Computational study on the aminolysis of beta-hydroxy-alpha,beta-unsaturated ester via the favorable path including the formation of alpha-oxo ketene intermediate.

The possible mechanisms of the aminolysis of N-methyl-3-(methoxycarbonyl)-4-hydroxy-2-pyridone (beta-hydroxy-alpha,beta-unsaturated ester) with dimethylamine are investigated at the hybrid density functional theory B3LYP/6-31G(d,p) level in the gas phase. Single-point computations at the B3LYP/6-311++G(d,p) and the Becke88-Becke95 1-parameter model BB1K/6-311++G(d,p) levels are performed for more precise energy predictions. Solvent effects are also assessed by single-point calculations at the integral equation formalism polarized continuum model IEFPCM-B3LYP/6-311++G(d,p) and IEFPCM-BB1K/6-311++G(d,p) levels on the gas-phase optimized geometries.

Theoretical study on the hydrolysis mechanism of N,N-dimethyl-N'-(2-oxo-1, 2-dihydro-pyrimidinyl)formamidine: water-assisted mechanism and cluster-continuum model.

The hydrolysis reaction of N,N-dimethyl-N'-(2-oxo-1, 2-dihydro-pyrimidinyl)formamidine (DMPFA), a model compound of the antivirus drug amidine-3TC (3TC = 2', 3'-dideoxy-3'-thiacytidine), is investigated by the hybrid density functional theory B3LYP/6-31+G (d,p) method. The hydrolysis reaction of the title compound is predicted to undergo via two pathways, each of which is a stepwise process. Path A is the addition of H2O to the C=N double bond in the amidine group to form a tetrahedral structure in its first step, and then the transfer of the H atom of hydroxyl leads to the corresponding products via four possible channels.

Theoretical studies on the hydrolysis mechanism of N-(2-oxo-1,2-dihydro-pyrimidinyl) formamide.

Density functional theory (B3LYP) and ab initio (MP2) methods with the 6-31G(d,p) basis set are used to study the mechanisms for the hydrolysis of N-(2-oxo-1,2-dihydro-pyrimidinyl) formamide (PFA) in the gas phase. The direct and the water-assisted hydrolysis processes are considered, involving one and two water molecules, respectively. Three different pathways are explored in each case.

DFT study and Monte Carlo simulation on proton transfers of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water.

Density functional theory (DFT) and Monte Carlo (MC) simulation with free energy perturbation (FEP) techniques have been used to study the tautomeric proton transfer reaction of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water. Two reaction pathways were considered: the direct and water-assisted transfers. The optimized structures and thermodynamic properties of stationary points for the title reaction system in the gas phase were calculated at the B3LYP/6-311+G(d, p) level of theory.