Di-<i>tert</i>-butyl Ethynylimidodicarbonate as a General Synthon for the β-Aminoethylation of Organic Electrophiles: Application to the Formal Synthesis of Pyrrolidinoindoline Alkaloids (±)-CPC-1 and (±)-Alline
Bibliographic record
Abstract
The reagent di- tert -butyl ethynylimidodicarbonate is demonstrated as a β-aminoethyl anion synthetic equivalent. It can be used to install ethyleneamine groups by exploiting its terminal alkyne reactivity with common organic electrophiles. Reactions exemplified with this terminal ynimide reagent include additions to imines, aldehydes, ketones, pyridinium salts, Michael acceptors, epoxides, and Pd-catalyzed Sonogashira couplings. Subsequent regioselective [3 + 2] cycloadditions of the alkynyl-imides (ynimides) generate N, N -di-Boc imide-functionalized triazole and isoxazole heterocycles. Reduction of the ynimides with Pd-catalyzed hydrogenation generates ethyleneimides with easily removable N, N -di-Boc-carbamate protecting groups, allowing for a flexible ynimide-based approach to ethyleneamine installation. The utility of this two-step aminoethylation strategy was demonstrated in the short formal syntheses of pyrrolidinoindoline alkaloids (±)-CPC-1 and (±)-alline. Analogously, the reagent ( N, N, N ′)-tri-Boc 2-ethynylhydrazine serves as a β-hydrazinoethyl anion synthetic equivalent.
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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 | 0.001 |
| 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".