Efficient and novel one-pot synthesis of polycycles bearing cyclols by FeCl3-promoted [2 + 2] cycloaddition: application to cannabicyclol, cannabicyclovarin, and ranhuadujuanine A

Simple and facile synthetic routes for the preparation of biologically interesting cyclol bearing polycycles were developed using FeCl3-promoted [2 + 2] cycloaddition from readily available benzopyrans possessing a variety of substituents. As examples of this methodology, one-step syntheses of cannabicyclol, cannabicyclovarin, and ranhuadujuanine A were accomplished in good yield.