Stereoselective Synthesis of <i>N</i>‐Propargyl Alkynes and Axial Chiral <i>N</i>‐Allenes with Epimeric Pyrroloimidazolone Auxiliaries
Why this work is in the frame
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Bibliographic record
Abstract
Abstract An N ‐propargyl pyrroloimidazolone with syn stereochemistry derived from L‐proline serves as a starting material for the diastereoselective synthesis (>95:5 dr) of propargyl alkynes or allenamides by direct quench of its lithiated intermediate with alkylating agents or aldehydes/ketones, respectively. Use of the epimeric anti pyrroloimidazolone starting material results in reversal of stereochemistry at the propargyl position in the products, without the need to prepare a separate substrate from D‐proline. Lithiation of the syn pyrroloimidazolone and quench with prochiral benzaldehydes without prior transmetalation gives allenamides with crystallographically verified atypical stereochemistry of the benzylic alcohol in >95:5 dr. The epimeric series of benzylic alcohols may also be obtained in >95:5 dr by employing transmetalation with chlorotitanium triisopropoxide prior to aldehyde quench. Density Functional Theory (DFT) computational studies provide a rationale for the change in benzylic alcohol stereochemistry by virtue of differing stereofacial attack in 6,5‐bicyclic (Li) or 6‐membered (Ti) transition states. magnified image
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| 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 it