Stereoselective Introduction of Oxygen Functionalities at the 11β-Position of Erythrinan Skeleton : Total Syntheses of (±)-Erythristemine and (+)-Erythrartine

抄録

Oxidation of 8-oxoerythrinan and 8-oxo-1, 7-cycloerythrinan derivatives with 2 mol eq of ceric ammonium nitrate in alcohols or acetic acid gave the corresponding 11β-alkoxy or acetoxy compounds in moderate yield. Thus, (±)-3, 3, 15, 16-tetramethoxy-1, 7-cycloerythrinan-2, 8-dione and (+)-erysotramidine gave the corresoponding 11β-methoxy and 11β-acetoxy derivatives on oxidation in methanol and in acetic acid, respectively. Those compounds were respectively converted into (±)-erythristemine and (+)-erythrartine in several steps, thus achieving the total synthesis of these alkaloids.