The Regioselective Cleavage of Aryl Tosylates by Electrochemical Reduction

The electrochemical reductions of eight bis(tosyloxy)benzenoid compounds were studied as a method for the regioselective cleavage of aryl tosylates. For the methyl bis(tosyloxy)benzoate isomers, a strong preference was observed for cleavage of the tosyl group in conjugation with the electron-withdrawing ester moiety. Thus it was possible to selectively cleave tosyl groups to the ortho or para positions over tosyl groups at the meta positions. The bis(tosyloxy)anisole isomers displayed the opposite regioselectivity favoring cleavage of tosyl groups that were meta to the electron-donating methoxy substituent. The general electrochemical process for the reduction of aryl tosylates has been shown to be selective, high yielding, and reproducible on gram quantities.