Nucleophilic allylation, alkali-metal alkyl

The driving force in the mechanism of these reactions is the formation of an alkyl cation R , attacking the neighboring nucleophilic group at the metal center either a halide or an alkoxide. The reaction is facilitated by the improved stability of involved alkyl cation CH2=CH—CH2 (allyl)>C6H5CH2 (benzyl)>(CH3)3C (t-but>d)>(CH3)2CH (i-prop)d)>CH3CH2 (ethyl)>CH3 (methyl) [130] and catalyzed by both acids (e.g., traces of water/humidity, especially when halides are applied [131]) and bases (alkali or alkaline earth alkoxides [132]). 

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