It has been reported that trimethyl (trifluoromethy1)-tin releases difluorocarbene at 150".'We report here a procedure that allows utilization of this compound in CF2 generation at 80" in a nonbasic medium to give, in the presence of olefins, gem-difluorocyclopropanes in very good yield. This procedure also can be used to generate CClz from C6HSHgCC12X (X= C1 and Br) at room temperature. Several examples serve to illustrate the utility of our method. ...