Mini-Reviews in Organic Chemistry - Volume 14, Issue 3, 2017

Carménère is the emblematic grape of Chile. Recent studies indicate that it has a different polyphenolic profile than other commercial varieties of grape among other factors, due to its long maturation period. The grape and wine of Carménère stand out for having high concentrations of anthocyanins (malvidin), flavonols (quercetin and myricetin) and flavanols (catechin, epicatechin and epigallocatechin). These compounds are related to the distinctive characteristic of Carménère wine regarding astringency and color. In vivo and in vitro models suggest some positive effects of these polyphenols in the treatment and prevention of chronic diseases, such as atherosclerosis and cancer. Therefore, there is a high level of interest to develop scalable industrial methods in order to obtain and purify Carménère grape polyphenol extracts that could be used to improve the characteristics of wines from other varieties or produce nutraceuticals or functional foods for preventing and treating various chronic diseases.

Quinolines and their derivatives are an important class of heterocyclic compounds that occur widely in natural products, drugs and biologically active compounds. A large variety of quinolines have displayed interesting physiological activities and found attractive applications as pharmaceuticals and agrochemicals. In accordance with these useful properties and related applications as above-mentioned, a number of methods have been reported for the synthesis of quinolines. Although other methods such as the Skraup, Doebner-Miller and Combes procedures have been reported, the Friedländer heteroannulation is still one of the most simple and straightforward methods used to produce poly-substituted quinolines. The Friedländer synthesis involves a condensation reaction followed by a cyclodehydration reaction between an 2128;aminoaryl aldehyde or ketone and an aldehyde or ketone containing an α128; methylene group. This procedure has been catalyzed by several homogeneous and heterogeneous catalysts, such as bases, Brönsted acids, Lewis acids, ionic liquids, etc.

Epoxides and aziridines are very useful small heterocycles. The synthesis of these threemembered heterocycles including those derived from α,β-unsaturated aldehydes is a dynamic area of research. Among numerous approaches to construction of three-membered cycles with O- or Nheteroatoms are metallo- and organocatalysis. This review summarizes and highlights the methods for the synthesis of epoxides and aziridines via transformations of α,β-enals, which have been developed over the last 10 years.

This review surveys carbon-carbon bond forming reactions of acetylene radical-cations, generated under the one-electron oxidation of alkynes in the systems lead dioxide (PbO2) – strong acid (CF3CO2H, FSO3H, HF). The oxidative dimerization proceeds very regioselectively at acetylene carbons. This approach is a powerful synthetic tool, leading to complex and polyfunctional organic molecules, such as, dicarbonyl- and tetracarbonyl-substituted ethylenes, 1,4-difluoro- and 1,4- dichlorobutadienes, etc. Reaction mechanisms of acetylene radical-cations are considered. The reactivity of acetylene radical-cations may be explained by their electronic structure, determined by means of electron spin resonance spectroscopy and cyclic voltammetry.

Taxus is a genus of 12 species mainly distributed in the Northern Hemisphere, with four species in North America, one in Europe, and the remaining native to Southeast Asia. Taxus contains numerous compounds of taxane derivatives, polysaccharides, and flavanoids. The compound with the greatest significance for humans is an oxygen-rich diterpene called taxol, which can be used as an inhibitor of cancer cell growth. Many new biological activities of these chemical compounds have been discovered to fight against various cancers (e.g., ovarian, breast, esophagus, gastric, lung, and prostate cancers), anti-oxidation, cure inflammatory and HIV effects, and eliminate free radicals. This review revises the information on the morphological characteristics and geographical distribution, generalizes the relationship of special secondary metabolites among species, summarizes the main pharmacological activities of the compounds contained in plant, and also puts forward some effective strategies for the exploitation and protection of the Taxus species. These works may be helpful for the researcher and utilizer.

Due to the widespread application of nanoparticles they can be utilized as a catalyst in various organic reactions today. Recent research has been directed towards the utilization of TiO2 nanoparticles which have emerged as an attractive multi-functional material. This paper aims to present a short review on the catalytic potential of TiO2 nanoparticles in a wide range of reactions and syntheses of bioactive heterocycles.

Electrochemical reactions, with clean power, can prepare valuable chemicals directly and improve yield efficiency and reduce the three wastes, which have become one of the green methodologies. Ionic liquids have attracted increasing attention in the area of electrochemistry due to their significant properties including good chemical and thermal stability, wide liquid temperature range, considerable ionic conductivity, nonflammability, broad electrochemical potential window and tunable solvent properties. This review covers recent studies on the applications of ILs as green and universal replacements for the traditional reagents in electrochemical reactions such as oxidation, reduction, electrosynthesis, and some other reactions. The adaptabilities of ILs in these reactions are predicted as a solution to the problems of conventional electrochemical processes and to become a powerful method in electrochemical reactions.