New synthesis of condensed heterocycles from isoxazole derivatives VI . 2,5‐Dimethyl‐3‐aeetyl‐7‐amino‐1 H ‐pyrrolo[3,2‐b] pyridine

A new synthesis of pyrrolo[3,2‐ b ] pyridine starting with pyrrole ring is described. The procedure allows the synthesis of 4‐azaindoles bearing a sensitive group at C‐7. The nitration of 4b with nitric acid and acetic anhydride at −15° gave 5 . The hydrogenation of 5 led to simultaneous reduction of N ‐hydroxy and nitro groups and to hydrogenolysis of the isoxazole nucleus, affording an appropriate chain of atoms to building up the pyrrolo[3,2‐ b ] pyridine ring.