Condensed benzopyrans III. 3H,4H[1] benzopyrano [3,4-b] pyrrol-4-ones

The diazotization of 3-aminocoumarin followed by its reduction gave the cournarin-3-yl-hydrazine which, without isolation, reacted with various carbonyl compounds in a Fisher's indohzation reaction to give derivatives (Ib-Ih) of the yet unreported system 3H,4H1]benzopyrano3,4-b]pyrrol-4-one.