State of knowledge in photoredox-catalysed direct difluoromethylation

The direct introduction of diverse fluorinated motifs into feedstock molecules and advanced intermediates is widely studied in pharmaceutical research and drug development. Among the emerging motifs, difluoromethyl CF2H is isosteric and isopolar to hydroxy and thiol, while acting as a lipophilic hydrogen donor. These properties have prompted the recent remarkable progress made in direct difluoromethylation. In this context, photoredox catalysis serving difluoromethylation is a powerful strategy for the construction of CF2H-containing organic compounds. This review describes the recent developments in visible-light-mediated radical difluoromethylation by means of easily accessible sources of CF2H radical donors, with an emphasis on mechanistic considerations.