DFT-Based Stereochemical Rationales for the Bifunctional Brønsted Acid/Base-Catalyzed Diastereodivergent and Enantioselective aza-Henry Reactions of α-Nitro Esters
Bibliographic record
Abstract
A pair of chiral bis(amidine) [BAM] proton complexes provide reagent (catalyst)-controlled, highly diastereo- and enantioselective direct aza-Henry reactions leading to α-alkyl-substituted α,β-diamino esters. A C2-symmetric ligand provides high anti-selectivity, while a nonsymmetric congener exhibits syn-selectivity in this example of diastereodivergent, enantioselective catalysis. A detailed computational analysis is reported for the first time, one that supports distinct models for selectivity resulting from the more hindered binding cavity of the C1-symmetric ligand. Binding in this congested pocket accommodates four hydrogen bond contacts among ligands and substrates, ultimately favoring a pre-syn arrangement highlighted by pyridinium-azomethine activation and quinolinium-nitronate activation. The complementary transition states reveal a wide range of alternatives. Comparing the C1- and C2-symmetric catalysts highlights distinct electrophile binding orientations despite their common hydrogen bond donor–acceptor features. Among the factors driving unusual high syn-diastereoselection are favorable dispersion forces that leverage the anthracenyl substituent of the C1-symmetric ligand.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 | 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".