Asymmetric Lewis Acid Catalysis in Water: α‐Amino Acids as Effective Ligands in Aqueous Biphasic Catalytic Michael Additions
Bibliographic record
Abstract
Abstract This article explores the potential of native α‐amino acids as chiral ligands in aqueous asymmetric Lewis acid catalysis, employing the C–C bond forming Michael addition as a model reaction. Some insights are provided regarding the details of Yb(OTf) 3 /α‐amino acid‐catalyzed Michael additions in water through new kinetic data as well as studies on how both yield and selectivity are influenced by variations in metal/ligand ratio, pH, temperature, and structure of the α‐amino acid. Through this investigation it was found that reaction conditions that require only 5 mol‐% of the Lewis acid, provides enantiomeric excesses of up to 79 % and is applicable to a wider range of donors and acceptors than previously demonstrated. Importantly, it was also demonstrated that the α‐amino acid complexed ytterbium catalyst might have potential for large‐scale applications as it displays not only large ligand accelerations, but also good solubility and stability in water. It can be recycled multiple times without appreciable loss of activity. The result is a promising example of a water‐compatible chiral Lewis acid.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| 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) | 0.001 | 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 teacher head, 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".