Phosphorus oxychloride → methyl 3-formyl-1H-indole-4-carboxylate

Participants

Reaction Steps

To a stirred mixture of N-methylformanilide (15.6 g) and phosphorus oxychloride (17.7 g) is added ethylene dichloride (75 g ) followed by 4-indolecarboxylic acid methyl ester (17.5 g). The reaction mixture is stirred at room temperature for 1 1/2 hr., then at 45°-50°C for 30 minutes more. The mixture is now poured into a solution of 75 g of sodium acetate in 150 ml of ice-water. More ethylene dichloride is added. The layers are separated and the organic phase is washed with water, dried (Na2SO4) and evaporated under reduced pressure. The residual brown oil is passed through a silica gel column using 3% methanol in chloroform. Concentration of the eluate affords a solid which on recrystallization from benzene affords the pure title compound, mp 135°C.

Provenance & Evidence