A solution of 1,2-dihydro-3-[[5-methyl-1-(triphenylmethyl)-1H-imidazol-4-yl]methylene]-4(3H)-phenanthrenone (0.5 g) in a mixture of THF (15 ml), acetic acid (5 ml) and water (5 ml) was heated on a steam bath for 45 min. 0.5M Hydrochloric acid (25 ml) was added and the mixture was extracted with ether (2×15 ml; discarded). The aqueous solution was basified with solid potassium carbonate and the mixture was extracted with dichloromethane (3×15 ml). The dried extracts were evaporated and the residue (0.21 g) was dissolved in ethanol (25 ml) and hydrogenated at room temperature and atmospheric pressure over a stirred suspension of 10% palladium on carbon (0.05 g) for 1.5 h. The solution was filtered and the filtrate evaporated to give a gum which was purified by FCC eluting firstly with ethyl acetate and then with ethyl acetate/methanol (3:1) to give the free base of the title compound as a gum (0.13 g). This was dissolved in methanol (20 ml) containing maleic acid (50 mg) and the solution was evaporated to give a gum which on trituration with ether gave the title compound as a solid (0.11 g), m.p. 133°-134° .
