Methylation and Hydroxylation Studies on Aloe-emodin

Article abstract of DOI:10.1021/jo01289a004

The chemistry of aloe-emodin (3) has been explored with a view toward its use as a synthon for the regiospecific synthesis of adriamycin and analogues of it.Routes for satisfactory large-scale monomethyl ether formation at C8 (4) and regiospecific introduction of a phenolic oxygen function at C4 (21) are described.Interesting side reactions were encountered, including an apparent peri O to O acyl wandering reaction during methylation and a reductive debromination reaction during displacement of an aryl bromide by methanolic methoxide.