Radiosynthesis of the <sup>11</sup>C‐methyl derivative of LBQ657 for PET investigation of the neprilysin inhibitor sacubitril
Bibliographic record
Abstract
Neprilysin, also known as neutral endopeptidase, is a cell surface membrane metalo‐endopeptidase that cleaves various peptides. Altered neprilysin expression has been correlated with various cancers and cardiovascular diseases. In this work, we present the radiosynthesis of the novel O ‐ 11 C‐methylated derivative of LBQ657 (a potent neprilysin inhibitor). (2 R ,4 S )‐5‐(Biphenyl‐4‐yl)‐4‐[(3‐carboxypropionyl)amino]‐2‐methylpentanoic acid [ 11 C]methyl ester ([ 11 C]MeOLBQ) is an analog of sacubitril where the alkyl ester is a 11 C‐methyl instead of an ethyl. [ 11 C]MeOLBQ was produced in a one‐pot two‐step synthesis. The O ‐ 11 C‐methylation of the pentanoic acid part was done with [ 11 C]methyl triflate followed by the deprotection of the tert ‐butyl ester precursor in acidic conditions. [ 11 C]MeOLBQ ([ 11 C] 7 ) was produced in 9.5 ± 2.5% RCY (25 ± 6% decay‐corrected from [ 11 C]CO 2 , n = 3) high molar activity 348 ± 100 GBq/μmol (9425 ± 2720 mCi/μmol) at EOS, in high chemical (>95%) and radiochemical (>99%) purities. The total synthesis time including HPLC purification and reformulation was 29 minutes. To our knowledge, this is the first PET‐labeled analog of the clinically used NEP inhibitor sacubitril.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".