Reductive cyclisation of propargyloxy and allyloxy alfa-bromoester derivatives using environmentally friendly electrochemical methodologies

Abstract

The electrochemical intramolecular cyclisation of alfa-bromo propargyloxy (1 and 2) and allyloxy (3) esters was carried out in ethanol and in ethanol–water mixtures as environmentally friendly systems using Ni(II) complexes as the catalysts. The reduction of the substrates proceeds via one-electron cleavage of the carbon–bromine bond to form a radical-type intermediate that undergoes cyclisation to afford cyclic ethers in moderate to good yields.