Electrochemical reduction of bicyclic 1,1-dibromocyclopropans in DMF or THF at a sacrificial magnesium anode in the presence of chlorotrimethylsilane proceeds with replacement of one or both bromine atoms by the trimethylsilyl group, depending on the amount of current passed. a novel ultrasonically induced "anodic reduction" process is described : sonication during electrolysis results in an apparent increase in current efficiency. This has been shown to involve sonochemical formation of the same products at the anode which are produced electrochemically at the cathode.