiang, Mengyuan,Wang, Mengyu,Tang, Lin,Wei, Mengmeng,Zhou, Qiuju
supporting information, p. 4593 - 4596 (2019/07/05)
In this work, an unexpected promoting effect of by-product thioether was observed, leading to a mild and regioselective bromination of phenols with TMSBr. This method can tolerate a series of functional groups such as the reactive methoxyl, amide, fluoro, chloro, bromo, aldehyde, ketone and ester groups, and has the potential to recycle the by-product thioether and isolate the desired product under column chromatography-free conditions. Mechanism studies revealed that O–H···S hydrogen bond may be formed between phenol and by-product thioether. Possibly owing to the steric hindrance effect from by-product thioether, the electrophilic bromination at para-position of phenols is much favorable.
Method for catalyzing deaminized boric acid esterification or halogenation of arylamine
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Paragraph 0063; 0091-0093; 0120-0121, (2020/01/12)
The invention belongs to the technical field of organic synthesis and in particular discloses a method for catalyzing deaminized boric acid esterification or halogenation of arylamine. The method comprises the following steps: putting arylamine and a nitroso type compound into a mixed solvent, and performing a reaction at 0-5 DEG; and further adding a raw material capable of providing a functionalization group A and a catalysis amount of a reaction accelerator, and performing deamination functionalization reaction under light radiation at 10-50 DEG C, so as to obtain a product that an amino site of the arylamine is modified by the functionalization group A. Due to synergetic control on substrates, reaction solvents, material mixing modes, temperatures, reaction accelerators and addition amounts, boric acid esterification or halogenation of arylamine, particularly electron donating substituted arylamine which is hard to treat effectively in technical schemes of the industry, can be achieved.
Application of biosynthesized palladium nanoparticles (Pd NPs) on Rosa canina fruit extract-modified graphene oxide as heterogeneous nanocatalyst for cyanation of aryl halides
Hemmati, Saba,Sedrpoushan, Alireza,Soudalizadeh, Nazanin,Khosravi, Kaveh,Hekmati, Malak
, (2019/08/12)
A green palladium (Pd)-based catalyst supported on Rosa canina fruit extract-modified graphene oxide [Pd nanoparticles (NPs)/reduced graphene oxide (RGO)-Rosa canina] hybrid materials has been used as a recoverable and heterogeneous nanocatalyst for cyanating aryl halides using K4[Fe (CN)6] as the resource of cyanide. The nitriles were achieved in good to high yield, and the catalyst can be recovered and reused for up to seven cycles with no remarkable decrease in its catalytic activity.
Iridium-Catalyzed C(sp3)?H Addition of Methyl Ethers across Intramolecular Carbon–Carbon Double Bonds Giving 2,3-Dihydrobenzofurans
Ohmura, Toshimichi,Kusaka, Satoshi,Torigoe, Takeru,Suginome, Michinori
supporting information, p. 4448 - 4453 (2019/09/16)
Intramolecular addition of an O-methyl C(sp3)?H bond across a carbon-carbon double bond occurs in the iridium-catalyzed reaction of methyl 2-(propen-2-yl)phenyl ethers. The Ir/(S)-DTBM-SEGPHOS catalyst promotes the reaction efficiently in toluene at 110–135 °C to afford 3,3-dimethyl-2,3-dihydrobenzofurans. Enantioselective C(sp3)?H addition is achieved in the reaction of methyl 2-(1-siloxyethenyl)phenyl ethers, affording enantioenriched 3-hydroxy-2,3-dihydrobenzofuran derivatives with up to 96% ee. (Figure presented.).
