2-Amino-5-chloropyridine-3-sulfonamide (II) was obtained by the reaction of 2-amino-5-chloropyridine (I) with chlorosulfonic acid, followed by treatment of the sulfonyl chloride intermediate with aqueous ammonia. Condensation of amino sulfonamide (II) with thiocarbonyldiimidazole (III) produced the imidazolyl pyridothiadiazine (IV). Nucleophilic substitution of the imidazolyl group with 1,2,2-trimethylpropylamine (V) in a sealed vessel at 180 C furnished the corresponding amino pyridothiadiazine.