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AbstractImidazole, a five-membered heterocyclic compound, has multipurpose applications for its bioactivity, uses in charge transport materials, and NLO materials. The review provides a comprehensive survey of the synthetic strategies of imidazole from various starting materials, highlighting their percentage yield and mechanistic insights. The most popular starting materials for the syntheses of imidazole include diketones, cyanides, imines, amidines, imidamides, di-amines, and oximes. Although the selection of a particular synthetic strategy will depend largely on the desired imidazole derivative, the survey consists of more than a century of research on imidazole synthetic procedures, starting with Heinrich Debus synthesis in 1858 till the present day. Most recent advancements and future perspectives in the field have been explored. The study will help researchers choose the most suitable starting material, catalyst, solvent, or reaction conditions for the synthesis of various imidazole derivatives. [ABSTRACT FROM AUTHOR]

In this work, we have focused on the atmospheric reaction chemistry of two α-diketones 2,3-Pentanedione (2,3-PTD) and 2,3-hexanedione (2,3-HEX) with OH radical. The full reaction pathway was studied theoretically under H-atom abstraction reaction using density functional theory and wave-function-based MP2 calculations. Single-point energy calculations were performed at CCSD(T) level of theory with 6–31+G(d,p) basis set. The H-atom abstraction from –CH2group is the most dominant channel in both 2,3-PTD and 2,3-HEX with OH radical. The fate of secondary reactions of peroxy and alkoxy radical is studied in detail. The reaction force analysis shows that abstraction process is dominated by structural rearrangement than electronic reordering. The ETS-NOCV-based reaction scheme is studied in order to find out the pair wise interaction energy of the chemical bonding. The ETS-NOCV method for all the transition states shows π-bonding nature for the bond breaking (C–H) and bond formation (O–H) due to the presence of hydrogen bond. The theoretical rate constant value matches well with the experimental rate constant value for both α-diketones. Normal linear Arrhenius behaviour for all the pathways is found in the range of 278–350 K. The short atmospheric lifetime indicates the removal process of diketones with OH radical. [ABSTRACT FROM AUTHOR]

Simple syntheses of diverse bicyclo[3.3.1]nonanes and related compounds as the minimal substructure of bioactive natural products via Michael, aldol, and alkylation reactions from diketones are described herein. The structures of the synthesized compounds were determined by infrared spectroscopy, NMR (1H and13C), and electrospray ionization–high-resolution mass spectrometry. We also show the in vitro antimicrobial activity against Gram-positive and Gram-negative bacteria. The qualitative analysis has revealed that the new synthesized compounds5, 6, 9,and11present antibacterial properties. [ABSTRACT FROM PUBLISHER]

An efficient and environmentally benign process for the synthesis of quinoxalines has been developed using glycerine–cerium chloride as a reaction medium. This method is applicable to a variety of diketones and 1,2-phenylenediamines to afford the corresponding quinoxaline derivatives in excellent yields. The reaction medium was recovered and reused for further reactions without any problem. [ABSTRACT FROM AUTHOR]

The nickel(II) complexes of 2-substituted-1,3-diphenyl-1,3-propanedione and their 2,2'-bipyridine and 1,10-phenanthroline adducts have been prepared and characterized by microanalysis, conductance, magnetic and spectral measurements. The conductance data in nitromethane indicate that the compounds are non-electrolytes. The room temperature magnetic moments suggest that they are magnetically dilute compounds. The electronic spectra revealed the π3-π4 bathochromic shifts, which were observed upon chelation while the infrared spectra showed the different shifts of the carbonyl frequencies. The X-ray crystallography showed that nickel ion is coordinated by two units of 1,3-diphenyl-1,3-propanedione and a unit of bipyridine giving it a six coordinate octahedral geometry. [ABSTRACT FROM AUTHOR]

The nickel(II) and copper(II) complexes of 2-substituted-4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione (R-TTAH) and their 2,2' -bipyridine and 1,10-phenanthroline adducts have been prepared and characterized by microanalysis, conductance, magnetic and spectral measurements. The conductance data in nitromethane indicate that the compounds are non-electrolytes except for [Cu(Phen)2TTA](TTA) and [Ni(Phen)3](TTA)2, which are 1:1 and 1:2 electrolytes respectively. The room temperature magnetic moments suggest that they are magnetically dilute compounds while the electronic spectral (solid and solution) bands of the ligands shifted upon chelation. The infrared spectra showed the different shifts of the carbonyl frequencies and a six-coordinate octahedral geometry formed by coordination of the nickel(II) ion through four oxygen atoms of the 4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dione (TTAH) and two nitrogen atoms of the bipyridine was established for (2,2' -bipyridine)bis{4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dionato}nickel(II) using X-ray crystallography. [ABSTRACT FROM AUTHOR]

Camphor-derived a-dicarbonyl compounds and 3-oxo-camphorsulfonylimine have been synthesized from the corresponding ketones or sulfonylimine by microwave-assisted oxidation with selenium dioxide. Compared to the classical reaction conditions, good yields were obtained in much shorter reaction times. Additionally, the selenium precipitation is more quantitative, and its removal from the reaction mixture is easier. [ABSTRACT FROM AUTHOR]

Fe 3+ -montmorillonite clay catalyst was used for the first time for pyrroles preparation by Paal–Knorr condensation. The features of this catalytic system are improved yields, mild conditions, a simple procedure, and high catalytic efficiency. The catalyst could be easily recycled and reused for three times without visible losing of activity. [ABSTRACT FROM AUTHOR]

A novel and efficient method for the synthesis of a new variety of nitroso-N-arylsulfonylaminated pyridones and nitroso-N-substitutedamino pyridones via the reaction of oxime derivatives of β-diketones and β-ketoesters with N-cyanoacetoarylsulfonylhydrazides and substituted cyanoacetohydrazides has been investigated. The synthetic potential of the method is demonstrated. [ABSTRACT FROM AUTHOR]

Phenanthrene-9,10-quinone and P 4 S 10 react with phenols on being heated to give oxathiins, e.g., 9 the dioxin 22 , ethers, e.g., 14 arylphenanthrenols, e.g., 10 and furanols, e.g., 17 in addition to sulfides, e.g., 26 and disulfides, e.g., 25 . Under similar conditions benzil gives thiophene derivatives, e.g., 2 . Most of the reactions appear to proceed via thione intermediates but some of the products are also formed when P 4 S 10 is absent. [ABSTRACT FROM AUTHOR]