Electrochemical intramolecular cyclisation of propargyl bromoethers catalysed by nickel complexes

Abstract

The electrochemical intramolecular cyclisation of propargyl 2-bromoethers 1–3 in N,N′-dimethylformamide at constant current in a diaphragmless cell has been developed using NiII complexes as electron-transfer mediators. During controlled-current electrolyses of solutions of NiII complexes in the presence of bromoethers, catalytic reduction of the latter proceeds via one-electron cleavage of the carbon–bromine bond to form a radical intermediate that undergoes cyclisation to afford the cyclic compounds in moderate to good yields.