Atropisomerism in Tertiary Biaryl 2-Amides: A Study of Ar–CO and Ar–Ar′ Rotational Barriers
Bibliographic record
Abstract
A rotational barrier study was performed on eight tertiary biaryl 2-amides using variable-temperature (VT) NMR and exchange (EXSY) spectroscopy experiments. Seven out of the eight 2-amido-2′-methylbiphenyls with additional 3- and 6-substitution patterns ( 1 – 7 ) were found to have approximately similar rotational barriers (Δ G ⧧ Tc = 56.5–67.5 kJ/mol). However, for both 3- and 6-substitution ( 8 ), the rotational barrier was found to be significantly higher (Δ G ⧧ = 102.6–103.8 kJ/mol). Computational studies performed on all eight compounds gave results in good agreement with the experimental rotational barriers. A transition state in which atropisomerism occurs by a cooperative rotation of the Ar–CO and Ar–Ar′ bonds depending on substituent location is proposed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 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) | 0.002 | 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".