2-(Methylthio)aniline (I) was alkylated with 2-(chloromethyl)-2-imidazoline hydrochloride (II) in phenol at 120 C to afford the condensation product (III). Subsequent oxidation of the thioether functionality of (III) with m-chloroperbenzoic acid gave rise to the target sulfone.

5-Methoxy-2-methylbenzothiazole (I) is hydrolyzed by NaOH in ethylene glycol to furnish 2-amino-4-methoxythiophenol (II), which is further alkylated with iodomethane and potassium tert-butoxide, yielding thioether (III). Condensation of aniline (III) with 2-(chloromethyl)imidazoline (IV) in the presence of phenol provides (V). After oxidation of sulfide (V) to the corresponding sulfone by means of m-chloroperbenzoic acid, the title compound is isolated as its fumarate salt (1,2).