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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]

The interaction of Thorium(IV) with a group of non‐symmetric CF3‐diketones has been studied by means of electronic absorption spectroscopy in HCl aqueous solutions at I=0.5 M (NaCl) and T=298 K. Six heterocyclic dicarbonyl ligands (2‐thenoyl‐trifluoroacetone, 2‐furoyl‐trifluoroacetone, 2‐selenophen‐trifluoroacetone, 2‐tellurophen‐trifluoroacetone, phenyl‐trifluoroacetone, and 2‐naphthyl‐trifluoroacetone) demonstrate the chelation activity toward ThIV in the acidic pH range. Obtained values of the "true" stability constants lie in the range 6.2–6.8 logarithmic units, respectively. A significant (10–15 nm) bathochromic shift between the maximum absorption wavelength of lanthanide and actinide monocomplexes has been detected. Observed spectral shift increases with the atomic number of substituted chalcogen atoms in the heterocyclic ring of the corresponding ligand: 10 nm for furan, 11 nm for thiophen, 14 nm for selenophen, and 15 nm for tellurophene rings. The complexation with Thorium occurs in an acidic media, where studied ligands do not interact with transition and rare earth metals. Spectral and pH shifts make studied ligands useful reagents for the detection and analytical determination of Thorium in the mixture with other metals without prior separation. Quantum‐chemical simulations (DFT and TD‐DFT) demonstrate that the nine‐ and deco‐coordinated structures of ThoriumIV complexes reproduce experimental values within reasonable errors. [ABSTRACT FROM AUTHOR]

The first homometal dicubane nickel(II) complex based on unsymmetrically substituted 1,3-diketone (1,1,1-trifluoro-4-(2-methoxyphenyl)butan-2,4-dione) was synthesized and studied by X-ray diffraction using synchrotron radiation (CCDC no. 861889). In the crystal of the complex, nickel atoms are joined into tetrahedra sharing a common vertex with Ni...Ni distances of 3.026–3.127 Å; the geometry is completed to a distorted dicubane by μ3-bridging oxygen atoms of the hydroxyl groups. The coordination environment of each metal center is a distorted octahedron, the ligand is deprotonated and performs a bidentate function, forming six-membered chelate rings. [ABSTRACT FROM AUTHOR]

N-aryl-substituted pyrrolidines are important moieties widely found in bioactive substances and drugs. Herein, we present a practical reductive amination of diketones with anilines for the synthesis of N-aryl-substituted pyrrolidines in good to excellent yields. In this process, the N-aryl-substituted pyrrolidines were furnished via successive reductive amination of diketones via iridium-catalyzed transfer hydrogenation. The scale-up performance, water as a solvent, simple operation, as well as derivation of drug molecules showcased the potential application in organic synthesis. [ABSTRACT FROM AUTHOR]

This study shows an effective approach for the synthesis of spirooxindole‐pyrans and bis‐spirooxindole‐pyrans derivatives using 5 mol % of [CMMIM][BF4] ionic liquid. The synthesis of a library of 28 derivatives was accomplished with impressive yields, ranging from 81 % to 97 %. The derivatives were successfully characterized by 1H‐NMR, 13C‐NMR, FT‐IR, and high‐resolution mass spectral techniques. In addition, the photophysical properties of 17 selected derivatives, including the molar extinction coefficient (ϵ) and the Stokes shift (Δυ̅), have been investigated. The values for spirooxindole‐pyrans vary between 14863 to 47372 and 5516 to 9766 cm−1, respectively. On the other hand, the corresponding values vary from 30871 to 57622 and 9199 to 13351 cm−1 for bis‐spirooxindole‐pyrans. Furthermore, the experimental data is supported by density functional theory (DFT) and time‐dependent DFT calculations. The theoretical studies conducted demonstrated a trend remarkably consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Described herein is an effective and green reaction between diketones, amines and bio‐renewable glyoxal, affording a wide range of 2‐pyrrolin‐5‐ones and releasing water as the only byproduct. The reaction features step‐economy, high efficiency, mild conditions, broad substrate scope, hazardous waste avoiding and easy scale‐up. The further transformation between the products and aldehydes can be potentially applied for fluorescent dye synthesis. [ABSTRACT FROM AUTHOR]

This work reconsiders the known condensation reaction of 1,2-diketones with arylhydrazines in the synthesis of the corresponding bishydrazones. It was shown that the reaction outcome significantly depends on the nature of the substituent of the aromatic ring of arylhydrazine. In addition, representatives of unsymmetrically substituted bishydrazones, rarely found in the literature, were obtained. The proposed approach is easy to carry out and isolate target bishydrazones, which opens the way to the preparation of various nitrogen-containing molecular systems based on them. [ABSTRACT FROM AUTHOR]

N-aryl-substituted pyrrolidines are important moieties widely found in bioactive substances and drugs. Herein, we present a practical reductive amination of diketones with anilines for the synthesis of N-aryl-substituted pyrrolidines in good to excellent yields. In this process, the N-aryl-substituted pyrrolidines were furnished via successive reductive amination of diketones via iridium-catalyzed transfer hydrogenation. The scale-up performance, water as a solvent, simple operation, as well as derivation of drug molecules showcased the potential application in organic synthesis.

We investigated direct addition reaction of β-diketone with several alcohols and alkenes employing solid acid zeolites (HY & Hβ). The presence of acidic sites and the porous structures exhibits and influences the catalytic activity. These heterogeneous catalysts were used directly for the nucleophilic addition/substitution reactions. HY zeolite was utilized for the reaction of various aromatic alcohols containing substituents like electron-donating groups, halogens, diphenyl alcohols, propargylic alcohols with acetyl acetone and gave the respective products in 14–99% yields. Hβ zeolite was used for the reaction of several substituted alkenes with acetyl acetone and afforded their corresponding products from 35 to 98% yields. The validation of large-scale experiments (10 mmol) adds additional dividend to this protocol. Moreover, these heterogeneous zeolites were readily separated from the reaction mixture by simple filtration process. The efficiency of these zeolites (HY and Hβ) for recyclability was proved for five cycles. [ABSTRACT FROM AUTHOR]

In conclusion, a nucleophilic intramolecular ring transformation of 2-pyrone derivatives into 2-pyridone derivatives with a 1,5-diketo motif through a translocative rearrangement has been developed. Keywords: ring transformation; rearrangement; pyrones; pyridones; diketones; medicinal chemistry EN ring transformation rearrangement pyrones pyridones diketones medicinal chemistry 1631 1633 3 07/31/23 20230815 NES 230815 Graph 2-Pyridone derivatives are abundant in natural products, several of which have important pharmaceutical properties such as antimicrobial, antimalarial, antitumor, or cardiotonic activities. Ring transformation, rearrangement, pyrones, pyridones, diketones, medicinal chemistry. [Extracted from the article]

The reaction of 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)hexane-1,3-dione (HPyrC3F7) with freshly precipitated hydrated europium(ɪɪɪ) and samarium(ɪɪɪ) hydroxides in EtOH afforded crystalline complexes of the composition [Ln(PyrC3F7)3(EtOH)2], the features of their formation depending on the stoichiometric ligand/metal ratios were studied. The structure and composition of the complexes were characterized by physicochemical methods, including single-crystal X-ray diffraction. The luminescent properties of these compounds in the crystalline state and in solutions were studied in detail. Possible ways of transferring electronic excitation in the complex [Eu(PyrC3F7)3(EtOH)2] were considered. [ABSTRACT FROM AUTHOR]

A Knoevenagel based redox-reaction promoted by intramolecular phosphine sources is presented for the first time. The influence of different diketones, aldehydes, bases and acids was investigated. The effects of different substituents were evaluated based on their electronical influence on the diketone structure. With the obtained results a mechanism is proposed, giving information about transition states formed during the reaction, which can lead to different products. This type of an internal redox transformation with a phosphine oxide moiety remaining in the molecule after the redox reaction represents a new type of reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • This work deal with study of the structure, keto-enol, spectral and chelation properties of three β-diketones with pyrrole, pyrazole, and pyridine rings. • The formation constants for the sixteen rare earth complexes, dissociation and protonation constants have been determined in an aqueous solution. • Quantum-chemical simulations were performed with using DFT and TD-DFT. Aqueous equilibria of three substituted perfluorinated 1,3-diketones with pyrrole, pyrazole, and pyridine rings have been extensively studied in aqueous solutions. Thermodynamic characteristics of dissociation, protonation, and chelation processes have been investigated by UV–Vis spectroscopy using non-linear regression analysis. Acid-base parameters were discovered in the acidity range from highly acidic media (C(HCl) = 10 M) to alkaline pH region. Dissociation constants (pK a) have been determined in glycine-HCl, phosphate-citrate, and TRIS-HCl buffered media. Protonation activities were studied by the Cox-Yates approach in concentrated hydrochloric acid solutions. First formation constants of ML complex species with trivalent ions of Sc3+, Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Tb3+, Ho3+, Er3+, Tm3+, Yb3+, and Lu3+ have been obtained in the pH within 3.0–5.6 (I = 0.5 M, NaCl). True stability constants have been calculated using determined acid-base parameters considering side reactions. The "True" formation constants lie from 3.7 to 6.9 logarithmic units and have a linear relationship with the ionic (Coulomb) potential of metals. DFT and TD-DFT simulations have been performed for the modeling of the data obtained. [ABSTRACT FROM AUTHOR]

A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2–4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] (1) and the corresponding pyridyl ligands. Single X-ray crystallography showed that the complexes displayed 8-coordinated geometry. The solid pyridyl adducts 2–4 exhibited emission of luminescence in the NIR and visible regions with close quantum yields (QY = 0.20–0.25%). The magnetic data of 1–4 showed larger values than those expected for magnetically noncoupled Sm(III) complexes in the 6H5/2 ground state, with no saturation on the applied high magnetic field static at a temperature of 2 K. [ABSTRACT FROM AUTHOR]

Acid–base, spectral and complexing properties, as well as keto–enol tautomerism of the para-fluorinated derivative of benzoyl-trifluoroacetone have been investigated. Thermodynamic parameters were studied by UV–vis spectroscopy, NMR, and quantum-chemical modeling. Dissociation constants (pKa) were obtained in the citric-phosphate buffer (pH 2.0–7.0) for various ionic strengths. The protonation constant (pKH) was determined in concentrated HCl solution by the non-linear Cox–Yeates method. 1H-,13C-, and 19F-NMR spectra demonstrate the enolization of the studied ligand in a non-polar solvent. Study of aqueous complexation with rare-earth metals (Sc(III), Y(III), La(III), and trivalent lanthanides, except Pm) have been performed in acetate and glycine–HCl buffer media. The formation of mono-complex species and their conditional stability constants were computed through mathematic modeling of spectrophotometric data. Using the obtained acid–base parameters and taking into account the side reactions, sixteen "true" formation constants were determined. The "true" (thermodynamic) stability constants lie in the range of 4.8–12.0 logarithmic units. Thermodynamic and spectral characteristics have been reproduced by DFT simulations using several density functionals. [ABSTRACT FROM AUTHOR]

A novel series of polypyridyl adducts, [Sm(ntfa)3(NN)] (2–4), with ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate, NN = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me2bipy), and 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bipy) were synthesized from the precursor complex [Sm(ntfa)3(MeOH)2] (1) and the corresponding pyridyl ligands. Single X-ray crystallography showed that the complexes displayed 8-coordinated geometry. The solid pyridyl adducts 2–4 exhibited emission of luminescence in the NIR and visible regions with close quantum yields (QY = 0.20–0.25%). The magnetic data of 1–4 showed larger values than those expected for magnetically noncoupled Sm(III) complexes in the 6H5/2 ground state, with no saturation on the applied high magnetic field static at a temperature of 2 K.

A Knoevenagel based redox-reaction promoted by intramolecular phosphine sources is presented for the first time. The influence of different diketones, aldehydes, bases and acids was investigated. The effects of different substituents were evaluated based on their electronical influence on the diketone structure. With the obtained results a mechanism is proposed, giving information about transition states formed during the reaction, which can lead to different products. This type of an internal redox transformation with a phosphine oxide moiety remaining in the molecule after the redox reaction represents a new type of reaction.

A pyridine‐catalysed desulfonylative addition of β‐diketones to arylazosulfones was developed to obtain diazenyl β‐dicarbonyl compounds. The aryldiazenyl group was observed in the desired product from arylazosulfones, and this diazenylation reaction was achieved via a possible rearrangement process based on diaziridine ring cleavage. The scope of the protocol was investigated and a plausible mechanism was given. [ABSTRACT FROM AUTHOR]

A new series of mononuclear Ho3+ complexes derived from the β-diketonate anions: 4,4,4-trifluoro-1-phenyl-1,3-butanedioneate (btfa−) and 4,4,4-trifuoro-1-(naphthalen-2-yl)-1,3-butanedionate (ntfa−) have been synthesized, [Ho(btfa)3(H2O)2] (1a), [Ho(ntfa)3(MeOH)2] (1b), (1), [Ho(btfa)3(phen)] (2), [Ho(btfa)3(bipy)] (3), [Ho(btfa)3(di-tbubipy)] (4), [Ho(ntfa)3(Me2bipy)] (5), and [Ho(ntfa)3(bipy)] (6), where phen is 1,10-phenantroline, bipy is 2,2′-bipyridyl, di-tbubipy is 4,4′-di-tert-butyl-2,2′-bipyridyl, and Me2bipy is 4,4′-dimethyl-2,2′-bipyridyl. These compounds have been characterized by elemental microanalysis and infrared spectroscopy as well as single-crystal X-ray difraction for 2–6. The central Ho3+ ions in these compounds display coordination number 8. The luminescence-emission properties of the pyridyl adducts 2–6 display a strong characteristic band in the visible region at 661 nm and a series of bands in the NIR region (excitation wavelengths (λex) of 367 nm for 2–4 and 380 nm for 5 and 6). The magnetic properties of the complexes revealed magnetically uncoupled Ho3+ compounds with no field-induced, single-molecule magnet (SMMs).

Reductive desymmetrization of achiral or meso diketones has attracted considerable attention due to these motifs which play important roles in organic synthesis, pharmaceuticals and functional materials. This review focuses on recent advances in homogeneous reductive desymmetrization of 1,2‐, 1,3‐ and 1,4‐diketones, which provides an efficient and practical access to structurally diverse chiral α‐, β‐ or γ‐hydroxy ketone derivatives. [ABSTRACT FROM AUTHOR]

Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL3(H2O)2], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [EuxTb1-xL3(H2O)2] (EuxTb1-xL3), [EuxGd1-xL3(H2O)2] (EuxGd1-xL3), and [GdxTb1-xL3(H2O)2] (GdxTb1-xL3), were studied. The EuxTb1-xL3 complexes exhibit the simultaneous emission of both Eu3+ and Tb3+ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu3+. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb3+ and Eu3+ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation.

Isatin derivatives containing a 4-nitrophenyl group in the side chain or a nitro group in the aromatic fragment reacted with tris(diethylamino)phosphine to give the corresponding isoindigo derivatives with high yields and chemoselectivity. [ABSTRACT FROM AUTHOR]

Asymmetric hydrogenation and transfer hydrogenation of ketones are efficient and direct methods allowing access to enantiomerically enriched secondary alcohols, and have been widely studied and applied in both academia and industry. While the asymmetric (transfer) hydrogenation of ketones having one carbonyl group has been extensively investigated, the related study on ketones bearing multiple carbonyl groups such as diketones is still relatively underdeveloped. Due to the challenge of regioselectivity control raised by multiple reactive sites, and the difficulty of stereoselectivity control caused by several potential coordination groups, multiple carbonyl substrates are more difficult to be hydrogenated in a highly regio- and stereoselective manner. Nonetheless, significant progress has been achieved in the past several decades. This review summarizes the related investigations and illustrates the influences of catalysts, substrates, temperatures, solvents, and reaction times on the regio- and stereoselectivities of the reactions. The asymmetric hydrogenation and transfer hydrogenation of substrates with multiple carbonyl groups especially diketones are summarized. The factors influencing the regio- and stereoselectivities are discussed, which will be instructive for new reaction design to address the challenging research topic. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyridine-functionalised β -diketones are used as building blocks for obtaining novel metallomesogens or ionic liquid crystals. • Zinc(II), palladium(II) and platinum(II) complexes are synthesised. • The influence of the pyridine nitrogen position on the liquid crystal properties is analysed. • Smectic A or lamellar columnar mesophases are formed. • The photophysical behaviour of the compounds has also been studied in solution and in the solid state. Pyridine-functionalized β -diketones with the pyridine nitrogen atom at 3 or 4 position (L 3N and L 4N , respectively) have been used as building blocks to obtain two new families of compounds with mesomorphic and luminescent behaviors. The N -pyridine coordination of the β -diketones to zinc(II), palladium(II) and platinum(II) metal centers has allowed to synthesize neutral coordination compounds of the type [MCl 2 (L ZN) 2 ] (M = Zn(II), Pd(II), Pt(II); Z = 3, 4). Particularly, coordination of L 4N towards Pt(II) gives rise to the cationic species [Pt(NH 3) 2 (L 4N) 2 ]2+. Otherwise, protonation of the pyridine moiety was strategically used to obtain a novel series of pyridinium ionic salts of the type (HL ZN) n A (n = 1, A = Cl; n = 2, A = MCl 4 , M = Zn(II), Pd(II), Pt(II); Z = 3, 4). The neutral or ionic nature of the complexes, as well as the β -diketone ligands and the metal center in both the neutral and anionic complexes, has a great influence on the mesomorphic behavior. Thus, columnar or smectic mesophases can be selectively formed. Single-crystal and temperature-dependent powder X-ray diffraction studies have been performed to analyze the molecular packing in the crystal and the supramolecular ordering in the mesophase. All the aforementioned factors also play a key role on the luminescence properties, the Zn(II) coordination compounds and ionic salts being the best candidates as bifunctional materials. [ABSTRACT FROM AUTHOR]

Benzil and its derivatives naphthil and pyridil have been found to undergo a dianionic oxy-Cope rearrangement upon reaction with 2-lithio-4,5-dihydrofuran to give 3,3'-octahydrobifuranyls selectively as the meso diastereomers. The diastereoselectivity is explained based on the reaction mechanism and the conformation of the starting material. 4,4'-Di-tertbutylbenzil gave the respective intramolecular aldol adduct, whose relative configuration was determined by NOE experiments. [ABSTRACT FROM AUTHOR]

The one-pot, regioselective synthesis of branched diacid derivatives – diesters, dithioesters, diamides [YC(O)O(CH 2 ) m C(Me) 2 OC(O)Y] and diketones of aromatic and heteroaromatic series, [ArCO(CH 2 ) m C(Me) 2 C(O)Ar,) from available linear acyl halides, C n H 2 n+1 COCl (n = 7–9), CO (1 at) and various nucleophiles (YH = EtOH, CF 3 CH 2 OH, H(CF 2 ) 2 CH 2 OH, thiophene, anisole, Et 2 NH, aniline, and morpholine) in the presence of the superelectrophilic complex, CBr 4 ·2AlBr 3 has been performed for the first time. This method provides access to new and promising groups of dicarboxylic acid derivatives and diketones containing quaternary carbon atom and remote functional groups. [ABSTRACT FROM AUTHOR]

Robinson-type cyclopentannulations of cyclic ß-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of ß-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of a-propargylation followed by palladium-catalyzed alkyne hydration is used. [ABSTRACT FROM AUTHOR]

An asymmetric organocatalytic Michael addition-cyclization cascade reaction has been developed using cyclopentane-1,2-dione as a Michael donor and α,β-unsaturated aldehydes as Michael acceptors. Bicyclic hemiacetals were obtained in excellent yields and enantioselectivities. On the basis of the results, a one-pot reaction has been developed to obtain chiral 3-substituted cyclopentane-1,2-diones and substituted dihydropyrans in good yields and excellent enantioselectivity. [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]

The β-diketone scaffold is a key intermediate in the synthesis of COX-2 inhibitors, a type of non-steroidal anti-inflammatory agents of the coxib family, which have also been shown to have excellent anticancer potential at the preclinical stage of research. Moreover, it is also present in the family of natural products named curcuminoids. Both natural products and their synthetic analogues possess interesting antibacterial, neuroprotective and anticancer properties. Coordination compounds of curcuminoids with platinum-group metals as potential anticancer agents are a hot topic of current research, with most scientific articles on this topic having been published in the last five years. Structurally simpler diketones, such as acetylacetone derivatives, are also employed in the design of new metal-based agents. Most notably, the first metal-based, non-platinum anticancer compound to enter clinical trials was budotitane - cis-diethoxy(1-phenylbutane-1,3-dionato)titanium(IV). Recently, several studies of platinum-group coordination and organometallic compounds, their biological evaluation and mode-of-action studies have been published in high-impact journals in the field of inorganic and medicinal chemistry. [ABSTRACT FROM AUTHOR]

The cyclization reaction between N-sulfonyl-1,2,3-triazoles and 1,3-diketones was explored. This reaction provides a new and powerful method for the synthesis of highly functionalized pyrroles and fused pyrrole derivatives. Mechanistically, the reaction was found to proceed through tandem O-H or C-H insertion/condensation of in situ generated α-imino rhodium carbenoids with 1,3-diketones. The initial O-H or C-H insertion was determined to be dependent on the type of 1,3-diketone. [ABSTRACT FROM AUTHOR]

A series of renewable C9-C12 triketones with repeating [COCH2CH2] units were synthesized in high carbon yields (ca. 90 %) by the aqueous-phase hydrogenation of the aldol-condensation products of 5-hydroxylmethylfurfural (HMF) and ketones over an Au/TiO2 catalyst. Compared with the reported routes, this new route has many advantages such as being environmentally friendly, having fewer steps, using a cheaper and reusable catalyst, etc. The triketones as obtained can be used as feedstocks in the production of conducting or semi-conducting polymers. Through a solvent-free intramolecular aldol condensation over solid-base catalysts, the triketones were selectively converted to diketones, which can be used as intermediates in the synthesis of useful chemicals or polymers. As another application, the tri- and diketones can also be utilized as precursors for the synthesis of jet-fuel range branched cycloalkanes with low freezing points (224-248 K) and high densities (ca. 0.81 g mL−1). [ABSTRACT FROM AUTHOR]

The selective addition of carbamoylsilane to vicinal dike-tones in toluene solvent at 110 °C affords β-keto-a-siloxyamide derivatives in good yields (54-99%). The steric hindrance is an important factor in the addition reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • AA promoted the degradation of AO7 under UV irradiation. • Under solar irradiation, AA inhibited the self-sensitized degradation of AO7. • AA-CH 2 -AA had a nonstoichiometric enhancement effect on the photodegradation of AO7. • AA-CH 2 -AA interacted with the generated 1O 2 from the self-sensitization of AO7. • Electron-donating α -substituents make the AA derivatives less sensitive to energy transfer. Self-sensitized degradation is a typical fate of azo dyes in aquatic systems but its kinetics is far too slow to meet the requirement for a thorough decolorization. Small diketones were found being able to enhance the degradation of dyes under UV irradiation and the introduction of an electron-denoting group at the α -position of the simplest β -diketone (acetylacetone, AA) had a further enhancement effect on the degradation. However, it is unclear whether such enhancement effects exist in the solar-irradiated systems. To clarify this question, the effects of three AA derivatives were investigated with Acid Orange 7 (AO7) as a representative azo dye. Compared with the AA derivatives with a methyl or an ethyl group at the central carbon (AA-CH 3 and AA-CH 2 CH 3), 3,5-diacetylheptane-2,6-dione (AA-CH 2 -AA, which is a condensed combination of AA and AA-CH 3) showed a >2-fold stronger enhancement effect. The nonstoichiometric enhancement effect of AA-CH 2 -AA on AO7 photodegradation disclosed a novel pathway for dye degradation: AA-CH 2 -AA could enhance the degradation of AO7 by reacting with the photo-sensitized 1O 2 , whereas AA led to an inhibitory effect on the self-sensitized degradation of AO7 by quenching the excited state of the azo dye. These results demonstrate that small diketones could be designed to regulate the photodegradation of azo dyes in multiple pathways. [ABSTRACT FROM AUTHOR]

An unexplored ability of the long-known chemical transformation, Borsche's cyclopentenone synthesis (the construction of a 1,4-diketone with subsequent base-induced cyclization), is reported. Double alkylation of ethyl 4-(het)aryl-3-oxobutanoates with 2-bromo-1-(het)arylethanones, with subsequent alkali treatment, provides access to cyclopentenones substituted with a 2-oxoethyl group at the 5-position. These products might serve as valuable synthons for heterocyclization, and this feature was demonstrated by synthesis of 4 H -cyclopenta[ b ]thiophene derivatives. [ABSTRACT FROM AUTHOR]

An efficient and mild method for the synthesis of some novel 7-(1H-Benzimidazol-2-ylazo)-1,3-dimethyl-6,8-disubstituted-1,5-dihydropyrimi-do[4,5-b] [1,4] diazepine-2,4-diones in water has been developed. This method is a good option to obtain the title compounds in quantitative yields in a simple and inexpensive way. Further, -NH of the title compounds was replaced by various substituents in an ionic liquid, [bmim]PF6, a recyclable and environmentally benign solvent. Synthesized compounds were characterized by analytical and spectral (IR, 1H NMR, 13C NMR and Fmass) data and have been screened for their antianxiety activity in mice.

[Display omitted] • The visible-light photocatalytic method described here is based on the coupling- and oxidation reactions using easily accessible vinylarenes and arylhydrazines as starting materials. Additionally, when compared to previously reported visible-light photocatalytic methods, this protocol meets a significant number of the requirements of green chemistry because: i) the reaction used airborne O 2 as the oxidant and water as a solvent, ii) an organic dye is used as a catalyst in the reaction, and iii) free of inconvenience brought on by the availability and prior synthesis of precursors. Also, it is important to note that the cost of 100 mg of 97 % pure 1-(3,4-dimethylphenyl)-2-phenylethane-1,2-dione (3bk) and 1-(3-methyl-4-nitrophenyl)-2-phenylethane-1,2-dione (3ga) is approximately $250–300 USD from reputable manufacturers. This price also underscores the significance of the cost-effective and environmentally friendly protocol described here. The synthesis of a number of (un)symmetrical 1,2-diarylethane-1,2-diones from readily available vinylarenes and arylhydrazines in water under aerobic conditions has been established using rose bengal visible-light photocatalysis. The reactions proceeded through a free-radical mechanism, in which the aryl radical formed from arylhydrazine couples with vinylarene to produce desired 1,2-diarylethane-1,2-diones via subsequent aerial oxidations. When compared to reported visible-light photocatalytic methods, the primary benefit of this protocol for the synthesis of (un)symmetrical 1,2-diarylethane-1,2-diones is free of incommodious caused by the availability and prior synthesis of precursors. Moreover, this procedure offers a number of important advantages that include eco-friendly, cost-effective, amenability to gram-scale synthesis and devoid of hazardous organic solvents and transition-metal catalysts. [ABSTRACT FROM AUTHOR]

Site-selectivity, differentiating members of the same functional group type on one substrate, is an emerging tactic for shortened advanced building block and biomolecule synthesis. Despite its potential, site-selectivity remains less studied and especially so for ketone-based substrates. During this work ketone site-selectivity has been coupled with the chiral amine-catalyzed aldol desymmetrization of 4-keto-substituted cyclohexanones, allowing three stereogenic centers to form in the aldol product while leaving the acyclic ketone unreacted. Unique here, compared to all previous 4-substituted cyclohexanone desymmetrizations, is the first access to synthetically useful quantities of an epimeric (remote stereogenic center) aldol product. To demonstrate the value of these aldol products, we show their elaboration into eight keto-acetonide and one keto-lactone products. All compounds were isolated as single diastereomers and in high ee (≥96%). These efforts represent the first full characterization of aldol products with type III, Figure 2, relative stereochemistry, regardless of the enantiomer formed. [ABSTRACT FROM AUTHOR]

Cuticular waxes are complex mixtures consisting mostly of very-long-chain aliphatics with single, primary functional groups. However, the waxes of many plant species also include aliphatics with one or more functional groups residing on subterminal or mid-chain carbons. In the present work, the cuticular wax mixtures from flag leaf blades and peduncles of Triticum aestivum cv. Bethlehem were analyzed in a search for novel wax constituents with in-chain functionalities, potentially of polyketide origin. The structures of compounds belonging to six different compound classes were elucidated using gas chromatography-mass spectrometry of various derivatives. Among them, a series of 2,4-ketols was identified, with odd carbon numbers ranging from C to C and peaking at C. The analogous C 2,4-diketone was identified as well, together with a pair of co-eluting C mid-chain β-ketol isomers (16-hydroxyhentriacontan-14-one and 14-hydroxyhentriacontan-16-one), a pair of co-eluting C mid-chain α-ketol isomers (15-hydroxytriacontan-14-one and 14-hydroxytriacontan-15-one), the corresponding C 14,15-diketone, and a pair of co-eluting C ketones (hentriacontan-14-one and hentriacontan-16-one). All newly discovered structures contain ketone functional groups, with similar CH and CH alkyl chains on either side of the functionalities, thus resembling the previously reported very-long-chain β-diketones dominating the wheat wax mixtures. Based on these structural characteristics, possible biosynthetic pathways leading to the newly identified polyketide-like compounds are proposed. [ABSTRACT FROM AUTHOR]

Site selectivity, differentiating instances of the same functional group type on one substrate, represents a forward-looking theme within chemistry: reduced dependence on protection/deprotection protocols for increased overall yield and step-efficiency. Despite these potential benefits and the expanded tactical advantages afforded to synthetic design, site selectivity remains elusive and especially so for ketone-based substrates. Herein, site-selective intermolecular mono-aldolization has been demonstrated for an array of prochiral 4-keto-substituted cyclohexanones with concomitant regio-, diastereo-, and enantiocontrol. Importantly, the aldol products allow rapid access to molecularly complex ketolactones or keto-1,3-diols, respectively containing three and four stereogenic centers. The reaction conditions are of immediate practical value and general enough to be applicable to other reaction types. These findings are applied in the first enantioselective, formal, synthesis of a leading Alzheimer's research drug, a γ-secretase modulator (GSM), in the highest known yield. [ABSTRACT FROM AUTHOR]

Nano-SiO efficiently catalyzed the synthesis of β-enaminones using direct condensation of various (cyclic and acyclic) β-diketones with aromatic and aliphatic amines under solvent-free conditions. This eco-friendly catalyst can be recovered and reused without significant loss of activity. This methodology provides a simple synthetic route to enaminones in excellent yields at room temperature. Graphical abstract: [ABSTRACT FROM AUTHOR]

A regioselective synthesis of carbazole analogs belonging to both the categories of natural origin, viz., microorganisms and higher plant source is reported. The synthesis of carbazole derivatives possessing a methylester group at C-1 position has been achieved by Cadogan cyclization of nitro bi-phenyl derivatives, whereas, the carbazole analog possessing a methylester group at C-3 position was synthesized by Buchwald–Hartwig Pd-catalyzed cyclization of amino bi-phenyl derivatives. Suitably substituted bi-phenyl precursors were accessed from norbornyl α-diketones via Grob fragmentation, O-methylation and DBU aromatization reaction sequence. The reported carbazole derivatives possess structural features that are common with many carbazole natural products: mukonine, clausine-L, murrayafoline-A, and their sibling natural products. [ABSTRACT FROM AUTHOR]

We report on a facile synthetic route for the preparation of substituted 1,4-diketones by thulium triflate mediated hydration of substituted 4-alkynones in MeNO2 at 25 °C for five hours. The products were obtained in moderate to high yields. [ABSTRACT FROM AUTHOR]

The present work deals with selective transformations of peroxides into organic compounds via the cleavage of the O–O bond using variable valence metals. A selective transformation of tricyclic peroxides promoted by Fe 2+ salts was discovered. This selective transformation is unexpected for compounds with structural features which allow diverse decomposition pathways. 2-Hydroxy-1,5-diketones are prepared in yields up to 92% in the reactions of tricyclic peroxides with FeSO 4 , Fe(ClO 4 ) 2 , or FeCl 2 . This is a new preparative method for the synthesis of 1,5-diketones. 2-Hydroxy-1,5-diketones in CDCl 3 at 25 °C exist mainly in the open-chain form of the hydroxyketone over the cyclic hemiacetal. The results of this work can be of interest to understand the mechanism of the antiparasitic action of peroxides. [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]