Regioselective Propargylation of Aldehydes and Ketones by Electrochemical Reaction using Zinc and Aluminum Anodes

Electrochemical propargylation of aldehydes and ketones with unsubstituted or α-substituted propargylic bromides using platinum cathode and zinc anode proceeded efficiently under mild conditions to give the corresponding homopropargyl alcohols exclusively in high yields. Similar electrochemical propargylation with γ-substituted propargyl bromides gave the corresponding homoallenyl alcohols as major products. Regioselectivity in the introduction of a propargyl or an allenyl group was controlled simply by a change of the anode material, zinc or aluminum.