Search

The pervasive effects of plastic waste pollution affect both humanity and the environment, thus innovative and environmentally-friendly methods for recycling of plastics are crucially needed. The application of light to degrade or transform plastics into valuable products has gained significant attention. Numerous researchers have explored irradiation to achieve the photocatalytic breakdown of highly resilient plastic waste components into valuable monomers, which can be utilized for the synthesis of novel materials of synthetic or pharmacological interest. Many of these techniques have resulted in H2 evolution, while efforts were also made to reduce carbon emissions. In some cases, light was combined with additional energy sources, leading to development of photothermal or photoelectrochemical processes. With this tutorial review, our aim is to offer an overview of these novel photochemical upcycling protocols for the degradation of polymers, aspiring toward the introduction of novel processes in the near future. [ABSTRACT FROM AUTHOR]

This article discusses the use of boronic acids in the synthesis of phenols, which are important compounds found in natural products and pharmaceuticals. The researchers focus on developing environmentally friendly and sustainable methods for preparing phenols from boronic acids. They explore different photocatalysts and solvents to optimize the oxidation reaction. The study finds that anthraquinone is an effective photocatalyst and 2-Me-THF is the best solvent for the reaction. The researchers aim to provide a more sustainable protocol for the oxidation of boronic acids. Another study described in the document investigates the photochemical aerobic oxidation of boronic acids to phenols. The researchers tested different additives and found that N,N'-diisopropylethylamine (DIPEA) was the most suitable base, resulting in the complete formation of phenol. They also explored the range of substrates and found that various aryl-substituted boronic acids could be converted into the corresponding phenols with moderate to excellent yields. Mechanistic studies suggested a mixed pathway involving the generation of a superoxide anion and the formation of hydrogen peroxide. Overall, this study presents an environmentally friendly and efficient method for the oxidation of boronic acids. [Extracted from the article]

The Friedel–Crafts arylation is among the most known organic reactions, usually being promoted by a Lewis acid, that have been employed for the synthesis of bis-indolyl methanes. Herein, we report a mild, inexpensive, green and organocatalytic protocol for the promotion of a Friedel–Crafts-type reaction between indoles and aldehydes, where N-heterocyclic iod(az)olium salts are utilized as halogen-bonding catalysts, leading to the double addition of the indole motif. A variety of aliphatic and aromatic aldehydes were converted into diarylmethanes in good to high yields, while the scope of indoles was also investigated. Water was employed as the solvent, while the reaction time was short. The reaction mechanism was also studied. [ABSTRACT FROM AUTHOR]

Group VIA calcium-independent phospholipase A(2) (GVIA iPLA(2)) has recently emerged as a novel pharmaceutical target. We have now explored the structure-activity relationship between fluoroketones and GVIA iPLA(2) inhibition. The presence of a naphthyl group proved to be of paramount importance. 1,1,1-Trifluoro-6-(naphthalen-2-yl)hexan-2-one (FKGK18) is the most potent inhibitor of GVIA iPLA(2) (X(I)(50) = 0.0002) ever reported. Being 195 and >455 times more potent for GVIA iPLA(2) than for GIVA cPLA(2) and GV sPLA(2), respectively, makes it a valuable tool to explore the role of GVIA iPLA(2) in cells and in vivo models. 1,1,1,2,2,3,3-Heptafluoro-8-(naphthalene-2-yl)octan-4-one inhibited GVIA iPLA(2) with a X(I)(50) value of 0.001 while inhibiting the other intracellular GIVA cPLA(2) and GV sPLA(2) at least 90 times less potently. Hexa- and octafluoro ketones were also found to be potent inhibitors of GVIA iPLA(2); however, they are not selective.

In this study, 3H‐phenothiazin‐3‐one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This photocatalytic method uses a low catalyst loading (0.05 mol%), molecular oxygen as the sole oxidant, and a blue LED lamp as the irradiation source. It can be applied to the oxidation of both alkyl‐aryl and alkyl‐alkyl sulfides. Moreover, the method is also applicable in the synthesis of the known pharmaceutically active compounds Modafinil and Sulforaphane. [ABSTRACT FROM AUTHOR]

The direct amide bond formation between a carboxylic acid and an amine still constitutes a challenging reaction for both academia and industry. We demonstrate herein that several pairs of amines (halogen bond acceptors) and organohalogen sources may be used for the photochemical amidation reaction under either UVA or sunlight irradiation. Our studies led to the identification of pyridine‐CBr4 as an efficient agent to perform amide synthesis under LED 370 nm irradiation, avoiding super‐stoichiometric quantities. An extended substrate scope was demonstrated, showing that the widely used amino and carboxyl protecting groups are compatible with this photochemical protocol, while a number of industrially interesting products and bioactive compounds were synthesized. Direct infusion‐high resolution mass spectrometry studies suggest an unprecedented type of carboxylic acid activation mode upon irradiation, involving the generation of a symmetric anhydride, an active ester with pyridine N‐oxide and a mixed anhydride with hypobromous acid. [ABSTRACT FROM AUTHOR]

The protection of a carbonyl is a standard procedure to mask the reactivity of this group towards nucleophiles and reductants. The present work pointed out the potentialities of arylazo sulfones as non‐ionic photoacid generators (PAGs) to promote the efficient conversion of aldehydes and ketones into acetals, ketals, and 1,3‐oxazolidines upon visible‐light irradiation. This approach employed mild conditions and exhibited an easy scalability and a broad scope (80 examples included). [ABSTRACT FROM AUTHOR]