A GENERAL METHOD FOR THE SYNTHESIS OF POLYCYCLIC AROMATIC HYDROCARBONS BASED ON SEQUENCIAL CATIONIC CYCLIZATIONS

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Fluorine substituent has an α-cation-stabilizing effect as well as a leaving-group ability as a fluoride ion. Using these two properties in combination allows α-fluoro carbocations to be readily generated from fluoroalkenes and fluoroallenes. We have succeeded in highly efficient and selective domino and tandem cyclizations, which proceed via the α-fluoro carbocations to construct PAHs such as helicenes and acenes including higher-order helicenes. Moreover, fluorinated PAHs are produced by our methods. In the course of study, we have also established facile methods for the syntheses of 1, 1-difluoroalkenes and 1, 1-difluoroallenes as starting materials of our cyclizations.