A stereoselective synthesis of a chiral anthracyclinone AB-synthon from a carbohydrate precursor

Reaction of tetralinol 5 with phenylboronic acid removed the isopropylidene group with concomitant formation of phenylboronate 12. Oxidation of the latter with PCC gave keto-ester 13, a key intermediate in the synthesis of enantiopure anthracyclinones. Attempts at cleavage of the isopropylidene group in 5 by the usual procedures led first to substitution and epimerization at the benzylic position, then removal of the acetonide followed by formation of the cyclic ether 11a as the final product.