Is Schleyer’s Predicted All-Cis [10]Annulene an Unstable Framework?
Bibliographic record
Abstract
In this work we describe the synthesis of a long sought after planar [10]annulene. Remarkably, the efforts also led us to discover a completely unexpected and highly aromatic cyclopropa mono-trans[10]annulene. The parent [10]annulene (cyclodecapentaene) is non-planar and thus non-aromatic because the aromatic stabilization energy is not sufficient to overcome the strain involved in expanding CCC bond angles from the standard 120° to the necessary 144°. Interestingly, it was theorized by Schleyer (10.1021/ja953126i) that planar structures could be attained by adding cyclopropane (or cyclobutane) rings to the periphery. We opted to target the dicyclopropa[10]annulene derivative that was proposed as it was a formal cyclopropanation of our previously found stable dehydrocyclopropa[10]annulene (10.1038/s44160-022-00135-z, 10.26434/chemrxiv.14458653.v1). It was also presumed that the symmetry present within the structure would make the Kekulé structures degenerate, thus improving aromaticity substantially. However, we were uncertain if the structure would be kinetically stable and wished to attempt a synthesis to investigate it further. In this paper we describe our evolving synthetic strategy that ultimately led us to the preparation of the dicyclopropa[10]annulene. Interestingly we noted that the framework itself was rather unstable and degraded quite rapidly. We also observed that the final preparation of the desired material led to a significant side product that was identified as a cyclopropa mono-trans[10]annulene. This side product was completely unexpected and found to be more kinetically persistent than the original target.
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.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.186 | 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".