Enantioselective Hydrogenation of N-H Imines
Bibliographic record
Abstract
Significance Chiral amines are common structural motifs in a large number of commercially important compounds. Catalytic hydrogenation of imines represents an important synthetic tool for introduction of the amine moiety. Despite a number of successful examples of asymmetric hydrogenation, many systems leave quite a bit of room for improvement of enantiocontrol. The necessity of using protective groups in many cases decreases the synthetic value of the corresponding methods. This paper provides a fundamentally important synthetic approach to chiral amines via hydrogenation of unprotected ketoimines, which can be easily prepared on multigram scale in the form of hydrochlorides. Surprisingly, these compounds received no attention so far as substrates for asymmetric hydrogenation. High yields and good to excellent enantioselectivities were obtained for a number of variously substituted ketimines (R ¹ = Ar, R ² = Me, Et, n -Bu, t -Bu, Ph).
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".