Treatment of 1,6-dialkylhexa-1,5-diene-3,4-diones with bis(iodozincio)methane at -78 degrees C for several hours gave cis-dialkenylcyclopropane-1,2-diols which rearranged into the zinc alkoxides of cis-5,6-dialkylcyclohepta-3,7-diene-1,3-diol in good yields at room temperature as a one-pot reaction. The reaction should be performed under the careful temperature control. When the reaction was performed using a microflow system, these two-step reactions were able to be performed in a few seconds at room temperature.