A general and highly efficient asymmetric synthesis of optically active anthracyclinones

The title asymmetric synthesis has been developed by featuring bromolactonization of (?)-acetals, derived from 2-acetyl-3,4-dihydronaphthacene-6,11-diones and (2R,3R)-(+)-N,N,N′,N′-tetraalkyltartaric acid diamides, as a key diastereoselective reaction. The produced bromolactone mixtures could be readily converted to the highly optically active key synthetic intermediates of 4-demethoxy- and 11-deoxy-4-demethoxyanthracyclinones.