Dimethylformamide → Methyl 3-formyl-1H-indole-7-carboxylate

Participants

Reaction Steps

To a stirred mixture of phosphorus oxychloride-dimethylformamide in anhydrous 1,2-dichloroethane (prepared by the slow addition of phosphorus oxychloride (0.43 ml, 4.6 mmol) to anhydrous DMF (0.35 ml, 4.6 mmol) in anhydrous 1,2-dichloroethane (6 ml) cooled below 5° C.) a solution of 7-methoxycarbonylindole (0.69 g, 4 mmol) in anhydrous 1,2-dichloroethane (6 ml) was dropwise below 5° C. The mixture was stirred at room temperature for 2 h and then was heated at 50° C. for 30 minutes. After cooling, the precipitate was filtered off and washed with 1,2-dichloroethane. This precipitate was suspended in aq Na2CO3 10% (30 ml) and stirred at room temperature for 20 minutes; dichloromethane was added and stirring was continued 10 minutes more. The organic phase was separated and the aqueous phase was extracted with dichloromethane. The combined organic extracts were washed with brine, dried over anhydrous magnesium sulfate and evaporated to yield 0.75 g (93%) of the entitled product. Mp: 153–4° C.

Provenance & Evidence