Cobalt-catalyzed chelation-assisted alkylation of arenes with primary and secondary alkyl halides
Date of Issue2014
School of Physical and Mathematical Sciences
Cobalt–N-heterocyclic carbene catalytic systems have been developed for chelation-assisted ortho-alkylation of aromatic compounds with alkyl halides. Aryl imines can be selectively monoalkylated at room temperature by various primary or secondary alkyl chlorides or bromides. The catalytic system can also be applied to 2-arylpyridine derivatives, which in the absence of steric hindrance are amenable to dialkylation by an excess of the alkyl halide. Mechanistic experiments, including reactions of stereochemical probes and radical clocks, indicate that the reaction involves single-electron transfer from the cobalt center to the alkyl halide to form the corresponding alkyl radical, which has a finite lifetime before it undergoes C–C bond formation.
© 2014 Georg Thieme Verlag Stuttgart. This is the author created version of a work that has been peer reviewed and accepted for publication by Synthesis, Georg Thieme Verlag Stuttgart. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1055/s-0033-1338658].