Synthesis of fused ring of Nitrogen and Sulphur Compounds. They were studied by I.R. and PMR Spectra. Introduction deals with literature survey of isoxazole-5-ones, with special emphasis on fused ring and Spiro compounds. The reaction of 4-bromo-3subs isoxazolin (I) with thio carbamide resulting in the formation of the 5-alkyl/ aryl amino-3-subs.thiazolo(5,4-d)isoxazole, 5-Aminoderivative on reaction with isothiocyanates afforded the corresponding thioureido compounds.