Synthesis of some new 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2<i>H</i>-pyran-3-yl)pyrazoles using the Vilsmeier–Haack reaction — Isolation of the key intermediate 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2<i>H</i>-pyran-3-yl)pyrazoles
Bibliographic record
Abstract
Arylhydrazones of dehydroacetic acid (DHA) underwent Vilsmeier–Haack reaction to generate the corresponding 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (1) with the pyrone moiety of the DHA remaining intact. However, when the reaction was performed using 1 equiv. of the reagent, compounds of 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (2a–2f) were obtained, which underwent smooth conversion to 1-aryl-4-formyl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (1) on further treatment with another equivalent of the Vilsmeier–Haack reagent. This unreported observation suggests the intermediacy of 1-aryl-3-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)pyrazoles (2) in Vilsmeier–Haack reactions of hydrazones with a pyrone moiety. Several analogous compounds were also prepared using arylhydrazones of DHA.Key words: dehydroacetic acid, pyrazoles, Vilsmeier–Haack reaction, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".