We report a novel example of electro‐mediated photoredox catalysis (e‐PRC) in the reductive cleavage of C(sp3)−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(sp3)−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.
Synthetic photoelectrochemistry (PEC) is receiving increasing attention as a new frontier for the generation and handling of reactive intermediates. PEC permits selective single‐electron transfer (SET) reactions in a much greener way and broadens the redox window of possible transformations. Herein, the most recent contributions are reviewed, demonstrating exciting new opportunities, namely, the combination of PEC with other reactivity paradigms (hydrogen‐atom transfer, radical polar crossover, energy transfer sensitization), scalability up to multigram scale, novel selectivities in SET super‐oxidations/reductions and the importance of precomplexation to temporally enable excited radical ion catalysis.
A broadly applicable method for the trifluoromethylthiolation of methylene C(sp 3 )−H, methine C(sp 3 )−H, αoxygen C(sp 3 )−H, and formyl C(sp 2 )−H bonds is presented using the decatungstate anion as the sole catalyst. By adjusting the substrate ratio and reaction concentration, this method was applied to 40 examples in good regioselectivities, including the derivatization of natural products. Furthermore, SCF 3 −drug analogues were synthesized by subsequent functionalization of the SCF 3 products, highlighting the importance of this photocatalyzed C−H functionalization.
Molecular photoelectrochemistry , allowing access to a broader window of single electron transfer chemistry in a greener way, is a rapidly expanding toolbox for synthesis and selective functionalizations of complex molecules. In their Review (e202107811), Joshua P. Barham and co‐workers capture exciting synthetic opportunities, key mechanistic insights and evolving batch and flow reactor platforms allowing screening and scalability of reactions.
We report the iridium–nickel dual photocatalytic
acceptorless
and redox neutral dehydrogenation of aliphatic heterocycles yielding
cyclic alkenes without overoxidation at room temperature. Excitation
of the iridium photocatalyst initiates the formation of a nickel hydride
intermediate that yields alkenes and H2 via β-hydride
elimination. The reaction proceeds regioselectively and the scope
was demonstrated by the synthesis of 12 biologically relevant molecules
and drugs. In addition, commercially and easily available N-heterocyclic
alkane starting materials were converted into functionalized alkenes
of high synthetic and commercial value using the method.
We report a novel example of electro-mediated photoredox catalysis
(e-PRC) in the reductive cleavage of C(sp<sup>3</sup>)-O bonds of phosphinates
to alkyl carbanions. As well as deoxygenations, olefinations are reported which
are <i>E</i>-selective and can be made <i>Z</i>-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 a
more intimate dispersive precomplexation of its radical anion form with the
phosphinate substrate, facilitating a reactivity-determining C(sp<sup>3</sup>)-O
cleavage. Surprisingly and in contrast to previously
reported photoexcited radical anion chemistries, our conditions i) tolerate
aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.
We report a novel example of electro‐mediated photoredox catalysis (e‐PRC) in the reductive cleavage of C(sp3)−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(sp3)−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.
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