Sodium hydride (0.075 g) was added to a solution of 1,2,3,9-tetrahydro-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one (0.7 g) in dimethylformamide (10 ml) and the mixture was stirred for 30 min. Methanesulphonyl chloride (0.25 ml) was added and stirring continued at room temperature for 5 h. The resulting solution was partitioned between sodium carbonate (100 ml) and ethyl acetate (3×50 ml). The combined organic layers were washed with water (3×50 ml), dried (Na2SO4), and evaporated in vacuo to give an oil. Purification by flash chromatography (A) gave an oil, which was dissolved in ethanol (10 ml) and added to a solution of maleic acid (0.15 g) in ethanol (5 ml). Addition of dry ether precipitated the title compound (0.7 g) m.p. 141°-142.5°.
