7509-00-4Relevant academic research and scientific papers
Cerium Ammonium Nitrate-Mediated Access to Biaryl Lactones: Substrate Scopes and Mechanism Studies
Chao, Mianran,Wang, Fang,Xu, Linlin,Ju, Yanping,Chen, Zixuan,Wang, Bin,Gong, Peiwei,You, Jinmao,Jin, Ming,Shen, Duyi
, p. 13371 - 13380 (2021/10/01)
Herein we described an access to biaryl lactones from ortho-aryl benzoic acids via intramolecular O-H/C-H oxidative coupling with the commonly used cerium ammonium nitrate (CAN) as the one-electron oxidant under a thermal condition. The radical interrupting experiment suggested a radical process, while the kinetic isotope effect (KIE) showed that the C-H cleavage likely was not involved in the rate-determining step. Competitive reactions, especially the strikingly different ρ values of Hammett equations, indicated that the reaction rate was more sensitive to the electronic properties on the aryl moiety rather than the carboxylic moiety, which corresponded to the first single electron transfer (SET) step. In addition, the quite negative ρ values (-4.7) of the aryl moiety unveiled the remarkable electrophilic nature of the second intramolecular radical addition process, which was also consistent with product yields and regioselectivity. Moreover, control experiments disclosed that the single electron in the third step was also transferred to CeIV instead of molecular oxygen. Besides, the possible role of co-solvents trifluoroethanol (TFE) and its influences on the CeIV species were discussed. This work elucidated the possible mechanism by proposing the step that had more effects on the total reaction rate and the species that was responsible for the last single electron transfer.
Facile preparation of 3,4-benzocoumarins from 2-arylbenzoic acids with NCS and NAI
Nakamura, Momoko,Togo, Hideo
, (2020/09/15)
– Treatment of 2-arylbenzoic acids with N-chlorosuccinimide (NCS) and NaI at 70 °C under fluorescent lighting condition gave the corresponding 3,4-benzocoumarins in good yields under transition-metal-free condition. It was found that the reactivity of NCS
3, 4-benzocoumarin derivative as well as preparation method and application thereof
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Paragraph 0178-0180, (2020/08/02)
The general formula of the 3, 4-benzocoumarin derivative is shown as a formula I, and definitions of substituent groups are shown in the specification in detail. The 3, 4-benzocoumarin derivative witha novel structure provided by the invention is simple in preparation method, nontoxic and harmless, has blue fluorescence, and can be used as a potential organic functional material. The structure ofthe compound has modifiability, and has high optical stability and thermal stability.
Palladium-Catalyzed Site-Selective Benzocylization of Aromatic Acids with o-Fluoro-Substituted Diaryliodonium Salts toward 3,4-Benzocoumarins
Pan, Cheng,Wang, Limin,Han, Jianwei,Han, Jianwei
, p. 4776 - 4780 (2020/07/02)
By using 2-fluoro-substituted diaryliodonium salts, a novel benzocylization has been accomplished for the synthesis of 3,4-benzocoumarin derivatives via a cascade of ortho-arylation and defluorination in the presence of palladium catalysts. The reaction exhibits a broad compatibility of readily available aromatic acids with an excellent level of site-selectivity. Mechanistic investigations revealed a unique reactivity of carboxylic acid directed arylation by followed nucleophilic substitution of aromatic fluoride in the present system.
Visible-Light-Induced Arene C(sp 2)-H Lactonization Promoted by DDQ and tert -Butyl Nitrite
Chen, Bajin,Hu, Baoxiang,Hu, Xinquan,Jin, Liqun,Li, Meichao,Shen, Zhenlu,Sun, Nan,Wang, Shengpeng,Wang, Yiqing
, p. 261 - 266 (2020/02/18)
A visible-light photocatalytic aerobic oxidative lactonization of arene C(sp 2)-H bonds proceeds in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tert -butyl nitrite (TBN). Under the optimized conditions, a range of 2-arylbenzoic acids is converted into the corresponding benzocoumarin derivatives in moderate to excellent yields. This method is characterized by its atom economy, mild reaction conditions, the use of a green oxidant and metal-free catalysis.
Cerium photocatalyzed dehydrogenative lactonization of 2-arylbenzoic acids
Wadekar, Ketan,Aswale, Suraj,Yatham, Veera Reddy
supporting information, p. 983 - 987 (2020/02/15)
The first cerium photocatalyzed dehydrogenative lactonization of 2-arylbenzoic acids has been developed. This operationally simple protocol allows rapid access to synthetically useful coumarins on gram scale by employing CeCl3 as a photocatalyst and O2 as a terminal oxidant. Overall, this delivers an economical and environmentally amiable entry to diversely substituted coumarins, important structural motifs in bioactive molecules.
Photocatalytic oxidation synthesis method of benzocoumarin compound
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Paragraph 0037; 0038, (2020/03/17)
The synthesis method disclosed by the invention takes,aryl-aryl formic acid compound as a reaction raw material 2 - to react the substrate in an organic solvent, DEG C - 5555,6-dinitrile - 1111, 4-benzoquinone 2,3 - and tert-butyl nitrite (DDQ) as a catal
Intramolecular Aromatic C-H Acyloxylation Enabled by Iron Photocatalysis
Xia, Siqi,Hu, Kunjun,Lei, Chuanhu,Jin, Jian
supporting information, p. 1385 - 1389 (2020/02/13)
A mild and efficient protocol for the intramolecular aromatic C-H oxygenation of 2-biphenylcarboxylic acids has been achieved via iron photocatalysis. The 2-biphenylcarboxylic acids with a diverse array of substituents at both phenyl rings could furnish the oxygenation products in good to excellent yields. We speculate that the aryl carboxylate-iron(III) complexes should generate the aroyloxy radicals and iron(II) upon visible light irradiation.
Visible light mediated oxidative lactonization of 2-methyl-1,1′-biaryls for the synthesis of benzocoumarins
Luo, Zhi,Gao, Zhong-Hua,Song, Zhi-Yong,Han, You-Feng,Ye, Song
supporting information, p. 4212 - 4215 (2019/05/06)
A visible light mediated oxidative lactonization of 2-methyl-1,1′-biaryls was developed, giving benzocoumarins in good yields. The reaction features multiple C-H functionalization processes with oxygen as the final oxidant. The corresponding 2-aldehdyes, alcohols and carboxylic acids of the 1,1′-biaryls also worked well for the reaction.
Organocatalytic Electrochemical C-H Lactonization of Aromatic Carboxylic Acids
Li, Longji,Yang, Qi,Jia, Zongbin,Luo, Sanzhong
supporting information, p. 2924 - 2929 (2018/04/05)
An electrochemical strategy has been developed for radical arene carbon-oxygen bond formation. This reaction utilizes DDQ as a redox mediator, with inexpensive glassy carbon electrodes to facilitate an intramolecular lactonization of biphenyl-2-carboxylic
