Total Syntheses of (±)-Gusanlung A,(±)-Gusanlung D and 8-Oxyberberrubine and the Uncertainty Concerning the Structures of (-)-Gusanlung A,(-)-Gusanlung …
Abstract:(±)-Gusanlung A, 8-oxyberberrubine and (±)-gusanlung D have been synthesized by radical cyclisation of the corresponding 2-aroyl-1-methylenetetra-hydroisoquinolines. The 1 H and 13 C spectra of (-)-gusanlung D were found to be different from those of synthetic (±)- gusanlung D. Careful analyses of the 13 C spectra of (–)-gusanlung A and natural 8- oxyberberrubine also cast doubt on the correctness of the structures previously assigned ...