Toward new camptothecins. Part 4: On the reactivity of nitro and amino precursors of aza analogs of 5-methoxycarbonyl camptothecin

In the context of formation of new aza analogs of camptothecin, nitration then reduction of condensed pyridones was realized, leading to new derivatives of pyrrolo-aza-indoles. Treatment of these compounds with hydrobromic acid led to new structure rearrangements while oxidation of the α-position was unsuccessful. Mechanisms of formation of the new products are discussed.