Domino Friedel-Crafts-Type Cyclizations of Difluoroalkenes Promoted by the α-Cation-Stabilizing Effect of Fluorine: An Efficient Method for Synthesizing Angular PAHs
based on 6/n/m/6 ring systems (n,m=5–7) in good to high yields. Protonation of 1,1‐difluoroalka‐1,3‐dienes took place at their electron‐rich methylene (CH2) carbon atoms in the presence of milder acids such as camphorsulfonic acid and trifluoromethanesulfonic acid. Domino cyclizations of the resulting fluorine‐stabilized allylic carbocations afford carbocycles based on 6/6/6/6 or 6/6/5/6 ring systems in