Syntheses of Anthracyclines and Fredericamycin A via Strong Base-Induced Cycloaddition Reaction of Homophthalic Anhydrides

Abstract

Strong base-induced cycloaddition reactions of homophthalic anhydrides with quinone derivatives afford peri-hydroxyl aromatic compounds in a regioselective manner. The reactions have been applied to the syntheses of biologically important natural products. This review focuses on the following topics: (i) preparation of homophthalic anhydrides from homophthalic acids using (trimethylsilyl)ethoxyacetylene, (ii) strong base-induced cycloaddition of homophthalic anhydrides with the carbon-carbon double bond and the reaction mechanism, especially addressing the regiochemistry of the reaction, and (iii) application of the reaction to the efficient asymmetric syntheses of anthracyclines and fredericamycin A.