Anthracyclines Friedel-Crafts reaction

Dihydioxytetiahydionapthacenedione derivatives, used as intermediates for the anthracycline antibiotics have been prepared by Friedel-Crafts reaction of tetralin derivatives with orthophthaloyl chlotide [88-95-9J in high yields (93). 

The hydroxylated anthraquinone chromophore of the anthracyclines would seem an ideal candidate for synthesis through two Friedel-Crafts acylations, either in a concurrent or a stepwise manner with formation of ring C. However, the fact that the first acylation deactivates the future ring B toward further electrophilic substitution necessitates vigorous reaction conditions, and this... 

Numerous synthetic approaches to anthracyclines are based on carbanion mediated cyclisations. These reactions often occur under mild conditions, allowing incorporation of highly functionalised precursors. Some approaches follow an initial base-catalysed coupling of two fragments by cyclisation under Friedel-Crafts conditions (previous section), while other strategies bring about both condensation and cyclisation under basic conditions. Syntheses based on closure of rings C, B or A have been described. 

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