H. Schmidhammer et P. Schwarz, UNEXPECTED REACTION OF MIXED AZINES OF DI HYDROCODEINONE WITH METHANESULFONIC-ACID, Liebigs Annalen der Chemie, (4), 1994, pp. 445-447
By treatment of the mixed azines 7 and 8 with methanesulfonic acid in
dimethyl sulfoxide the corresponding pyrroles 9 and 10 were not obtain
ed. In both cases the main product was the pyrrole 11, which was also
synthesized from dihydrocodeinone azine (12) by reaction with methanes
ulfonic acid in dimethyl sulfoxide.