Cobalt-Catalyzed Borylation of Fluorinated Arenes: Thermodynamic Control of C(sp<sup>2</sup>)-H Oxidative Addition Results in <i>ortho</i>-to-Fluorine Selectivity
Bibliographic record
Abstract
The mechanism of C(sp2)–H borylation of fluorinated arenes with B2Pin2 (Pin = pinacolato) catalyzed by bis(phosphino)pyridine (iPrPNP) cobalt complexes was studied to understand the origins of the uniquely high ortho-to-fluorine regioselectivity observed in these reactions. Variable time normalization analysis (VTNA) of reaction time courses and deuterium kinetic isotope effect measurements established a kinetic regime wherein C(sp2)–H oxidative addition is fast and reversible. Monitoring the reaction by in situ NMR spectroscopy revealed the intermediacy of a cobalt(I)–aryl complex that was generated with the same high ortho-to-fluorine regioselectivity associated with the overall catalytic transformation. Deuterium labeling experiments and stoichiometric studies established C(sp2)–H oxidative addition of the fluorinated arene as the selectivity-determining step of the reaction. This step favors the formation of ortho-fluoroaryl cobalt intermediates due to the ortho fluorine effect, a phenomenon whereby ortho fluorine substituents stabilize transition metal–carbon bonds. Computational studies provided evidence that the cobalt–carbon bonds of the relevant intermediates in (iPrPNP)Co-catalyzed borylation are strengthened with increasing ortho fluorine substitution. The atypical kinetic regime involving fast and reversible C(sp2)–H oxidative addition in combination with the thermodynamic preference for forming cobalt–aryl bonds adjacent to fluorinated sites are the origin of the high regioselectivity in the catalytic borylation reaction.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| 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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".