Synthesis of New Thiadiazoles, 1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazoles, and 1,2,4-Triazolo[2,3-c]quinazoline Derivatives from 3,1-Benzoxazin(4H)-one Derivative

3,1-benzoxazin-4H-one derivative was reacted with Grignard reagents, primary and secondary amines, glycine, hydrazine hydrate, azines, and Schiff's base. The acid hydrazide derivative was the key starting material for the synthesis of triazole, triazolo[3,4-b]thiadiazole, thiadiazole, and triazolo[2,3-c]quinazoline.