Mini-Reviews in Organic Chemistry - Volume 8, Issue 3, 2011

The major aim of molecular modelling is to predict structures and other properties of molecules and molecular assemblies. In principle, conformation and dynamics of any molecule can be studied by equilibrium simulation in an appropriate environment. However, for example de novo prediction of protein structures by simulating the folding process is still a dream rather than a routine method and it has been succ Read More

X-ray crystallographic studies have shown that C-H groups of saccharides interact with aromatic amino acid residues in binding sites in proteins. Such C-H…pi interactions have been shown to be dominated by London's dispersion interactions. The strength of interaction depends on a number of factors: (i) the nature of aromatic residue and saccharide, (ii) the form (acyclic, pyranose or furanose) and conformation of the sacch Read More

Glycoproteins are synthesized in most of the living organisms, being major components of the outer surface of mammalian cells and most of the secreted proteins in eukaryotes. Accordingly, a better comprehension of the biological processes in which they are involved requires the characterization of their structure and conformation. As such rationale faces several difficulties from both experimental and theoretical Read More

Many theoretical studies on carbohydrates have been published in the last century. Building on these developments, a procedure is presented to select stable conformations of monosaccharides in aqueous solution from samplings on potential energy surfaces (PES) obtained from quantum mechanics. Considerations regarding the property chosen to validate conformational samplings are also presented. The conformations f Read More

Carbohydrates are polar molecules and their conformational and anomeric equilibrium can be strongly influenced by solvents. This review provides examples of studies addressing different issues of glycochemistry, such as anomeric equilibrium, conformational changes in rings, modelling of inter-residue linkages or complex carbohydrates and formation of carbohydrate-protein complexes. All these phenomena provide bench Read More

Although free energy calculations have been extensively employed to explore the conformational space of proteins, to date carbohydrates have received considerably less attention. This review provides a survey of recent computational free energy studies of the preferred conformations and characteristic dynamics of carbohydrate molecules in solution. The article comprises a motivation for employing expensive free energy Read More

Glycosyltransferases comprise a group of enzymes that catalyze the transfer of glycosyl residues from donors containing nucleoside phosphates to other molecules. The molecular details of the catalytic mechanism involving these enzymes are not well understood. Hybrid QM/MM methods have become important in providing new insights into the atomic details of enzymatic reactions. The QM/MM calculations of GnT-I and β4GalT- Read More

Besides their implication in human physiology and disease, β-N-acetylhexosaminidases (EC 3.2.1.52, CAZy GH 20) have recently gained a lot of attention thanks to their great potential in the enzymatic synthesis of carbohydrates and glycomimetics. Extracellular β-N-acetylhexosaminidases from filamentous fungi proved to be a powerful synthetic tool for the preparation of both natural and modified glycosides under mild co Read More

Traditional chemistry has typically involved thermal energy to drive chemical reactions. In the 20th century, photochemical, catalytic, sonic, and high pressure techniques have been exploited to drive chemical reactions, thereby providing the tools to expand the breadth of organic chemistry. The early organic syntheses performed in the mid-1980s that used microwave radiation as the principal heating source were carried out Read More

This review article is the second of the comprehensive series on survey of the microwave photochemical and photocatalytic processes, and is focused specially on the microwave-assisted photochemical applications of the electrodeless discharge lamps (EDLs) in organic synthesis. The concept of microwave organic photochemistry is an important issue in synthetic chemistry and material science, and is presented in sev Read More

A broad range of research on chemical reactions by microwave heating has been conducted, because unlike reactions by conventional heating, reactions by microwave heating underwent a reaction acceleration phenomenon. The microwave effect on chemical reactions has been previously discussed as a thermal or non-thermal effect without universal knowledge. Measuring temperature accurately is essential for discussing Read More

This brief article reviews the behavior of microwaves in organic syntheses from the viewpoint of the frequency effect, which has been examined on various common solvents with a newly fabricated 5.80-GHz microwave organic synthesis apparatus, whose features are compared with a similar 2.45-GHz microwave apparatus. Results from usage of the 5.80-GHz microwaves are also compared to the more frequently used MW fr Read More

Microwave-assisted polymerizations such as radical polymerization, polycondensation, and cation polymerization have been numerously reported. Recently, researches on condensed polymers by microwave heating have been energetically conducted about not only basic synthesis research but also scale-up for a commercial process. This mini review focuses on microwave-assisted polyester and polyamide syntheses and describ Read More

Microwave heating has received considerable attention as a powerful synthetic tool for metal complexes in many fields of inorganic chemistry and material science. Since the 1990s, numerous metal complexes have been synthesized using the microwave technique. However, only a few studies have discussed such synthesis. In this review, we focus on microwave-assisted synthesis of metal complexes. We discuss the backgroun Read More

Several reviews have been published on the application of microwaves to various aspects of chemistry, such as heterogeneous catalysis and eco-friendly green chemistry. In particular, the investigation of metal-catalyzed reactions, such as Suzuki-Miyaura and Heck reactions, has attracted the attention of organic chemists. The aim of this review is to show how microwave effects have been used in metal-catalyzed reactions.

Electrophilic amination constitutes a unique strategy for the synthesis of C-N bonds. One often-overlooked example of this type of process involves the reaction of organometallic nucleophiles with electrophilic nitrogen sources to yield aryl and alkyl amine derivatives. Such transformations are mechanistically intriguing and have the potential to drastically alter the logic by which nitrogencontaining compounds are synthesized.