- The polyhedral nature of selenium-catalysed reactions: Se(iv) species instead of Se(vi) species make the difference in the on water selenium-mediated oxidation of arylamines
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Selenium-catalysed oxidations are highly sought after in organic synthesis and biology. Herein, we report our studies on the on water selenium mediated oxidation of anilines. In the presence of diphenyl diselenide or benzeneseleninic acid, anilines react with hydrogen peroxide, providing direct and selective access to nitroarenes. On the other hand, the use of selenium dioxide or sodium selenite leads to azoxyarenes. Careful mechanistic analysis and 77Se NMR studies revealed that only Se(iv) species, such as benzeneperoxyseleninic acid, are the active oxidants involved in the catalytic cycle operating in water and leading to nitroarenes. While other selenium-catalysed oxidations occurring in organic solvents have been recently demonstrated to proceed through Se(vi) key intermediates, the on water oxidation of anilines to nitroarenes does not. These findings shed new light on the multifaceted nature of organoselenium-catalysed transformations and open new directions to exploit selenium-based catalysis.
- Capperucci, Antonella,Dalia, Camilla,Tanini, Damiano
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supporting information
p. 5680 - 5686
(2021/08/16)
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- Synthesis of 5,9-Diaza[5]helicenes
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A new method for the synthesis of 5,9-diaza[5]helicenes is presented using 2,3-bis(acylamino)-substituted ortho-terphenyls as precursors. Activation of the amide groups and electrophilic substitution at the ortho positions of the adjacent phenyl groups leads to the 5,9-diaza[5]helicenes. A stepwise reaction including protection of the first amino group, amide formation at the second amino group with subsequent cyclization, followed by deprotection, amide formation and cyclization at the first amino group ensures that both electrophilic substitutions take place at sufficiently activated arenes and allows for the different substituents at the diaza[5]helicenes brought in with the amide groups. The terphenyl precursors are synthesized by two Suzuki couplings of suitably substituted building blocks. Three different 5,9-diaza[5]helicenes with aliphatic, alkenyl and methoxycarbonylalkyl substituents were prepared; the latter would allow to attach further functionalities by ester or amide linkage.
- Wei?, Aaron,Podlech, Joachim
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supporting information
p. 6697 - 6701
(2019/11/02)
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- 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
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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.
- Fu, Zhengjiang,Jiang, Ligao,Zuo, Qianming,Li, Zhaojie,Liu, Yanzhu,Wei, Zhenhong,Cai, Hu
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supporting information
p. 5416 - 5421
(2018/08/12)
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- PROCESS FOR THE PREPARATION OF ORGANIC HALIDES
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The present invention provides a halo-de-carboxylation process for the preparation of organic chlorides, organic bromides and mixtures thereof, from their corresponding carboxylic acids, using a chlorinating agent selected from trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA), or combination thereof, and a brominating agent.
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Paragraph 00138
(2017/08/01)
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- Synthetic method of aryl halide taking aryl carboxylic acid as raw material
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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.
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Paragraph 0118
(2018/01/03)
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- 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
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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.
- Fu, Zhengjiang,Li, Zhaojie,Song, Yuanyuan,Yang, Ruchun,Liu, Yanzhu,Cai, Hu
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p. 2794 - 2803
(2016/04/26)
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- Halogenation and DNA cleavage via thermally stable arenediazonium camphorsulfonate salts
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A series of stable arenediazonium camphorsulfonate salts (2a-2j) were synthesized by simple diazotization of several aromatic amines in the presence of sodium nitrite and camphorsulfonic acid. All the new arenediazonium camphorsulfonates, which were characterized by multinuclear (1H and 13C) NMR, IR, DSC, and X-ray diffraction analysis (2e and 2f) provide unambiguous proof for the molecular structures of 2e and 2f. The efficient application of these salts in halogenation reactions was studied in solvent and solvent-free conditions and the DNA cleavage activity was also assessed. These arenediazonium camphorsulfonate salts are noticed as efficient DNA cleaving agents.
- Vajpayee, Vaishali,Moon, Mi Eun,Lee, Sunmi,Ravikumar, Sambandam,Kim, Hyunuk,Ahn, Byungchan,Choi, Seoyoon,Hong, Soon Ho,Chi, Ki-Whan
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p. 3511 - 3517
(2013/04/23)
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- Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
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A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
- Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
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p. 6782 - 6785,4
(2012/12/12)
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- Ex situ generation of stoichiometric and substoichiometric 12CO and 13CO and its efficient incorporation in palladium catalyzed aminocarbonylations
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A new technique for the ex situ generation of carbon monoxide (CO) and its efficient incorporation in palladium catalyzed carbonylation reactions was achieved using a simple sealed two-chamber system. The ex situ generation of CO was derived by a palladium catalyzed decarbonylation of tertiary acid chlorides using a catalyst originating from Pd(dba)2 and P(tBu)3. Preliminary studies using pivaloyl chloride as the CO-precursor provided an alternative approach for the aminocarbonylation of 2-pyridyl tosylate derivatives using only 1.5 equiv of CO. Further design of the acid chloride CO-precursor led to the development of a new solid, stable, and easy to handle source of CO for chemical transformations. The synthesis of this CO-precursor also provided an entry point for the late installment of an isotopically carbon-labeled acid chloride for the subsequent release of gaseous [ 13C]CO. In combination with studies aimed toward application of CO as the limiting reagent, this method provided highly efficient palladium catalyzed aminocarbonylations with CO-incorporations up to 96%. The ex situ generated CO and the two-chamber system were tested in the synthesis of several compounds of pharmaceutical interest and all of them were labeled as their [ 13C]carbonyl counterparts in good to excellent yields based on limiting CO. Finally, palladium catalyzed decarbonylation at room temperature also allowed for a successful double carbonylation. This new protocol provides a facile and clean source of gaseous CO, which is safely handled and stored. Furthermore, since the CO is generated ex situ, excellent functional group tolerance is secured in the carbonylation chamber. Finally, CO is only generated and released in minute amounts, hence, eliminating the need for specialized equipment such as CO-detectors and equipment for running high pressure reactions.
- Hermange, Philippe,Lindhardt, Anders T.,Taaning, Rolf H.,Bjerglund, Klaus,Lupp, Daniel,Skrydstrup, Troels
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supporting information; experimental part
p. 6061 - 6071
(2011/06/19)
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- Selective activation of enantiotopic C(sp3)-hydrogen by means of chiral phosphoric acid: Asymmetric synthesis of tetrahydroquinoline derivatives
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Chiral phosphoric acid-catalyzed asymmetric C-H functionalization has been achieved. In this process, enantiotopic C(sp3)-hydrogen is selectively activated by chiral phosphoric acid to afford tetrahydroquinoline derivatives with excellent enantioselectivities (up to 97% ee).
- Mori, Keiji,Ehara, Kensuke,Kurihara, Kazuki,Akiyama, Takahiko
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supporting information; scheme or table
p. 6166 - 6169
(2011/06/21)
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- Efficient and economic halogenation of aryl amines via arenediazonium tosylate salts
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Arenediazonium tosylate salts have been successfully employed as a new and efficient reagent in halogenation reactions. A novel and economic protocol has been developed for the bromination and chlorination of various anilines using arenediazonium tosylate salts. A wide variety of reaction conditions were studied in acetonitrile at either room temperature or 60 °C in the presence or absence of catalyst with good to excellent yields. A surprising result showed the formation of acetanilides as a major product of aniline and methyl-substituted aniline halogenations in high yields.
- Lee, Young Min,Moon, Mi Eun,Vajpayee, Vaishali,Filimonov, Victor D.,Chi, Ki-Whan
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experimental part
p. 7418 - 7422
(2010/10/01)
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- An expeditious and environmentally benign preparation of aryl halides from aryl amines by solvent-free grinding
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An efficient solvent-free methodology for conversion of various aryl amines into bromides and chlorides via arenediazonium tosylate salts under grinding conditions is disclosed. This new methodology not only avoids the use of strong acids and expensive reagents for diazotization-halogenation reactions, but also decreases the amount of organic waste from the reaction process.
- Moon, Mi Eun,Choi, Younghwa,Lee, Young Min,Vajpayee, Vaishali,Trusova, Marina,Filimonov, Victor D.,Chi, Ki-Whan
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scheme or table
p. 6769 - 6771
(2011/03/17)
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- Synthesis of charge transporting block copolymers containing 2,7-dimethoxycarbazole units for light emitting device
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The block copolymers consisting of 2,7-dimethoxycarbazole- and oxadiazole-containing segments as hole and electron transporting units, respectively, were synthesized by NMRP manner. OLED devices were fabricated using block copolymer, random copolymer, and polymer blend for matrix of the emitting layer with Ir(ppy)3 as a phosphorescent dopant in order to investigate morphological effect on the performance. From the finding that the block copolymer system overwhelmed the others in EQE, we assumed that a morphology with dimethoxycarbazole units assembled to the surface of PEDOT:PSS played a considerable role for effective recombination of charges as well as sufficient charge injection into the emitting layer.
- Tsuchiya, Kousuke,Sakaguchi, Kota,Kasuga, Hidemasa,Kawakami, Akira,Taka, Hideo,Kita, Hiroshi,Ogino, Kenji
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experimental part
p. 616 - 622
(2011/03/17)
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- Indazoles, benzothiazoles, benzoisothiazoles, benzisoxazoles, pyrazolopyridines, isothiazolopyridines, and preparation and uses thereof
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The present invention relates generally to the field of ligands for nicotinic acetylcholine receptors (nACh receptors), activation of nACh receptors, and the treatment of disease conditions associated with defective or malfunctioning nicotinic acetylcholine receptors, especially of the brain. Further, this invention relates to novel compounds (e.g., indazoles and benzothiazoles), which act as ligands for the α7 nACh receptor subtype, methods of preparing such compounds, compositions containing such compounds, and methods of use thereof.
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Page/Page column 68
(2010/11/26)
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- 1 H-INDAZOLES, BENZOTHIAZOLES, 1,2-BENZOISOXAZOLES, 1,2-BENZOISOTHIAZOLES, AND CHROMONES AND PREPARATION AND USES THEREOF
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The present invention relates generally to the field of ligands for nicotinic acetylcholine receptors (nAChR), activation of nAChRs, and the treatment of -disease conditions associated with defective or malfunctioning nicotinic acetylcholine receptors, especially of the brain. Further, this invention relates to novel compounds (indazoles and benzothiazoles), which act as ligands for the α7 nAChR subtype, methods of preparing such compounds, compositions containing such compounds, and methods of use thereof.
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Page/Page column 77
(2010/11/27)
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- Investigation of the asymmetric Birch reduction-alkylation of a chiral 5-arylbenzamide containing a carbamate group
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The synthesis and asymmetric Birch reduction-alkylation of chiral benzamide 17 are described. Birch reductive alkylation of benzamide 17 was optimized to give the corresponding cyclohexa-1,4-diene products in 66-78% isolated yield and with high diastereoselectivity (dr: >98:2). The effects of performing the reduction in the presence and in the absence of tert-butyl alcohol are discussed.
- Casimiro-Garcia, Agustin,Schultz, Arthur G.
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p. 2739 - 2742
(2007/10/03)
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- Synthesis of polysubstituted indoles and indolines by means of zirconocene-stabilized benzyne complexes
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The development of a new method for the regiospecific synthesis of polysubstituted indoles and indolines is reported. The key steps involve the generation of zirconocene-stabilized benzyne complexes and subsequent intramolecular olefin insertion reactions to provide tricyclic indoline zirconacycles. The zirconacyclic intermediates were cleaved with iodine to yield diiodo indolines, which were converted to a wide variety of indole and indoline products, such as analogs of tryptamine, serotonin, tryptophan, and the pharmacophore of CC-1065.
- Tidwell, Jeffrey H.,Buchwald, Stephen L.
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p. 11797 - 11810
(2007/10/02)
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- A New Approach to the Synthesis of the CC-1065/Duocarmycin Pharmacophore
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The spirocyclic 1,2,7,7a-tetrahydrocyclopropindol-4-one subunit of CC-1065 and duocarmycin A, which comprises the common pharmacophore of the two antibiotics, has been efficiently synthesized in six steps from readily available starting materials.The key step of the synthesis utilizes a zirconocene-stabilized benzyne complex.
- Tidwell, Jeffrey H.,Buchwald, Stephen L.
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p. 6380 - 6382
(2007/10/02)
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