N-Heterocyclic Carbene Organocatalyzed Redox-Active/Ring Expansion Reactions: Mechanistic Insights Unveiling Base Cooperativity
Bibliographic record
Abstract
N-Heterocyclic carbene (NHC) organocatalyzed transformations of redox-active chemical manifolds is a powerful strategy for interconverting and expanding the chemical space. This approach in the context of ring expansion holds promise for preparing lactones from plentiful redox active aldehydes, despite a lack of rigorous mechanistic insights into the underlying elements governing this reactivity and with-it relevance to other NHC organocatalyzed transformations. Herein, in investigating this reactivity under the lens of modern day quantum mechanical calculations, we explore the mechanism of redox-active/ring expansion reactions of aldehydes furnishing lactone products by means of NHC organocatalysis. Through this comprehensive study, the underpinning mechanism of Breslow intermediate formation and ensuing downstream processes such as intermolecular C-C bond formation providing benzoin products versus intramolecular redox pathways are outlined. Notably, this study of NHC organocatalysis reveals the diverse role of bases as cooperative agents in directing and selectively routing reactivity, as highlighted here toward ring expanded lactone products.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".