The presence of an intramolecular hydrogen bond has been proposed to play a key role in the catalysis of amide isomerization by peptidylprolyl isomerases (PPIases), which are highly conserved and ubiquitous rotamase enzymes that catalyze the cis-trans isomerization of proline residues in peptides and proteins. We present herein kinetic and spectroscopic evidence that indicates the existence of ...

Two reaction strategies are developed to promote the highly selective 1,3-isomerization of a variety of allylic alcohols using O3ReOSiPh3 as a catalyst. The first strategy utilizes substrates whose 1,3-regioisomer contains a conjugated alkene, which relies on thermodynamics to obtain high selectivity. The second strategy employs N,O-bis(trimethylsilyl)acetamide as an additive to selectively and...

Selective transformation of 2-propargylthio-6-methyl-pyrimidin-4(1H)On e (2) to 3,5-dimethyl-7H-thiazolo [3,2-a] pyrimidin-7-one (3) is performed under the conditionof base catalysis . For elucidation of structure, palladium catalyzed cyclization reaction of (2) was carried out and the structures of the products were assigned (5) and (6). These compounds underwent isomerization to (3) and (4...

Molecular dynamics simulation techniques together with time-dependent density functional theory calculations have been used to investigate the effect of photon absorption by a 4-hydroxy-cinnamic acid chromophore on the structural properties of the photoactive yellow protein (PYP) from Ectothiorodospira halophila. The calculations suggest that the protein not only modifies the absorption spectru...

A novel class of chiral phosphanyl-oxazoline (PHOX) ligands with a conformationally rigid cyclopropyl backbone was synthesized and tested in the intermolecular asymmetric Heck reaction. Mechanistic modelling and crystallographic studies were used to predict the optimal ligand structure and helped to design a very efficient and highly selective catalytic system. Employment of the optimized ligan...

The allyl and propenyl ethers of diols and polyols have recently attracted increasing attention as monomers and comonomers [1–2]. Most convenient method of the preparation of propenyl ethers consists in isomerization of the corresponding, readily available allyl ethers. Moreover, this isomerization is a key step of deprotection of hydroxyl group, protected as allyl ether [3,4]. Particularly con...

Infrared-induced conformational isomerization of N-acetyl-tryptophan methyl amide is studied theoretically using a microcanonical Rice-Ramsperger-Kassel-Marcus description of the rates on potential energy surfaces calculated using the AMBER and OPLS-AA force fields. The results are compared with the experimental data from Dian et al. in the preceding paper [J. Chem. Phys. 120, 133 (2004)]. An e...

The reaction kinetics of the isomerization 3,4-dichlorobutene-1 to 1,4-dichlorobutene-2 was investigated by using gas-liquid chromatography method in the presence of Fe2O3/MgO as solid catalyst in the temperature range 25-55°C. Fe2O3/MgO has been prepared by the support saturation method, tested in the isomerization of 3, 4-dichlorobutene-1 into 1, 4-dichlorobutene-2. This catalyst shows a high...

The primary products of n-butoxy and 2-pentoxy isomerization in the presence and absence of O(2) have been detected using pulsed laser photolysis-cavity ringdown spectroscopy (PLP-CRDS). Alkoxy radicals n-butoxy and 2-pentoxy were generated by photolysis of alkyl nitrite precursors (n-butyl nitrite or 2-pentyl nitrite, respectively), and the isomerization products with and without O(2) were det...