Dinitrostrycholcarboxylic acid

A number of guesses had already been made concerning the over-all structure of these alkaloids all such structures contained a quinoline or isoquinoline ring system because of the unproved view, current for a long time, that dinitrostrycholcarboxylic acid was a quinoline or isoquinoline derivative. Thus Robinson, in his Bakerian lecture to the Royal Society in 1930 (19), proposed structure XIV1 for strychnine. Not long... 

The most probable formula for dinitrostrycholcarboxylic acid is I, for alternative formulas with the carboxyl attached to the benzene nucleus are highly improbable in view of the simultaneous formation of picric acid and 3,5-dinitrobenzoic acid, and secondly because of the oxidation (alkaline permanganate) of strychnine to oxalylanthranilic acid (XI) (114). These other alternatives are definitely precluded by a consideration of the relation of strychnine to brucine and of the course of the degradation of the aromatic nucleus in derivatives of both these alkaloids. 

---