Highly Reactive Hydrocarbon Soluble Alkylsodium Reagents for Benzylic Aroylation of Toluenes using Weinreb Amides

Deaggregating the alkyl sodium NaCH2SiMe3 with polydentate nitrogen ligands enables the preparation and characterisation of new, hydrocarbon soluble chelated alkylsodium reagents. Equipped with significantly enhanced metalating power over their organolithium counterparts, these systems can promote controlled sodiation of weakly acidic benzylic C−H bonds from a series of toluene derivatives under mild stoichiometric conditions. This has been demonstrated through the benzylic aroylation of toluenes with Weinreb amides, that delivers a wide range of 2‐arylacetophenones in good to excellent yields. Success in isolating and determining the structures of key organometallic intermediates has provided useful mechanistic insight into these new sodium‐mediated transformations. Exploiting coordination effects to prepare hydrocarbon‐soluble alkyl organosodium reagents enables the efficient metalation of toluene derivatives under mild and stoichiometric conditions, and their facile conversion into 2‐arylacetophenones. Through the isolation of key organometallic intermediates and their study in solution, new mechanistic insights have been gained into these sodium‐mediated reactions.