Highly Efficient and Stereoselective Synthesis of 6,7‐Dideoxy‐β‐<scp>d‐</scp><i>ido</i>‐octopyranuronates
Bibliographic record
Abstract
Abstract 6‐Deoxy‐β‐ido‐heptopyranosides are challenging glycosides to synthesize due to their unusual 6‐deoxy‐heptose backbone, rare ido‐configuration and most importantly, the β‐1,2‐cis anomeric linkage. They are found in nature, such as being part of the repeating disaccharide of C. jejuni HS:4 capsular polysaccharides (CPs). Interestingly, the bacterial CPs is found to be partially modified with an O‐methyl phosphoramidate (MeOPN) functionality at the O‐2 or O‐7 position of the 6‐deoxy‐β‐d‐ido‐heptopyranosides. In this work, we report the first synthesis of three analogous of β‐d‐ido‐octopyranosides (1–3) that contain a 6,7‐dideoxy‐functionality and either a terminal methyl ester or carboxylic acid or amide. Since carboxylic acids have been reported as bioisosteres of phosphate group, compound 1–3 can be regarded as carbon‐based bioisosteres of 6‐Deoxy‐β‐ido‐heptopyranoside containing the MeOPN group without a chiral center. Compounds (1–3) were efficiently synthesized from a O‐2 activated β‐d‐galacto‐octopyranuronate (19) that was efficiently converted to the desired β‐d‐ido‐octopyranuronate configuration using an elegant one‐pot process.
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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 | 0.000 |
| 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".