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Substituted Isoxazoles were prepared from hydroxylamine hydrochloride andchalcones. 429 Naik and co-workers 430 have synthesised Isoxazoles by bromination ofchalcones, followed by cyclocondensation of the α,β-dibrominated, satd. Chalconeswith hydroxylamine hydrochloride in ethanol, in presence of KOH. Other methodwas reported by El.Kholy et al. 431 The Isoxazole of type (II) was prepared by thereaction of ethyl-3-oxo-butanoate with malononitrile and ethyl cyano acetate.C H 3COOEtNO CH 2 XX=CN,COOEt( II )Chalcones of 2-(4'-chlorophenylamino)-4-(4'-fluorophenylamino)-6-(4'-acetylphenylamino)-s-triazine have been synthesized by condensation with differentaromatic aldehydes. These chalcones on treatment with hydroxylaminehydrochloride in presence of alkali give isoxazoles and on treatment withmalononitrile in presence of ammonium acetate give cyanopyridines. 432A series of 2,4-bis-(4'-chloro phenyl amino) -6- [4'-{1''- acetyl- 5''-aryl- 2''-pyrazolin-3''-yl}phenyl amino]-s-triazines have been prepared by the reaction ofchalcone and hydrazine hydrate in presence of glacial acetic acid and 2,4-bis-(4'-chlorophenylamino)-6-[4'-{5''-aryl-2''-isoxazol-3''-yl}phenylamino]-s-triazines weresimilarly prepared with hydroxylamine hydrochloride in presence of alkali. All thesynthesized compounds have been screened for their antimicrobial activity. Thestructure of synthesized compds. have been confirmed on the basis of elementalanal., IR and 1 H NMR spectral data. 433134Isoxazole…..