Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinated Alcohols to Carbanions

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp(3))-O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp(3))-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch-type reductions.

Automated summary

This study reports a novel electro-mediated photoredox catalysis for the reductive cleavage of C(sp(3))-O bonds, allowing for the conversion of phosphinated alcohols to alkyl carbanions. In addition to deoxygenations, E-selective olefinations are reported, which can be made Z-selective in a tandem reduction/photosensitization process. Spectroscopy, computation, and catalyst structural variations reveal that the new naphthalene monoimide-type catalyst facilitates an intimate dispersive precomplexation with the phosphinate substrate, promoting the reactivity-determining C(sp(3))-O cleavage. Surprisingly, this method tolerates aryl chlorides/bromides and does not lead to Birch-type reductions, unlike previously reported photoexcited radical anion chemistries.