Amidolithium and Amidoaluminum Catalyzed Synthesis of Substituted Guanidines: An Interplay of DFT Modeling and Experiment
Bibliographic record
Abstract
The synthesis of substituted guanidines is of significant interest for their use as versatile ligands and for the synthesis of bioactive molecules. Lithium amides supported by tetramethylethylenediamine have recently been shown to catalyze the guanylation of amines with carbodiimide. In this report, density functional theory (DFT) calculations are used to provide insight into the mechanism of this transformation. The mechanism identified through our calculations is a carbodiimide insertion into the lithium-amide bond to form a lithium guanidinate, followed by a proton transfer from the amine. The proton transfer transition state requires the dissociation of one of the chelating nitrogen centers of the lithium guanidinate, proton abstraction from the amine, and bond formation between the lithium center and the amine nitrogen. On the basis of this mechanism, further calculations predicted that aluminum amides would also function as active catalysts for the guanylation of amines. We confirm this experimentally and report the development of aluminum amides as a new main group catalyst for the guanylation of a range of electron-poor amines with carbodiimide.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".