Photooxidative Copper(II) Catalysis for Promoting anti-Markovnikov Hydration of Alkenes

Photoredox catalysis enables the generation of radical intermediates under mild conditions, yet photoredox catalysts have heavily relied on precious transition metal complexes. Therefore, the development of photocatalysts based on earth-abundant metals is increasingly demanded. Here, we report a highly photooxidative capability of a heteroleptic copper(II) complex for promoting anti-Markovnikov hydration of alkenes. The copper(II) complex containing bathophenanthroline and 3,4-dimethoxybenzenethiolate ligands is generated in situ from copper(II) chloride dihydrate. Upon visible-light irradiation, the copper(II) complex is photoexcited and exhibits an excited-state lifetime sufficiently long to oxidize various alkenes, including aliphatic substrates. Consequently, anti-Markovnikov hydration can be achieved under mild conditions, and the late-stage functionalization of natural products and pharmaceutical derivatives is also feasible. The developed catalytic system can be extended for photooxidative reactions of alkenes, such as intramolecular cyclization reactions and anti-Markovnikov addition of nucleophiles other than water. Alkene hydration provides an atom-economical and redox-neutral route to aliphatic alcohols yet controlling regioselectivity remains challenging. Here, the authors reveal that a photooxidative heteroleptic copper(II) complex enables efficient anti-Markovnikov hydration of alkenes.