Decarboxylative Oxygenation Enabled by O–H Bond Selective Proton-Coupled Electron Transfer Ability of Photoexcited Nitroarenes
Bibliographic record
Abstract
The valorization of fully oxidized feedstock chemicals is a central objective of synthetic chemistry. To this end, we report that tuning the aromatic substituents of photoexcited nitroarenes enables selective decarboxylative oxygenation of carboxylic acids via proton-coupled electron transfer (PCET). The direct engagement of carboxylic acids constitutes a new reactivity for photoexcited nitroarenes, which are known to act as potent and selective HAT agents for thermodynamically accessible, hydridic C–H bonds. After PCET and CO2 extrusion from carboxylic acids, oxygen atom transfer (OAT) from the photoexcited nitroarene to the resulting alkyl radicals yields carbonyl products. Overall, this transformation is distinct from prior approaches that require photoredox or transition metal catalysts with exogenous oxidants and necessitate prefunctionalization or deprotonation of carboxylic acid substrates. Markedly, the combined O–H and C–H bond abstraction ability of photoexcited nitroarenes enables the dehomologation of arylacetaldehydes and arylacetic acids. The mechanistic details of the transformation were elucidated through experimental and theoretical studies that, taken together, support both stepwise and concerted PCET-type mechanisms dependent on the oxidation potentials of substrates. The selectivity reported herein for PCET reactivity with O–H bonds in the presence of weaker C–H bonds reveals the tunability of photoexcited nitroarene reagents, as well as their utility in transformations involving the single-electron activation of thermodynamically challenging heteroatom–H bonds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".