Unprecedented One-Pot Stereoselective Synthesis of Knoevenagel-Type Derivatives via in situ Condensation of <i>N</i>-Methyleniminium Salts of Ethylenethiourea and Ethyleneurea with Active Methylene Reagents
Why this work is in the frame
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Bibliographic record
Abstract
A facile stereoselective synthesis of Knoevenagel-type compds. I (e.g., X = O, S, Y = CN, COMe, CO2Me, COPh, Z = CN, CO2Me, PO(OEt)2, CONH2, COMe, CO2Et, SO2Ph) was accomplished through a 1-pot two-step procedure. The reaction of ethylenethiourea (2-imidazolidinethione, 1) and ethyleneurea (2-imidazolidone, 2) with benzoyl chloride-DMF complex in DMF gave the corresponding isolable ternary N-methyleniminium chlorides II, along with HOBz (5) as a byproduct. Hydrolysis of salts II yielded the N-formyl derivs. 6 and 7, thus confirming the N-methyleniminium structure. Salts II condensed in situ at 120° with a variety of acyclic active methylene reagents Y-CH2-Z (Y = or ≠ Z), in the presence of 5 (Procedure A) or of 5 and NEt3 (1.5 equiv) (Procedure B), afforded α,β-unsatd. compds. I. The overall yields ranged from poor to good. Mechanistic hypotheses concerning the formation of II and the origin of the stereoselectivity are also discussed
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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 | 0.001 | 0.003 |
| 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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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