Sodium hydroxide (3M, 20 ml) was added to a vigorously stirred solution of ethyl 4-nitroindole-2-carboxylate (4 g), 3,4-dichlorobenzyl chloride (4.73 ml) and tetra-n-butylammonium hydrogensulphate (0.2 g) in dichloromethane (60 ml). The reaction was stirred for 48 hours then partitioned between 2M HCl and dichloromethane. Combined organic extracts were dried (MgSO4) and concentrated in vacuo and the residue purified by column chromatography using iso-hexane: 20% ethyl acetate as eluent to give the product as a yellow crystalline solid (5.26 g, 78%); NMR δ (CD3SOCD3) 1.3 (t, 3H), 4.3 (q, 2H), 5.95 (s, 2H), 6.9 (m, 1H), 7.6 (m, 4H), 8.2 (t, 2H); M/z (+) 393.3 (M+).
