Efficient Heterogeneous Asymmetric Catalysis of the Mukaiyama Aldol Reaction by Silica‐ and Ionic Liquid‐Supported Lewis Acid Copper(II) Complexes of Bis(oxazolines)
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Bibliographic record
Abstract
Abstract Lewis acid complexes based on copper(II) and an imidazolium‐tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1‐methoxy‐1‐trimethylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ee s obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2 min compared with only 55 % conversion after 60 min in dichloromethane. However, this rate enhancement was offset by lower chemoselectivity in ionic liquids due to the formation of 3‐hydroxy‐1,3‐diphenylbutan‐1‐one as a by‐product. Supporting the catalyst on silica or an imidazolium‐modified silica using the ionic liquid or in an ionic liquid‐diethyl ether system completely suppressed the formation of this by‐product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee .
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
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