Synthesis of a Tetracyclic G∧C Scaffold for the Assembly of Rosette Nanotubes with 1.7 nm Inner Diameter
Bibliographic record
Abstract
The synthesis of a tetracyclic self-complementary molecule 4 for self-assembly into rosette nanotubes is presented. This new heterocycle has a core structure containing two pyrido[2,3-d]pyrimidine molecules fused together and features the Watson-Crick hydrogen bond donor-acceptor arrays of both guanine (G) and cytosine (C). Current methods to synthesize pyrido[2,3-d]pyrimidines require harsh conditions and long reaction times and result usually in low product yields. This is particularly problematic for the direct incorporation of functional groups that cannot withstand these conditions. Here, we present an efficient approach to access the multifunctional pyrido[2,3-d]pyrimidine intermediate 2 under relatively mild conditions using three regioselective S(N)Ar reactions at C2, C4, and C7 on the trichloro compound 1. The electron-withdrawing group and amino functionalities on 2 are then used as a handle to install the third and fourth rings of 4 using a Friedländer-type condensation followed by mixed urea synthesis and cyclization.
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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) | 0.001 | 0.001 |
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".