Current Organic Chemistry - Volume 25, Issue 11, 2021

Dendrimers are highly branched three-dimensional macromolecules with a highly controlled structure, a single molecular weight, numerous controllable dendritic branches and peripheral functionalities, as well as the tendency to adopt an ellipsoid or spheroid shape once a certain size is reached. These features have made them attractive for application in pharmaceutical and medicinal chemistry in gene transfection, as medical imaging agents, and as drug carriers in potential drug delivery agents. The incorporation of metallic species into dendritic molecules has also been reported; the focus has been on organometallic dendrimers with metallic species only at specific positions of the molecules, such as the core, dendritic branches and the periphery, studied for their magnetic, electronic, and photo-optical or catalytic properties. Dendrimers have been investigated for optoelectronic applications (adsorption, emission, laser emission, nonlinear optics) through the encapsulation of active units by dendritic branches, core and peripheral. This review briefly discusses their use in nanomedicine, cancer treatment, treatment of other diseases, tissue repair, catalysis and applications in OLEDs and solar cells.

Heterocyclic compounds are the largest and most diverse family of organic compounds. Among them, aromatic heterocyclic compounds are the structural motifs found in a great number of biologically active synthetic and natural compounds, agrochemicals, and medicines. Moreover, aromatic heterocyclic compounds are extensively utilized for the formation of dyes and polymeric materials of great importance. In organic synthesis, there are several reports on the uses of aromatic heterocyclic compounds as intermediates. In this review article, we have focused on the synthesis of heterocycles using crown ethers.

In recent years, diaryliodonium salts have been extensively exploited as green, efficient electrophilic arylation reagents in a large range of organic synthesis. These arylating reagents exhibit relatively high reactivity and good selectivity in many transformations. In this review, the synthetic methods towards diaryliodonium salts are described briefly, and the research progress in arylation reactions by using diaryliodoniums in C-C and carbonheteroatom bond formation, especially in enantioselective C-C bond formation and cascade reactions, in recent ten years is summarized and discussed in detail.

Oxindoles are an important class of heterocyclic scaffolds widely present in natural products and bioactive compounds. For this reason, a plethora of methodologies for the stereoselective synthesis of enantioenriched oxindoles has been studied over the years. Among all the reported synthetic strategies, organocatalysis has proven to be a powerful tool for the asymmetric synthesis of this class of compounds being a step- and atom-economical, environmentally friendly, and non-toxic approach. This review will outline the application of asymmetric organocatalysis in the synthesis of chiral oxindole-based structures, relying on domino/one-pot reaction sequences in a step-economical fashion.

Herein, the synthesis of 6-deoxygenated α(1→4)-oligoglucans via thermostable α- glucan phosphorylase (from Aquifex aeolicus VF5)-catalyzed enzymatic chain-elongation is reported from a maltotriose primer using a non-native substrate, 6-deoxy-α-D-glucose 1- phosphate. The enzymatic reaction of the two substrates mainly produced a tetrasaccharide with one 6-deoxy-α-D-glucose unit at the non-reducing end, together with a minor pentasaccharide with two 6-deoxy-α-D-glucose units. The enzymatic chain-elongation from the primer in the presence of 6-deoxy-α-D-glucose 1-phosphate and a native substrate, α-D-glucose 1- phosphate, afforded 6-deoxygenated α(1→4)-oligoglucans with varying degrees of polymerization. This enzymatic chain-elongation catalyzed by thermostable α-glucan phosphorylase is an efficient method to produce non-natural oligosaccharides, that is, 6-deoxygenated α(1→4)- oligoglucans.