Ammonia → 4,5-Dihydro-5-methyl-4-oxopyrano[3,2-b]indole-2-carboxamide
Reaction equation
[CH3:1][N:2]1[C:10]2[CH:9]=[CH:8][CH:7]=[CH:6][C:5]=2[C:4]2[O:11][C:12]([C:16]([O:18]CC)=O)=[CH:13][C:14](=[O:15])[C:3]1=2.[NH3:21]>C(O)C>[CH3:1][N:2]1[C:10]2[CH:9]=[CH:8][CH:7]=[CH:6][C:5]=2[C:4]2[O:11][C:12]([C:16]([NH2:21])=[O:18])=[CH:13][C:14](=[O:15])[C:3]1=2Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
A suspension of 11.0 g (40.7 mmole) of ethyl 4,5-dihydro-5-methyl-4-oxopyrano[3,2-b]indole-2-carboxylate in 500 ml ethanol was stirred in ice while gaseous ammonia was added until the reaction mixture temperature reached 20° C. (ca. 10 min). The ice bath was removed, and stirring at room temperature was continued for a total of 24 hr. The light yellow solid was filtered and washed with a little cold ethanol. Recrystallization from 50% aqueous DMF gave light yellow needles of mp >295° C.