1-dibromo-2-vinylcyclopropane derivatives with MeLi yielded cyclopentadienes as the main products together with small amounts of allenic compounds (Table 1). By the same reaction 2,2,2′,2′-tetrabromobicyclopropyl derivatives yielded, in all but one case, only small amounts of diallenes; the exception is the exclusive formation of 2,7-dimethyl-2,3,5,6-octatetraene, (XIII) from2,2,2′,2′-tetrabromo-3,3,3′,