For the metalation of allylic and benzylic positions Me3SiCH2K is the most powerful reagent. BuLi in the presence of KOCMe3, however, can usually replace it. Olefinic and cyclopropane H atoms are most readily attacked by pentylsodium, esp. in the presence of KOCMe3. Me3SiCH2K, however, will work equally if an activating group, such as MeO, is present in the substrate. [on SciFinder (R)]