Development of a Strategy for Convergent Total Synthesis of the Aureolic Acid Antitumor Antibiotics

It has been found that condensation of an o-toluate carbanion with a 3-alkoxycyclohexen-2-one will produce the dihydroanthracenone system found in olivin (3) and chromomycinone (4), the aglycons of the aureolic acids. Several examples of this reaction are described, leading to synthesis of model aromatic systems 17, 18, 21, 23, 24, and 26. A route to compound 34, having the complete carbon framework and most of the functionality of olivin, has been developed which uses the above type of condensation as the critical step.