- TfOH-Promoted Decyanative Cyclization toward the Synthesis of 2,1-Benzisoxazoles
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A novel solvent-free, TfOH-promoted decyanative cyclization approach for the synthesis of 2,1-benzisoxazoles has been developed. The reactions are complete instantly at room temperature and result in the formation of the desired 2,1-benzisoxazoles in a 34-97% isolated yield.
- Zhang, Mengge,Meng, Yonggang,Wu, Yangang,Song, Chuanjun
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p. 7326 - 7332
(2021/06/25)
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- Metal-Free Synthesis of Anthranils by PhIO Mediated Heterocyclization of ortho-Carbonyl Anilines
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Here, we report a metal-free synthesis of anthranils from ortho-carbonyl anilines using PhIO as a sole additive under ambient conditions. This methodology did not require any external additives and delivered anthranils in excellent yields with broad substrate scope. The mechanistic studies suggest that the reaction proceeds via in-situ generation of iminoiodane leading to nitrene and a subsequent nucleophilic attack from oxygen of ortho-carbonyl aniline on nitrene results in heterocyclization.
- Garia, Alankrita,Grover, Jatin,Jain, Nidhi
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p. 4125 - 4131
(2021/08/24)
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- Metal-Free [3+2] Annulation of Ynamides with Anthranils to Construct 2-Aminoindoles
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A novel metal-free [3+2] annulation of ynamides with anthranils provides a facile, flexible, environmentally friendly, and atom-economical route to 2-aminoindoles. This synthetic process proceeds with efficiency, excellent regioselectivity, and wide functional group tolerance under mild conditions. Moreover, the obtained 2-aminoindole products represent a multifunctional platform for the construction of various 2-aminoindolyl frameworks.
- Zhang, Jingyi,Li, Ying,Zhang, Chaofeng,Wang, Xiao-Na,Chang, Junbiao
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supporting information
p. 2029 - 2035
(2021/04/05)
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- Metal-Free, Visible-Light-Enabled Direct C3-H Arylation of Anthranils
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An eosin Y disodium salt-catalyzed photoredox C-H arylation of anthranils is reported. A variety of aryl diazonium tetrafluoroborates were used as aryl sources, providing the C3 cross-coupled products. The in situ generated reactive radicals were trapped by anthranils, providing an alternative method to transition-metal-catalyzed C-H arylations of anthranils. Gold-catalyzed downstream transformations demonstrate the synthetic potential of these valuable building blocks.
- Adak, Tapas,Hashmi, A. Stephen K.,Hu, Chao,Li, Jun,Rudolph, Matthias
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supporting information
(2020/07/24)
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- Practical Synthesis of Benzimidazo[1,2- A[quinolines via Rh(III)-Catalyzed C-H Activation Cascade Reaction from Imidamides and Anthranils
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We report a novel and practical one-pot Rh(III)-catalyzed strategy to construct benzimidazo[1,2-a]quinolines from readily available imidamides and anthranils. The cascade reaction proceeds via a C-H amination-cyclization-cyclization process in ionic liquid without any additives and possesses simple operation, moderate-to-high yield, and broad substrate scope features, which will provide the reference for the construction of biologically active fused benzimidazoles.
- Hu, Yao,Wang, Ting,Liu, Yanzhao,Nie, Ruifang,Yang, Ninghong,Wang, Qiantao,Li, Guo-Bo,Wu, Yong
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supporting information
p. 501 - 504
(2020/01/31)
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- Synthesis of 3-phenylbenzo[c]isoxazoles by thermocyclization of 2-azidobenzophenones
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3-Phenylbenzo[c]isoxazoles were synthesized by non-catalytic thermolysis of 2-azidobenzophenones in dry xylene with quantitative yields. The trace content of water in solvents reduces the yields of the reaction products. 2-Azidobenzoic acid esters are sta
- Odinokov,Plekhovich,Budruev
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p. 1298 - 1300
(2019/07/15)
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- Gold(III)-Catalyzed Site-Selective and Divergent Synthesis of 2-Aminopyrroles and Quinoline-Based Polyazaheterocycles
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A facile, site-selective, and divergent approach to construct 2-aminopyrroles and quinoline-fused polyazaheterocycles enabled by a simple gold(III) catalyst from ynamides and anthranils under mild reaction conditions is described. This one-pot strategy uses readily available starting materials, proceeds in a highly step- and atom-economical manner, with broad substrate scope and scale-up potential. The key element for success in this tandem reaction is a catalyst-directed preferred quenching of the in situ generated gold carbene intermediates by a nucleophilic benzyl/2-furylmethyl moiety on the ynamides as an alternative to the known C?H annulation leading to indoles.
- Zeng, Zhongyi,Jin, Hongming,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 16549 - 16553
(2018/11/23)
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- Cp*RhIII-Catalyzed Directed Amidation of Aldehydes with Anthranils
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An approach towards construction of amide C–N bonds under mild conditions through rhodium(III) catalysis has been explored. Previous waste-free amidations were generally limited to the condensation of carboxylic acids and amines. In this report, we directly applied amination of the aldehyde C(sp2)–H bond to extend the scope of amidation reactions. The amination shows a wide substrates scope, and several important functional groups were tolerated under the benign reaction conditions. The synthesized amides are important precursors for the preparation of benzoxazinone derivatives, found in various bioactive natural products.q.
- Debbarma, Suvankar,Sudan Maji, Modhu
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p. 3699 - 3706
(2017/07/22)
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- Synthesis of 3-Substituted 2,1-Benzisoxazoles by the Oxidative Cyclization of 2-Aminoacylbenzenes with Oxone
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An efficient approach to the synthesis of 2,1-benzisoxazoles through direct construction of the N-O bond by the chemoselective oxidation of 2-aminoacylbenzenes with Oxone is described. This alternative methodology is characterized by its simple and transition-metal-free conditions and good functional group compatibility utilizing Oxone as a green oxidant instead of hypervalent iodine compounds. Moreover, this new procedure simplifies the number of steps compared to the previously reported procedure by circumventing the use of 2-azido-substituted aryl ketones.
- Chiarini, Marco,Del Vecchio, Luana,Marinelli, Fabio,Rossi, Leucio,Arcadi, Antonio
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p. 3017 - 3030
(2016/10/12)
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- Gold-Catalyzed C-H Annulation of Anthranils with Alkynes: A Facile, Flexible, and Atom-Economical Synthesis of Unprotected 7-Acylindoles
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The gold-catalyzed C-H annulation of anthranil derivatives with alkynes offers a facile, flexible, and atom-economical one-step route to unprotected 7-acylindoles. An intermediate α-imino gold carbene, generated by an intermolecular reaction, promotes ortho-aryl C-H functionalization to afford the target products. The transformation proceeds with a broad range of substrates under mild conditions. Moreover, the obtained functionalized indole products represent a versatile platform for the construction of diverse indolyl frameworks.
- Jin, Hongming,Huang, Long,Xie, Jin,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 794 - 797
(2016/02/27)
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- Palladium(ii)-catalysed regioselective synthesis of 3,4-disubstituted quinolines and 2,3,5-trisubstituted pyrroles from alkenes via anti-Markovnikov selectivity
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A novel strategy has been identified for the regioselective synthesis of 3,4-disubstituted quinolines and 2,3,5-trisubstituted pyrroles from simple alkenes via anti-Markovnikov selectivity under palladium catalysis. The salient features are synthesis of two different heterocycles, readily available starting materials, broad substrate scope, moderate to good yields and use of molecular oxygen as a terminal oxidant.
- Senadi, Gopal Chandru,Hu, Wan-Ping,Garkhedkar, Amol Milind,Boominathan, Siva Senthil Kumar,Wang, Jeh-Jeng
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supporting information
p. 13795 - 13798
(2015/09/07)
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- Potassium iodide-catalyzed three-component synthesis of 2-arylquinazolines via amination of benzylic C-H bonds of methylarenes
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A novel potassium iodide-catalyzed three-component synthesis of quinazolines via benzylic C-H bonds amination was developed. Commonly used ammonia salt and the sp3 carbon in commercially available methylarenes were used as nitrogen and C1 sources, respectively. Mechanistic studies indicated that an aryl aldehyde is involved as a key intermediate in the reaction.
- Zhao, Dan,Shen, Qi,Li, Jian-Xin
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supporting information
p. 339 - 344
(2015/03/04)
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- One-pot synthesis of 2,1-benzisoxazoles (anthranils) by a stannous chloride-mediated tandem reduction-heterocyclization of 2-nitroacylbenzenes under neutral conditions
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Classically, 2,1-benzisoxazoles (anthranils) are prepared from 2-nitroacylbenzenes by a reductive heterocyclization reaction with Sn or SnCl2 concentrated HCl. Acid sensitive functionalities are expected to be incompatible with these conditions; milder approaches to the synthesis of 2,1-benzisoxazoles would be welcomed. We demonstrate that SnCl 2·2H2O in a 1:1 mixture of EtOAc/MeOH is capable of mediating the tandem reduction-heterocyclization of a variety of 2-nitroacylbenzenes to their corresponding 2,1-benzisoxazoles in good to excellent yields under essentially neutral conditions. Importantly, several commonly used acid-labile protecting groups, including Boc carbamate, tert-butyl ether, and tert-butyl ester, proved orthogonal to these reaction conditions.
- Chauhan, Jay,Fletcher, Steven
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supporting information
p. 4951 - 4954
(2012/11/07)
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- Intramolecular Fe(II)-Catalyzed N-O or N-N bond formation from aryl azides
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(Figure presented) Iron(II) bromide catalyzes the transformation of aryl and vinyl azides with ketone or methyl oxime substituents into 2,1-benzisoxazoles, indazoles, or pyrazoles through the formation of an N-O or N-N bond. This transformation tolerates a variety of different functional groups to facilitate access to a range of benzisoxazoles or indazoles. The unreactivity of the Z-methyloxime indicates that N-heterocycle formation occurs through a nucleophilic attack of the ketone or oxime onto an activated planar iron azide complex.
- Stokes, Benjamin J.,Vogel, Carl V.,Urnezis, Linda K.,Pan, Minjie,Driver, Tom G.
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supporting information; experimental part
p. 2884 - 2887
(2010/08/21)
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- Revisiting the thermal decomposition of five ortho-substituted phenyl azides by calorimetric techniques
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The thermal decomposition (TD) of 2-azidophenylmethanol (1), 2-azidobenzenecarbaldehyde (2), 1-(2-azidophenyl)-1-ethanone (3), (2-azidophenyl)(phenyl)methanone (4) and 1-azido-2-nitrobenzene (5) was analysed by DSC, TG and C80 calorimetric techniques under both oxidative and non-oxidative conditions. The TD of these azides in solution is well known to give the corresponding benzoxazoles, generally in good yields, with the exception of azide 1. When both the outcomes from the solid phase and in 'solution phase' TD reactions combined with the results from EI-MS experiments were considered, sufficient information was available to estimate the azides intrinsic molecular reactivity (MIR).
- Cardillo, Paolo,Gigante, Lucia,Lunghi, Angelo,Zanirato, Paolo
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experimental part
p. 191 - 198
(2010/08/04)
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- 2-(2,1-Benzoxazol-3-yl)-3,5-dimethoxyphenol and 3-phenyl-2,1-benzoxazole
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The title compounds, C15H13NO4, (I), and C13H9NO, (II), are produced, along with the corresponding anilines, by the reduction of the appropriate o-nitrobenzophenones. In (I), the planar benzisoxazole and phenol fragments are tilted relative to one another by a rotation of 53.02 (14)° about the bond joining them, and the molecules are linked into chains by phenol O-H...N and phenyl C-H...O oxazole hydrogen bonds. The cell of (II) (space group 12/c) contains eight molecules in general positions, four more in the 2b sites, with twofold axial symmetry that induces a degree of disorder, and a further four as centrosymmetric pairs of complete molecules, each with an occupancy of one-half. The relative tilt of the planar fragments varies slightly from one molecule to another but is much less than that in (I), ranging from 8.8 (8) to 12.58 (15)°.
- Howie,Jabbar, Abdul,Lewis, John R.,Nizami, Shaikh S.,Ritchie, Craig F.
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p. o516-o519
(2007/10/03)
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- Synthesis of 2,1-benzisoxazole derivatives from nitroarenes and CH acids in aprotic media
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DBU/MgCl2 mediated reaction between nitroarenes and some CH acids bearing leaving group lead to 2,1-benzisoxazole derivatives under aprotic conditions. Ortho-directing effect was observed.
- Wrobel
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p. 2384 - 2388
(2007/10/03)
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- Oxidative Cyclizations. VIII. Mechanisms of Oxidation of ortho-Substituted Benzenamines and Improved Cyclizations by Bis(acetato-O)phenyliodine
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Published reports describe the oxidative cyclization of suitable ortho-substituted arenamines to form such products as 2,1-benzisoxazoles, benzofurazan 1-oxides and benzotriazoles, by using bis(acetato-O)phenyliodine at room temperature.However, the reactions are often inconveniently slow.We now report attempts to achieve short reaction times with more powerful iodine(III) oxidants.These often failed to give cyclic products, but the results enable us to argue that the reaction competing with cyclization involves the arenaminyl cation ArN+H.When such cations are predicted to be relatively unstable, the parent arenamine can be rapidly cyclized in high yield by oxidation with bis(acetato-O)phenyliodine in boiling benzene.
- Dyall, Leonard K.,Harvey, Jacqueline J.,Jarman, Tony B.
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p. 371 - 384
(2007/10/02)
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- Pyrolysis of Aryl Azides. VIII. Hammett Correlations of Rates of Pyrolysis of Substituted 2-Azidobenzophenones
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Eight 2-azidobenzophenones with 4- or 5-substituents have been pyrolysed in decalin solution to yield 3-phenyl-2,1-benzisoxazoles.Rate values at 100 deg are correlated with the Hammett substituent constants, with respect to both the azido (A) and benzoyl (B) reaction centres, and yield the eqation log k = -4.38 + 2.08?-A -1.52?B.There is a similar equation for rates measured at 120 deg.Although nitro and benzoyl differ considerably in their neighbouring group abilitites in azide pyrolyses, it is concluded that they exert their effects through the same mechanism.The results are consistent with both published variants of an electrocyclic mechanism (Dyall; Smith, Budde and Chou).
- Dyall, Leonard K.,Karpa, Gary J.
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p. 1231 - 1241
(2007/10/02)
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- Photolyis of 2-Nitrodiphenylmethanes in Isopropanol and Acidified Aqueous Ethanol
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2-Nitrodiphenylmethane (1a) on irradiation in isopropanol and acidified ethanol yields benzoic acids as the major product. 3-Phenyl-2,1-benzisoxazole (2a) and acridone (3a) are also formed, though in lower yields. 4,4'-Dichloro/bromo-5,5'-dimethyl-2-nitrodiphenylmethanes (1b, c) on similar irradiation yields 4-halo-3-methylbezoic acid (4) as the major product. 5-Methyl-4-halo-3-(4'-halo-3'-methylphenyl)-2,1-benzisoxazole (2b, c) and acridones (3b, c) are also formed.A plausible mechanism for the formation of various products in the photoreactions is discussed.
- Christudhas, M.,Jacob, E. Dominic,Joshua, C. P.
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p. 815 - 817
(2007/10/02)
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- Oxidative Cyclizations. VII. Cyclization of 2-Substituted Anilines with Alkaline Hypohalite
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The Green-Rowe oxidation of 2-nitroanilines with alkaline hypohlorite, to yield benzofuroxans, is demonstrated by studies of the visible spectra of transient intermediates to proceed through N-chlorination and a singlet nitrene.Two variations on the route to the nitrene are possible.The cyclization step is represented as an internal capture of the nitrene by the ortho substituent, and on this basis the Green-Rowe oxidative cyclization is now extended to anilines whose ortho substituent is benzoyl or phenylazo.It is not however successful for ortho phenyl.Azo compounds were observed as byproducts in some of these reactions, and are shown to arise via N,N-dichloroanilines.
- Dyall, Leonard K.
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p. 2013 - 2026
(2007/10/02)
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- REACTIONS OF ORGANIC ANIONS. PART XCVII. CLEAVAGE OF SUBSTITUTED α-(p- AND o-NITROPHENYL)-DEOXYBENZOINS BY SODIUM METHOXIDE IN METHANOL. DISPROPORTIONATION AND INTRAMOLECULAR CYCLIZATION REACTIONS OF NITRODIPHENYLMETHANE ANIONS
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Cleavage of substituted α-(p- and o-nitrophenyl) deoxybenzoins by sodium methoxide in methanol and subsequent transformations of resulting p- and o-nitrophenylphenylmethane anions have been investigated.
- Jawdosiuk, Mikolaj,Kmiotek-Skarzynska, Irena,Czarnecka, Ewa
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p. 379 - 385
(2007/10/02)
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