Synthesis and crystal structures of 3-hydroxy-2,4-dimethyl-2<i>H</i>-thiophen-5-one and 3-hydroxy-4-methyl-2<i>H</i>-thiophen-5-one
Bibliographic record
Abstract
The structures of two hydroxy-thiophenone derivatives related to the antibiotic thiolactomycin are presented. These are the racemic 3-hydroxy-2,4-dimethyl-2 H -thiophen-5-one, C 6 H 8 O 2 S, and 3-hydroxy-4-methyl-2 H -thiophen-5-one, C 5 H 6 O 2 S. The main structural feature of both compounds is C (6) hydrogen-bonded chains formed between the OH and C=O groups. In achiral C 5 H 6 O 2 S, these chains propagate only by translation, corresponding to x + 1, y , z + 1. However, in contrast, for racemic C 6 H 8 O 2 S the hydrogen-bonded chains propagate through a − x + {3\over 2}, y + {1\over 2}, z operation, giving chains lying parallel to the crystallographic b -axis direction that are composed of alternate R and S enantiomers. The crystals of 3-hydroxy-4-methyl-2H-thiophen-5-one were found to be twinned by a 180° rotation about the reciprocal 001 direction. In the final refinement the twin ratio refined to 0.568 (2):0.432 (2).
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".