6277-17-4Relevant academic research and scientific papers
Evolution of N-Heterocycle-Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)-Mediated Oxidative Transformations
Boelke, Andreas,Nachtsheim, Boris J.
supporting information, p. 184 - 191 (2019/12/11)
The reactivity of ortho-functionalized N-heterocycle-substituted iodoarenes (NHIAs) as organocatalysts in iodine(I/III)-mediated oxidations was systematically investigated in the α-tosyloxylation of ketones as the model reaction. During a systematic catalyst evolution, it was found that NH-triazoles and benzoxazoles have the most significant positive influence on the reactivity of the central iodine atom. A further catalyst improvement which focused on the substitution pattern of the arene revealed a remarkable ortho-effect. By introduction of an o-OMe group we were able to generate a novel NHIA with a so far unseen catalytic efficiency. This new catalyst is not only easy to synthesize but also enabled the α-tosyloxylation of carbonyl compounds at the lowest reported catalyst loading of only 1 mol%. Finally, the performance of this iodine(I) catalyst was successfully demonstrated in intramolecular oxidative couplings of biphenyls and oxidative rearrangements. (Figure presented.).
Inexpensive NaX (X = I, Br, Cl) as a halogen donor in the practical Ag/Cu-mediated decarboxylative halogenation of aryl carboxylic acids under aerobic conditions
Fu, Zhengjiang,Jiang, Ligao,Zuo, Qianming,Li, Zhaojie,Liu, Yanzhu,Wei, Zhenhong,Cai, Hu
supporting information, p. 5416 - 5421 (2018/08/12)
Versatile and practical Ag/Cu-mediated decarboxylative halogenation between readily available aryl carboxylic acids and abundant NaX (X = I, Br, Cl) has been achieved under aerobic conditions in moderate to good yields. The halodecarboxylation is shown to be an effective strategy for S-containing heteroaromatic carboxylic acid and benzoic acids with nitro, chloro and methoxyl substituents at the ortho position. A gram-scale reaction and a three-step procedure to synthesize iniparib have been performed to evaluate the practicality of this protocol. A preliminary mechanistic investigation indicates that Cu plays a vital role and a radical pathway is involved in the transformation.
Synthetic method of aryl halide taking aryl carboxylic acid as raw material
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Paragraph 0118, (2018/01/03)
A synthetic method of an aryl halide taking aryl carboxylic acid as a raw material is characterized in that a corresponding aryl halide is formed by carrying out substitution reaction on an aryl carboxylic acid compound and haloid salt MX in an organic solvent under the condition that oxygen, a silver catalyst, a copper additive and a bidentate nitrogen ligand exist, wherein M in MX represents alkali metal or alkaline earth metal, and X represents F, Cl, Br or I. Compared with a conventional aryl halide synthetic method, the synthetic method disclosed by the invention has the obvious advantages that reaction raw materials (comprising aryl carboxylic acid and MX) are cheap and easy to obtain, the using amount of a metal catalyst is small, pollution to the environment when the oxygen is used as an oxidant is the smallest, good tolerance to various functional groups on an aromatic ring is obtained, the yield is high, and the like. The synthetic method disclosed by the invention can be widely applied to synthesis in the fields of medicine, materials, natural products and the like in industry and academia.
Biphenyl-Based Bis(thiourea) Organocatalyst for Asymmetric and syn -Selective Henry Reaction
Otevrel, Jan,Bobal, Pavel
, p. 593 - 603 (2017/01/25)
A scalable, efficient and chromatography-free synthesis of a new enantiopure C 2-symmetric bis(thiourea) catalyst was accomplished from a readily available starting material. The developed strategy could be conducted on a multi-gram scale. Both the prepared enantiomers of the bis(thiourea) organocatalyst have been tested in the asymmetric Henry reaction under thoroughly optimized conditions during which an unusual solvent effect on enantioselectivity was found. The corresponding adducts were obtained in excellent yields with good to excellent enantioselectivities. The achieved high reactivity and enantioselectivity in the nitroaldol reaction of nitroalkanes with aromatic aldehydes suggests promising potential for this catalyst. Moreover, a significant syn-diastereoselectivity was observed.
Decarboxylative Halogenation and Cyanation of Electron-Deficient Aryl Carboxylic Acids via Cu Mediator as Well as Electron-Rich Ones through Pd Catalyst under Aerobic Conditions
Fu, Zhengjiang,Li, Zhaojie,Song, Yuanyuan,Yang, Ruchun,Liu, Yanzhu,Cai, Hu
, p. 2794 - 2803 (2016/04/26)
Simple strategies for decarboxylative functionalizations of electron-deficient benzoic acids via using Cu(I) as promoter and electron-rich ones by employing Pd(II) as catalyst under aerobic conditions have been established, which lead to smooth synthesis of aryl halides (-I, Br, and Cl) through the decarboxylative functionalization of benzoic acids with readily available halogen sources CuX (X = I, Br, Cl), and easy preparation of benzonitriles from decarboxylative cyanation of aryl carboxylic acids with nontoxic and low-cost K4Fe(CN)6 under an oxygen atmosphere for the first time.
Axially Chiral Bifunctional 8,8′-Biquinolyl: Synthesis of 7,7′-Dihydroxymethyl-8,8′-biquinolyl via Pd-Catalyzed Double C-H Oxidation of 7,7′-Dimethyl-8,8′-biquinolyl
Kitamura, Mitsuru,Fukuma, Hiroaki,Kobayashi, Mitsuaki,Okayama, Shinya,Okauchi, Tatsuo
, p. 3956 - 3960 (2016/05/24)
Bifunctional C2-symmetric 7,7′-dihydroxymethyl-8,8′-biquinolyl (2) was synthesized in short steps via (i) Cu/Pd-catalyzed homo coupling of 7-methyl-8-bromoquinoline and (ii) Pd(II)-catalyzed double C-H oxidation. Axial chirality of 2 and its synthetic precursor 7,7′-dimethyl-8,8′-biquinolyl (3) is stable. Optically active 2 was obtained through separation of racemic 2 by chiral column HPLC or Pd(II)-catalyzed double C-H oxidation of optically active 3. The absolute stereochemistry of enantiomers of 2 and 3 was determined using the exciton chirality method.
Au-catalyzed formation of functionalized quinolines from 2-alkynyl arylazide derivatives
Gronnier, Colombe,Boissonnat, Guillaume,Gagosz, Fabien
supporting information, p. 4234 - 4237 (2013/09/12)
A new method for converting 2-alkynyl arylazide derivatives into functionalized polysubstituted quinolines following a gold-catalyzed 1,3-acetoxy shift/cyclization/1,2-group shift sequence has been developed. This transformation proceeds under mild reaction conditions, is efficient, and tolerates a large variety of functional groups.
Syntheses and resolutions of new chiral biphenyl backbones: 2-Amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl and 2-amino-2′-hydroxy-4,4′,6,6′-tetramethyl-1,1′- biphenyl
Liang, Yuxue,Gao, Shuang,Wan, Huihui,Wang, Junwei,Chen, Huilin,Zheng, Zhuo,Hu, Xinquan
, p. 1267 - 1273 (2007/10/03)
The new chiral backbones (R)-(+)- and S-(-)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl and (R)-(+)- and (S)-(-)-2-amino-2′-hydroxy-4,4′,6,6′- tetramethyl-1,1′-biphenyl were synthesized from o-methylaniline and 2,4-dimethyl-aniline respectively in seven steps. A new resolution method was developed to provide homochiral enantiomers (from diastereomeric salts) in reasonably high yields. The absolute configuration of the new biphenyls was confirmed by X-ray structural analysis.
Enantioselective aziridination using copper complexes of biaryl Schiff bases
Gillespie, Kevin M.,Sanders, Christopher J.,O'Shaughnessy, Paul,Westmoreland, Ian,Thickitt, Christopher P.,Scott, Peter
, p. 3450 - 3458 (2007/10/03)
Racemic 2,2′-diamino-6,6′-dimethylbiphenyl is resolved using simulated moving bed chromatography, and the absolute configuration of the enantiomers is confirmed via the X-ray crystal structure of a derivative. The diamine is condensed with a range of aldehydes to give bidentate aldimine proligands L. Molecular structures of the complexes formed between L and Cu(I) fall into two classes; bimetallic double helices ([Cu2L2]2+) and monometallic ([CuL]+). The latter are strikingly more efficient in the aziridination of alkenes than are the former in terms of rate, turnover, and enantioselection. In particular, the imine ligand formed from the diamine and 2,6-dichlorobenzaldehyde gives, in combination with Cu(I) or Cu(II), up to 99% ee in the aziridination of 6-acyl-2,2-dimethylchromene and 88-98% ee for a range of cinnamate esters. Styrenic and other alkenes are converted with lower selectivities (5-54%). The catalytic system shows a linear response in product ee to catalyst ee, and the product ee does not vary significantly during the reaction. UV spectrophotometric investigations indicate that conversion of Cu(I) to Cu(II) is not essential for catalysis but that Cu(II) is probably also a competent system.
Synthesis and characterization of a superoxo complex of the dicobalt cofacial diporphyrin [(μ-O2)Co2(DPB)(1,5-diphenylimidazole) 2][PF6], the structure of the parent dicobalt diporphyrin Co2(DPB), and a new synthesis of the free-base cofacial diporphyrin H4(DPB)
Collman, James P.,Hutchison, James E.,Lopez, Michel Angel,Tabard, Alain,Guilard, Roger,Seok, Won K.,Ibers, James A.,L'Her, Maurice
, p. 9869 - 9877 (2007/10/02)
Chemical oxidation of the dicobalt cofacial diporphyrin Co2II/II(DPB), followed by exposure to dioxygen affords the bridged superoxo complex [(μ-O2)Co2(DPB)] [PF6]. This μ-superoxo complex has been implicated in possible mechanisms of four-electron dioxygen reduction by dicobalt cofacial diporphyrins but had not been isolated and fully-characterized previously. Although the superoxo complex is unstable with respect to loss of dioxygen, addition of 2 equiv of 1,5-diphenylimidazole yields [(μ-O2)Co2 III/III(DPB)(1,5-diphenylimidazole)2][PF6], a μ-superoxo complex that is stable toward loss of dioxygen. Analytically pure samples of the latter complex have been prepared, and their spectral and electrochemical properties are described. The crystal structure of the parent dicobalt cofacial diporphyrin Co2II/II(DPB) is reported. The Co-Co distance (3.726 (1) A?) and other structural features are compared to those of Co2(FTF4) and of other known metallo-DPB structures. A new, improved total synthesis of the free-base porphyrin H4(DPB) is presented. The combination of new reaction sequences, increased reaction scales, and improved product yields allows for large scale synthesis (gram quantities) of the free-base porphyrin needed to develop fully the coordination chemistry of the cofacial metallodiporphyrins.
