Spectroscopic and Calorimetric Studies on the Mechanism of Methylenecyclopropane Rearrangements Triggered by Photoinduced Electron Transfer
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
2-(dideuteriomethylene)-1,1-bis(4-methoxyphenyl)cyclopropane (d(2)-1) undergoes degenerate rearrangement in both singlet- and triplet-sensitized electron-transfer photoreactions. Nanosecond time-resolved absorption spectroscopy on laser flash photolysis of the unlabeled 1 with 9,10-dicyanoanthracene, 1,2,4,5-tetracyanobenzene, or N-methylquinolinium tetrafluoroborate as an electron-accepting photosensitizer gives rise to two transients with lambda(max) at 500 and 350 nm assigned to the dianisyl-substituted largely twisted trimethylenemethane cation radical (6.+) and the corresponding diradical (6..), respectively. These intermediates are also detected, respectively, by steady state and nanosecond time-resolved EPR with chloranil or anthraquinone as a sensitizer. The degenerate rearrangement of d(2)-1 thus proceeds via these two different types of intermediates in a cation radical cleavage-diradical cyclization mechanism. Energetics based on nanosecond time-resolved photoacoustic calorimetry support this mechanism. A comparison of the reactivities and the spectroscopic results of 1, 1,1-bis(4-methoxyphenyl)-2-methylenespiro[2.2]pentane (2), and 1-cyclopropylidene-2,2-bis(4-methoxyphenyl)cyclopropane (3) suggest that the reversible methylenecyclopropane rearrangement between 2 and 3 proceeds via a similar mechanism.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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