Direct <i>N</i>-Cyclopropylation of Cyclic Amides and Azoles Employing a Cyclopropylbismuth Reagent
Bibliographic record
Abstract
Cyclopropanes are commonly found in medicinal chemistry since they provide unique spatial and electronic features, combined with high metabolic stability in liver microsomes. Although many methods are found in the chemist's arsenal to connect a cyclopropyl group to a carbon atom, none exist that perform the direct transfer of this useful fragment onto the nitrogen of a heterocycle or an amide. Considering the importance of nitrogenated compounds in the pharmaceutical industry, we sought to develop an expedient method to N -cyclopropylate azoles and amides. We report herein the direct cyclopropyl transfer reaction onto cyclic amides, isatins, oxindoles, imides, and carbamates employing a nonpyrophoric cyclopropylbismuth reagent. The reaction is catalyzed by copper acetate and proceeds smoothly in dichloromethane at 50 °C in the presence of pyridine. The N -cyclopropylation reaction can also be applied to the preparation of N -cyclopropyl indoles, benzimidazoles, pyrroles, and pyrazoles.
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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) | 0.001 | 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 | 0.001 |
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".