Malonic acid (106 mg) and piperidine (1 drop) were added to a solution of ethyl 3-formyl-N-(3,4-dichlorobenzyl)indole-2-carboxylate (315 mg) in pyridine (5 ml) and the reaction stirred at 100° C. overnight. The reaction was concentrated in vacuo and the residue dissolved in ethyl acetate (30 ml), washed with HCl (2M, 30 ml) and water (30 ml), dried (MgSO4) and concentrated in vacuo to give the crude product which was triturated with a mixture of dichloromethane, ethyl acetate and hexane to give the product as a tan coloured solid (68 mg, 19%); NMR d (CD3SOCD3) 1.25 (t, 3H), 4.35 (q, 2H), 5.80 (s, 2H), 6.55 (d, 1H), 6.90 (m, 1H), 7.25-7.45 (m, 3H), 7.50 (m, 1H), 7.60 (m, 1H), 8.05 (m, 1H), 8.35 (d, 1H) 12.24 (s, 1H); M/(−) 416.4 (M−H+).
