The reaction of cis and rans 2-iodomethyl 1-tosyloxycyclohexanes and 4-enes with nBuLi was studied and found to be stereospecific, the products being respectively bicyclo (4.1. 0) hexane (ene) cis and methylene cyclohexane (ène). A parallel is drawn between this reaction and alkaline deshydrohalogenation of cyclic 1, 2-halohydrins; a reaction pathway is proposed.