Stereochemistry of Allylic Metallations

Compounds like cyclopentadiene, indene, and fluorene are considerably more acidic than the normal olefinic hydrocarbons. Their metallation can be conveniently achieved with a variety of basic reagents, including the conventional ones, such as butyllithium and alkali amides in liquid ammonia [17,18]. 

Schlosser M, Hartmann J, David V (1974) Helv Chim Acta 57 1567 

Klusener PAA, Hommes HH, Verkruijsse HD, Brandsma L (1985) J Chem Soc Chem Comm 1677 

Kloosterziel H, van Drunen JAA (1970) Reel Trav Chim Pays-Bas 89 368 

The allylic metal derivative formed by deprotonation of a 1-alkene or 2-alkene (at the most acidic allylic position) can occur in two conformations  

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