One-pot synthesis of 2,1-benzisoxazoles (anthranils) by a stannous chloride-mediated tandem reduction–heterocyclization of 2-nitroacylbenzenes under neutral conditions (original) (raw)
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.
Molecules, 2019
The alkylation of a series of nitroindazole derivatives with 1,2-dibromoethane afforded the corresponding N-(2-bromoethyl)- and N-vinyl-nitro-1H-indazoles. The Cu(I)-catalysed azide- alkyne 1,3-dipolar cycloaddition was selected to substitute the nitroindazole core with 1,4-disubstituted triazole units after converting one of the N-(2-bromoethyl)nitroindazoles into the corresponding azide. The reactivity in 1,3-dipolar cycloaddition reactions with nitrile imines generated in situ from ethyl hydrazono-α-bromoglyoxylates was studied with nitroindazoles bearing a vinyl unit. The corresponding nitroindazole-pyrazoline derivatives were obtained in good to excellent yields.