Current Organic Chemistry - Volume 22, Issue 16, 2018

Transition metal-catalyzed cross-coupling reactions represent one of the most powerful tools in modern organic chemistry. Due to the relevance of nitrogen heterocyclic compounds for many areas, the development of new and effective methods to afford coupled products from these reagents has become very attractive for organic synthesis. Quinoxaline derivatives encompass one of the most privileged classes of heterocycles, being part of several biologically and technologically relevant compounds. Cross-coupling reactions involving the building block 2,3-dichloroquinoxaline (DCQX) emerge as a promising approach from several synthetic approaches reported for the synthesis of quinoxaline derivatives. The present article consists of a literature review regarding the substrate DCQX as a partner for C-C and C-N cross-coupling reactions. Examples of classical Suzuki- Miyaura, Heck and Sonogashira cross-coupling reactions are presented, as well as other synthetic transformations that lead to the formation of fused polycyclic compounds through heterocyclization processes. Some mechanistic insights are also presented. Notably, most of the publications addressing the subject presented herein are from the last decade, and several of the synthesized compounds are relevant due to their applications in many fields. These features emphasize the relevance of DCQX as a substrate for cross-coupling reactions for organic synthesis.

One of the most valuable principles out of twelve principles of green chemistry is the use of catalysis. The use of serious principles including reducing the utilization or production of hazardous material in chemistry reactions is green chemistry. This paper claims to review the catalytic importance of one of the most important organocatalysts called Ph3P. One of the most successful organocatalysts is phosphine that has been greatly utilized in isomerization of ynones or ynonates, Aza-Michael reactions, Baylis- Hillman reactions, allylic amination, and asymmetric [3+2] cycloadditions. These catalysts have become important for the synthesis of numerous cyclic and heterocyclic compounds.

Molecular Imprinting Technology (MIT) is a significant method which can be used to prepare adsorbents with recognition property for target molecules. Those intelligent materials, namely, Molecular Imprinted Polymers (MIPs) are designed with the help of the idea that mimics the matching process of key and lock. Based on the theory of MIPs, Ion-Imprinted Polymers (IIPs) are prepared by using cations or anions as targets. Compared with traditional adsorbents, they have unique advantages such as high selectivity, high adsorption capacity and easy regeneration. Owing to the above characteristics, Imprinting Technology (IT) has become a good candidate for pollutants removal and resources recycled from environment under the backgrounds of pollution aggravation and resource shortages. Thus, the present review aims to briefly narrate the fundamentals and current preparation methods of imprinted polymers, and particularly focus on the applications on human-living environment involving water, atmosphere and soil.

Acetylcholinesterase (AChE) is well-known enzyme studied in many fields of research, e.g. in Alzheimer's disease, Parkinson's disease, or in eco-toxicology as a biological marker. Many inhibitors of AChE have been identified in nature as well as prepared in chemical labs as a result of systematic synthetic efforts. The organophosphorus (OP) inhibitors of AChE are one of the oldest artificial inhibitors being purposely developed as military nerve agents (e.g. sarin, soman, tabun, VX, RVX). Some of the compounds with decreased toxicity are currently used in agriculture as pesticides (e.g. parathion, chlorpyrifos, paraoxon) or in the industry as softening agents and flame retardants. The common mechanism of action of all organophosphate compounds is the irreversible inhibition of AChE via a binding to the hydroxyl group of the serine residue within the active site of the enzyme. Subsequently, AChE loses its ability to fulfill its physiological role in cholinergic transmission, which leads to the cholinergic crisis with the possibility of respiratory failure and death. The reactivators of AChE are classified as strong nucleophilic agents capable to cleave the non-aged organophosphate- serine adduct and thereby restoring the activity of the enzyme. This work provides a unique overview of the most potent oximes reactivators of inhibited AChE since 1955 to the present. In this review article, we have reviewed different synthetic approaches of known and widely used oxime reactivators of AChE such as pralidoxime, methoxime, trimedoxime, obidoxime, asoxime (HI-6), HS-6, HLo-7, K027, K048, K203, K075 and BI-6. The review covers the original articles as well as patented research.

Novel compounds containing both benzothiazole and azelayl scaffolds were synthesized through Schotten Baumann type reaction between azelayl chloride methyl ester and a series of 2-aminobenzothiazole derivatives bearing different substituents on the aromatic carbocyclic ring. The design of the new hybrids was inspired by their analogy with the structure of some HDAC inhibitors, such as Vorinostat and 9-hydroxystearic acid. Molecular docking on some compounds predicted an activity as inhibitors of HDAC, and this prediction was confirmed by in vitro essays on a human colon cancer cells line (HT 29). The antimicrobial activity against some representative human pathogens and several Lactobacillus and Bifidobacterium strains isolated from human microbiotas was also evaluated. The new hybrids showed antiproliferative activity on cancer cells while no antimicrobial activity was observed in the range of concentrations used for cancer cells and this finding might represent an important tool in the fight against cancer minimizing some side effects on the microbiotas typical of an anticancer treatment.