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.

Automated summary

Deaggregation of alkyl sodium NaCH2SiMe3 with polydentate nitrogen ligands allows the preparation and characterization of new, hydrocarbon soluble chelated alkylsodium reagents. These systems, equipped with significantly enhanced metalating power, can promote controlled sodiation of weakly acidic benzylic C-H bonds from a series of toluene derivatives under mild stoichiometric conditions. The successful isolation and determination of the structures of key organometallic intermediates provide useful mechanistic insights into these new sodium-mediated transformations.