To a solution of 8.0 g (0.027 mole) of 7-chloro-2-(2-chloroethyl)-2,3-dihydro-4-methyl-1,4-benzoxazepine-5(4H)-thione in 50 ml of absolute ethanol was added 6 ml (0.054 mole) of 40% aqueous solution of dimethylamine. The solution was heated in a steel bomb at 90° C. for 14 hr. The ethanol was removed under reduced pressure and the residue was partitioned between chloroform and aqueous sodium hydroxide. The chloroform layer was concentrated to give a viscous yellow oil. The oil was dissolved in isopropyl alcohol and reacted with oxalic acid. The oxalate salt immediately precipitated. The mixture was heated and a small amount of water was added to dissolve the salt. A white crystalline powder was obtained, m.p. 150°-151° C.
