Ecole Nationale Superieure de Chimie de Montpellier 1 article published in JoVE Chemistry Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes Tarun Kumar1,2, Amira Ben Hassine1, Agathe Martinez1, Dominique Harakat1, Sylviane Chevreux1, Fabien Massicot1, Marc Taillefer2, Jean-Bernard Behr1, Jean-Luc Vasse1, Florian Jaroschik1,2 1Institut de Chimie Moléculaire de Reims UMR 7312, Université de Reims Champagne Ardenne, 2Institut Charles Gerhardt Montpellier UMR 5253, Ecole Nationale Supérieure de Chimie de Montpellier This protocol describes the preparation of elemental lanthanides under inert atmosphere and their application in a selective C-F activation process involving trifluoromethylated benzofulvenes.