The versatile reactivity of 2-aryl-4,6-dinitrobenzotriazole 1-oxides in Diels-Alder type condensations and in σ-complexation - A relationship between superelectrophilicity and pericyclic reactivity
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Bibliographic record
Abstract
A two-pronged study of a series of 2-aryl-4,6-dinitrobenzotriazole 1-oxide substrates (2ac) is reported: DielsAlder type pericyclic reactivity and covalent hydration to yield Meisenheimer type hydroxy anionic σ-adducts. The most activated benzotriazole 1-oxide 2a is found to exhibit both dienophilic and heterodienic behaviour on treatment with cyclopentadiene, providing a highly functionalized stereoselective diadduct (7). This diadduct is shown to be the result of two consecutive inverse demand DielsAlder condensations proceeding through the endo mode with a trans addition of two cyclopentadiene molecules. Kinetic and thermodynamic measurements of the ease of covalent hydration of 2ac to give σ-adducts 4ac in aqueous solution indicate that the electrophilic reactivity of the 4,6-dinitrobenzotriazole 1-oxide structure is much closer to that of the superelectrophilic 4,6-dinitrobenzofuroxan (DNBF, 1a) than that of the standard Meisenheimer electrophile 1,3,5-trinitrobenzene (TNB). The pK a values range from 6.70 for the 2-(2',4',6'-trinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide (Pi-DNBT, 2a) to 10.73 for the 2-phenyl-4,6-dinitrobenzotriazole 1-oxide (Ph-DNBT, 2c). The observation that the most activated benzotriazole 1-oxide structure 2a which resembles 4,6-dinitrobenzofuroxan (DNBF) in superelectrophilic behaviour, is the only one that undergoes DielsAlder reactions, points to a direct relationship between superelectrophilic and pericyclic reactivity.Key words: σ-complexes, arylnitrobenzotriazole 1-oxides, super-electrophiles, DielsAlder condensations, pericyclic reactions.
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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 | 0.002 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
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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 it