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This article explores the use of Acridine Yellow G (AYG) as a photocatalyst for the synthesis of pyrano[2,3-d]pyrimidines in water. The researchers discovered that AYG was most effective as a catalyst at a loading of 0.2 mol%. The reaction yielded a compound called 4a with a 96% yield. The method was successful with various substrates and the resulting products were easily obtained and purified. The article also provides a plausible mechanism for the photocatalytic process and includes optimization studies for the solvent and light source. Additionally, the article discusses the application of AYG as a photocatalyst in a tandem Knoevenagel-Michael radical cyclocondensation reaction. The study found that visible light could be used as an energy source at room temperature in an air atmosphere for reactions in an aqueous medium. The method was efficient, utilized non-toxic solvents, and achieved excellent yields. Furthermore, the reaction could be scaled up to meet industrial and environmental requirements. [Extracted from the article]

This document provides a concise summary of an article discussing the use of photocatalysis in organic synthesis, specifically focusing on the synthesis of tetrahydrobenzo[b]pyrans using a carbazole-based photocatalyst called 4CzIPN. The article highlights the advantages of photocatalysis and the diverse applications of tetrahydrobenzo[b]pyrans. It also describes the optimization of the synthesis process and concludes that 4CzIPN is an effective photocatalyst for this purpose. The document includes experimental details and data on the synthesized compounds, and acknowledges the support of the Research Council of the Apadana Institute of Higher Education. [Extracted from the article]

A sustainable methodology for the synthesis of pyrano [2,3-d] pyrimidine scaffolds have been developed, employing the Knoevenagel-Michael tandem cyclocondensation reaction of barbituric acid/1,3-dimethylbarbituric acid, malononitrile, and aryl aldehydes. This study elucidates the advancement of a sustainable and environmentally conscious approach to synthesizing this category of chemical compounds. In the present investigation, a novel photosensitizer comprising proflavine (PFH+) bio-photocatalyst was employed in an aqueous medium, subjected to air atmosphere at room temperature, and stimulated by a blue-light-emitting diode (LED) to harness renewable energy. The fundamental objective of this initiative is to utilize a photosensitizer (PS) biocatalyst that has been recently developed, can be conveniently acquired, and is priced affordably. The proflavine (PFH+) photocatalyst, demonstrates the ability to initiate photoinduced-electron transfer (PET) through exposure to visible light. This property endows the photocatalyst with a practical and efficient method of achieving high effectiveness, energy efficiency, and environmentally friendly outcomes. The current research endeavor has the objective of examining the turnover number (TON) and turnover frequency (TOF) pertaining to pyrano [2,3-d] pyrimidine scaffolds. Moreover, it has been validated that cyclization at the gram-scale is a feasible approach that can be employed in various industrial settings. [ABSTRACT FROM AUTHOR]

Background: Organic dyes often have shorter lifetimes in the excited state, which is a major obstacle to the development of effective photoredox methods. The scientific community has shown a great deal of interest in a certain class of organic chromophores because of their unique characteristics and effectiveness. One characteristic of the molecules under research is thermally activated delayed fluorescence (TADF), which is only observed in molecules with a tiny energy gap (often less than 0.2 eV) between their lowest two excited states, i.e., singlet excited state (S1) and triplet excited state (T1). The extended singlet excited states arising from TADF and the simplicity with which their redox potentials may be altered make the isophthalonitrile family of chromophores an attractive option for organic photocatalyst applications. Methods: The Biginelli reaction between β-ketoesters, arylaldehydes, and urea/ thiourea has been used to build a sustainable technique for the production of 3,4- dihydropyrimidin-2-(1H)-one/thione derivatives. In the present study, the development of a green radical synthesis approach for this class of compounds is addressed in depth. As a photocatalyst, a new halogenated dicyanobenzene-based photosensitizer was employed in this study. As a renewable energy source activated by a blue LED, it was dissolved in ethanol, at room temperature in air atmosphere. The primary objective of this research is to employ a novel donor-acceptor (D-A) based on halogenated cyanoarene that is affordable, easily available, and innovative. Findings: The 3DPAFIPN [2,4,6-tris(diphenylamino)-5-fluoroisophthalonitrile] photocatalyst, a thermally activated delayed fluorescence (TADF), induces single-electron transfer (SET) in response to visible light, offering a straightforward, eco-friendly, and highly efficient process. Additionally, we determined the 3,4-dihydropyrimidin-2-(1H)-one/thione derivatives turnover frequency (TOF) and turnover number (TON). It has also been demonstrated that gram-scale cyclization is a workable method for industrial purposes. [ABSTRACT FROM AUTHOR]

Utilizing the Knoevenagel–Michael tandem cyclocondensation reaction of barbituric acid/1,3-dimethylbarbituric acid, malononitrile, and aryl aldehydes, a sustainable methodology for the photosynthesis of pyrano[2,3-d]pyrimidine scaffolds has been devised. The present study expounds on the development of a green radical synthetic approach toward this class of compounds. In this study, a novel halogenated dicyanobenzene-based photosensitizer was utilized in an aqueous solution, exposed to air at room temperature, and activated by a blue LED as a renewable energy source for the purpose of generating energy. The primary aim of this endeavor is to employ a recently developed, easily obtainable, and affordably priced halogenated cyanoarene-based donor–acceptor (D–A). The 3DPAFIPN [2,4,6-tris(diphenylamino)-5-fluoroisophthalonitrile]} photocatalyst, as a thermally activated delayed fluorescence (TADF), is capable of inducing single electron transfer (SET) upon irradiation with visible light, thereby offering a facile and efficient approach with a high degree of effectiveness, energy efficiency, and eco-friendliness. The aforementioned phenomenon facilitates the exploration of the temporal changes that have occurred in the interactions between the surroundings and chemical constituents. The present study aimed to investigate the turnover number (TON) and turnover frequency (TOF) for pyrano[2,3-d]pyrimidine scaffolds. Additionally, it has been demonstrated that gram-scale cyclization is a viable method for utilization in industrial applications. [ABSTRACT FROM AUTHOR]

By employing the Knoevenagel–Michael tandem cyclocondensation of malononitrile, aldehydes, and resorcinol, we developed a green method for the radical synthesis of 2-amino-4 H-chromene scaffolds. A photo-induced electron transfer (PET) photocatalyst was employed in an aqueous solution to use visible light as a renewable energy source. This study aims to develop a non-metal dye that is inexpensive and easily accessible. In addition to having speed-saving features and being simple to use, the photochemically catalyzed AYG demonstrates high yields, energy efficiency, and environmental friendliness. This makes it possible to track changes in chemical and environmental variables throughout time. It is amazing that gram-scale cyclization is practical, proving that it has industrial applications. [ABSTRACT FROM AUTHOR]

The Knoevenagel-Michael cyclocondensation of barbituric acid/1,3-dimethylbarbituric acid, malononitrile, and arylaldehyde derivatives was used to construct a multicomponent green tandem method for the metal-free synthesis of pyrano[2,3-d]pyrimidine scaffolds. At room temperature in aqueous ethanol, photo-excited state functions generated from Na2 eosin Y were employed as direct hydrogen atom transfer (HAT) catalysts by visible light mediated in the air atmosphere. This research looks towards expanding the use of a non-metallic organic dye that is both affordable and readily available. Because of its good yields, energy-effectiveness, high atom economy, time-saving qualities of the reaction, and operational simplicity, Na2 eosin Y is photochemically produced with the least amount of a catalyst. As a result, various ecological and sustainable chemical properties are met. Surprisingly, such cyclization may be carried out on a gram scale, indicating the reaction's potential industrial application. [ABSTRACT FROM AUTHOR]

A catalyst-free and solvent-free three-component tandem strategy for synthesizing tetrahydrobenzo[b]pyran scaffolds through Knoevenagel–Michael cyclocondensation is reported using visible light irradiation as a green promoter at room temperature. The prominent benefits of the existing protocol are catalyst-free, solvent-free, using commercially accessible, inexpensive preliminary substances, operational simplicity, energy-effectiveness, great yields, high atom-economy, thus meeting some features of sustainability and green chemistry. [ABSTRACT FROM AUTHOR]

We developed a green radical synthesis method for polyfunctionalized dihydro-2-oxypyrroles based on the Michael–Mannich cyclocondensation of amines, dialkyl acetylenedicarboxylates, and formaldehyde. To generate a renewable energy sources from visible light, a PCET (proton-coupled electron transfer) photocatalyst was used in an ethanol solution in an air environment and at room temperature. In this study, we aim to develop an inexpensive and easily accessible novel donor–acceptor (D–A) fluorophore. Besides its speed-saving features and ease of use, the carbazole-based photocatalyst (4CzIPN) also shows high yields, energy-efficient, and is environmentally friendly. In this way, it is possible to monitor changes in chemical and environmental variables over time. The variety of yields is pretty uniform (84–97%, average 92.3%), and the kind of response times be very speedy (15–25 min, average 17.6 min), and the element noted within the dialogue is that the system tolerates a variety of donating and withdrawing functional groups, at the same time as nevertheless giving very fast rate and tremendous yields. A study of polyfunctionalized dihydro-2-oxypyrroles was conducted to calculate the turnover number (TON) and turnover frequency (TOF). Gram-scale cyclization proves that it can be applied to industry in a practical manner. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal-free synthesizing dihydropyrano[2,3- c ]pyrazole scaffolds. • Organic dye Na 2 eosin Y as catalyst. • Visible light mediated. Evidence indicates that Na 2 eosin Y-derived photoexcited states functions as a direct hydrogen atom transfer (HAT) catalyst to synthesize dihydropyrano[2,3- c ]pyrazole scaffolds photochemically via four-condensation domino reaction of tandem Knoevenagel-Michael cyclocondensation reaction ethyl acetoacetate, hydrazine hydrate, aryl aldehyde derivatives and malononitrile via visible light-mediated in aqueous ethanol at ambient temperature under air atmosphere. This study paves the new role for further the use of a metal-free organic dye with commercial availability and inexpensiveness, Na 2 eosin Y in photochemical synthesis with use of the lowest amount of catalyst, excellent yields, time-saving aspects of the reaction and high atom economy. Notably, this cyclization is also runnable on the gram scale, which highlights the potentiality of using this reaction in industrial uses. [ABSTRACT FROM AUTHOR]

• The study indicated a catalyst-free preparation of spiroacenaphthylenes and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones -a biologically significant scaffold- via visible light irradiation as a low-cost and green promoter in aqueous ethyl lactate at room temperature according to the principles of green chemistry. The important points in the current study include the use of non-hazardous reaction circumstances, application of cheap initiating substances, operational simplicity, catalyst-free, separation of the pure product by easy filtration thus avoids the need for column chromatography, efficient features of the reaction, excellent yields, metal-free, one key characteristic of the existing work is to use CFL irradiation as green endorsing media sufficiently remarking the rising potential of CFL irradiation in organic synthesis. Catalyst-free three-component tandem approach can synthesize spiroacenaphthylenes and 1 H -pyrazolo[1,2- b ]phthalazine-5,10-diones by Knoevenagel-Michael cyclocondensation via visible light irradiation in aqueous ethyl lactate at room temperature. The significant advantages of the present protocol include energy-effectiveness, catalyst-free, excellent yields, operational simplicity, high atom-economy, commercially accessible, inexpensive preliminary substances, so it meets some features of sustainablility and green chemistry. [ABSTRACT FROM AUTHOR]