To a solution of 1-(4-Methoxy benzenesulfonyl)-5-methoxy-1H-indole-3-carbaldehyde 5 (0.51 g, 1.5 mmol) dissolved in pyridine (10 mL), malonic acid (0.53 g, 5.1 mmol) and piperidine, (1 mL) were combined in a reaction vessel. The yellow solution was heated for 3 hours at 80° C. The reaction was allowed to cool to ambient temperature and diluted with 150 mL of ethyl acetate. The organic layer was washed with 1N HCl (6×50 mL) and saturated sodium chloride solution (1×50 mL). After drying over sodium sulfate, the organic layer was filtered through a pad of sodium sulfate and evaporated under reduced pressure to yield product 118 as an off-white solid. (0.521 g, 90%) 1HNMR (CDCl3) δ 7.86 (m, 5H), 7.2 (d, J=2.4 Hz, 1H), 7.0 (dd, J=2.8 Hz, 9.2 Hz, 1H), 6.91 (d, J=8.8 Hz, 2H), 6.46 (d, J=16, 1H), 3.87 (s, 3H, CH3) (M−1=386.2).
