Pyridylketenes. Structure reactivity effects in nucleophilic and radical addition
Bibliographic record
Abstract
Abstract 2-, 3-, and 4-Pyridylketenes have been generated in CH 3 CN by photochemical Wolff rearrangements and identified by their ketenyl absorption in the infrared at 2127, 2125, and 2128 cm –1 , respectively. Reaction of these pyridylketenes with n -BuNH 2 results in the formation of intermediate amide enols from the 3- and 4-pyridylketenes, which are then converted to the corresponding pyridylacetamides. However , 2-pyridylketene forms a long-lived 1,2-dihydropyridine intermediate stabilized by an intramolecular hydrogen bond, and this is converted to the 2-pyridylacetamide with a rate constant 10 7 less than those for the conversion of the amide enols from the 3- and 4-pyridylketenes to amides. Hydration of the pyridylketenes results in the formation of an acid enol intermediate in the case of the 3-isomer, while the 2- and 4-isomers form longer-lived dihydropyridines. The pyridylketenes react with the stable free radical tetramethylpiperidinyloxyl (TEMPO,TO) forming 1,2-diaddition products ArCH(OT)CO 2 T.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".