Experiments Directed Towards the Synthesis of Anthracyclinones. XIX. Elaboration of 2-Formylquinizarin Through a Wittig Reaction

Reaction of 2-formylquinizarin dimethyl ether (3) with the dimethoxy ylide (6) gives an α,β -unsaturated ester (8) which on hydrogenation, reduction and methylation gives the tetramethoxyanthracene diester (18). When linked to work by Dotz and Popall this sequence provides a route to (±)-4-demethoxydaunomycinone.