Studies in simultaneous generation of central and axial chirality via the Buchwald-Hartwig reaction
Bibliographic record
Abstract
The Buchwald-Hartwig reaction has been investigated previously by the Viirre group to show that intramolecular cyclization using palladium and (R)-(+)-2-(diphenylphosphino)-2′-methoxy-1,1′-binaphthyl, can instill enantioselectivity. This system was continued to show that steric bulk on the 2’ position on the phenyl ring attached to the nitrogen malonamide can lock the rotation ending in a chiral axis. The diastereomers resulting from this chiral axis can be selectively formed when the substrate is 2-(2-bromobenzyl)-N1,N3-bis(2-(tert-butyl)phenyl)-2-methylmalonamide and using a similar ligand (R)-dicyclohexyl(2'-methoxy-[1,1'-binaphthalen]-2-yl)phosphane with enantio- and diastereoselectivities of 88% and 99% respectively. The work presented in this thesis continues on this class of substrates to include N,1-Di([1,1'-biphenyl]-2-yl)-3-methyl-2-oxo-1,2,3,4-tetrahydroquinoline-3-carboxamide, as well as a newer class of monoamide substrates. The monoamide substrates allowed the interpretation of events occurring in the Buchwald-Hartwig reaction, ultimately showing that the chiral center on the substrate has some control as to the outcome of the chiral axis. Lastly, a timed sampling kinetics experiment was done to investigate if the enantiomers of the starting material were being consumed at different rates or if one diastereomeric product was being produced favourably. The kinetics experiment shows that the system does not have a preference as to the starting material or product being produced.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".