Hydrochloric Acid → HCID 178497600, compound

Participants

Reaction Steps

Aqueous HCl (56.0 mL of 6N solution in water, 0.33 mol) was added dropwise over 1 hour to a stirring suspension of methyl 1H-indole-4-carboxylate (5.0 g, 28.5 mmol) in a solution of sodium nitrite (24.0 g, 0.34 mol) in water (500 mL) at ambient temperature. The mixture was stirred overnight at ambient temperature, and then extracted with ethyl acetate (5×300 mL). The combined organic layers were washed with water (2×300 mL), brine (200 mL), and dried (Na2SO4). The organics were concentrated under reduced pressure until precipitation was observed. After cooling in a dry ice bath the precipitate was collected by filtration, washed with cold ethyl acetate (50 mL), and hexanes (100 mL) and dried (Na2SO4) to afford methyl 3-formyl-1H-indazole-4-carboxylate (B1, 2.1 g, 35%) as a yellow powder: 1H NMR (300 MHz, DMSO-d6) δ 10.33 (s, 1H), 7.92 (d, J=8.1 Hz, 1H), 7.67 (d, J=7.2 Hz, 1H), 7.58 (t, J=7.2 Hz 1H), 3.96 (s, 3H); MS (ESI+) m/z 205 (M+H).

Provenance & Evidence