Applications of 5-<i>exo</i>-trig Thiyl Radical Cyclizations for the Synthesis of Thiosugars
Bibliographic record
Abstract
The application of thiyl-radical-mediated 5-exo-trig cyclization reactions for the preparation of a series of C-linked 4-thiofuranoside sugars has been investigated. The cyclization reactions were found to proceed in high yield with complete regioselectivity and moderate to excellent diastereoselectivity for a number of benzyl-protected precursors. The diastereoselectivity of the radical cyclization was determined by a number of factors, primarily the stereochemistry at the C-2 position and the nature of the substituents attached to the olefin. The cyclization reactions proceed via transition-state intermediates that favor formation of the 1,2-trans products. For D-sugars, a chairlike transition state is proposed. For L-sugars, both chair- and boatlike transition states could be considered. Inversion of the stereochemistry at C-4 also induced a significant effect on the diastereoselectivity of the radical process. The synthetic route is general for both D- and L-sugars and offers a highly novel and efficient strategy for accessing C-linked 4-thiofuranosides. A fluorescently labeled thiosugar was prepared as a putative glycosidase inhibitor.
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How this classification was reachedexpand
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 | 0.001 |
| 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) | 0.006 | 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 teacher head, 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".