Photocatalytic Cross-Couplings of Aryl Halides Enabled by o-Phosphinophenolate and o-Phosphinothiophenolate

o-Phosphinophenolate and o-phosphinothiophenolate are potent photocatalysts with strong reducing ability to activate aryl chlorides and bromides under visible light for borylation, arylation, and phosphorylation. Experimental and theoretical studies revealed that the o-diphenylphosphino substituent results in a narrow optical gap and facilitates intersystem crossing to access triplet states, which promote phenolate and thiophenolate to function as effective visible-light-photoredox catalysts. The results presented herein suggest promising utility of synthetically modified phenolates and thiophenolates as photoredox catalysts.