The mechanism of acylation of oxaloacetic acid (OA) with acetyl—CoA was studied at the DFT level using basis functions 6-311G(d,p) and different numbers of diffuse functions. Four mechanisms were considered in this study. It was found that the most probable mechanism, in the approximation of isolated molecules, starts with the enol forms of oxaloacetic acid and acetylcysteamine (final fragment ...

AM1 calculations on equilibrium and transition state geometries of keto and enol forms of glitazones were carried out and compared with those of some carbonyl compounds. The results show that the energy requirements for enolisation of glitazones are much higher than the standard carbonyl systems. Neither the ring system, nor the additional functional groups in thiazolidinedione terminal ring fa...

A new procedure for the stereoselective synthesis of syn α-amino β-oxy ketones is reported. It consists of two steps; in the first step, α-amino silyl enol ethers having a (Z) geometry are prepared from 1-alkynes via 1-sulfonyl-1,2,3-triazoles. In the second step, the silyl enol ethers undergo the TiCl4-mediated Mukaiyama aldol reaction with aldehydes to produce α-amino β-oxy ketones with excel...

Enol forms of trifluoroacetylacetone (TFacac) isolated in molecular and rare gas matrices were studied using infrared (IR) Raman spectroscopy. Additionally, calculations DFT B3LYP M06...

Based on a preactivation protocol with (p-Tol)2SO/Tf2O, a practical, straightforward, and high-yielding synthesis of α-sialyl C-glycosides was accomplished by coupling N-acetyl-5-N,4-O-oxazolidione protected thiosialoside with various trimethylsilyl enol ethers and allyltrimethylsilanes. High yields and excellent α-selectivities were obtained for the strong π-nucleophiles with large nucleophili...

molecular structure, isomerism, conformational stability and intramolecular hydrogen bonding (ihb) of cis-enol forms of 1-(n-pyridyl)butane-1,3-diones (npbd) (n = 2, 3, or 4) have been investigated by means of density functional theory (dft) calculations. energy differences for all possible npbd cis-enol forms of isomers with respect to the most stable form of the corresponding isomer have been...

A nonheme iron catalyst catalyzed stereoselective oxidation of alkanes with H2O2 with remarkable efficiency and exhibiting an unprecedented high incorporation of water into the oxidized products. The present results challenge the canonical description of oxygenases, the standard oxo-hydroxo tautomerism that applies to heme systems and serves as a precedent for alternative pathways for the oxida...