Density Functional Theory Guided Design of Exo-Selective Dehydroalanine Dienophiles for Application Toward the Synthesis of Palau'amine
Bibliographic record
Abstract
Diels-Alder cycloadditions of dehydroalanine derivatives with cyclopentadiene, applicable to the synthesis of palau'amine, were investigated experimentally and using DFT computations at the B3LYP/6-31G* level of theory. Oxazolone and thiohydantoin dienophiles were found to be significantly more reactive than hydantoins or dehydroalanine methyl esters. The increased reactivity of the thiohydantoins relative to hydantoins is attributed to increased conjugation of nitrogen lone pairs into the thiocarbonyl group. beta-Substitution greatly decelerates the cycloadditions due to steric interactions in the transition states outweighing any electronic activation by chlorine. Hydantoins and thiohydantoins were found to be exo-selective, while the corresponding oxazolones and dehydroalanines were unselective.
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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 | 0.000 |
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 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".