Photoredox α-Arylation of cyclic ketones



The direct α-arylation of unactivated carbonyl compounds using aryl halides represents a powerful method to synthesize criti-cal building blocks for diverse useful compounds. Numerous synthetic methods exist to forge C(sp2)-C(sp3) bonds, albeit metal free direct α-arylation of unactivated cyclic ketones has long been an elusive transformation. Herein, we report a green-light-mediated α-arylation of unactivated ketones from readily available aryl halides via activation of a C(sp2)-X bond (X=I, Br, Cl) and an α-carbonyl C(sp3)-H bond in a single photocatalytic cycle. This approach is characterized by its mild reaction conditions, operational simplicity, and wide functional group tolerance. Importantly, the impressive outcome from multi-gram photocatalytic reaction underpins the strength of this method as a potentially practical and attractive approach for scale-up industrial purposes. The utility and scope of this reaction were further demonstrated by new syntheses of several feedstock chemicals that are commercially expensive but critical for synthesizing numerous pharmaceutical agents.

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Additional mechanistic experiments have been performed, including Transient Absorption spectroscopy and spectro electrochemical measurements, to support the involvement of PET mechanism via the formation of a radical dication acridinium.


Supplementary material

Supportive Information - Photoredox α-Arylation of Carbonyl Compounds
This document contains the supporting information for the manuscript entitled - Photoredox α-Arylation of Carbonyl Compounds - and contains general information, catalyst synthesis and characterization, mechanistic investigation, experimental procedures, as well as NMR spectroscopy and X-ray data.