Anthracyclines. Part 3. The total synthesis of 4-demethoxydaunomycin

Abstract

Procedures selected from our earlier work have been applied to the synthesis of (+)-4-demethoxydaunomycinone (10) and (–)-4-demethoxy-7,9-bisepidaunomycinone. 4-Demethoxydaunomycin has been prepared from the (+)-aglycone by specific glycosidation using 1-chloro-4-O-p-nitrobenzoyl-3-N-trifluoroacetyldaunosamine and silver trifluoromethanesulphonate as catalyst. Analogous glycosidation of the (–)-algycone has given 4-demethoxy-7,9-bisepidaunomycin whose properties differ from those previously reported.