The development of imin-based tandem Michael–Mannich cyclocondensation through a single-electron transfer (SET)/energy transfer (EnT) pathway in the use of methylene blue (MB<sup>+</sup>) as a photo-redox catalyst

2022

Front. Chem.

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In a green tandem reaction using aldehyde derivatives, malononitrile, and dimedone, a radical tandem Knoevenagel–Michael cyclocondensation reaction of tetrahydrobenzo[b]pyran scaffolds was developed. Using visible light as a sustainable energy source, methylene blue (MB+)-derived photo-excited state functions were employed in an aqueous solution as single-electron transfer (SET) and energy transfer catalysts. The range of yields is quite uniform (81–98%, average 92.18%), and the range of reaction time is very fast (2–7 min, average 3.7 min), and the point mentioned in the discussion is that the procedure tolerates a range of donating and withdrawing groups, while still giving very excellent yields. The reaction is fairly insensitive to the nature of the substituents. Research conducted in this project aims to develop a non-metallic cationic dye that is both inexpensive and widely available for more widespread use. In addition to energy efficiency and environmental friendliness, methylene blue also offers an excellent atom economy, time-saving features, and ease of use. As a result, a wide range of long-term chemical and environmental properties can be obtained. The turnover number and turnover frequency of tetrahydrobenzo[b]pyran scaffolds have been computed. Surprisingly, gram-scale cyclization is a possibility, implying that the technology may be applied in industries.

Section: Introductionmentioning

confidence: 81%

Methylene Blue as a Photo-Redox Catalyst: The Development Synthesis of Tetrahydrobenzo[b]pyran Scaffolds via a Single-Electron Transfer/Energy Transfer

2022

Front. Chem.

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“…Due to the aforementioned challenges and our concern for ecologically benign procedures, most scientists have been intrigued by the quest for easy, efficient, and environmentally safe methods that may enhance organic reactions under green conditions [ 38 – 40 ]. Considering the above concerns and our desire to build pyrano[2,3 -d ]pyrimidine scaffolds production, it is critical to investigate environmentally safe catalysts under green conditions for the correct synthesizing of the nitrogen heterocyclic complexes.…”

Section: Introductionmentioning

confidence: 99%

Photochemical synthesis of pyrano[2,3-d]pyrimidine scaffolds using photoexcited organic dye, Na2 eosin Y as direct hydrogen atom transfer (HAT) photocatalyst via visible light-mediated under air atmosphere

2023

BMC Chemistry

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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.

“…Furthermore, it is difficult to separate a homogeneous catalyst from the reaction mixture. The goal of our study was to look at photocatalysts [36][37][38][39] in green environments in order to synthesize heterocyclic compounds, which have been attempted before. This study also shows how to employ a metal-free cationic dye photo-redox catalyst that is inexpensive and widely available.…”

Section: Introductionmentioning

confidence: 99%

Methylene blue as a photo‐redox catalyst employed for the synthesis of pyrano[2,3‐d]pyrimidine scaffolds via a single‐electron transfer/energy transfer pathway

Journal of Heterocyclic Chem

2023

Self Cite

The radical tandem Knoevenagel‐Michael cyclocondensation reaction of barbituric acid/1,3‐dimethylbarbituric acid, malononitrile, and aryl aldehydes was used to establish a green tandem method for the metal‐free synthesis of pyrano[2,3‐d]pyrimidine scaffolds. At ambient temperature, photo‐excited state functions made from methylene blue (MB+) were used as single‐electron transfer and energy transfer catalysts in an aqueous solvent, utilizing visible light as a sustainable energy source. The purpose of this project is to enhance the use of a non‐metal cationic dye that is both affordable and widely available. Methylene blue is photochemically catalyzed with the least amount of catalyst feasible, yielding excellent yields, energy efficiency, and environmental friendliness, as well as excellent atom economy, time‐saving features, and ease of operation. As a result, a wide range of environmental and long‐term chemical properties can be obtained. The pyrano[2,3‐d]pyrimidine scaffolds' turnover number and turnover frequency have been calculated. Surprisingly, gram‐scale cyclization is conceivable, indicating that the technology could be used in industry.