Diethyl 1,4-Dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate
Bibliographic record
Abstract
[1149-23-1] C13H19NO4 (MW 253.29) InChI = 1S/C13H19NO4/c1-5-17-12(15)10-7-11(13(16)18-6-2)9(4)14-8(10)3/h14H,5-7H2,1-4H3 InChIKey = LJXTYJXBORAIHX-UHFFFAOYSA-N (reagent used as a source of hydride) Alternate Name: HEH; Hantzsch ester hydride; Hantzsch ester; Hantzsch dihydropyridine; 1,4-dihydropyridine. Physical Data: mp 175–180 °C, bright yellow solid.2 Large variations in the melting point have been reported depending on the method of synthesis and purification. Solubility: sol in most organic solvents. Form Supplied in: solid (95% purity). Analysis of Reagent Purity: 1H NMR (1:1 DMSO/CDCl3, 400 MHz); δ 7.99 (s, 1H), 4.04 (q, J = 6.8 Hz, 4H), 3.09 (s, 2H), 2.09 (s, 6H), 1.20 (t, J = 7.2 Hz, 6H).13C NMR (CHCl3, 100 MHz): δ 168.3, 145.1, 99.7, 59.9, 25.0, 19.3, 14.7. FTIR (cm−1) (neat): 3346, 3108, 2953, 2924, 2854, 1697, 1646, 1506. Preparative Method: the reagent is most often prepared by a multicomponent reaction involving formaldehyde, ethyl acetoacetate, and ammonium acetate or ammonia.2-6 Purification: recrystallization from EtOH or flash chromatography with petroleum/ethyl acetate (7:3).4, 5 Handling, Storage, and Precautions: wear suitable gloves. Store compound in a dry container and in a cool place. Avoid contact with eyes and skin. Do not breathe dust.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.048 | 0.061 |
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".