Dearomatization through Halofunctionalization Reactions

Recent advances in dearomatization through halofunctionalization reactions are summarized in this Minire-view. Two general categories of strategies are currently employed in this field. On one hand, the reaction can be initiated with electrophilic halogenation at an alkyne or alkene moiety. The resulting halonium ion intermediate is then captured by a pendant aromatic ring at the ipso position, affording the dearomatization product. On the other hand, electrophilic halogenation can directly take place at a substituted arene, and the final dearomatization product is furnished by deprotonation or intramolecular nucleophilic trap. Highly enantioselective variants have been realized in the latter case by organocatalysis or transition metal catalysis. By applying these methods, various valuable halogenated polycyclic molecular architectures have been obtained from readily available starting materials.