Cationic Cyclizations of Fluoro Alkenes: Fluorine as a Controller and an Activator

摘要

A new function of fluorine as a synthetic tool has been discovered in cationic cyclizations. Ring-forming reactions via fluorine-containing carbocations have been achieved starting from fluoro alkenes by using the properties of fluorine, such as electronic effects and leaving-group ability. Fluoro alkenes with an alkenoyl or an aryl group undergo fluorine-directed and -accelerated Nazarov-type or Friedel-Crafts-type cyclizations, respectively. These cyclizations and their domino cyclizations allow the efficient construction of highly functionalized and fused ring systems. Throughout the reactions, fluorine functions as a controller over the reaction pathways and an activator of the substrates.