The Use of Polysaccharide Matrices as a Basis for the Formation of Tellurium Nanoparticles with Different Morphologies.

The widening of possible areas of practical uses for zero-valent tellurium nanoparticles (TeNPs) from biomedicine to optoelectronic and thermoelectric applications determines the actuality of the development of simple and affordable methods for their preparation. Among the existing variety of approaches to the synthesis of TeNPs, special attention should be paid to chemical methods, and especially to "green" approaches, which are based on the use of precursors of tellurium in their powder bulk form and natural galactose-containing polysaccharides-arabinogalactan (Ar-Gal), galactomannan-(GM-dP) and κ-carrageenan (κ-CG) acting as ligands stabilizing the surface of the TeNPs. The use of basic-reduction system "NH HO-NaOH" for preliminary activation of bulk-Te and Ar-Gal, GM-dP and κ-CG allowed us to obtain in aqueous medium a number of stable nanocomposites consisting of TeNPs stabilized by the polysaccharides' macromolecules.

Game of Aliphatics: A Density Functional Theory Study of Base-Catalyzed Substrate-Controlled Dimerizations of Aliphatic Alkynones.

The present work focuses on a comprehensive density functional theory (DFT) study of newly discovered base-catalyzed substrate-controlled dimerizations of aliphatic alkynones. In order to understand the origin of selectivity of the cascade assemblies of 6-methylene-5-oxaspiro[2.4]heptanones and 2-alkenylfurans, structural and electronic properties of neutral and deprotonated alkynone molecules, thermodynamic and kinetic characteristics of the deprotonation of alkynones having diverse C-H active substituents at the carbonyl function under the action of a base, and thermodynamic and kinetic characteristics of possible mechanisms of the discussed cascade reactions were theoretically assessed.

Novel Route to Cationic Palladium(II)-Cyclopentadienyl Complexes Containing Phosphine Ligands and Their Catalytic Activities.

The Pd(II) complexes [Pd(Cp)(L)][BF] were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF∙OEt ( = 2, = 1: L = PPh (), P(-Tol), (-methoxyphenyl)phosphine (TOMPP), -2-furylphosphine, -2-thienylphosphine; = 1, = 1: L = dppf, dppp (), dppb (), 1,5-bis(diphenylphosphino)pentane; = 1, = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes - were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp)⋯(Ph-group) and (Cp)⋯(CH-group) interactions, which are of C-H…π nature.

Diastereoselective synthesis of tetrahydropyrrolo[1,2-]oxadiazoles from functionalized Δ-pyrrolines and generated nitrile oxides.

Tetrahydropyrrolo[1,2-]oxadiazoles have been synthesized in good-to-excellent yields the cycloaddition of nitrile oxides ( generated from aldoximes) to readily accessible functionalized Δ-pyrrolines. The reaction proceeds smoothly at room temperature in a two-phase system in the presence of sodium hypochloride as an oxidant to diastereoselectively afford pharmaceutically prospective 1,2,4-oxadiazolines fused with a five-membered ring. The reaction tolerates a broad range of substrates, including those with oxidant-sensitive functional groups and competitive reaction sites.

Regio- and stereoselective base-catalyzed assembly of 6-methylene-5-oxaspiro[2.4]heptanones from alkynyl cyclopropyl ketones.

6-Methylene-5-oxaspiro[2.4]heptanones have been synthesized base-catalyzed dimerization of available alkynyl cyclopropyl ketones. The reaction proceeds effectively in the presence of the -BuOK/-BuOH/THF catalytic system at room temperature to afford the desired spirocycles in a regio- and stereoselective manner.

Synthesis of Pyrrolo[2,1-]isoquinolinium Salts from 1-Pyrrolines and Alkynes via Rhodium-Catalyzed C-H Functionalization/N-Annulation Tandem Reaction.

A convenient synthesis of pyrrolo[2,1-]isoquinolinium salts from 1-pyrrolines and alkynes through rhodium-catalyzed C-H functionalization/N-annulation tandem reaction is described. The protocol features a good substrate tolerance, mild reaction conditions, and high yields of target products. Exploration of the alkyne scope unexpectedly revealed a novel labile functional group-promoted rhodium-catalyzed C-H functionalization/C-annulation/elimination cascade reaction of 1-pyrrolines with electron-deficient alkynes.

Recent advances and future challenges in the synthesis of 2,4,6-triarylpyridines.

2,4,6-Triarylpyridines are key building blocks to access functional molecules that are used in the design of advanced materials, metal-organic frameworks, supramolecules, reactive chemical intermediates and drugs. A number of synthetic protocols to construct this heterocyclic scaffold have been developed to date, the most recent of which (2015-present) are included and discussed in the present review. An emphasis has been placed on the utility of each synthetic approach in view of the scope of aryl/hetaryl substituents, limitations and an outlook of each method to be used in applied sciences.

Regiocontrolled synthesis of 2,4,6-triarylpyridines from methyl ketones, electron-deficient acetylenes and ammonium acetate.

A novel one-pot two-step approach for the synthesis of 2,4,6-triarylpyridines via t-BuOK/DMSO-promoted C-vinylation of a variety of methyl ketones with electron-deficient acetylenes (alkynones) followed by a cyclization of the in situ generated unsaturated 1,5-dicarbonyl species with ammonium acetate has been developed. This approach possesses competitive advantages such as high regioselectivity, available starting materials and the absence of transition-metal catalysts, oxidants and undesirable byproducts. A wide synthetic utility of the developed approach was demonstrated by the synthesis of trisubstituted, tetrasubstituted and fused pyridines.

Recent advances in the synthesis of imidazoles.

The review highlights the recent advances (2018-present) in the regiocontrolled synthesis of substituted imidazoles. These heterocycles are key components to functional molecules that are used in a variety of everyday applications. An emphasis has been placed on the bonds constructed during the formation of the imidazole.