[18F]CuCF3: A [18F]Trifluoromethylating Agent for Arylboronic Acids and Aryl Iodides

Positron emission tomography has emerged as the leading method for medical imaging with fluorine‐18 as the most widely used radioactive isotope. Here we report a semi‐automated method for the preparation of valuable [¹⁸F]trifluoromethylcopper, as well as its use for the radiosynthesis of [¹⁸F]trifluoromethylarenes and heteroarenes. Mild conditions of [¹⁸F]trifluoromethylation make this method particularly useful for the radiosynthesis of pharmacologically relevant [¹⁸F]trifluoromethylarenes and heteroarenes.     

One-pot enantioselective aziridination of olefins catalyzed by a copper(I) complex of a novel diimine ligand by using PhI(OAc)(2) and sulfonamide as nitrene precursors

A novel chiral C(2)-symmetric 1,4-diamine with multistereogenic centers at the backbone of the ligand has been synthesized from cheap natural product D-mannitol through multistep transformations. Its diimine derivative (3 a) was found to be highly effective for the enantioselective control of the copper-catalyzed asymmetric aziridination of olefin derivatives with PhI==NTs as the nitrene source, affording the corresponding N-sulfonylated azirindine derivatives in good to excellent yields with up to 99 % ee (ee=enantiomeric excess). The catalyst system discovered in the present work was also extended to a one-pot enantioselective aziridination by using sulfonamide/iodobenzene diacetate as the nitrene source. In this case, most reactions proceeded smoothly to give the corresponding products in moderate yields with good to excellent enantiomeric excesses (75-96 % ee).     

A Universal Procedure for the [18F]Trifluoromethylation of Aryl Iodides and Aryl Boronic Acids with Highly Improved Specific Activity

Herein, we describe a valuable method for the introduction of the [¹⁸F]CF₃ group into arenes with highly improved specific activity by the reaction of [¹⁸F]trifluoromethane with aryl iodides or aryl boronic acids. This [¹⁸F]trifluoromethylation reaction is the first to be described in which the [¹⁸F]CF₃ products are generated in actual trace amounts and can therefore effectively be used as PET tracers. The method shows broad scope with respect to possible aryl iodide and aryl boronic acid substrates, as well as good to excellent conversion. In particular, the [¹⁸F]trifluoromethylation of boronic acids was found to outperform [¹⁸F]trifluoromethylation reactions of halogenated aryl precursors with regard to conversion, reaction conditions, and kinetics.     

Copper(II) Acetylacetonate: An Efficient Catalyst for Huisgen‐Click Reaction for Synthesis of 1,2,3‐Triazoles in Water

An efficient and green copper(II ) acetylacetonate‐catalyzed protocol for the Huisgen‐click reaction in water at 100 °C has been established. The protocol was not only suitable for the reaction between organic azides and alkynes, but also suitable for one‐pot three‐component reaction among alkyl halides, NaN₃ and alkynes.     

A facile and mild Pd-catalyzed one-pot process for direct hydrodeoxygenation (HDO) phenols to arenes through a ArOSO2F intermediates transformation

A practical one-pot process for hydrodeoxygenation (HDO) of phenolic derivatives to their corresponding arenes was developed. This method provided a facile route to upgrading bio-oil. The substrate scope of this protocol was wide, complicated and multi-phenolic compounds were also smoothly hydrodeoxygenated to their corresponding arenes.     

A green approach for the synthesis of 2‐oxazolidinones using gold(I) complex immobilized on KCC‐1 as nanocatalyst at room temperature

A novel gold(I)‐containing ionic liquid‐based KCC‐1 catalyst was applied for the cyclization of propargylic amines with CO₂ to provide 2‐oxazolidinones. High catalytic activity and ease of recovery from the reaction mixture using an external magnet, and several recycle runs without significant loss in performance are additional eco‐friendly attributes of this catalytic system. Copyright © 2016 John Wiley & Sons, Ltd.     

Desymmetrization of meso diols using enantiopure zinc (II) dimers: Synthesis and chiroptical properties

The one‐pot metal templated synthesis of enantiopure binuclear Zn (II) complexes Zn₂L¹–Zn₂L⁴ were obtained by treating (1R,2R)‐diphenylethylenediamine or (1S,2S)‐diphenylethylenediamine with 2‐hydroxy‐5‐methyl‐1,3‐benzenedicarboxaldehyde or 4‐tert‐butyl‐2,6‐diformylphenol and zinc acetate. The chiroptical properties of the complexes were studied by using circular dichroism spectroscopy. These ΔΔ and ΛΛ complexes were used as enantioselective catalysts for desymmetrization of meso diol to achieve monobenzoylated product with 96% yield and 88% ee.     

A one-pot synthesis of (E)-disubstituted alkenes by a bimetallic [Rh-Pd]-catalyzed hydrosilylation/hiyama cross-coupling sequence

A bimetallic [Rh-Pd] catalyst was prepared by soaking into an iodide ionic gel an equimolar solution of [RhCl(PPh(3))(3)] and Pd(OAc)(2) in CH(2)Cl(2). Its catalytic activity was evaluated by rhodium-catalyzed hydrosilylation (H), palladium-catalyzed Hiyama coupling (C), and in the one-pot hydrosilylation/Hiyama coupling sequence (H/C). It was found that the homogeneous combination [RhCl(PPh(3))(3)]/NaI was a superior system compared to the polyionic mono- and bimetallic rhodium catalysts in the hydrosilylation of terminal alkynes. Interestingly, the most effective catalyst in terms of stereo- and chemoselectivities was observed to be the bimetallic ionic gel [Rh-Pd] in the one-pot process leading to (E)-alkenes with good yields. The remarkable stereocontrol is ascribed to a beneficial Pd-catalyzed isomerization from the mixture of stereoisomeric vinylsilanes obtained in the initial hydrosilylation step into the more stable (E)-adduct. The [Rh-Pd] heterogeneous catalyst also showed a higher chemoselectivity than the homogeneous catalytic combination, and no detrimental formation of Sonogashira side product was observed due to an ionic-gel-mediated kinetic modulation. To illustrate its scope and limitations, the described one-pot bimetallic catalytic sequence was extended to functionalized terminal alkynes and various iodide substrates. Conjugated systems, such as hydroxycinnamaldehyde, dienes, and trienes, were synthesized in good overall yields. To avoid deactivation of the Rh species, N-heterocyclic iodides had to be added sequentially after completion of hydrosilylation.     

A three‐component process for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives using nanosized nickel aluminate spinel crystals as highly efficient catalysts

NiAl₂O₄ spinel nanocrystals were synthesized as mesoporous catalysts and were fully characterized using Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction patterns (XRD), scanning electron microscopy (SEM), and Energy‐dispersive X‐ray spectroscopy (EDS). These nanocrystals catalyzed the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives via a one‐pot, three‐component condensation reaction of aromatic aldehydes, isatoic anhydride, and ammonium acetate or primary aromatic amine under microwave irradiation. By far, the most obvious advantages of the offered process are efficiency and recyclability of the catalyst as well as a significantly shorter reaction time.     

Application of Cu(Hdmg)2 as a simple and cost‐effective catalyst for the convenient one‐pot reductive acetylation of aromatic nitro compounds

In this article, we have developed a novel and simple one‐pot reductive acetylation of aromatic nitro compounds with sodium borohydride (NaBH₄) in ethyl acetate (EtOAc) under reflux conditions in the presence of the bis(dimethylglyoximato)copper(II) complex [Cu(Hdmg)₂] as an efficient and cost‐effective copper‐containing catalyst. Notably, using the above‐mentioned one‐pot reaction, the corresponding acetamide derivatives were obtained in high to excellent yields.     

Rapid on-plate and one-pot derivatization of carbonyl compounds for enhanced detection by reactive matrix LDI-TOF MS using the tailor-made reactive matrix, 4-dimethylamino-6-(4-methoxy-1-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH)

In this study, a very sensitive and economical high-throughput methodology has been developed for the analysis of small carbonyl compounds using rapid derivatization with 4-dimethylamino-6-(4-methoxy-1-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH), a derivatizing agent developed by the Karst group at the University of Münster. DMNTH is highly ionizable by the UV laser and reacts selectively and rapidly with carbonyl moieties. The resulting hydrazone is easily detectable by laser desorption ionization time of flight mass spectrometry (LDI-TOF MS), eliminating the need for the matrix assisted variant (MALDI) and the associated issue of matrix optimization, which greatly simplifies the analysis. It has been demonstrated that a range of carbonyl compounds can be conveniently analyzed by this reactive matrix LDI-TOF MS (RM-LDI-TOF MS) procedure and that furfural DMNThydrazone (prior labeled and labeled in situ) can be used as an internal standard for semiquantitative analysis. Amounts as low as 0.5 ng ml(-1) of 4-methoxybenzaldehyde have been detected using a one-pot derivatization methodology. Rapid on-plate derivatization was also found to be a simple approach for fast and reliable screening of various analytes, although with slightly higher detection limits. To test its applicability in complex matrices, analysis of furfural spiked in beer has been demonstrated. This RM-LDI-TOF MS method shows considerable promise for the analysis of carbonyl compounds in water, particularly for disinfection by-products that result from reaction of natural organic matter with oxidative disinfectants.     

Internally Reuse Waste: Catalytic Asymmetric One‐Pot Strecker Reaction of Fluoroalkyl Ketones,Anilines and TMSCN by Sequential Catalysis

We report a highly enantioselective one‐pot facile synthesis of fluorinated C^α‐tetrasubstituted amino nitriles from α‐fluoroalkyl α‐aryl ketones, anilines, and TMSCN through a sequential p‐TsOH catalyzed ketimine formation and chiral bifunctional tertiary amine mediated asymmetric Strecker reaction. This one‐pot approach has two important advantages. First, it greatly improves the overall yield of the synthesis of chiral C^α‐tetrasubstituted fluorinated aminonitriles from ketones, because the purification of α‐fluorinated ketimines by column chromatography suffers from great yield loss. Second, it represents the first example of asymmetric tandem reactions that can simultaneously reuse the by‐product and catalyst from the upstream step as a promoter and an additive to improve the reactivity and enantioselectivity of the subsequent catalytic enantioselective reaction, respectively. It could utilize the by‐product H₂O generated in‐situ from the ketimine formation step to activate TMSCN to form HCN, and concurrently reuse the remaining p‐TsOH acid as an additive to improve enantioselectivity.     

Hydrophobic Modification of Pd/SiO2@Single‐Site Mesoporous Silicas by Triethoxyfluorosilane: Enhanced Catalytic Activity and Selectivity for One‐Pot Oxidation

To enhance the catalytic activity in a selective one‐pot oxidation using in‐situ generated H₂O₂, a hydrophobically modified core–shell catalyst was synthesized by means of a simple silylation reaction using the fluorine‐containing silylation agent triethoxyfluorosilane (TEFS, SiF(OEt)₃). The catalyst consisted of a Pd‐supported silica nanosphere and a mesoporous silica shell containing isolated Ti^IV and F ions bonded with silicon (Si?F bond). Structural analyses using XRD and N₂ adsorption–desorption suggested that the mesoporous structure and large surface area of the mesoporous shells were retained even after the modification. During the one‐pot oxidation of sulfide, catalytic activity was enhanced significantly by increasing the amount of fluorine in the shell. A hydrophobic surface enhanced adsorption of the hydrophobic reactant into the mesopore, while the less hydrophobic oxygenated products efficiently diffused into the outside of the shell, which improved the catalytic activity and selectivity. In addition, the present methodology can be used to enhance the catalytic activity and selectivity in the one‐pot oxidation of cyclohexane by using an Fe‐based core–shell catalytic system.     

A convenient one‐pot method for the synthesis of symmetrical dialkyl trithiocarbonates using NH4OAc under mild neutral conditions

A facial, new, one‐pot method for the preparation of symmetrical organic trithiocarbonates from various alkyl halides and carbon disulfide is described. This is a convenient, clean, and mild procedure, which involves the use of the neutral, nontoxic, commercially available, and inexpensive reagent NH₄OAc in the preparation of the trithiocarbonate ion from carbon disulfide.     

A Robust,Eco‐Friendly Access to Secondary Thioamides through the Addition of Organolithium Reagents to Isothiocyanates in Cyclopentyl Methyl Ether (CPME)

The nucleophilic addition of widely available and variously functionalized organolithium reagents to isothiocyanates represents a straightforward, high‐yielding, one‐pot method to access secondary thioamides. The simple reaction conditions required and the broad scope (>50 cases examples) makes it a robust and reliable method to access both simple and complex thioamides, including enantiopure ones. Noxious and unpleasant‐smelling sulfurating agents, usually employed in the literature established methods, are avoided during the whole synthetic procedure thus, rendering the protocol highly attractive, also for sustainability aspects.