Synthesis and Reactivity of Organozinc Reagents Derived From γ-Bromocrotonate Ester in Continuous Flow
Bibliographic record
Abstract
Abstract The Reformatsky reaction is a well-established method for the synthesis of β-hydroxyesters, a structural motif commonly found in natural products. While continuous-flow adaptations of the traditional Reformatsky reaction, which offer improved safety and efficiency, have been reported, related transformations using γ-bromocrotonate esters have not yet been explored in flow chemistry. Under batch conditions, the corresponding organozinc reagent can yield both γ- and α-adducts, depending on the metal employed and the specific reaction parameters. In this study, we report the first Reformatsky-type reaction in continuous flow using ethyl γ-bromocrotonate, with conditions optimized to favor γ-selectivity and the synthesis of homoallylic alcohols. Zinc dust was utilized as the reagent, and the reaction scope was demonstrated with a variety of carbonyl compounds, including in a four-step synthesis of piperine. Furthermore, the synthesis of ethyl γ-bromocrotonate was efficiently accomplished under continuous-flow conditions on a multigram scale via a Wohl–Ziegler bromination.
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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 | 0.000 |
| 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".