Protonation studies on epimeric homoallylic adamantylideneadamantyl alcohols, 4-methyleneadamantylideneadamantane, adamantylideneadamantane (AdAd) and sesquihomoadamantene, and reaction of AdAd and sesquihomoadamantene with NO2+BF4– and PhI(OH)OTs: a stable-ion NMR and theoretical (GIAO-NMR) studyElectronic supplementary information (ESI) available: representative 1D-NMR spectra and tables of cartesian coordinates. See http://www.rsc.org/suppdata/p2/b2/b201660e/
Bibliographic record
Abstract
Under stable-ion conditions, the “pseudo-axial” homoallylic alcohol 1-ax is protonated at the AdAd double-bond and the resulting carbocation undergoes rapid cyclization to produce the oxonium ion 9H+ as the only observable species, which on quenching furnishes the cyclic ether 9. In contrast, protonation of the “pseudo-equatorial” homoallylic alcohol 1-eq gave a persistent homoallylic cation 1a+. Protonation of the methylene-substituted derivative 8 gave a 5 ∶ 1 mixture of two carbocations, in which the minor ion is homoallylic 8aH+. Adamantylideneadamantane AdAd 5 reacts with FSO3H–CH2Cl2 to give the previously observed 5H+ (as a rapidly equilibrating pair of carbocations), together with the oxonium ion 6H+. The outcome of the reaction of AdAd with NO2BF4, NOBF4 and with PhI(OH)OTs is the same, in all cases producing the spirocyclic ketone 6. Sesquihomoadamantene 7 is protonated in FSO3H–SO2ClF and the initially formed carbocation (not observed) rapidly rearranges to 5H+. Compound 7 also reacts with NO2BF4, and TFA–CH2Cl2 to produce the spirocyclic ketone 6 and 5, after quenching. With PhI(OH)OTs the recovered material is 7 itself plus PhI. For comparison, the homoallylic carbocations 1a+, 8aH+, their skeletally rearranged allylic cations 1b+, 8cH+, and the oxonium ions 9H+ and 6H+ were studied computationally by GIAO-NMR at the BLYP/6-31G(d)//BLYP/6-31G(d) level.
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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) | 0.003 | 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".