3‐Oxidopyridinium Ions Are Versatile Bioorthogonal Dipoles for Use in Cycloadditions with Cyclooctynes
Bibliographic record
Abstract
Abstract 3‐oxidopyridinium ions are water stable and soluble heteroaromatic betaines that behave as latent dipoles and undergo a wide variety of cycloadditions. Research into the cycloaddition reactions of 3‐oxidopyridiniums was spearheaded by Alan R. Katritzky and collaborators from the early 1970s until the late 1980s, but they have yet to be used for bioorthogonal applications. Herein we report that 3‐oxidopyridiniums can readily react with 4‐dibenzocyclooctynol (DIBO), a common bioorthogonal handle, in a [3+2] cycloaddition. The mechanism was investigated by altering the electronics of the reaction by changing the substituent on the 5 position of the pyridinium. Electron‐donating 5‐substituents have been shown to significantly increase the rate of the reaction, with bimolecular rate constants ranging from 3.3×10 −4 s −1 with 5‐trifluoromethyl‐ N ‐methyl‐3‐oxidopyridinium to 1.07 M −1 s −1 with 5‐amino‐ N ‐methyl‐3‐oxidopyridinium. 3‐oxidopyridiniums’ appreciable cycloaddition rates and compatibility with bioorthogonally relevant environments give them the potential to be used in a variety of bioconjugation applications.
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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) | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".