Efficient synthesis of benzophenone derivatives in Lewis acid ionic liquids

Benzophenone and its derivatives were prepared via Friedel–Crafts acylation reactions using ionic liquids (ILs) of BmimCl–FeCl₃, BmimCl–AlCl₃ and BmimCl–ZnCl₂ as dual catalyst–solvent. Among them, BmimCl–FeCl₃ showed much higher catalytic activity than that observed for the other two ILs, and in conventional organic solvents. In these reaction systems, good to excellent yields (up to 97%) of acylation products were obtained in a short reaction time. This method features high yield, a simple product isolation procedure, ILs reusability and reduced waste discharge, thus rendering this catalytic system both efficient and environmentally friendly.     

Structopendant unsaturated cellulose esters via acylation in homogeneous lithium chloride/N,N-dimethylacetamide solutions

Novel acylation reactions of cellulose were accomplished with a series of unsaturated carboxylic acids or their respective anhydrides including crotonic acid (CRA), methacrylic acid (MAA), vinyl acetic acid (VAA), fumaric acid monoethyl ester (FAME), and cinnamic acid (CINA) in lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solutions. The acylation reactions were conducted at room temperature using dicyclohexylcarbodiimide (DCC) as a condensation agent and 4-dialkyl-aminopyridine (4-[N,N-dimethylamino-] or 4-pyrrolidino-pyridine, DMAP or PP) as a catalyst. A reaction mechanism is proposed based on experimental evidence. The acylated cellulose derivatives obtained from CRA, MAA, or their anhydrides exhibit poor solubility in organic solvents. Side reactions, e.g., the Michael addition, likely occur at the high temperatures required for reaction of these acyl groups. However, acylation of cellulose with VAA, FAME, and CINA is facile with derivatives readily soluble in DMSO. The structures of these derivatized celluloses were characterized with FTIR and ¹H-NMR spectroscopy and degrees of substitution were calculated. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 293–305, 1997     

Palladium(II)‐Catalyzed Direct ortho‐C?H Acylation of Anilides by Oxidative Cross‐Coupling with Aldehydes using tert‐Butyl Hydroperoxide as Oxidant

An efficient palladium‐catalyzed C H acylation with aldehydes using tert‐butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2‐aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromatic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate‐limiting electrophilic C H cyclopalladation (k_H/k_D=3.6; ρ⁺=−0.74) to form an arylpalladium complex, followed by acyl radical functionalization.     

Effect of polymer architecture on the efficiency of acyl transfer reactions

A series of spacer-modified polystyrene-supported hydroxamic esters and hydroxamic dithiocarbonic anhydrides were prepared starting from divinyl benzene and ethyleneglycol dimethacrylate crosslinked polystyrene resins through multistage polymer-analogous reactions. Acyl transfer reactions using these polymer-supported hydroxamic acylating agents containing spacer arms of various lengths were carried out. The investigation revealed a sharp increase in reactivity as the length of the spacer arm was increased from zero methylene spacer to five methylene spacers. Investigations were also carried out to correlate the extent of acyl transfer with the nature and degree of crosslinking and the relative polarity of the polymer network. It was found that the extent of functionalization in each of the polymer analogous reactions and the extent of acylation reaction decreased with an increase in the degree of crosslinking. © 1996 John Wiley & Sons, Inc.     

对丙氧基苦杏仁酸的合成

本文以苯丙醚为原料，经酰化、溴化和水解反应合成了苯并二呋喃酮类染料分散红356的重要中间体一对丙氧基苦杏仁酸。探讨优化了酰化反应和溴化反应的反应条件，这三步反应的收率分别80．9％，78．0％和84．7％。     

杂多酸催化剂在有机合成中的应用

介绍了杂多酸催化剂在Friedel-Crafts酰基化和烷基化反应、Diels-Alder反应、酯化反应、环缩合反应、重排反应、溴化反应、氧化反应及不对称催化反应等有机合成反应中的应用。展望了该领域未来的研究方向。     

Novel Solid Acid Catalyst,Bentonite-Supported Polytrifluoromethanesulfosiloxane for Friedel–Crafts Acylation of Ferrocene

Solid acid catalyst, bentonite-supported polytrifluoromethanesulfosiloxane (B-PTFMSS) has been for the first time prepared and used in the Friedel–Crafts acylation of ferrocene with various acyl chlorides. The catalytic activities were influenced by reaction time, reaction temperature, solvent and loaded amount of B-PTFMSS. It was found that the new catalyst B-PTFMSS possessed the advantages of high activities giving similar yield of aliphatic acyl ferrocene (>70%) as conventional Lewis acid catalyst aluminum chloride and it can be used repeatedly and easily regenerated. B-PTFMSS has also been characterized by IR spectra, pyridine adsorbed IR, specific surface area and XRD.     

Synthesis Of di- and tri-substituted thiourea derivatives in water using choline chloride–urea catalyst

In this work, di- and tri-substituted thiourea derivatives have been synthesized via a one-pot, three-component reaction from carbon disulfide and aliphatic or aromatic amines using choline chloride-urea deep eutectic solvent as a catalyst in water. Both cyclic and acyclic thiourea derivatives with two or three substituents were synthesized successfully. The reactions were done at 25–100°C, using 5–20?mol% catalyst, in 3–5?h and the GC-Mass yields were between 60% and 95%. All products were characterized using FT-IR, ¹H-NMR, ¹³C-NMR, GC-MS and melting point analyses. The results showed that both water and the DES have important effects on the yield and the rate of this reaction and both of them are necessary to obtain higher yields in less time. The extra experiment, which was designed to study the mechanism of the reaction, showed that an isothiocyanate intermediate was formed in the reaction. Finally, the results showed that by the increase of the amine's nucleophilicity, the reaction occurs faster and gives higher yield.     

Hairy fluorescent nanoparticles from one‐pot click chemistry and atom transfer radical emulsion polymerization

Well‐defined hairy and crosslinked fluorescent nanoparticles with diameters in the range 70–220 nm were obtained from simultaneous copper‐catalyzed alkyne–azide cycloaddition (CuAAC) and atom transfer radical emulsion polymerization (ATREP) of a mixture of styrene, divinylbenzene, 4‐vinylbenzylazide and 7‐propinyloxycoumarin (Cr), using bromide‐terminated poly(ethylene glycol) (PEG) as macroinitiator, Tween‐20 as emulsifier, copper(I) bromide as catalyst and pentamethyldiethylenetriamine as ligand. The generation of biocompatible PEG brushes and the introduction of fluorescent functionalities as well as crosslinking of nanoparticles were realized in one step. In order to verify that functionalization and propagation of polymer chains could be realized in a controlled manner by one‐pot simultaneous ATREP and CuAAC, linear block copolymers of PEG and polystyrene (PS) with partially clicked pendent Cr groups (PEG‐b‐(PS‐c‐Cr)) were synthesized. All prepared PEG‐b‐(PS‐c‐Cr) copolymers had a controlled molecular weight and defined molecular structure. The hairy fluorescent nanoparticles exhibit a low cytotoxicity and could find applications in cell labeling. © 2013 Society of Chemical Industry     

Functionalized polysulfone membranes by heterogeneous lithiation

Polysulfone membranes were modified heterogeneously by lithiation, using n-butyllithium and low concentrations of tetrahydrofuran (THF). The effects of various conditions of reactant concentration, temperature, and time were determined quantitatively. The degree of substitution was measured by XPS and FTIR, using the carbonyl absorption band of lithium-activated membranes that had been converted to ones containing acyl fluoride substituents. The optimum conditions for membrane functionalization were 0.2M n-butyllithium in hexane at room temperature. The reaction rate increased substantially in the presence of 2% THF. The surface-lithiated membranes can be derivatized, potentially with a wide variety of functional groups. © 1993 John Wiley & Sons, Inc.     

Polymer reagents: preparation of polymer esters of thiocarboxylic acids based on crosslinked polystyrene

Summary The process of acylation of polymer thiols based on microporous poly (styrene-co-divinylbenzene) (crosslinking agent content 1–2%) with carboxylic acids was investigated depending of the degree of functionalization, on the crosslinking of the polymer carrier and on the structure of acids. In the presence of dicyclohexylcarbodiimide and 4-dimethylaminopyridine the acylation reactions can be conducted to high degrees of the transformation of SH groups already at room temperature. The extent of such refunctionalization reactions depends neither on the degree of functionalization of the starting polymer thiol nor on the structure of the acids. Reactions of polymer esters of thiocarboxylic acids with primary, secondary and tertiary alcohols activated with mercury (II) trifluoroacetate lead to low ester yields.     

Porous modified bentonite as efficient and selective catalyst in the synthesis of 1,5-benzodiazepines

The synthesis of 1,5 benzodiazepine using natural and modified Argentinean bentonite (pillared layered clay and porous clay heterostructure) as catalysts through a condensation reaction between o-phenylenediamine (o-PDA) and excess of acetone as reactive and solvent at room temperature is reported. The catalysts were found to be highly active and selective, affording a high yield of the corresponding benzodiazepine. The effects of the modification of the natural bentonite and reaction conditions, such as temperature, time and amount of catalyst were investigated. The catalysts were also successfully employed for the preparation of other derivatives of 1,5-benzodiazepine using substituted o-PDAs and ketones. In all cases, the reactions are highly selective and are completed within 1–3 h. The catalyst showed excellent activity in all cases, showing 86–90% isolated yields of the corresponding derivatives of 1,5-benzodiazepine. The easy work-up procedure and the recyclable catalyst make this methodology attractive for large-scale operations.     

Antimony(V) Chloride‐Benzyltriethylammonium Chloride Complex as an Efficient Catalyst for Friedel−Crafts Acylation Reactions

A novel catalytic system, the complex of antimony(V) chloride (SbCl₅) and benzyltriethylammonium chloride (TEBA), C₆H₅CH₂NEt₃(SbCl₅)₂Cl complex, is described for Friedel–Crafts acylation reactions of aromatics with acyl and sulfonyl chlorides. The catalyst has a number of useful characteristics, such as ready access, minimal toxicity, reusability, insensitivity to atmosphere and moisture, rapid acylation with high yield, and ease of operation.     

The Copper‐Catalyzed Oxidative N‐Acylation of Sulfoximines

An oxidative cross‐coupling reaction between aldehydes and sulfoximines involving dual C H/N H functionalization has been developed. This reaction process is facilitated by a simple copper catalyst (1 mol% loading) and tert‐butyl hydroperoxide (TBHP) as the oxidant and proceeds under mild reaction conditions to afford a series of valuable N‐acylated sulfoximine derivatives in excellent yields.     

Oxidation and Oxidative Bromination Reactions Catalyzed By a Reusable Polymer-Anchored Iron(III) Complex in Water at Room Temperature

A polymer-anchored iron(III) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the oxidation of various alkenes, sulfides, aromatic alcohols and ethylbenzene with 30 % H₂O₂ as the oxidizing agent. The catalyst was also effective for the oxidative bromination reaction with 80–100 % selectivity of monobrominated products with H₂O₂/KBr at room temperature. The above reactions require a minimum amount of H₂O₂ and short reaction time. Most importantly, all the above reactions occur in aqueous medium. The catalyst can be facilely recovered and reused six-atimes without significant decrease in its activity and selectivity.     

New Concepts in Solid Acid Catalysis: Some Opportunities Offered by Dispersed Copper Oxide

Copper oxide supported on silica by the Chemisorption–Hydrolysis technique shows a moderate Lewis acidic character due to coordinative unsaturation of the finely dispersed supported metallic phase. Comparison of this material with a conventional acidic catalyst, namely SiO₂–Al₂O₃, puts in light the advantages of this kind of acidic material in three different reactions. Thus, the use of CuO/SiO₂ boosts selectivity toward glucose formation in cellulose deconstruction reactions while β-alkoxyalcohol are formed with 100 % regioselectivity in epoxide ring opening ones. Moreover, preliminary tests on Friedel Crafts acylation of anisole with acetic anhydride show that only the catalyst containing finely dispersed CuO is able to promote this reaction due to both Lewis acidic properties and easy desorption of the acylating agent from the surface.     

Palladium‐Iminodiacetic Acid Immobilized on pH‐Responsive Polymeric Microspheres: Efficient Quasi‐Homogeneous Catalyst for Suzuki and Heck Reactions in Aqueous Solution

The pH‐responsive core‐shell microspheres of poly(styrene‐co‐methylacrylic acid) (PS‐co‐PMAA) containing a polystyrene (PS) core and a poly(methylacrylic acid) (PMAA) shell are synthesized by one‐stage soap‐free copolymerization and the catalyst system palladium‐iminodiacetic acid (IDA‐Pd) is immobilized on the outer shell‐layer of the core‐shell microspheres to form the quasi‐homogeneous and easily accessible catalyst PS‐co‐PMAA‐IDA‐Pd. This quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst is highly dispersed in the reaction medium just like a homogeneous one and can be separated like a heterogeneous catalyst by adjusting the pH of the reaction medium. Suzuki reactions employing the quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst are efficiently performed in water as the sole solvent under mild conditions such as room temperature. The PS‐co‐PMAA‐IDA‐Pd catalyst is also used in Heck reactions of a wide range of aryl halides with styrene and proves to be efficient in aqueous solution. The PS‐co‐PMAA‐IDA‐Pd catalyst has a low leaching loss and can be reused at least 4 times without loss of activity.     

Synergistic promoting effect of ball milling and KF–alumina support as a green tool for solvent-free synthesis of 2-arylidene-benzothiazinones

A solvent-free procedure is developed for the reaction of benzothiazinones with benzaldehyde derivatives, where the solid KF–Al₂O₃ support and ball milling synergistically leads to a green and efficient synthesis of several 2-arylidene-benzothiazinones. Therefore, a cooperative effect of the solid support and ball milling leads to excellent yields of the target dienes, while the catalyst can be recycled for subsequent reactions without significant loss of its activity.     

ATR-FTIR Study of the Decomposition of Acetic Anhydride on Fosfotungstic Wells–Dawson Heteropoly Acid Using Concentration-Modulation Excitation Spectroscopy

The decomposition of acetic anhydride in liquid phase on a fosfotungstic Wells–Dawson heteropoly acid (HPA) was investigated by in situ ATR-FTIR spectroscopy. Transient and concentration-modulation excitation spectroscopy (MES) experiments in combination with phase-sensitive detection (PSD) were used to monitor the solid–liquid interface. The MES method is based on the periodic variation of a parameter of the reaction media such as, the reactant concentration. That periodic alteration causes varying infrared signals of the surface adsorbed species that are subsequently demodulated with the PSD methodology. Thus, the separation of the static signals from the changing ones is achieved, and species with different response can be observed in the spectra. Using MES-PSD coupled with ATR-FTIR, acetic anhydride was observed to decompose to acetic acid, acetate and acyl [CH₃C(O)⁺] species, involving Brønsted acid sites of the HPA catalyst. The CH₃C(O)⁺ is a very unstable intermediate species and it is the key intermediate in the Friedel–Crafts acylation reactions. Moreover, the acetate groups are spectator species since remain strongly adsorbed on the catalyst surface and do not further react.     

Preparation and characterization of brominated polyethersulfones

A novel derivative of aromatic polyethersulfone (PES) was obtained by bromination. Victrex PES was reacted with bromine under various conditions: in solution, in suspension, and without solvent; with or without catalyst; and at low and elevated temperatures. Practically no bromination occurred in solution; in the other cases, brominated PESs to various extents were obtained. The degree of substitution (DS) varied between 0.3 and 2.3. It was found that no catalyst is required for this reaction; the temperature, the concentrations of bromine and of polymer in the reaction mixture, and the duration of the reaction are the determinant factors of the DS. The modified polymers were characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, and PGC‐MS, and their thermal properties were investigated by TGA and DSC methods. Further transformations of brominated PES as well as other new chemical reactions of PES will be the subject of later publications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1–13, 1999