Component analysis of the X-C-Y anomeric effect (X = O, S; Y = F, OMe, NHMe) by DFT molecular orbital calculations and natural bond orbital analysis
Bibliographic record
Abstract
Six 2-Y-substituted oxacyclohexane and thiacyclohexane heterocycles (Y = F, OMe, NHMe) were examined using DFT molecular orbital calculations. Natural bond orbital (NBO) analysis of the total energy behaviour yielded the orbital-interaction factors contributing to the conformational equilibria. The dipole moments of the optimized systems were used to estimate the electrostatic contributions to the anomeric effect. The primary determinant of the X-C-Y anomeric effect was found to be the orbital interaction components associated with the combined endo- and exo-anomeric effects acting in concert in the axial conformers. Electrostatic interactions made a contribution to the observed conformer stabilization in all cases, but did not account for the relative magnitudes of the energy differences among conformers of homologous molecules. In the case of the methylamino substituent, accentuated steric interactions in the axial conformer precluded stabilization by the exo-anomeric interaction and consequently, the net endo/exo anomeric stabilization did not dominate the conformational equilibria.Key words: anomeric effect, component analysis, natural bond orbital analysis, electrostatic, steric, and orbital interaction effects.
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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 | 0.001 |
| 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 | 0.000 | 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".