Competing DielsAlder intramolecular pathways from cross-conjugated trienes: Fused hydrindenones (bicyclo[4.3.0]nonenones) vs. bridged-ring (bicyclo[3.3.1]nonenones) adducts from a diene-transmissive precursor
Bibliographic record
Abstract
D-Isoascorbic acid was converted to the tetraenone 12 to examine its behaviour in the intramolecular DielsAlder reaction with pendant dienes in a diene-transmissive environment. These studies were directed toward the synthesis of the hydrindenone nucleus via a tether-controlled DielsAlder reaction. It was anticipated that this would lead to a diene-transmissive strategy for steroids such as Desogestrel®. In contrast to our previous studies with decalins, the dominant isomer (150 °C) was the bicyclo[3.3.1]nonadieneone adduct 23, and none of fused adduct 27 was detected. These products were accompanied by two minor hydrindenone adducts 24 and 25. The isomer ratio was dependent on the temperature of the reaction.Key words: DielsAlder, hydrindane, pentadienylation, intramolecular cycloaddition, bicyclo[3.3.1]nonenone.
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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) | 0.002 | 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".