Organolithium addition to styrene and styrene derivatives: scope and limitations

Abstract

Styrene and a range of aryl-substituted styrene derivatives are shown to undergo efficient carbolithiation–trapping reactions in diethyl ether at −78 to −25 °C. The reactivities of different types of organolithium reagents were found to be: tertiary, secondary > primary; ≫ alkenyl, methyl, phenyl. Electron donating groups (e.g. methoxy and dialkylamino) at the ortho- or para- positions of the benzene ring deactivate the double bond towards organolithium addition, but their reactions with butyllithium can be facilitated by using TMEDA as co-solvent. 2-Benzyloxystyrene and 2-allyloxystyrene undergo efficient carbolithiation at −78 °C, but at room temperature alkyl transfer occurs, generating the corresponding alkylated phenol. 2-Vinylnaphthalene also undergoes carbolithiation–carboxylation in reasonable yield.