Structures of the 2:1 adducts of benzyne with 2-methylanisole and benzene
Bibliographic record
Abstract
The 2:1 adduct of benzyne with 2-methylanisole is shown to have the bisbenzotricyclic structure 6,6a,11,11a-tetrahydro-5-methoxy-6-methyl-5,6,11-metheno-5H-benzo[a]fluorene by a single-crystal X-ray diffraction study (C20H18O: Pca21, a = 15.0497(17), b = 9.87783(11), c = 9.6846(11); Z = 4; 1672 data points, R1 = 0.0325). This structure is compared to an unpublished crystal structure of the parent hydrocarbon 6,6a,11,11a-tetrahydro-5,6,11-metheno-5H-benzo[a]fluorene, C18H14. Both structures have also been computed by DFT methods at the B3LYP/6-311(d,p) level of theory. Bond distances and angles between the solid-state measurements and gas-phase calculations are found to agree well; average deviations are well below 1%. The 1H NMR spectra show surprisingly small 3JHH couplings in the central tricyclic cage, but can be assigned using 2D spectroscopy.Key words: Hydrocarbon cages, strained rings, cyclopropane, X-ray crystallography, NMR.
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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) | 0.000 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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 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".