To the solution of 88 mg of 5-(4-methylpiperazino)-imidazo[2,1-b][1,3,5]benzothiadiazepine in 1 ml of methylene chloride, 74 mg of m-chloroperbenzoic acid are added at 0° C. The mixture is stirred at 0° C. overnight; this is diluted with 1 ml of ether, one equivalent of ethereal hydrochloric acid solution is added and the resulting precipitate is collected. Recrystallization from methanol-ethyl acetate yields 5-(4-methyl-4-oxidopiperazino)-imidazo[2,1-b][1,3,5]benzothiadiazepine hydrochloride, melting at 155° with decomposition.
