" BISCYCLISATION" SYNTHESIS OF 1,8-DIHYDROXY-9, 1 0- ANTHRAQUINONE (1,8-DHA)

The synthetic route in this work is based on the classical Friedel-Crafts strategy, and began with 1,4-dimethoxybenzene (I), followed by alkylation and selective demethylation of 2-methoxy function in 0x0-acid (3). The orthoformylation to synthesize aldehyde (6) was based on the Reimer-Tieman reaction. Chain extension of this aldehyde required methylation of the hydroxyl group and condensation with pyruvic acid which afforded acid (8) in 85% yield. Two steps reduction process of this acid led to diacid (1 1) in good yield. A direct "biscylisation" of (1 1) afforded diketone (12) as the main product. This compound was converted to (1,8-DHA), 15, via an aromatization process