Conjugate Additions of <i>o</i>-Iodoanilines and Methyl Anthranilates to Acetylenic Sulfones. A New Route to Quinolones Including First Syntheses of Two Alkaloids from the Medicinal Herb <i>Ruta chalepensis</i>
Bibliographic record
Abstract
A novel synthesis of 2-substituted 4-quinolones was developed on the basis of the conjugate additions of appropriately ortho-substituted anilines to acetylenic sulfones followed by intramolecular acylation of the corresponding sulfone-stabilized anions. Conjugate additions of variously substituted anilines to alkyl-substituted acetylenic sulfones generally proceeded slowly and in poor yield, especially when the aniline contained an electron-withdrawing substituent such as an ester group. In some cases, the reactions were enhanced by the presence of DMAP and the use of an excess of the sulfone in aqueous DMF. N-Formylanilines proved superior to free anilines. The products were either vinyl or allyl sulfones, depending on the conditions and the structure of the reactants. The acetylenic sulfone exists in equilibrium with its allenic and propargylic isomers under base-catalyzed conditions. Therefore, any of the three unsaturated sulfones can serve as the starting material for the conjugate additions. o-Iodoanilines proved superior to methyl anthranilate derivatives and underwent conjugate additions smoothly. The products were subjected to palladium-catalyzed carbonylation in methanol, and the resulting methyl esters were cyclized by treatment with strong bases such as LiHMDS or LiTMP, followed by reductive desulfonylation with aluminum amalgam. The resulting 2-substituted 4-quinolones included the naturally occurring medicinal compounds 1 and 2 and the O-methyl derivative 3.
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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) | 0.001 | 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".