Assisted hydrolysis of <i>cis</i>-2-(3-phenylthioureido)cyclo pentane-carbonitrile in alkaline solution. Solvent dependent switch from hydrolysis to rearrangement of the iminothiooxopyrimidine intermediate
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Bibliographic record
Abstract
The cis and trans isomers of 2-(3-phenylthioureido)cyclopentanecarbonitrile, 1, and the respective carboxamides, 3, and acids, 4, have been prepared. Acid cyclization of both nitriles, faster with the cis isomer, gave the more stable cis-2-thiooxo-cyclopenta[d]pyrimidin-4-one, 7. In base cis-1 formed the cis 4-imino-2-thiooxopyrimidine 2 which in aqueous alkali broke down via 3 to the acid 4; while in the presence of 66% acetonitrile 2 rearranged to the 4-phenyliminopyrimidine 5 to give as final product the thioureido acid 6 carrying no phenyl group. The 1 H NMR data for imino and phenylimino derivatives 2 and 5 showed strong bias for conformation A with 1-N pseudoaxial in the cyclopentane ring. Spectra of the E andZ isomers of the iminopyrimidine 2 under slow exchange could be recorded in DMSO-d 6 . The phenylimino tautomer of 5 is observed in CD 3 OD and in CDCl 3 with the E and Z isomers in a 1:1 ratio. In DMSO-d 6 the phenylamino tautomer 5a is also detected. The first process in aqueous KOH, the conversion of nitrile cis-1 into the imino intermediate 2, reaches an equilibrium which shifts towards the nitrile at higher alkalinities because of ionization of the phenylthioureido group (K e = [2]/[1] = 2.43 and pK AH = 12.74). The cyclization of 1 to 2 is first order in [OH - ] while the slower breakdown of 2 is pH independent. The latter is 10 4 times faster than the hydrolysis of acetonitrile evidencing substantial anchimeric assistance. The change in the reaction route towards the rearranged phenyliminopyrimidine 5 upon addition of acetonitrile can be caused by the lower dielectric constant favouring the elimination step leading to the intermediate isothiocyanate, and by increased activity of OH - accelerating the (presumably) second order elimination step as opposed to the pH-independent hydrolysis of the imino derivative 2. Key words: anchimeric assistance, phenylthioureido nitriles, iminothiooxopyrimidine tautomers, alkaline hydrolysis, solvent effects.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.011 | 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 it