The homolytic aromatic substitution of nitrogen containing heterocycles is a versatile and well-studied class of transformations and is a viable reaction for late-stage functionalization of organic compounds.

The alkylation or acylation of a protonated, electron-poor heteroaromatic base using a nucleophilic carbon-centered radical was extensively studied by Minisci. Due to polar effects, the reaction shows selectivities that would be impossible to obtain under Friedel-Crafts reaction conditions.^[1]

However, the reaction suffers from drawbacks such as use of a stoichiometric amount of oxidant, low regioselectivity and polyalkylation. Due to its viability in natural product synthesis and -functionalization, it is of great interest to overcome this reaction’s limitations.

Herein, we describe a method that uses non-protic activation of the substrate. Alkylboranes (RBCat^[2,3], R₃B) react with N-methoxypyridinium salts in the presence of a radical initiator to afford substituted pyridines. Interestingly, no external oxidizing agent is required to run this reaction. The scope and limitation of this reaction will be discussed.

[1] M. A. J. Duncton, Med. Chem. Commun. 2011, 2, 1135–27.
[2] A.-P. Schaffner, P. Renaud, Eur. J. Org. Chem. 2004, 2291–2298.
[3] C. E. Garrett, G. C. Fu, J. Org. Chem. 1996, 61, 3224–3225.