Synthesis of 2,2-difluoro-homoallylic alcohols via ring-opening of gem-difluorocyclopropane and aerobic oxidation by photo-irradiation in the presence of an organic pigment.

We found that aerobic oxidation took place after the visible light-mediated ring-opening reaction of gem-difluorocyclopropane in the presence of an organic dye and amine to furnish 2,2-difluoro-homoallylic alcohols in good yields.

Synthesis of gem-difluoromethylene building blocks through regioselective allylation of gem-difluorocyclopropanes.

gem-Difluorocyclopropane derivatives react with allyltributylstannane in the presence of 2,2'-azobis(isobutyronitrile) to afford 1,6-dienes with a gem-difluoromethylene moiety at the allylic position. The reaction proceeds regioselectively with high yields, and the 1,6-dinenes obtained are good precursors for cyclic systems containing a gem-difluoromethylene moiety. Although S-methyl carbonodithioate also works as a leaving group, rearrangement of the leaving group competes with the desired allylation, depending on the amount of allyltributylstannane.