Current Organocatalysis - Volume 9, Issue 4, 2022

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This brief perspective outlines the pivotal role of Machine Learning methods in the green, digital transition of industrial chemistry. The focus on homogenous catalysis highlights the recent methodologies in the development of industrial processes, including the design of new catalysts and the enhancement of sustainable reaction conditions to lower production costs. We report several examples of Machine Learning assisted methodologies through recent Data Science trends in the innovation of industrial homogeneous organocatalytic systems. We also stress the current benefits, drawbacks, and limitations of the mass implementation of these Data Science methodologies.

Compounds with three membered rings experience greater strain than those with other ring systems. In general, the synthesis of small ring compounds, particularly three-membered molecules, faces major challenges because of the severe strain in this system. Moreover, microwaveassisted method creates a higher temperature due to the heat and radiation of a reaction mixture more rapidly than conventional methods. This paper reports the successful synthesis of threemembered heterocyclic compounds via microwave-assisted reactions. Microwaves have assisted in making three-membered compounds while inducing high energy to the reaction mixtures. No reviews have reported the synthesis of these types of molecules either by microwave or conventional procedure. In addition, the reaction of a few three-membered ring compounds to other products through the ring rupture method is also included. On this basis of the chemistry (formation and breakage) of three-membered compounds described here, this report can be considered novel, timely, and highly significant. This review may help numerous researchers for further study in this field as the synthesis and cleavage of three-membered ring structures using a microwave is a challenging objective.

Aims: The study aims to synthesize oxadiazole, imidazole, benzimidazole, and cyclohexano analogues of 1, 5-benzodiazepines through phenoxyl/phenylamino linkage. Background: It is worthwhile to mention that imidazoles, benzimidazoles, oxadiazoles, are analysed extensively mainly as per their ready availability, broad chemical reactivity, and wide spectrum of biochemical activities, like antimicrobial, anti-inflammatory, antitumor, anticonvulsant drugs, antitubercular medicines, and having an anti-HIV effect, etc. Objective: The oxadiazole, imidazole, benzimidazole derivatives were synthesized via cyclohexano analogues of 1, 5-benzodiazepines through phenoxyl/phenylamino linkage. Methods: The characteristic drift of our interest towards these molecules prompted us to think about the structural modification of [1, 5]-benzodiazepine compound by incorporating on its 2-position imidazole, benzimidazole, oxadiazole, nuclei through an aminophenyl or phenoxyl bridge to synthesize these novel heterocyclic analogues of 1, 5-benzodiazepines. Results: These derivatives have been analysed by various spectrophometric techniques like UV, IR, NMR, and MS. The synthesis of these compounds via the mentioned methods is unique as cyclohexano analogues of 1, 5-benzodiazepines through phenoxyl/phenylamino is a totally new way of synthesis. The derivatives can be analysed for various properties in chemistry and pharmacology, as their parent compounds have many pharmacological properties. Conclusion: The synthesis of these types of compounds does provide new hope to the medicinal and pharmaceutical industries. Therefore further efforts should be taken into consideration for the synthesis and analysis of their medicinal properties.

Aims: Catalytic degradation of azo dye. Background: Azo dyes are toxic agents and pollutants, and the degradation of these dyes has an important application in the treatment of textile industry wastes.Catalytic decolorization of fast yellow dye by hexacyanoferrate (III), abbreviated as HCF(III) using polyvinylpyrrolidone abbreviated as PVP stabilized Ir-Ni bimetallic nanocrystals has been evaluated by kinetic spectrophotometric method at 440nm wavelength of the reaction mixture. Methods: The impact of various operational factors such as fast yellow dye abbreviated as [FY], oxidant [HCF(III)] ions, promoter iridium-nickel bimetallic nanoparticles abbreviated as [(Ir-Ni)] BMNPs, and solution pH on the rate of the reaction have been examined. Results: The results represent that the reaction follows the first-order kinetics model with respect to [oxidant] at optimum pH 8 and fix temperature 40 ± 0.1°C. Thermodynamic parameters such as activation energy (Ea), enthalpy (ΔH#), entropy (ΔS#), frequency factor (A), and free energy of activation (ΔF#) have been evaluated by examining the reaction rate at four temperatures i.e., 40°C, 45°C, 50°C, and 55°C. On the basis of experimental outcomes, an appropriate mechanism involving complex formation has been proposed. Conclusion: Analytical techniques such as UV-Vis spectroscopy, FTIR, and LCMS of degraded products represent the formation of easier and less harmful compounds.

Background: Carbon-based materials, due to their unique properties such as lightweight, different forms, doping capability with hetero atoms, low cost, and ease of processability, are suitable support, for heterogeneous catalysts. Among them, cellulose, as one of the most abundant and renewable organic polymers, preserves a key position in many organic raw materials. Pyranopyrimidine derivatives, due to their high biological activity are of interest to both medicinal chemists and biochemists. Moreover, they play the most fundamental structural role in many natural compounds and are medicinally useful molecules. Owing to the great variety of biologically active pyridines, it is not surprising that the pyridine ring system has become a vital basic component in many pharmaceutical agents. Methods: In this study, cellulose as a heterogeneous support was used to prepare an efficient solid catalyst. Cellulose, as the most abundant organic polymer, is a suitable material for this purpose. Then, by immobilizing polyoxomolybdate by a linker on the surface of this carbon-based material, we succeeded in producing Cell@(CH2)3N=Mo[Mo5O18] nanocatalyst. The structure and properties of this catalyst were confirmed by various analyses including FT-IR, XRD, EDS-map, FESEM, and TGA, and its efficacy was evaluated by its use in the preparation of Pyrano[2,3- d]pyrimidine derivatives through a multicomponent reaction between aryl aldehydes, malononitrile, and barbituric acid. Results: The results of this study showed that this new and non-toxic organo-inorganic hybrid nanocatalyst provides the desired products in a short time and with appropriate efficiency. Conclusion: The key features of the present protocol include reusability of the catalyst, ease of recovery, ambient reaction conditions, and simple work-up procedure that make it economic and sustainable.

Aims: The aim of this study is to investigate the p-toluene sulphonic acid (p-Ts.OH)- catalyzed reaction of racemic-azetidine-2,3-diones with enantiomerically pure cis and trans-4- hydroxy-L-proline in refluxing ethanol culminating in a synthesis of substituted novel 3-(pyrrol-1- yl)-azetidin-2-ones at the C-3 position. Methods: This work describes an alternative synthetic route enabling the tandem transformation of proline to pyrrole, followed by intramolecular chirality transfer to the β -lactams ring. Results: All four diastereomers of 3-(pyrrol-1-yl)-azetidin-2-ones could be achieved in good to excellent yield with high diastereoselectivity in a single-pot operation. Conclusion: This method can be applied to other activated carbonyl compounds and functionalized pyrroles can be obtained through an expeditious process.

Background: Quinazolinones are a class of heterocyclic compounds that have a wide variety of applications. They are also used in agrochemicals. There are several methodologies reported for the synthesis of 2,3-dihydroquinazolines using various catalysts. Methods: Here, by using 1-butyl-1,2,4-triazolium as cation and trifluoroacetate as anion, 2,3- dihydroquinazolin-4(1H)-one has been synthesized. For the synthesis of 2,3-dihydroquinazolin- 4(1H)-one, the condensation of anthranilamide with the corresponding aldehyde in the presence of organocatalyst and solvent was done. Using benzaldehyde as the parent aldehyde, to validate the outcome, the benzaldehydes were selected as follows: a) benzaldehyde; b) 4-methoxybenzaldehyde, an electron-releasing group; and c) 4-nitrobenzaldehyde, an electron-withdrawing group. A solvent study has been done with solvents varying from polar to apolar. Both polar protic and polar aprotic solvents have been used for the reactions. The polar protic solvents used were water, methanol, ethanol, isopropanol, butanol, hexane-1-ol, and glycerol. The polar aprotic solvents used were ethyl acetate, DMF, acetonitrile, and DMSO. The moderately apolar solvents used were DCM, carbon tetrachloride, 1,4 dioxane, and chloroform. Results: The synthesized triazolium salts have been found to be soluble in polar aprotic and polar protic solvents, and a few moderately apolar solvents, such as DCM, chloroform, acetonitrile, water, methanol and ethanol, whereas insoluble in apolar solvents, like toluene, benzene, and hexane. The yield of 2-phenyl-2,3-dihydroquinazolin-4(1H)-one was low for 1-butyl-1,2,4-triazolium trifluoroacetate- based organocatalyst. But for substituted benzaldehyde, the yield was comparatively high. Comparatively, the yield for 2-(4-methoxyphenyl)-2,3-dihydroquinazolin-4(1H)-one, where the aromatic benzaldehyde had an electron-donating group, was less than 2-(4-nitrophenyl)-2,3- dihydroquinazolin-4(1H)-one, where the aromatic benzaldehyde had an electron-withdrawing group. Conclusion: Substituted benzaldehyde provided better yields than benzaldehyde. The nitro group, which is an electron-withdrawing group, when attached to benzaldehyde, enhanced the electrophilic nature at the carbonyl center, providing higher yields than the methoxy group, which is an electron-donating group; when it attaches to benzaldehyde, it deactivates the carbonyl carbon. The polar protic solvents, like water, ethanol and methanol, stabilize the ionic intermediates, providing a better yield. Even the moderately apolar solvents, like DCM and chloroform, resulted in good yields; green solvents, like water, ethanol and methanol, would be a better choice as solvents. The carbon chain on the solvent has an effect on the product yield. As the carbon chain increases in the solvent, the yield decreases due to the separation difficulty. The polar aprotic solvents provided better yields but not as good as polar protic solvents.