Reaction of 1,3-cyclohexadiene with dibromo-and with dichlorocarbene gave 7,7dibromo-(Ia, X=Br) and 7,7-dichlorobicyclo [4.1.0] heptene-[2] (Ib, X=Cl) respectively.Both compounds were further characterized by hydrogenation to give 7,7-dibromo-and 7,7-dichlorobicyclo [4.1.0] heptane and by oxidation to yield β-[2-carboxy-3,3-dibromoand β-[2-carboxy-3,3-dichlorocyclopropane] propionic acid respectively.