Aspidosperma nigricans

N-Oxygenated C=N functionalities also occur in plants. Thus, harman N-oxide (har-manine, 9) is the main alkaloid in all parts of Calligonium minimum14. The trunk bark of Aspidosperma nigricans contains the unstable olivacine N-oxide (10)74. Orellanine (11) has been isolated from the toadstool Cortinarius orellanus15. The substance is heat-stable and exerts considerable nephrotoxicity. 

Recent investigation of Aspidosperma nigricans has resulted in the isolation of olivacine IV-oxide (CCLXXXIII-A). This somewhat unstable compound may be reduced to olivacine (CCLVIII) by brief treatment with zinc and mineral acid. The IV-oxide (CCLXXXIII-A) may be prepared from olivacine by perbenzoic oxidation. It is also the initial product of the action of hydrogen peroxide in warm acetic acid on olivacine, a reaction which yields as one of its final products the red isomeric amide, 2-oxo-2,3 dihydroolivacine (CCLXXXIII-B). The IV-oxide may be distinguished from the latter not only by its UV-spectrum... 

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