Radical Chain Monoalkylation of Pyridines

21 May 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and does not require the use of an external oxidant. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M–1 s–1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radical to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction could be extended to a three component carbopyridinylation of electron rich alkenes including enol esters, enol ethers and enamides.


Kinetic study
Three-component reactions
carboarylation of alkene
Alkoxyl Radicals
homolytic substitution
Organoboron Reagents

Supplementary materials

SI full subm


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