A Novel and Efficient Continuous-Flow Route To Prepare Trifluoromethylated N-Fused Heterocycles for Drug Discovery and Pharmaceutical Manufacturing

Synthetic, biological and optoelectronic properties of phenoxazine and its derivatives: a state of the art review

Phenoxazines have sparked a lot of interest owing to their numerous applications in material science, organic light-emitting diodes, photoredox catalyst, dye-sensitized solar cells and chemotherapy. Among other things, they have antioxidant, antidiabetic, antimalarial, anti-alzheimer, antiviral, anti-inflammatory and antibiotic properties. Actinomycin D, which contains a phenoxazine moiety, functions both as an antibiotic and anticancer agent. Several research groups have worked on various structural modifications over the years in order to develop new phenoxazines with improved properties. Both phenothiazines and phenoxazines have gained prominence in medicine as pharmacological lead structures from their traditional uses as dyes and pigments. Organoelectronics and material sciences have recently found these compounds and their derivatives to be quite useful. Due to this, organic synthesis has been used in an unprecedented amount of exploratory alteration of the parent structures in an effort to create novel derivatives with enhanced biological and material capabilities. As a result, it is critical to conduct more frequent reviews of the work done in this area. Various stages of the synthetic transformation of phenoxazine scaffolds have been depicted in this article. This article aims to provide a state of the art review for the better understanding of the phenoxazine derivatives highlighting the progress and prospects of the same in medicinal and material applications.

Formal (4+2) cycloaddition of azoalkenes with trifluoromethylimidoyl sulfoxonium ylides: synthesis of trifluoromethyl pyridazine derivatives

CF3-substituted imidoyl sulfoxonium ylides (TFISYs) are extraordinarily versatile and powerful synthons for use in cyclization chemistry that affords diverse CF3-substituted N-heterocycles. We first reacted TFISYs as a two-atom synthon with readily available azoalkenes and then subjected the products to metal-free formal (4+2) cycloaddition chemistry. This protocol features mild conditions and broad substrate scope, is simple to operate, and provides highly functionalized trifluoromethylpyridazines that are widely found in bioactive molecules.

Nanostructured Carbon Nitride for Continuous-Flow Trifluoromethylation of (Hetero)arenes

Efficient catalytic methods for the trifluoromethylation of (hetero)arenes are of particular importance in organic and pharmaceutical manufacturing. However, many existing protocols rely on toxic reagents and expensive or sterically hindered homogeneous catalysts. One promising alternative to conduct this transformation involves the use of carbon nitride, a non-toxic photocatalyst prepared from inexpensive precursors. Nonetheless, there is still little understanding regarding the interplay between physicochemical features of this photocatalyst and the corresponding effects on the reaction rate. In this work, we elucidate the role of carbon nitride nanostructuring on the catalytic performance, understanding the effect of surface area and band gap tuning via metal insertion. Our findings provide new insights into the structure-function relationships of the catalyst, which we exploit to design a continuous-flow process that maximizes catalyst-light interaction, facilitates catalyst reusability, and enables intensified reaction scale-up. This is particularly significant given that photocatalyzed batch protocols often face challenges during industrial exploitation. Finally, we extrapolate the rapid and simplified continuous-flow method to the synthesis of a variety of functionalized heteroaromatics, which have numerous applications in the pharmaceutical and fine chemical industries.

Ligand-free nickel catalyzed perfluoroalkylation of arenes and heteroarenes

We describe a "ligand-free" Ni-catalyzed perfluoroalkylation of heteroarenes to produce a diverse array of trfiluoromethyl, pentafluoroethyl and heptafluoropropyl adducts. Catalysis proceeds at room temperature via a radical pathway. The catalytic protocol is distinguished by its simplicity, and its wide scope demonstrates the potential in the late-stage functionalization of drug analogues and peptides.

Photoinduced Trifluoromethylation of Arenes and Heteroarenes Catalyzed by High-Valent Nickel Complexes

We describe a series of air-stable Ni^III complexes supported by a simple, robust naphthyridine-based ligand. Access to the high-valent oxidation state is enabled by the CF₃ ligands on the nickel, while the naphthyridine exhibits either a monodentate or bidentate coordination mode that depends on the oxidation state and sterics, and enables facile aerobic oxidation of Ni^II to Ni^III . These Ni^III complexes act as efficient catalysts for photoinduced C(sp² )-H bond trifluoromethylation reactions of (hetero)arenes using versatile synthetic protocols. This blue LED light-mediated catalytic protocol proceeds via a radical pathway and demonstrates potential in the late-stage functionalization of drug analogs.

Electrophilically Activated Nitroalkanes in Synthesis of 3,4-Dihydroquinozalines

Nitroalkanes activated with polyphosphoric acid serve as efficient electrophiles in reactions with various nucleophilic amines. Strategically placed second functionality allows for the design of annulation reactions enabling preparation of various heterocycles. This strategy was employed to develop an innovative synthetic approach towards 3,4-dihydroquinazolines from readily available 2-(aminomethyl)anilines.

Evaluating the Green Credentials of Flow Chemistry towards Industrial Applications

Continuous flow chemistry is becoming an established technology platform that finds frequent application in industrial chemical manufacture with support and endorsements by the FDA for pharmaceuticals. Amongst the various advantages that are commonly cited for flow chemistry over batch processing, sustainability continues to require further advances and joint efforts by chemists and chemical engineers in both academia and industry. This short review highlights developments between 2015 and early 2021 that positively impact on the green credentials associated with flow chemistry, specifically when applied to the preparation of pharmaceuticals. An industrial perspective on current challenges is provided to whet discussion and stimulate further investment towards achieving greener modern synthetic technologies.

1 Introduction

2 Subject Areas and Relevant Case Studies

3 Industrial Outlook on Future Sustainability Driven through Continuous Manufacturing Approaches

4 Conclusions and Outlook

Synthesis, in vitro and computational studies of novel glycosyl-1, 2, 3-1H-triazolyl methyl benzamide derivatives as potential α-glucosidase inhibitory activity

A series of novel glycosyl-1,2,3-1H-triazolyl methyl benzamide analogues were synthesized by the unambiguous strategy and evaluated for α-glucosidase inhibitory activity. Glycosyl benzamide exhibited a dose-dependent inhibition of α-glucosidase activity. The In-vitro α-glucosidase inhibition activity results indicated that all the synthesized triazolyl methyl benzamide compounds (IC₅₀ values ranging from 25.3 ± 0.8 to 118.5 ± 5.3 μM) exhibited more inhibitory activity in comparison with the standard drug acarbose (IC₅₀ = 750.0 ± 12.5 μM). Among all, the 3 deacetylated glycosyl methyl benzamide derivatives (4c, 4d and 4f) showed promising α-glucosidase enzyme inhibitory activities with IC₅₀ value 25.3 ± 0.8, 26.1 ± 1.5 and 30.6 ± 2.1 respectively. Furthermore, these compounds were subjected to molecular docking and molecular dynamics simulation studies. The molecular docking studies were performed between (PDB ID: 3A4A) target protein and these synthesized molecules. The compounds displayed good docking energies in the range of -7.5 to -7.8 Kcal/mol. This work could be used as an initial approach in identifying potential novel molecules with the promising activity of type-2 diabetes mellitus.

Investigation of the Turbulent Drag Reduction Mechanism of a Kind of Microstructure on Riblet Surface

With the k-ε renormalization group turbulence model, the drag reduction mechanism of three- dimensional spherical crown microstructure of different protruding heights distributing on the groove surface was studied in this paper. These spherical crown microstructures were divided into two categories according to the positive and negative of protruding height. The positive spherical crown micro-structures can destroy a large number of vortexes on the groove surface, which increases relative friction between water flow and the groove surface. With decreasing the vertical height of the spherical crown microstructure, the number of rupture vortexes gradually decreases. Due to the still water area causes by the blocking effect of the spherical crown microstructure, it was found that the shear stress on the groove surface can be reduced, which can form the entire drag reduction state. In another case, the spherical crown microstructures protrude in the negative direction, vortexes can be generated inside the spherical crown, it was found that these vortexes can effectively reduce the resistance in terms of pressure and friction. In a small volume, it was shown that the surface drag reduction rate of spherical crown microstructures protrudes in negative directions can be the same as high as 24.8%.

Photocatalytic materials and light-driven continuous processes to remove emerging pharmaceutical pollutants from water and selectively close the carbon cycle

Past and present technologies for wastewater purification and future research directions are critically discussed in this review.

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

Imidazo[1,5-a]pyridines were efficiently prepared via the cyclization of 2-picolylamines with nitroalkanes electrophilically activated in the presence of phosphorous acid in polyphosphoric acid (PPA) medium.

Emerging Concepts in Carbon Nitride Organic Photocatalysis

Carbon nitrides encompass a class of transition-metal-free materials possessing numerous advantages such as low cost (few Euros per gram), high chemical stability, broad tunability of redox potentials and optical bandgap, recyclability, and a high absorption coefficient (>10⁵  cm^-1 ), which make them highly attractive for application in photoredox catalysis. In this Review, we classify carbon nitrides based on their unique properties, structure, and redox potentials. We summarize recently emerging concepts in heterogeneous carbon nitride photocatalysis, with an emphasis on the synthesis of organic compounds: 1) Illumination-Driven Electron Accumulation in Semiconductors and Exploitation (IDEASE); 2) singlet-triplet intersystem crossing in carbon nitride excited states and related energy transfer; 3) architectures of flow photoreactors; and 4) dual metal/carbon nitride photocatalysis. The objective of this Review is to provide a detailed overview regarding innovative research in carbon nitride photocatalysis focusing on these topics.

Analysis of Entropy Production in Structured Chemical Reactors: Optimization for Catalytic Combustion of Air Pollutants

Optimization of structured reactors is not without some difficulties due to highly random economic issues. In this study, an entropic approach to optimization is proposed. The model of entropy production in a structured catalytic reactor is introduced and discussed. Entropy production due to flow friction, heat and mass transfer and chemical reaction is derived and referred to the process yield. The entropic optimization criterion is applied for the case of catalytic combustion of methane. Several variants of catalytic supports are considered including wire gauzes, classic (long-channel) and short-channel monoliths, packed bed and solid foam. The proposed entropic criterion may indicate technically rational solutions of a reactor process that is as close as possible to the equilibrium, taking into account all the process phenomena such as heat and mass transfer, flow friction and chemical reaction.

Flow chemistry as a tool to access novel chemical space for drug discovery

This perspective scrutinizes flow chemistry as a useful tool for medicinal chemists to expand the current chemical capabilities in drug discovery. This technology has demonstrated his value not only for the traditional reactions used in Pharma for the last 20 years, but also for bringing back to the lab underused chemistries to access novel chemical space. The combination with other technologies, such as photochemistry and electrochemistry, is opening new avenues for reactivity that will smoothen the access to complex molecules. The introduction of all these technologies in automated platforms will improve the productivity of medicinal chemistry labs reducing the cycle times to get novel and differentiated bioactive molecules, accelerating discovery cycle times.

FeCl3-Mediated Synthesis of 2-(Trifluoromethyl)quinazolin-4(3H)-ones from Isatins and Trifluoroacetimidoyl Chlorides

An FeCl₃-mediated cascade coupling/decarbonylative annulation reaction for the efficient construction of 2-(trifluoromethyl)quinazolin-4(3H)-ones has been developed. This transformation employs readily available isatins and trifluoroacetimidoyl chlorides as the starting materials, providing a facile and practical route to diverse biologically relevant quinazolin-4(3H)-one derivatives. A plausible reaction pathway has been proposed based on the mechanistic observations.

Palladium-catalyzed three-component carbonylative synthesis of 2-(trifluoromethyl)quinazolin-4(3H)-ones from trifluoroacetimidoyl chlorides and amines

An efficient and practical approach for the synthesis of 2-(trifluoromethyl)quinazolin-4(3H)-ones through palladium-catalyzed three-component carbonylative reaction has been developed.

Metal- and solvent-free synthesis of aminoalcohols under continuous flow conditions

Multifunctional organocatalysts were immobilized on porous hollow fiber polymer and used as intelligent and cooperative heterogeneous catalysts and continuous flow reactor for sustainable chemical transformation.