LEWIS ACID-INDUCED ENE-CYCLIZATION OF OMEGA-OLEFINIC TRIFLUOROMETHYL KETONES - ACCESS TO ALICYCLIC COMPOUNDS BEARING A CF3 GROUP

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.