Current Organic Chemistry - Volume 20, Issue 15, 2016

The carbon-carbon bond forming reactions are of central importance in organic synthesis and routinely practiced across the world in both research laboratories and industrial processes. Since its initial discovery in 2004, graphene, a two dimensional nanomaterial bearing a single layer of sp2-hybridized carbon sheet with hexagonal packed lattice structure, has received significant attention worldwide. Owing to its exceptional physicochemical properties such as thermal stability, ease of structural modulations, high surface area leading to considerably high mass transfer as well as high loading capacity of nanoscale structures, and easy recovery and recyclability, graphene domain and/or graphene- based nanomaterials (G-NMs) can be considered as the materials having a self-assembly of very likable or ideal properties for catalytic applications. Not surprisingly, therefore, the last few years have witnessed the significant progress in the fabrication and exploration of a variety of G-NMs as alternative heterogeneous or pseudo-homogeneous catalysts in organic synthesis. This review highlights the significant advancements in the synthesis and an up-to-date catalytic applications of G-NMs in carbon-carbon bond forming reactions with an emphasis on coupling reactions.

The control of molecular organization in donor-acceptor polymers over various length scales is essential for the charge carrier migration in organic field-effect transistors. Comprehensive understanding of the relation between chemical structure of the polymer, molecular packing, self-assembly, microstructure and charge carrier transport after solution processing, has been carried out thoroughly. The impact of the molecular structure variation on the local packing of the polymer chains within well-defined layer-type superstructures has been found. The role of molecular weight, bulkiness, and substitution position of the alkyl chains and backbone curvature on the packing, microstructure and device performance is discussed. The surface organization of polymer and its film microstructure are also influenced by the processing conditions. Corresponding processing techniques have been developed that allow a fine control over the film deposition, microstructure formation and molecular orientation. Under optimized conditions, defect-free and highly ordered mesoscopic fibers result in superior device properties. The following minireview is separated into two main topics which cover the influence of chemical design and processing conditions on local packing and microstructure formation of polymeric organic semiconductors applied in field-effect transistors.

The widespread use of toxic and volatile organic solvents poses a serious threat to the environment and in consequence to people. Hence, a lot of alternative processes as well as more efficient recycling protocols have been developed to avoid the used organic solvents in the last decades. Unfortunately, also these alternative processes and recycling protocols also limitations. Therefore, the authors review different environmentally benign solvent alternatives. This report focuses on reactions using 2-methyltetrahydrofuran, ethyl lactate, cyclopentyl methyl ether, limonene and p-cymene, as well as solvent-free organic synthesis as an alternative to conventional organic solvents.

Regioisomerically pure 5(6)-substituted rhodamine is an outstanding molecular platform for functional probes and a very useful material for fluorescent labels. However, 5(6)-substituted rhodamine is difficult to be synthesized by general methods, which limits the application of the dye. This review highlights the progress regarding the methods for the synthesis and separation of regioisomerically pure 5(6)-substituted rhodamine, which are categorized by the four different protocols for acquiring 5(6)-substituted rhodamine. The advantages and disadvantages of each protocol are also discussed.

Huisgen cycloaddition reaction has been originally utilized for the synthesis of 1, 2, 3-triazoles regioisomers. In this review, its stereochemistry and also mechanistical features of Huisgen cycloaddition reaction based on the quantum chemistry are highlighted. Thermal and copper catalyzed approaches to the synthesis of 1,2,3- triazoles will also be re-visited. Finally, the synthesis of alternative region-isomer, 1,5-disubstituted-1,2,3-triazoles under ruthenium catalysis and transition metal free conditions is described.

Alkyl disulfamic acid-functionalized silica-coated magnetic nanoparticles (ADSA-MNPs) have been synthesized as a hybrid organic- inorganic acidic nanoparticles and its catalytic activity has been evaluated in the synthesis of mono-, bis- and tris 1,2-dihydrobenzo[4,5]imidazo[1,2-a]pyrimidine via a one-pot three, pseudo-five or pseudo-seven component condensation reaction of aromatic aldehydes, malononitrile and 2-aminobezimidazole under solvent-free heating. The heterogeneous catalyst was facilely separated from the reaction mixture by utilizing external magnetic field and reused for several times without considerable decrease of catalytic performance.