Triplet Energy Transfer Mechanism in Copper Photocatalytic N‐ and O‐Methylation

Abstract

AbstractMethylation reactions are chemically simple but challenging to perform under mild and non‐toxic conditions. A photochemical energy transfer strategy was merged with copper catalysis to enable fast reaction times of minutes and broad applicability to N‐heterocycles, (hetero−)aromatic carboxylic acids, and drug‐like molecules in high yields and good functional group tolerance. Detailed mechanistic investigations, using kinetic analysis, aprotic MS, UV/Vis, and luminescence quenching experiments revealed a triplet‐triplet energy transfer mechanism between hypervalent iodine(III) reagents and readily available photosensitizers.