10.1016/S0040-4039(00)82413-2
The research focuses on the biomimetic synthesis of hexahydrobenzo[c]phenanthridine alkaloids, specifically (+)-corynoline, (+)-ll-epicorynoline, (+)-isocorynoline, and (+)-ll-epiisocorynoline, from the protoberberine alkaloid corysamine. The purpose of this study was to develop a novel and efficient synthetic route that mimics the biogenetic process, providing a general method for the synthesis of these alkaloids. The researchers achieved this by transforming corysamine into the target alkaloids through a series of chemical reactions involving enamine-aldehyde (3) as a proposed biogenetic intermediate. Key chemicals used in the process included thallium (III) nitrate for oxygenation, sodium borohydride, hydrochloric acid, and sodium cyanoborohydride for reduction and cyclization, as well as lithium aluminum hydride and sodium cyanoborohydride for further reduction steps. The conclusions of the study were that the developed synthetic method was not only biomimetic but also simple and efficient, offering a practical approach to synthesizing hexahydrobenzo[c]phenanthridine alkaloids.