In the first paper of this series (de Waal, 1939) the isolation and chemical properties as well as the results of the preliminary hydrolysis and of the hydrogenation of the alkaloid isatidine were recorded. This alkaloid is the active principle particularly of Senecio isatideus, but was also found to be present in very much smaller quantities in S. retrorsus D.C. It was then found that when isatidine was hydrogenated in the presence of platinum dioxide four molecules of hydrogen were consumed, which at the time could not be explained. Continuous efforts have since led to the repeated and facilitated isolation of the reduced compound in the crystalline form, and this as well as some other structural results on isatidine are now reported upon.
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