synthesis, dft study and antibacterial activity of some isoxazoline derivatives containing 1,4-benzothiazin-3-one nucleus obtained using 1,3-dipolar cycloaddition reaction

Novel series of isoxazoline derivatives containing 1,4-benzothiazin-3-one ring (6a-h) were synthesized via 1,3-dipolar cycloaddition reactions of arylnitrile oxides 5a-d on 4-allyl-2-(substituted)-1,4-benzothiazin-3-ones 3 and 4 led to polyheterocyclic. systems. during our work, we mainly focused on the reactivity of nitrile oxides with carbon-carbon extracyclic double bond of the allyl group. the reaction leads exclusively to cycloadducts 6a-h with a good yield. the compounds were characterized using s spectral data (1h-nmr, 13c-nmr) and for some structures were also confirmed via single-crystal x-ray diffraction techniques. density functional theory (dft) optimized structures at the b3lyp/ 6–311g(d,p) level are compared with the experimentally determined molecular structure in the solid-state. the homo—lumo behavior was elucidated. the results are in agreement with the experimental data. the newly synthesized compounds 1, 2, 3, 4, 6a-g using cycloaddition reactions were evaluated in vitro for their antibacterial activities against some gram-positive and gram-negative microbial strains. several compounds tested showed significant activity.