Concise and Efficient Synthesis of 2-Acetamido-2-deoxy-β-<scp>d</scp>-hexopyranosides of Diverse Aminosugars from 2-Acetamido-2-deoxy-β-<scp>d</scp>-glucose
Bibliographic record
Abstract
The furanose acetonide derivative 1 is readily prepared from 2-acetamido-2-deoxy-D-glucose on a large scale without the need for chromatography. Mesylation of 1 provides an efficient, concise, synthetic route to rare 2-acetamido-2-deoxy-beta-D-hexopyranosides (2 and 3) via the corresponding methyl 2-acetamido-2-deoxy-3-O-methanesulfonyl-beta-D-glucopyranoside and subsequent inversion of configuration by direct displacement or formation of a 3,4-epoxide. Opening of this epoxide by azide provided a direct route to methyl 2-acetamido-4-amino-2,4,6-trideoxy-beta-D-gulopyranoside 4. Benzylation of 1 followed by ring expansion to the glucopyranoside, deoxygenation at C-6, and subsequent displacement of a C-4 triflate permitted the synthesis of methyl 2-acetamido-4-amino-2,4,6-trideoxy-beta-D-galactopyranoside 5. Methyl 2-acetamido-2-deoxy-beta-D-glucopyranoside available from 1 in quantitative yield was readily converted to methyl 2-acetamido-2-deoxy-beta-D-galactopyranoside 6 (>60%) by inversion of configuration at C-4. Introduction of a lactyl substituent at C-3 of oxazoline 1 also provides a facile synthesis of the biologically important muramic acid beta-glycoside 7. An interesting reaction to convert 2-acetamido-2-deoxyhexopyranosides to the corresponding 2-deoxy-2-tetrazole is also reported.
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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".