Benzenesulfonyl chloride → 1H-Pyrrolo[2,3-b]pyridine-3-carboxaldehyde, 5-bromo-1-(phenylsulfonyl)-

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Reaction Steps

To a suspension of 6 (5.0 g, 22.2 mmol) in dichloromethane (130 mL) was added benzenesulfonyl chloride (4.25 mL, 33.3 mmol), tetra-n-butylammonium hydrogen sulphate (0.98 g, 2.98 mmol) and 50% aqueous NaOH (4.2 mL). The reaction mixture was stirred for 2 h then poured onto water (500 mL), extracted with dichloromethane (3×200 mL). The combined organic extracts were washed with saturated aqueous NaHCO3 (2×150 mL) and dried (MgSO4). Concentration produced a white solid which was washed with ether (3×150 mL) to give product 7 as a light orange solid (7.34 g, 91%); 1H NMR (400 MHz, CDCl3+4 drops d4-MeOH) δ 9.95 (s, 1H), 8.61 (d, J=2.3 Hz, 1H), 8.46 (d, J=2.1 Hz, 1H), 8.38 (s, 1H), 8.19 (m, 2H), 7.62 (tt, J=7.5, 1.3 Hz, 1H), 7.51 (t, J=7.1 Hz, 2H).

Provenance & Evidence