Photoredox-catalysed regioselective synthesis of C-4-alkylated pyridines with N-(acyloxy)phthalimides

A method of direct C-4 selective alkylation of pyridines under visible light irradiation at room temperature has been reported, using simple maleate-derived pyridinium salts as pyridine precursors and the readily available carboxylic acid-derived N-(acyloxy)phthalimides as alkyl radical precursors, affording good to excellent yields without using stoichiometric oxidants and acids. A broad range of primary, secondary, and tertiary carboxylates can be used as alkylation reagents. Oxidant and acid-sensitive functional groups can be tolerated well.

Automated summary

A method of direct C-4 selective alkylation of pyridines under visible light irradiation at room temperature is reported. The method uses simple maleate-derived pyridinium salts as pyridine precursors and readily available carboxylic acid-derived N-(acyloxy)phthalimides as alkyl radical precursors, affording good to excellent yields without using stoichiometric oxidants and acids.