Preparation of methylene-gem-difluorocyclopropanes 3 was achieved through the selenoxide elimination reaction derived from gem-difluorocyclopropylmethanols 1, while this method can not be applied to non-fluorinated cyclopropylmethanols. The methylene-gem-difluorocyclopropane 3 showed a high reactivity as a Michael acceptor in the reaction with thiol or amine. (C) 1997 Elsevier Science Ltd.