Regio‐ and Stereoselectivity of the SiO<sub>2</sub>‐Catalyzed Reaction of Thiocamphor (=1,7,7‐Trimethylbicyclo[2.2.1]heptane‐2‐thione) with Optically Active Monosubstituted Oxiranes
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Bibliographic record
Abstract
Abstract The reactions of the enolizable thioketone (1 R ,4 R )‐thiocamphor (=(1 R ,4 R )‐1,7,7‐trimethylbicyclo[2.2.1]heptane‐2‐thione; 1 ) with ( S )‐2‐methyloxirane ( 2 ) in the presence of a Lewis acid such as SnCl 4 or SiO 2 in anhydrous CH 2 Cl 2 led to two diastereoisomeric spirocyclic 1,3‐oxathiolanes 3 and 4 with the Me group at C(5′), as well as the isomeric β ‐hydroxy thioether 5 ( Scheme 2 ). The analogous reactions of 1 with ( RS )‐, ( R )‐, and ( S )‐2‐phenyloxirane ( 7 ) yielded two isomeric spirocyclic 1,3‐oxathiolanes 8 and 9 with Ph at C(4′), an additional isomer 13 bearing the Ph group at C(5′), and three isomeric β ‐hydroxy thioethers 10, 11 , and 12 ( Scheme 4 ). In the presence of HCl, the β ‐hydroxy thioethers 5, 10, 11 , and 12 isomerized to the corresponding 1,3‐oxathiolanes 3 and 4 ( Scheme 3 ), and 8, 9 , and 13 , respectively ( Scheme 5 ). Under similar conditions, an epimerization of 3, 8 , and 9 occurred to yield the corresponding diastereoisomers 4, 14 , and 15 , respectively ( Schemes 3 and 6 ). The structures of 9 and 15 were confirmed by X‐ray crystallography ( Figs. 1 and 2 ). These results show that the Lewis acid‐catalyzed addition of oxiranes to enolizable thioketones proceeds with high regio‐ and stereoselectivity via an S n 2‐type mechanism.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it