Development of a novel [<sup>18</sup>F]fluorobenzyl derivative of the AT<sub>1</sub> receptor antagonist Candesartan
Bibliographic record
Abstract
Candesartan is a clinically approved angiotensin II type 1 receptor (AT1R)‐blocker that selectively binds AT1Rs in high affinity. We report here the radiosynthesis and automation of the novel [18F]fluorobenzyl derivative of Candesartan using the Sonogashira cross‐coupling reaction. [18F]Fluorobenzyl‐Candesartan ([18F]7) was developed from 4‐[18F]fluoroiodobenzene ([18F]FIB) that was conjugated with alkyne‐trityl‐candesartan with the assistance of a Pd (PPh3)4/CuI catalyst followed by acid deprotection. The three‐step two‐reactor 2‐HPLC purification process was automated resulting in >90% pure [18F]7 in a RCY of 4.6 ± 1.1% (decay corrected from EOB) and molar activities of 1,406‐5,513 GBq/mmol. [18F]FIB was reproducibly obtained by direct radiofluorination of the mono‐iodinated triphenylsulfonium salt in the presence of K222/K2CO3 in an ~30% yield (decay‐corrected). [18F]7 was stable (>97%) up to 4 h in solution and up to 1 h in rat plasma at 37°C. However, the use of Sonogashira cross‐coupling reaction to produce [18F]7 in high yields and molar activities was found to be challenging for routine use in radiochemistry labs.
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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) | 0.000 | 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 | 0.001 |
| 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".