Methylation of Dihydroquercetin Acetates: Synthesis of 5-<i>O</i>-Methyldihydroquercetin
Bibliographic record
Abstract
The major products of methylation of dihydroquercetin (1, dhq) with diazomethane have been identified as 7-O-methyldhq (9), 7,3'-di-O-methyldhq (10), 7,4'-di-O-methyldhq (11), and 7,3',4'-tri-O-methyldhq (2). With dhq 3,7,3',4'-tetraacetate (6), dhq 3,5,3',4'-tetraacetate (5), dhq 3,3',4'-triacetate (7), dhq 7,3',4'-triacetate (8), and dhq 3-acetate (4) the same reaction affords mainly 5-O-methyldhq 3,7,3',4'-tetraacetate (15), 7-O-methyldhq 3,5,3',4'-tetraacetate (13), 7-O-methyldhq 3,3',4'-triacetate (14), 5-O-methyldhq 7,3',4'-triacetate (25), and 7-O-methyldhq 3-acetate (12), respectively. The methylation of 8 is accompanied by intermolecular acetyl migration from phenolic oxygen to the hydroxy group of the heterocyclic ring. 5-O-Methyldhq (28) is accessible by deacetylation of 25. 5,7-Di-O-methyldhq (29), four known methyl ethers, 13 new and three known methyl ether acetates of dhq, and six new isomers with 2,3-cis stereochemistry were spectroscopically identified.
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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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".