The ylides Ph3E-C6H6N2O3 (7, E = P (a), As (b), Sb (c)) have been prepared through the reaction of Ph3E and 5- bromo-1,3-dimethyl-2,4,6(1H,3H,5H)-pyrimidinetrione (5-bromo-1,3-dimethylbarbituric acid) 6 in the presence of triethylamine. Their characterisation was performed by nuclear magnetic resonance (NMR), mass spectrometry (MS) and elemental analysis.
Understanding the Formation of 5-(Diethylammoniothio)-1,3-dimethylbarbituric Acid: Crystal Structure and DFT Studies
作者:Kamal Sweidan、Mansour H. Almatarneh、Murad A. AlDamen、Monther Khanfar、Reema A. Omeir、Caecilia Maichle Mössmer、Manfred Steimann
DOI:10.1007/s10870-020-00846-1
日期:2021.6
5-(Diethylammoniothio)-1,3-dimethylbarbituric acid (8) was obtained in good yield from the reaction of 5-bromo-1,3-dimethylbarbituric acid (5) and 1,3-diethylthiourea. The obtained product has been characterized using different techniques including single-crystal X-ray diffraction, FTIR, MS and NMR spectroscopy. For this reaction, a detailed computational study of the reaction steps has been performed using density functional theory (DFT). Both thermodynamic and kinetic parameters were calculated. Step B is the most favorable reaction with an activation energy of 33 kJ mol−1 using the solvation model that based on the solvent model density (SMD) calculated at B3LYP/6-31G(d). The rate-determining step of the most plausible mechanism involves the formation of C-S bond via proton transfer to oxygen (intramolecular attraction) with an activation barrier of 33 kJ mol-1 using the solvation model that based on density (SMD) solvent model calculated at B3LYP/6-31G(d).
Studies on the Smiles Rearrangement. XIV. Novel Reactions of 1, 3-Dimethyl-5-nitro-6-chlorouracil with 2-Aminothiophenol
作者:YOSHIFUMI MAKI、TOKIYUKI HIRAMITSU、MIKIO SUZUKI
DOI:10.1248/cpb.22.1265
日期:——
The reaction of 1, 3-dimethyl-5-nitro-6-chlorouracil with 2-aminothiophenol in benzene containing an excess of triethylamine gave 1, 3-dimethyl-10H-pyrimido (5, 4-b) (1, 4) benzothiazine-2, 4 (1H, 3H) dione quantitatively via the Smiles rearrangement. The reaction in acetic acid, however, resulted in the formation of 2-methyl-4-nitropyrimido (4, 3-b) benzothiazoline-1, 3 (2H, 10H)-dione in 78% yield, involving an unusual uracil-ring cleavage which appears to occur in a benzothiazoline intermediate in the course of the acid-catalized Smiles rearrangement.