Lewis acid-induced ene-cyclization of ω-olefinic trifluoromethyl ketones: access to alicyclic compounds bearing a CF3 group

Abstract

Several catalysts (Me₂AlCl, MeAlCl₂, EtAlCl₂ and TiCl₄) for the ene carbocyclization of olefinic trifluoromethyl ketonic compounds have been compared. Thus, five-, six-, seven- and eight-membered-ring compounds were obtained. Olefin regiochemistry and stereoselectivity are better controlled than in related non-fluorinated series. High yields of cyclic trifluoromethyl alcohols were obtained by the achievement of type-I, -II or -III ene processes, concerted or otherwise. The first example of an eight-membered cyclization is described.