Synthesis of Fused Heteroarylprolines and Pyrrolopyrroles
Bibliographic record
Abstract
Fused heteroarylprolines were prepared starting from 4-oxo-N-(PhF)proline benzyl ester (6, PhF = 9-(9-phenylfluorenyl)) following two approaches. First, allylation of oxoproline 6 followed by Wacker oxidation gave 1,4-dione 8 that was selectively converted to pyrroloproline 10b, pyrrolopyrrole 12, and pyridazinoproline 9. Second, aldol condensation of oxoproline 6 with a series of N-(Boc)-alpha-amino aldehydes 15a-e and acid-catalyzed cyclization gave pyrroloprolines 17a-e possessing a variety of pyrrole 5-position substituents. Conditions for the selective deprotection and alkylation of the pyrrole nitrogen of pyrroloprolines 17 were developed to expand the diversity of the heteoaryl systems. Finally, hydrogenolytic cleavage of the PhF and benzyl groups followed by subsequent protection with Boc, Fmoc, and Moz groups was performed to obtain analogues suitable for peptide synthesis. The enantiomeric purity of N-(Boc)pyrrolo-proline 21a was ascertained by coupling to l- and d-phenylalanine methyl ester and examination of the diastereotopic pyrrole protons, which demonstrated the dipeptides to be of >99% diastereomeric purity. These approaches have thus delivered the first series of enantiopure fused arylprolines for application as arylglycine-proline chimeras in structure-activity studies of biologically active compounds.
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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 | 0.000 |
| 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".