2-Iodoisophthalic acid (II) is reacted with o-toluidine (I) to give 2-N-(2-methylphenyl)aminoisophthalic acid (III). Cyclization with concentrated H2SO4 provides the 5-methyl-9-oxoacridan-4-carboxylic acid (IV). Conversion of this compound to 5-methyl-9-chloroacridine-4-carbonyl chloride (V) and subsequent selective reaction first with methylamine to provide the methylcarboxamide (VI) and secondly with 4-amino-3-methoxymethanesulfonanilide (VII) gives the hydrochloride salt (VIII) of the desired compound. Conversion via the free base to the isethionate salt provides CI-921.