Benzenesulfonyl chloride → 1-(benzenesulfonyl)-1H-indole-5-carbaldehyde

Participants

Reaction Steps

After a suspension of methyl indole-5-carboxylate (4) (1.00 g, 6.89 mmol), tetrabutylammonium bisulfate (0.35 g, 1.03 mmol) and KOH (0.77 g, 13.78 mmol) in CH2Cl2 (30 mL) was stirred for 20 min, benzenesulfonyl chloride (1.32 ml, 10.33 mmol) was added. The reaction mixture was stirred at room temperature overnight before it was quenched with water and extracted with CH2Cl2 (20 mL×3). The combined organic layer was dried over anhydrous MgSO4 and concentrated under reduced pressure to give a yellow residue, which was purified by silica gel chromatography (EtOAc:n-hexane=1:2) to afford 5 (1.79 g) as a white solid. 1H NMR (500 MHz, CDCl3): δ6.78 (d, J=3.6 Hz, 1H), 7.45-7.48 (m, 2H), 7.55-7.58 (m, 1H), 7.67 (d, J=3.7 Hz, 1H), 7.85-7.87 (m, 1H), 7.89 (d, J=7.6 Hz, 2H), 8.06 (s, 1H), 8.11 (d, J=8.6 Hz, 1H), 10.03 (s, 1H).

Provenance & Evidence