Species produced by electron transfer to variously substituted bicyclo[3.1.0]hex-3-en-2-ones provide a better insight into the origin of 1,6-addition products sometimes observed by reaction of lithium diorganocuprates with β-cyclopropyl α-enones. Cyclic voltammetry of eight such bicyclohexenones show that the half-lives of the corresponding anion radicals are very short (t12⩽10−4s) except when the