Density Functional Theory Computational Study on the Thermal Cycloreversion of 2-Acetoxy-2-methoxy-5,5-dimethyl-Δ<sup>3</sup>-1,3,4-oxadiazoline: Evidence for a Carbonyl Ylide Intermediate
Bibliographic record
Abstract
Three [3 + 2] cycloreversions of 2-acetoxy-2-methoxy-5,5-dimethyl-Delta(3)-1,3,4-oxadiazolines were examined by computation at the density functional level of theory. The lowest activation energies are those for cycloreversion to 2-diazopropane and acetic methylcarbonic anhydride and for cycloreversion to N(2) and a carbonyl ylide. Those are the reactions that are observed experimentally. A third cycloreversion, to acetoxy(methoxy)diazomethane and acetone, has a much larger barrier. The carbonyl ylide is a real intermediate, but it fragments easily to acetone and acetoxy(methoxy)carbene. The lifetime of the ylide may be so short, in some cases, as to blur the distinction between a two-step cycloreversion of the oxadiazoline and a concerted process that generates three fragments in one step.
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How this classification was reachedexpand
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 | 0.002 | 0.001 |
| 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) | 0.002 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".