Understanding the Intramolecular Diels‐Alder Reactions of N‐Substituted N‐Allyl‐Furfurylamines: An MEDT Study
Bibliographic record
Abstract
Abstract The intramolecular Diels‐Alder (IMDA) reactions of N ‐allyl‐furfurylamine ( 1a ) and N ‐trityl‐allyl‐furfurylamine ( 1b), were studied within the molecular electron density theory (MEDT) using density functional theory method [B3LYP/6‐31G(d)]. In spite of the high activation enthalpies, the low unfavourable activation entropies associated to these intramolecular processes permit these IMDA reactions to take place. The IMDA reaction of 1a is thermodynamically unfavourable. The presence of the bulky −CPh 3 group in the amine nitrogen atom that destabilises the extended conformation of 1b turns the process into an exergonic one. This behaviour does not only affect the thermochemistry of the reaction, but also the kinetic parameters, thus accelerating the reaction. Electron localisation function topological analysis of the C−C single bond formation along the IMDA reaction of 1a shows a bonding pattern similar to non‐polar intermolecular Diels‐Alder reactions. The present MEDT study explains the experimental results; although the steric buttress is able to change the direction of these reversible IMDA reactions, this change is only possible due to the aromatic nature of the furanyl diene system.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".