Synthesis of novel coumarin and benzocoumarin derivatives and their biological and photophysical studies
Bibliographic record
Abstract
Abstract magnified image Several derivatives of coumarin‐3N‐carboxamides (3‐21) have been prepared via the reaction of the coumarin‐3‐carbonyl chloride (1) with a number of nucleophiles. Novel double‐headed coumarin‐3N‐carboxamides (26‐33) were also produced using the same method. The Pechmann‐Duisberg reaction was applied to prepare new benzo[f]‐ benzo[h]coumarins and 4‐(chloromethyl)‐pyrano[3,2‐c]coumarin‐2‐one (36‐42). The reaction of 1‐chloromethylbenzo[f]coumarins (36) with cyanide anion under different reaction conditions was also investigated in order to assess its suitability for nucleophilic substitution reactions as well as ring transformation products (43‐49). Synthesis of 1‐((benzo[d]thiazol‐2‐yl)methyl)‐9‐hydroxybenzo[f]coumarin (50) represented the first example of methylene bridge‐head heterocyclecontaining benzo[f]coumarin. Some of the newly prepared coumarins exhibited anti‐bacterial activity against Gram Positive and Gram negative bacteria. Compound 36d was found to be active against all the screened bacteria. Photophysical studies were performed on selected fluorescent benzo[f]‐ and benzo[h]coumarin and the quantum yields were also calculated. All new compounds were characterized by IR, MS, 1H and 13C NMR, as well as elemental analysis.
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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) | 0.001 | 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".