Ammonia → 3-Methoxy-4-methyl-4H-furo[3,2-b]indole-2-carboxamide

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Reaction Steps

A flask fitted with a Dewar condenser containing dry ice/acetone was cooled in a dry ice/acetone bath and charged with 350 ml of anhydrous ammonia. A few crystals of hydrated ferric nitrate catalyst were added, and the cooling bath was removed. Lithium amide was then generated by the addition, over one hour, of 1.78 g (0.26 mole) of freshly cut lithium metal ribbon. After the addition of 65 ml of cold tetrahydrofuran, a solution of 16.5 g (0.060 mole) of 3-methoxy-4-methyl-4H-furo[3,2-b]indole-2-carboxylic acid ethyl ester in 75 ml of tetrahydrofuran was added over 30 minutes. The Dewar condenser was removed, and the mixture was stirred for 16 hours as the excess ammonia evaporated. The total reaction mixture was added to 600 g of ice/water, and the crude amide product was filtered and washed with water. Recrystallization from aqueous ethanol yielded 11.7 g (79% yield) of final product, mp 174°-177° C. An additional recrystallization as above yielded an analytically pure sample, mp 179°-182° C.

Provenance & Evidence