Synthesis of Two Isomeric Thiadiazine and Thiazole Derivatives from a Hydrazonoyl Halide

Thiadiazine and thiazoles have attracted importance due to their broad applicability as biologically active compounds. New thiadiazines and thiazoles are prepared <i>via</i> the simple reaction of an <i>α</i>-haloketohydrazonoyl with thiocarbohydrazone derivatives in a basic medium under reflux. A S-alkylated intermediate forms through nucleophile substitution involving the hydrazonoyl halogen and thiocarbohydrazone thiol. <i>In situ</i> cyclization <i>via</i> the condensation between the carbonyl and NH₂ or NH moieties of the intermediate forms 1,3,4-thiadiazine and thiazole derivatives, respectively. This method employs inexpensive, commercially available reagents and facile reaction conditions to afford novel thiadiazine/thiazole derivatives in good yields.