Radical chain monoalkylation of pyridines

Abstract

N-Methoxypyridinium salts are exceptionally reactive radical traps that can be used in efficient radical chain reactions with organoboranes.

Visible-Light-Catalyzed Tandem Radical Addition/1,5-Hydrogen Atom Transfer/Cyclization of 2-Alkynylarylethers with Sulfonyl Chlorides

“…One of them entails the direct generation of the reactant radical from the solvent radical via a radical relay process. 8 The second method relies on the redox chemistry between the solvent radical and catalyst to promote the catalytic cycle. 9 We envisioned that sulfonyl-functionalized dihydrobenzofurans could be synthesized from 2-alkynylarylethers and sulfonyl chlorides under visible-light catalysis by employing 2-MeTHF as the solvent and assisted impetus (Scheme 1).…”

“…Currently, there are two methods for enabling solvent-radical relay. One of them entails the direct generation of the reactant radical from the solvent radical via a radical relay process . The second method relies on the redox chemistry between the solvent radical and catalyst to promote the catalytic cycle .…”

Regioselective Syntheses of 2,3,5-Trisubstituted Pyridines via 5-Chloro-3-fluoro-2-(methylsulfonyl)pyridine

“…Many methods have been developed for the synthesis of functionalized pyridines containing various substitution patterns. These methods generally fall into one of three categories: (1) synthesis of the pyridine ring via condensation or cycloadditions, − (2) functionalization of simpler (unfunctionalized) pyridines via reactions mediated by radical, polar, or organometallic intermediates, − and (3) derivatization of prefunctionalized pyridine building blocks. , The last approach is particularly attractive, as high yields are often reached under practical reaction and workup conditions if the desired building block is readily accessible. Moreover, the reaction regioselectivity is determined by the substitution pattern of the starting pyridine building blocks.…”