Potentially Prebiotic Synthesis of a 3′-Amino-3′-deoxyribonucleoside
Bibliographic record
Abstract
A central challenge in origins-of-life research is to elucidate how primitive genetic polymers could have replicated and propagated nonenzymatically before the advent of macromolecular catalysts. Nucleosides and nucleotides are considered to be essential for the emergence of life, rendering their prebiotically plausible synthesis of fundamental importance. Several potentially prebiotic pathways have been demonstrated for the formation of genetic polymers, such as RNA, DNA, threose nucleic acids (TNA), and arabinose nucleic acids (ANA). More recently, the prebiotic assembly of 3'-amino-TNA nucleosides has been achieved, whereas the analogous 3'-amino-RNA has remained elusive. Here, we report a potentially prebiotic route to 3'-amino-3'-deoxy-2-thiocytidine starting from simple feedstock molecules. Although the key intermediate, 3'-amino-ribose-aminooxazoline, undergoes degradation over the period of days, as previously observed, we demonstrate that cyanovinyl protection via cyanoacetylene treatment suppresses the byproduct formation and enables the successful synthesis of the 3'-amino-3'-deoxy-anhydrocytidine intermediate. We further show that the cyanovinyl protecting group is compatible with thiolysis at the 2-position and is concurrently removed during this process. Finally, photoanomerization of the α-anomer affords the desired β-3'-amino-3'-deoxy-2-thiocytidine. These findings support the hypothesis that 3'-amino-modified ribonucleotides could have existed under prebiotic conditions on early Earth.
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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 | 0.001 |
| 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) | 0.000 | 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".