Investigations on an Alternative Approach to Fmoc Deprotection and Diversification of the Alumino-Mannich Reaction
Bibliographic record
Abstract
The Fmoc group is widely used for amine protection, but the classical deprotection approach, piperidine in DMF, has drawbacks due to toxicity and cost. Previous research explored alternative conditions using diethylamine and Lewis acids. This thesis outlines the synthesis of Fmoc-protected dipeptides and alternative deprotection conditions: classical, diethylamine alone, and diethylamine with Lewis acids (Ca(TFA)2, CaCl2, BF3•Et2O). NMR analysis reveals that CaCl2 and BF3•Et2O only slightly accelerate deprotection, making this an impractical alternative in peptide chemistry and amine protection.Chapter 2 broadens the substrate and product range of an asymmetric “alumino-Mannich” reaction using a range of sulfinyl imine and alkenylaluminum reagents for homochiral allylamine synthesis. Factors including temperature, steric bulk, and electronic effects are studied. Steric bulk of alkenylaluminum reagents dominates selectivity; electronic effects within sulfinyl aldimines dominates the yield, and electron deficiency is crucial at cryogenic temperatures. Surprisingly, high yields and selectivities were achieved at room temperature.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".