The Mechanism and Origin of Enantioselectivity in the Rhodium-Catalyzed Asymmetric Ring-Opening Reactions of Oxabicyclic Alkenes with Organoboronic Acids: A DFT Investigation
Bibliographic record
Abstract
The mechanism and origins of enantio- and stereoselectivity in the asymmetric ring-opening (ARO) reactions of oxabicyclic alkenes with organoboronic acids catalyzed by rhodium/Josiphos has been examined at the B3LYP/defTZVP level of theory. The mechanism consists of four steps including transmetalation, carborhodation, β-oxygen elimination, and hydrolysis. Energetic discrimination in the chirality-imparting step arises from attractive C–H−π interactions between the transmetalated aryl group and the Josiphos ligand, as well as steric clashes between the Josiphos ligand and the oxabicyclic alkene. Computational results indicate that the rate-determining step is involved in the hydrolysis of the rhodium(I) alkoxide from the ring-opened intermediate. In the overall catalytic cycle, the greatest free energy barrier is 23.4 kcal/mol, which supports that the Rh-catalyzed ARO reactions take place at mild reaction conditions, which is consistent with experimental observations.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".