Substitution of Hydroxybiaryls via Directed <i>o</i><i>rtho</i>-Lithiation of <i>N</i>-Silylated <i>O</i>-Aryl <i>N</i>-Isopropylcarbamates
Bibliographic record
Abstract
[reaction: see text] Herein we report regioselective substitution reactions of a series of 2- and 3-hydroxybiaryls including BINOL via a new directed ortho-metalation procedure. O-Aryl N-isopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, are temporarily and in situ N-protected by means of silyl triflates to form stable intermediates for low temperature lithiation reactions using butyllithium/TMEDA in diethyl ether. The resulting aryllithiums are efficiently substituted by a wide range of electrophilic reagents to afford functionalized biaryls in high yields. N-Desilylation already occurs during aqueous workup. The following deprotection of the urethanes to the corresponding phenols proceeds rapidly and in quantitative yields. Even sensitive substituents (e.g., CO2Me, CHO, SiMe3, I) in the products are preserved under mild alkaline conditions which have been established for carbamate ester cleavage. Furthermore, applications of ortho-substituted products in common cross-coupling reactions for further C-C bond formations are demonstrated.
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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 | 0.000 | 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) | 0.001 | 0.001 |
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".