Ammonia → furo(3,4-b)pyridin-5(7H)-one

Participants

Reaction Steps

20.0 g of quinolinic anhydride, 80 ml of acetic acid, 20.3 g of N-ethyl-2-methylindole and 2.74 g of zinc chloride are stirred at 20° C. for 5 hours. 23.6 g of 3-(N,N-diethylamino)-phenetole and 30 ml of acetic anhydride are then added, after which the reaction mixture is warmed to 50° to 60° C. and stirred at this temperature for 2 hours. After addition of 170 ml of 30% aqueous ammonia and 100 ml of water, the product precipitates as a paste and is isolated. 160 ml of isopropanol are added to the paste and the mixture is refluxed for 1 hour. After cooling, the recrystallised product is filtered off, washed with isopropanol and dried, affording 46.9 g of the isomer-free 4-azaphthalide compound of the formula ##STR15## of melting point 156° to 158° C.

Provenance & Evidence