Facial Selectivity in the Diels–Alder Reactions of 2,2‐Disubstituted Cyclopent‐4‐ene‐1,3‐dione Derivatives and a Computational Examination of the Facial Selectivity of the Diels–Alder Reactions of Structurally Related Dienes and Dienophiles
Bibliographic record
Abstract
Abstract The facial selectivity in the Diels–Alder reactions via endo transition states of the plane‐nonsymmetric dienophiles spiro[bicyclo[2.2.2]octane‐2,1′‐[3]cyclopentene]‐2′,5′‐dione ( 6 ) and spiro[bicyclo[2.2.1]heptane‐2,1′‐[3]cyclopentene]‐2′,5′‐dione ( 7 ) has been found to be very similar to the facial selectivity of reactions of cyclopentadienes fused to bicyclo[2.2.2]octane and bicyclo[2.2.1]heptane ( 4 and 5 ). This is strong evidence for steric control in their facial selectivities. Density functional computations involving the reactions of these compounds, as well as a series of conformationally locked model addends ( 26a – c and 27a – c ), revealed geometrical and energetic properties that confirmed that the facial selectivity is governed by steric effects. Steric interactions appeared to be the reason for the low endo / exo selectivity of dienophiles 6 , 7 , 2,2‐dimethylcyclopent‐4‐ene‐1,3‐dione ( 20 ), and spiro[5.4]dec‐8‐ene‐7,10‐dione ( 23 ).
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".