Electrostatic Effects Accelerate Decatungstate-Catalyzed C–H Fluorination Using [<sup>18</sup>F]- and [<sup>19</sup>F]NFSI in Small Molecules and Peptide Mimics
Bibliographic record
Abstract
The site-selective fluorination of unactivated C(sp3)-H bonds provides unique opportunities to rapidly alter drug properties or generate radiotracers for positron emission tomography (PET) imaging. Toward this goal, photoactivated decatungstate (DT) is capable of generating carbon radicals through hydrogen atom transfer that subsequently undergo fluorination by reaction with N-fluorobenzenesulfonimide (NFSI) or [18F]NFSI. This process enables C(sp3)-H fluorination of a wide range of aliphatic compounds, though reaction rates can be highly variable and limit applications in radiotracer synthesis. Here, we demonstrate that cationic ammonium functions in aliphatic molecules promote formation of a precursor complex with DT that significantly increases the rate of C–H abstraction. The general utility of this rate-accelerating electrostatic effect is demonstrated on more than 30 ammonium-containing molecules, including amino acids, heterocycles, and pseudopeptides. Moreover, this effect is highlighted in the rapid production of [18F]Glu-U-FHLeu, a 18F-labeled prostate specific membrane antigen (PSMA)-binding ligand.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| 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 | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".