Stereoselective Introduction of Oxygen Functionalities at the 11.BETA.-Position of Erythrinan Skeleton: Total Syntheses of (.+-.)-Erythristemine and (+)-Erythrartine.
1,7-cyclo-cis :erythrinan-8-one with ceric ammonium nitrate in methanol gave the appreciable yields of the corresponding 11β-methoxy compounds; these were converted into the natural 11-oxygenated erythrinan alkaloid, erythristemine, in high yield.