Utilization of Protopine and Related Alkaloids. III. Acid Catalyzed Cyclization of Anhydromethylberberine. The Revised Structures for Hydroxyisoanhydrodihydromethyl-berberine and Isoanhydromethylberberine

Abstract

When anhydromethylberberine derived from α-allocryptopine was treated with dilute hydrochloric acid, it gave three products, whose structures were identified to contain the spiro-type skelton instead of"Perkin's compound"by the nuclear magnetic resonance spectroscopy.