Synthesis, crystal structure, and in vitro antiprotozoal activity of some 5-phenyl(methyl)sulfonyl-substituted dihydroisoxazoles

4,5-Dihydroisoxazole derivatives are interesting synthetic targets that exhibit various biological activities, including anti-infective. Taking account of the principle of bioisosterism, a number of 4,5-dihydroisoxazoles carrying a phenyl- (or methyl-)sulfonyl group at position 5 were designed and synthesized by 1,3-dipolar cycloaddition of nitrolic acid-generated nitrile oxides with electron-deficient phenyl (or methyl) vinyl sulfones. The structures of all the cycloadducts were elucidated by means of spectroscopic methods (NMR, MS), X-ray diffraction, and physical characteristics. The in vitro antiprotozoal and cytotoxic activities of these heterocyclic compounds were investigated.