Use of <sup>1</sup>H NMR chemical shifts to determine the absolute configuration and enantiomeric purity for enantiomers of 3,3′-disubstituted-MeO-BIPHEP derivatives
Bibliographic record
Abstract
The absolute configuration of a series of 3,3′-disubstituted-MeO-BIPHEP derivatives can be determined by the 1 H NMR chemical shift of the methoxyl group when the 3,3′-disubsituted-MeO-BIPHEP derivative is mixed with ()-(2R,3R)-dibenzoyltartaric acid (()-DBTA) (1:2) and its NMR spectrum is run in CDCl 3 . The chemical shift of the methoxyl group in the S ax enantiomer always occurred at higher field than the corresponding R ax enantiomer. Integration of the corresponding methoxyl signals provides the enantiomeric purity of any mixtures.Key words: assignment of absolute configuration, 2,2′-bis(diphenylphosphino)-1,1′-biaryls, MeO-BIPHEP derivatives, asymmetric Heck reaction, 1 H NMR chemical shifts.
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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) | 0.000 | 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".