Rapid and Efficient Synthesis of <sup>11</sup> C‐Labeled Benzimidazolones Using [ <sup>11</sup> C]Carbon Dioxide
Bibliographic record
Abstract
Abstract [ 11 C]Carbon dioxide is an attractive synthon for the labeling of positron emission tomography (PET) tracers for subsequent use in biomedical research and drug development. In this study, [ 11 C]CO 2 was used for direct 11 C‐labeling of a set of cyclic aromatic ureas starting from their corresponding ortho ‐phenylenediamines, BEMP (2‐ tert ‐butylimino‐2‐diethylamino‐1,3‐dimethylperhydro‐1,3,2‐diazaphosphorine) as fixation base, and Mitsunobu reagents (DBAD, n Bu 3 P) for the intramolecular cyclization. The procedure is rapid (6 minutes total synthesis time), mild (proceeds at room temperature) and provided a set of 11 C‐benzimidazolones in good to excellent radiochemical yields. As a final testament to the utility of this method, the beta‐adrenoceptor PET ligand [ 11 C]CGP12177, was successfully prepared using the optimized conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".