On the chemistry of Beckurt’s test for physostigmine: A novel hydride transfer

Beckurt treated physostigmine hydrochloride with dilute potassium permanganate solution and observed separation of manganese dioxide. Since at first sight there is no reaction site for this oxidation, it was interesting to clear up the reaction route of this test. Acid hydrolysis of this O-phenylcarbamate yielded the phenolic derivative of the three-ring indole alkaloid hydrochloride. Now are present at para-position an electrodotic group and a positive charged nitrogen atom. However, this nitrogen has an octet of electrons; thus, for reaction to occur a hydride ion must be displaced. This can happen in the presence of a hydride acceptor, that is, by reduction of permanganate ion. This chemical deportment has been postulated recently in a completely different reaction sequence. So, our proposal is a novel one. The mechanism of the following inorganic steps to the final product has not been advanced, and it is provided in this communication.