1,3‐Oxathiolanes from the Reaction of Aromatic and Enolized Thioketones with Monosubstituted Oxiranes
Bibliographic record
Abstract
Abstract The reactions of 4,4′‐dimethoxythiobenzophenone ( 1 ) with ( S )‐2‐methyloxirane (( S )‐ 2 ) and ( R )‐2‐phenyloxirane (( R )‐ 6 ) in the presence of a Lewis acid such as BF 3 ⋅Et 2 O, ZnCl 2 , or SiO 2 in dry CH 2 Cl 2 led to the corresponding 1 : 1 adducts, i.e. , 1,3‐oxathiolanes ( S )‐ 3 with Me at C(5), and ( S )‐ 7 and ( R )‐ 8 with Ph at C(4) and C(5), respectively. A 1 : 2 adduct, 1,3,6‐dioxathiocane (4 S ,8 S )‐ 4 and 1,3‐dioxolane ( S )‐ 9 , respectively, were formed as minor products ( Schemes 3 and 5, Tables 1 and 2 ). Treatment of the 1 : 1 adduct ( S )‐ 3 with ( S )‐ 2 and BF 3 ⋅Et 2 O gave the 1 : 2 adduct (4 S ,8 S )‐ 4 ( Scheme 4 ). In the case of the enolized thioketone 1,3‐diphenylprop‐1‐ene‐2‐thiol ( 10 ) with ( S )‐ 2 and ( R )‐ 6 in the presence of SiO 2 , the enesulfanyl alcohols (1′ Z ,2 S )‐ 11 and (1′ E ,2 S )‐ 11 , and (1′ Z ,2 S )‐ 13 , (1′ E ,2 S )‐ 13 , (1′ Z ,1 R )‐ 15 , and (1′ E ,1 R )‐ 15 , respectively, as well as a 1,3‐oxathiolane ( S )‐ 14 were formed ( Schemes 6 and 8 ). In the presence of HCl, the enesulfanyl alcohols (1′ Z ,2 S )‐ 11 , (1′ Z ,2 S )‐ 13 , (1′ E ,2 S )‐ 13 , (1′ Z ,1 R )‐ 15 , and (1′ E ,1 R )‐ 15 cyclize to give the corresponding 1,3‐oxathiolanes ( S )‐ 12 , ( S )‐ 14 , and ( R )‐ 16 , respectively ( Schemes 7, 9 , and 10 ). The structures of (1′ E ,2 S )‐ 11 , ( S )‐ 12 , and ( S )‐ 14 were confirmed by X‐ray crystallography ( Figs. 1 – 3 ). These results show that 1,3‐oxathiolanes can be prepared directly via the Lewis acid‐catalyzed reactions of oxiranes with non‐enolizable thioketones, and also in two steps with enolized thioketones. The nucleophilic attack of the thiocarbonyl or enesulfanyl S‐atom at the Lewis acid‐complexed oxirane ring proceeds with high regio‐ and stereoselectivity via an S n 2‐type mechanism.
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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) | 0.002 | 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".