Ring constructions by the use of fluorine substituent as activator and controller

By using the properties of fluorine such as electronic effects: and leaving -group ability, two types of ring-forming reactions have been achieved star ting from fluoroolefins: (i) fluorinated vinyl ketones with a vinyl and/or an aryl group, which undergo fluorine-directed and/or -activated Nazarov, F riedel-Crafts, and tandem cyclizations in their combination to construct hi ghly functionalized and fused ring systems and (ii) gem-difluoroolefins bea ring a nucleophilic center on the carbon delta to the flourines undergo int ramolecular substitution for the fluorine via "anti-Baldwin" 5-endo-trig cl osures leading to ring-fluorinated heterocycles. Throughout these reactions , fluorines function as an activator of the substrates and a controller ove r the reaction pathways.