Synthetic Approaches to Anthracyclinones from Carbohydrates

Abstract

The Diels-Alder reaction of a cyclic carbohydrate enone with o-xylylenes derived from 1,2-bis (bromomethyl)benzene and 2,3-bis (bromomethyl)naphthalene by treatment with zinc powder under ultrasound irradiation afforded tri- and tetra-cyclic products which were converted into optically pure, functionalised hexahydro-anthracene and -naphthacene derivatives. The latter compounds have the carbon framework, A-ring functionality and stereochemistry similar to those of some anthracyclinones hence a potentially novel route to these pharmaceutically important compounds has been opened. The synthesis of a tricyclic analogue of α1-rhodomycinone with the required A-ring functionality was accomplished by the reaction of a hexahydro-anthracene-based ketone with methyllithium but attempts to achieve the B-ring functionality were not successful. The reaction of levoglucosenone with o-xylylene gave three products - an adduct and two novel tertiary alcohols which were formed by a nucleophilic attack on the carbonyl group.