Catalyst-Solvent System for PASE Approach to Hydroxyquinolinone-Substituted Chromeno[2,3-b]pyridines Its Quantum Chemical Study and Investigation of Reaction Mechanism

The Pot, Atom, and Step Economy (PASE) approach is based on the Pot economy principle and unites it with the Atom and Step Economy strategies; it ensures high efficiency, simplicity and low waste formation. The PASE approach is widely used in multicomponent chemistry. This approach was adopted for the synthesis of previously unknown hydroxyquinolinone substituted chromeno[2,3-b]pyridines via reaction of salicylaldehydes, malononitrile dimer and hydroxyquinolinone. It was shown that an ethanol-pyridine combination is more beneficial than other inorganic or organic catalysts. Quantum chemical studies showed that chromeno[2,3-b]pyridines has potential for corrosion inhibition. Real time 1H NMR monitoring was used for the investigation of reaction mechanism and 2-((2H-chromen-3-yl)methylene)malononitrile was defined as a key intermediate in the reaction

Approaches to the Functionalization of Organosilicon Dendrones Based on Limonene

Previously, we reported the synthesis of carbosilane and carbosilane-siloxane dendrons of various generations based limonene, a natural terpene. Limonene that contains two double bonds, namely cyclohexene and isoprenyl ones, was shown to undergo regioselective hydrosilylation exclusively at its isoprenyl double bond. This finding was used to prepare carbosilane dendrons (CDs) with a limonene moiety at the focal point. In this study, we present variants for the functionalization of the cyclohexene double bond by an epoxidation reaction in order to use the resulting dendrons for the preparation of various macromolecular objects, including Janus dendrimers (JDs), dendronized polymers, and macroinitiators. Moreover, it was shown that dendrons with peripheral azide functions could be obtained. These methods offer both the possibilities of the further growth of branches and the addition of polymers with a different nature by the azide–alkyne cycloaddition reaction

Approaches to the Functionalization of Organosilicon Dendrones Based on Limonene

Previously, we reported the synthesis of carbosilane and carbosilane-siloxane dendrons of various generations based limonene, a natural terpene. Limonene that contains two double bonds, namely cyclohexene and isoprenyl ones, was shown to undergo regioselective hydrosilylation exclusively at its isoprenyl double bond. This finding was used to prepare carbosilane dendrons (CDs) with a limonene moiety at the focal point. In this study, we present variants for the functionalization of the cyclohexene double bond by an epoxidation reaction in order to use the resulting dendrons for the preparation of various macromolecular objects, including Janus dendrimers (JDs), dendronized polymers, and macroinitiators. Moreover, it was shown that dendrons with peripheral azide functions could be obtained. These methods offer both the possibilities of the further growth of branches and the addition of polymers with a different nature by the azide–alkyne cycloaddition reaction

Synthesis of Carbosilane and Carbosilane-Siloxane Dendrons Based on Limonene

In this work, carbosilane dendrons of the first, second, and third generations were obtained on the basis of a natural terpenoid, limonene. Previously, we have shown the possibility of selective hydrosilylation and hydrothiolation of limonene. It is proved that during hydrosilylation, only the isoprenyl double bond reacts, while the cyclohexene double bond does not undergo into the hydrosilylation reaction. However, the cyclohexene double bond reacts by hydrothiolation. This selectivity makes it possible to use limonene as a dendron growth center, while maintaining a useful function—a double bond at the focal point. Thus, the sequence of hydrosilylation and Grignard reactions based on limonene formed carbosilane dendrons. After that, the end groups were blocked by heptamethyltrisiloxane or butyllithium. The obtained substances were characterized using NMR spectroscopy, elemental analysis and GPC. Thus, the proposed methodology for the synthesis of carbosilane dendrons based on the natural terpenoid limonene opens up wide possibilities for obtaining various macromolecules: dendrimers, Janus dendrimers, dendronized polymers, and macroinitiators

1,3-Dimethyl-3′,5-diphenyl-1,5-dihydro-2H,5′H-spiro[furo[2,3-d]pyrimidine-6,4′-isoxazole]-2,4,5′(3H)-trione

Michael addition–halogenation–intramolecular ring-closing (MHIRC) reactions are processes in which a halogen atom as a leaving group can attach to substrates or reactants during the reaction, which then undergoes intramolecular ring closure. In this communication the MHIRC transformation of 4-benzylidene-3-phenylisoxazol-5(4H)-one and 1,3-dimethylbarbituric acid in the presence of N-bromosuccinimide and sodium acetate in EtOH at room temperature was carefully investigated to give novel 1,3-dimethyl-3′,5-diphenyl-1,5-dihydro-2H,5′H-spiro[furo[2,3-d]pyrimi- dine-6,4′-isoxazole]-2,4,5′(3H)-trione in a good yield. The structure of the new compound was confirmed by the results of elemental analysis as well as mass, nuclear magnetic resonance, and infrared spectroscopy

Oxidative Cyclization of 5H-Chromeno[2,3-b]pyridines to Benzo[b]chromeno[4,3,2-de][1,6]naphthyridines, Their NMR Study and Computer Evaluation as Material for LED

Oxidative cyclization is one of the most significant reactions in organic synthesis. Naphthyridine derivatives are often used as luminescence materials in molecular recognition because of their rigid planar structure and as new drugs. Organic light-emitting diodes (OLEDs) have rapidly grown as one of the leading technologies for full-color display panels and eco-friendly lighting sources. In this work, we propose the synthesis of previously unknown benzo[b]chromeno[4,3,2-de][1,6]naphthyridines via intermolecular oxidative cyclization of 5-(2-hydroxy-6-oxocyclohexyl)-5H-chromeno[2,3-b]pyridines in formic acid. The investigation of the reaction mechanism using 1H-NMR monitoring made it possible to confirm the proposed mechanism of the transformation. The structure of synthesized benzo[b]chromeno[4,3,2-de][1,6]naphthyridines was confirmed by 2D-NMR spectroscopy. Such a rigid geometry of synthesized compounds is desired to minimize non-radiative energy losses in OLEDs. The quantum chemical calculations are also presented in the study

1,3-Dimethyl-3′,5-diphenyl-1,5-dihydro-2<i>H</i>,5′<i>H</i>-spiro[furo[2,3-<i>d</i>]pyrimidine-6,4′-isoxazole]-2,4,5′(3<i>H</i>)-trione

Michael addition–halogenation–intramolecular ring-closing (MHIRC) reactions are processes in which a halogen atom as a leaving group can attach to substrates or reactants during the reaction, which then undergoes intramolecular ring closure. In this communication the MHIRC transformation of 4-benzylidene-3-phenylisoxazol-5(4H)-one and 1,3-dimethylbarbituric acid in the presence of N-bromosuccinimide and sodium acetate in EtOH at room temperature was carefully investigated to give novel 1,3-dimethyl-3′,5-diphenyl-1,5-dihydro-2H,5′H-spiro[furo[2,3-d]pyrimi- dine-6,4′-isoxazole]-2,4,5′(3H)-trione in a good yield. The structure of the new compound was confirmed by the results of elemental analysis as well as mass, nuclear magnetic resonance, and infrared spectroscopy

2,4-Diamino-5-(nitromethyl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile

Dimethyl sulfoxide (DMSO) is a cheap polar aprotic solvent used in organic synthesis and in pharmacology because of its low cost, high stability, and non-toxicity. Multicomponent reactions (MCRs) are highly convergent processes and have good atom, step, and pot economies. In this communication, the multicomponent transformation of salicylaldehyde, malononitrile dimer, and nitromethane in DMSO at room temperature was investigated to give 2,4-diamino-5-(nitromethyl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile in good yield. The structure of the earlier unknown compound was confirmed by means of elemental analysis, mass-, nuclear magnetic resonance, and infrared spectroscopy

5-(1-(4-Hydroxy-6-methyl-2-oxo-2<i>H</i>-pyran-3-yl)-2-oxo-2-phenylethyl)-1,3-dimethylpyrimidine-2,4,6(1<i>H</i>,3<i>H</i>,5<i>H</i>)-trione

Multicomponent reactions have been demonstrated as a promising tool for the creation of diverse molecular structures with enhanced efficiency, reduced waste, and a high atom economy. Arylglyoxal monohydrates with two different carbonyl groups are well known as worthwhile synthons in organic synthesis. 2-Pyrone and pyrimidine-2,4,6-trione are versatile building blocks for the synthesis of key intermediates in synthetic organic chemistry as well as in medicinal chemistry. A simple and efficient tandem Knoevenagel–Michael protocol for the synthesis of the previously unknown 5-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-phenylethyl)-1,3-dimet-hylpyrimidine-2,4,6(1H,3H,5H)-trione was elaborated. The suggested method is based on the multicomponent reaction of phenylglyoxal hydrate, 1,3-dimethylbarbituric acid, and 4-hydroxy-6-methyl-2H-pyran-2-one. The structure of the synthesized compound was proven by 1H, 13C-NMR, and IR spectroscopy, mass spectrometry, and elemental analysis. A procedure for predicting the possible types of its biological activity was carried out for the title compound