Indole → Methyl 3-indoleglyoxylate

Participants

Reaction Steps

Oxalyl chloride (1.50 mL; 17.2 mmol) was added dropwise to an ice cold solution of indole, A1, (2.00 g; 17.1 mmol) in anhydrous diethyl ether (20 mL). The resulting solution was allowed to stir on ice for 1 hour after which time a yellow slurry had formed. A freshly prepared solution of sodium methoxide in methanol (780 mg Na metal in 20 mL methanol; 34.1 mmol) was added, the reaction allowed to warm to room temperature and stirred for 1 hour. The reaction was quenched with the addition of water (30 mL) and the resulting orange solid isolated by fitration, washed with diethyl ether and recrystallised from methanol. Yield 2.94 g; 85%. mp 226–228° C. 1H NMR (500 MHz, DMSO-d6) 12.40 (br s, 1H), 8.17 (dd, J=1.5, 7.6 Hz, 1H), 7.55 (dd, J=1.5, 7.6 Hz, 1H), 7.29 (dt, j=1.5, 7.6 Hz, 1H), 7.26 (dt, J=1.5, 7.6 Hz, 1H), 3.89 (s, 3H).

Provenance & Evidence