Aminolactone Chiral Modifiers for Heterogeneous Asymmetric Hydrogenation: Corrected Structure of Pantoyl-Naphthylethylamine, In-Situ Hydrogenolysis, and Scanning Tunneling Microscopy Observation of Supramolecular Aminolactone/Substrate Assemblies on Pt(111)
Bibliographic record
Abstract
As established by Baiker and co-workers, pantoyl-naphthylethylamine (PNEA) is an efficient synthetic chiral modifier for the asymmetric hydrogenation of ketopantolactone (KPL) to pantolactone on supported Pt catalysts. We report a scanning tunneling microscopy (STM) study of PNEA and PNEA-derived aminolactone species on Pt(111) and a reassignment of the relative stereochemistry of the modifier. Robust organic chemistry methods were used to establish that the structure of PNEA is R, S rather than R, R . The dissociative chemisorption of a fraction of PNEA adsorbed on Pt(111) yields two fragments that we attribute to a process involving C–N bond scission. We show that C–N bond scission occurs under hydrogenation conditions on PNEA-modified Pt/Al 2 O 3 catalysts, forming the aminolactone amino-4,4-dimethyldihydrofuran-2-one (AF). STM measurements on ( S )-AF and 2,2,2-trifluoroacetophenone coadsorbed on Pt(111) show the formation of isolated 1:1 complexes. In contrast, measurements on coadsorbed ( S )-AF and KPL show fluxional supramolecular AF/KPL assemblies. The possibility that such assemblies contribute to the overall enantioselectivity observed for PNEA-modified Pt catalysts is discussed.
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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 | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".