Studies of the selective O-alkylation and dealkylation of flavonoids. XVI. Demethylation of 2'-methoxyacetophenones with anhydrous aluminum chloride or bromide in acetonitrile

Article abstract of DOI:10.1246/bcsj.67.511

Demethylation of 2'-methoxyacetophenones with anhydrous aluminum chloride in acetonitrile was studied to survey its scope and limitations. The mechanism which the reaction proceeds via sterically constrained intermediates was proposed from the substituent effects. Additionally, dealkylation of 2'-benzyloxy-, 2'-ethoxy-, and 2'-isopropoxyacetophenones with two demethylating reagents, hydrochloric acid in acetic acid and anhydrous aluminum bromide in acetonitrile, was studied. It was found that the reactivity was greatly affected by the steric factor between the alkoxyl group and reagent. This behavior may have wide application in selection of protecting groups in organic synthesis.