The differing mechanisms of photo-formation of 7-cyanobenzocyclooctatetraene from 7- and 6-cyano-2,3-benzobicyclo[4.2.0]octa-2,4,7-triene
Bibliographic record
Abstract
It is known that 7-cyanobenzocyclooctatetraene (COT 2) is a product of the thermolysis and direct photolysis of 7- and 6-cyano-2,3-benzobicyclo[4.2.0]octa-2,4,7-triene (1 and 5), though the mechanisms of these rearrangements have not been reported. In the present study experiments have been carried out using the deuterium-labelled trienes 1a (93%-d1 at C-6) and 5a (93%-d1 at C-8), which were formed from 2π + 2π photo-closure (direct irradiation) of COT 2a labelled at C-8. The results reveal that whereas the thermolysis of 1a and 5a and the direct irradiation of 5a reform COT 2a, probably via cleavage of the strained cyclobutene C-1C-6 bond, the direct irradiation of triene 1a gives a differently labelled COT product, containing the deuterium exclusively at C-9. The mechanism proposed for the latter phototransformation is a modification of the Zimmerman di-π-methane rearrangement.Key words: mechanisms, rearrangements, photochemistry, di-π-methane rearrangement.
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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 | 0.000 |
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".