Polarization Effect on Regioselectivity of Pd‐Catalyzed Cyclization of 2‐Alkynylbenzaldehydes
Bibliographic record
Abstract
We report a study on the relationship between the polarization of C≡C bond in a series of 2‐alkynylbenzaldehydes and the regioselectivity of their Pd‐catalyzed annulation reactions. The electrophilic and nucleophilic character of the triple bond carbon atoms was examined using 13C and HMBC NMR experiments. The direction of polarization is determined only by the formyl group and its position on an aromatic ring. On the other hand, the strength of the polarization expressed through chemical shift difference Δδ of acetylenic carbon atoms is a result of electron‐withdrawing or electron‐donating ability of the other substituent. Out of two possible regioisomers, the Pd‐catalyzed cyclization reactions of 2‐alkynylbenzaldehydes that were studied predominantly afforded 1H‐isochromenes suggesting that the polarization of a triple bond is one of the contributing factors in the regioselectivity of this process.
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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".