One-pot synthesis of 2,1-benzisoxazoles (anthranils) by a stannous chloride-mediated tandem reduction–heterocyclization of 2-nitroacylbenzenes under neutral conditions (original) (raw)
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Synthesis of 2,1-benzisoxazoles (microreview)
This microreview summarizes data published over the past 10 years devoted to the synthesis of substituted 2,1-benzisoxazoles. The major synthetic approaches aim at increasing either the electrophilicity or nucleophilicity of ortho substituents or other substrates. Ortho-substituted aryl azides, anilines, nitroso- and nitrobenzenes were used as starting compounds.
Comptes Rendus Chimie, 2017
2,1-Benzisoxazoles, also called anthranils, are one of the two types of aromatic bicyclic heterocycles having a benzene ring fused with an isoxazole, which are particularly recognized as valuable intermediates in organic synthesis. Nevertheless several methods can be found in the literature to prepare 2,1-benzisoxazoles, we herein report a new, efficient, simple, mild, and alternative procedure to prepare 3-substituted-2,1benzisoxazoles from 5-(2-nitrobenzylidene)barbiturates in moderate to good yields (51 e82%). All the novel benzisoxazoles showed spectral data fully consistent with the assigned structures, which were unequivocally confirmed by single crystal X-ray analysis. A possible mechanism of the reaction is proposed. In addition, a screening of the bioactivity of these benzisoxazoles as xanthine oxidase inhibitors, antioxidants, and cytotoxic compounds was performed. The benzisoxazole formed from barbituric acid revealed moderate xanthine oxidase inhibitory effects (IC 50 ¼ 22.10 mM).
Zeitschrift für Naturforschung B, 1986
3-Thiocyanatomethyl C innam onitrile, R eductive Cleavage, Pyrrole Derivatives /3-Thiocyanatomethyl cinnam onitrile derivatives coupled with aromatic diazonium salts to afford the corresponding azo com pounds, which undergo reductive cyclization into pyrrole derivatives. The utility of organic cyano com pounds in heterocyclic synthesis has recently received consider able attention [1, 2], Our group has been involved in the last years in a program aiming to develop effi cient procedures for synthesis of polyfunctionally substituted azoles [3, 4], azines [5, 6 ] and their con densed derivatives [7, 8 ] utilizing simple and readily obtainable polyfunctionally substituted nitriles. D u ring this phase of our research we could show that whereas ethylidenem alononitrile derivative l a does not couple with aromatic diazonium salts, the pre sence o f cyano substituent on the methyl m oiety (as in lb ) sufficiently activates the adjacent m ethylene group for coupling [9], The resulting hydrazones could be utilized for synthesis of pyridazine-6 -imine derivatives [10]. It seem ed to us of value to see if the presence of other functional substituent on the methyl m oiety in 1 can effect similar activation.
Tetrahedron Letters, 2012
Revised regiochemistry for the heterocyclization of electrophilic alkenes with tetranitromethane (TNM) in the presence of triethylamine, providing rapid access to nitroisoxazoles, is reported. The formation of 5-nitroisoxazoles previously incorrectly assigned as 3-nitro regioisomers, has now been established unambiguously by X-ray crystallography. Empirical computations with ACD/CNMR Predictor, based both on hierarchical ordering of spherical environments (HOSE) and an algorithm of artificial neural networks (ANN), and also Density Functional Theory computations of the 13 C NMR chemical shifts for the 3-versus 5-nitroisoxazoles are shown to consistently match the spectra of the experimentally observed 5regioisomers.
New 3-substituted-2,1-benzisoxazoles: Synthesis and antimicrobial activities
Arabian Journal of Chemistry, 2013
A new series of 3-substituted-2,1-benzisoxazoles (anthranils) were prepared by different methods and characterized by spectroscopic methods and mass spectrometry. These 2,1-benzisoxazoles were tested in vitro for their antiplasmodial activity on a chloroquine-resistant strain of Plasmodium falciparum (P.f.) (FcB1), and for antimicrobial activity against representative bacterial and fungal strains, as well as for cytotoxicity on MCF7 human breast cancer cells. Given the log P calc and selectivity index values (cytotoxicity/antiplasmodial activity ratio), the benzo[c]isoxazol-3-ylmethylene-phenyl-amine (11) (imino-benzisoxazole) was identified as the best hit against P.f. (FcB1), and the benzo[c]isoxazol-3-yl-phenyl-methanone (3) (3-acyl-2,1-benzisoxazole) against P.f. and the Geotrichum candidum fungal strain.