Theoretical Study of Diastereoselective NHC-Catalyzed Cross-Benzoin Reactions between Furfural and <i>N</i>-Boc-Protected α-Amino Aldehydes
Bibliographic record
Abstract
The mechanism and origins of syn and anti selectivity of cross-benzoin reactions between furfural and α-amino aldehydes, catalyzed by a triazolium-based NHC, were investigated using density functional theory calculations. N -Boc-α-amino aldehydes were found to react with anti selectivity, while N -Bn- N -Boc-α-amino aldehydes react with syn selectivity. We find that the anti product is more thermodynamically favored than the syn product for reactions with N -Boc-α-amino aldehydes, and that the formation of the syn product for reactions involving N -Bn- N -Boc-α-amino aldehydes is kinetically favored. The switch in selectivity is a result of an intramolecular hydrogen bond in the N -Boc-α-amino aldehyde, whereas switching to N -Bn- N -Boc-α-amine removes the hydrogen bond. The steric and electronic interactions in the transition state are rationalized by a Felkin–Anh model.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".