Covalently anchored sulfonic acid on silica gel （SiO2-R-SO3H） as an efficient and reusable heterogeneous catalyst for the one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions

A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported.All types of aldehydes,including aromatic,unsaturated,and heterocyclic,are used.The silica gel/sulfonic acid catalyst (SiO2-R-SO3H) is completely heterogeneous and can be recycled.     

Zinc oxide nanoparticles:A highly efficient and readily recyclable catalyst for the synthesis of xanthenes

A novel and efficient route for the synthesis of 1,8-dioxooctahydroxanthenes and 14-aryl-14H-dibenzo[a,j]xanthenes is described through one-pot multi-component reaction of dimedone and 2-naphthol with various aryl aldehydes using ZnO nanoparticles under solvent-free conditions.This method provides a novel and improved pathway for the synthesis of xanthenes in the terms of excellent yields,short reaction times,reusability and low catalyst loading.     

绿色可磁性分离二氧化硅包裹镍铁尖晶石负载硫酸氢铁纳米粒子催化剂用于合成1,8-二氧十氢吖啶合成Amir Khojastehnezhad,Mohammad Rahimizadeh,简

A new magnetically separable catalyst consisting of ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles was prepared. The synthesized catalyst was characterized using vibrating sample magnetometry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. This new magnetic catalyst was shown to be an efficient heterogeneous catalyst for the synthesis of 1,8-dioxodecahydroacridines under solvent-free conditions. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.     

绿色可磁性分离二氧化硅包裹镍铁尖晶石负载硫酸氢铁纳米粒子催化剂用于合成1,8-二氧十氢吖啶合成(英文)

A new magnetically separable catalyst consisting of ferric hydrogen sulfate supported on silica-coated nickel ferrite nanoparticles was prepared.The synthesized catalyst was characterized using vibrating sample magnetometry,X-ray diffraction,transmission electron microscopy,scanning electron microscopy,and Fourier transform infrared spectroscopy.This new magnetic catalyst was shown to be an efficient heterogeneous catalyst for the synthesis of 1,8- dioxodecahydroacridines under solvent-free conditions.The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.     

Clean synthesis of 1,8-dioxooctahydroxanthenes promoted by DABCO-bromine in aqueous media

<正>An efficient procedure is reported for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5,5-dimethyl-1,3-cyclohexandione in the presence of DABCO-bromine(TDB) as an acid catalyst.To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction.This method provides several advantages such as use of water as solvent,easy and clean synthesis,simple work up and versatility.     

Amberlite IRA900N3 as a new catalyst for the azidation of alpha,beta-unsaturated ketones under solvent-free conditions

Amberlite IRA900N3 is an excellent organocatalyst for the azidation of alpha,beta-unsaturated ketones with trimethylsilyl azide under solvent-free conditions. By avoiding the use of metallic species and of the organic reaction medium, the procedure is a green tool for the preparation of beta-azido ketones under mild conditions with yields from good to excellent. The catalyst can be recovered and re-used with no loss of its efficiency.     

One-pot synthesis of xanthene derivatives under solvent-free conditions

One-pot synthesis of aryl-14H-dibenzo[a,j]xanthene and 1,8-dioxo-octahydroxanthene derivatives using montmorillonite K10 as reusable eco-friendly catalyst under solvent-free conditions is described.     

Ceric ammonium nitrate supported HY-zeolite：An efficient catalyst for the synthesis of 1, 8-dioxo-octahydroxanthenes

Ceric ammonium nitrate （CAN） supported HY-zeolite has been used as an efficient catalyst for the one- pot synthesis of 1,8-dioxo-octahydroxanthenes from the readily available 1,3-diketone and aromatic aldehydes under solvent-free conditions. The present methodology is cost-effective in addition to other advantages like high yields of products in shorter reaction time and simple workup procedure without the use of any injurious solvents.     

Fe3O4 nanoparticles: As an efficient,green and magnetically reusable catalyst for the one-pot synthesis of 1,8-dioxo-decahydroacridine derivatives under solvent-free conditions

An efficient and environmentally friendly method for the one-pot synthesis of 1,8-dioxo-decahydroacridines has been developed in the presence of Fe₃O₄ nanoparticles. The multicomponent reactions of aldehydes, dimedone and amines were carried out under solvent-free conditions to obtain some 1,8-dioxo-9-aryl-10-aryl-decahydroacridine derivatives. The present approach provides several advantages including high yields, short reaction times, little catalyst loading and facile catalyst separation.     

Activation of trimethylsilyl cyanide by potassium phthalimide for facile synthesis of TMS-protected cyanohydrins

Potassium phthalimide was found to be a highly effective and easily accessible organocatalyst for the cyanosilylation of various carbonyl compounds under extremely mild conditions. The corresponding cyanohydrin trimethylsilyl ethers were obtained in high to quantitative yields in solvent-free conditions at room temperature using 2.5 mol% catalyst loading.     

Aza-Michael addition of aliphatic or aromatic amines to α,β-unsaturated compounds catalyzed by a DBU-derived ionic liquid under solvent-free conditions

A task-specific ionic liquid, 1,8-diazabicyclo[5.4.0]-undec-7-en-8-ium acetate has been successfully used as a catalyst for aza-conjugate addition of aliphatic or aromatic amines to various electron deficient alkenes under solvent-free conditions and at room temperature. The catalyst can be reused for six times without noticeable loss of activity.     

Tris(hydroxymethyl)aminomethane as an efficient organobase catalyst for the synthesis of β-phosphonomalonates

Tris(hydroxymethyl)aminomethane (THAM) is a highly efficient and recyclable organobase catalyst for the nucleophilic phosphonylation of benzylidene malononitrile under solvent-free conditions. This new catalytic methodology is applicable without a solvent, eco-friendly, economically viable, avoids conventional isolation procedures, and has a facile work-up procedure and wide scope. THAM is an inexpensive, commercially available, non-toxic, and biodegradable novel organocatalyst. Furthermore, it can be reused in up to five cycles without loss in catalytic activity, and no chromatographic separation is needed to obtain the desired products.     

Microwave assisted convenient synthesis of quino[2,3-b][1,5]benzoxazepines

A convenient synthesis of quino[2,3-b][1,5]benzoxazepines from substituted 2-chloroquinoline-3-carbaldehyde and 2-hydroxy-aniline by using stable,non-toxic and inexpensive catalyst 1,8-diazabicyclo-undecan-7-ene (DBU)/silica gel is described.This method affords the quino[2,3-b][1,5]benzoxazepines under the influence of microwave irradiation (360 W) in solvent-free conditions within short reaction times (2-3 min),giving high yields of products (93-96%).     

Phospho sulfonic acid as efficient heterogeneous Brønsted acidic catalyst for one-pot synthesis of 14<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a,j</Emphasis>]xanthenes and 1,8-dioxo-octahydro-xanthenes

A simple, efficient procedure for the preparation of phospho sulfonic acid PO(OSO₃H)₃ as a Brønsted acidic and recoverable heterogeneous catalyst is described, used for the one-pot synthesis of aryl-14H-dibenzo[a,j]xanthenes and 1,8-dioxo-octahydro-xanthenes. A cost-effective, simple and convenient procedure for the synthesis of aryl-14H-dibenzo[a,j]xanthenes was developed via a one-pot condensation from substituted benzaldehydes and β-naphthol under solvent-free conditions. The one-pot condensation of substituted benzaldehydes and 5,5-dimethyl-1,3-cyclohexanedione (dimedone) under solvent-free conditions leads to 1,8-dioxo-octahydro-xanthenes. These protocols afford a number of advantages, such as: excellent yields, very short reaction times, easy procedure, simple methodology and ease of preparation and regeneration of the catalyst.     

Recoverable silica-gel supported binam-prolinamides as organocatalysts for the enantioselective solvent-free intra- and intermolecular aldol reaction

Silica-gel supported binam-derived prolinamides are efficient organocatalysts for the direct intramolecular and intermolecular aldol reaction under solvent-free conditions using conventional magnetic stirring. These organocatalysts in combination with benzoic acid showed similar results to those obtained under similar homogeneous reaction conditions using an organocatalyst of related structure. For the intermolecular process, the aldol products were obtained at room temperature and using only 2 equiv of the ketone with high yields, regio-, diastereo- and enantioselectivities. Under these reaction conditions, also the cross aldol reaction between aldehydes is possible. The recovered catalyst can be reused up to nine times providing similar results. More interestingly, these heterogeneous organocatalysts can be used in the intramolecular aldol reaction allowing the synthesis of the Wieland–Miescher and ketone analogues with up to 92% ee, with its reused being possible up to five times without detrimental on the obtained results.     

新型五氟苯铵三氟有机催化剂高效合成14-芳基(烷基)-14H-二苯并[a,j]呫吨类化合物和1,8-二氧代氧杂蒽衍生物(英文)

A simple and facile synthesis of 14-aryl and alkyl-14H-dibenzo[a,j]xanthenes and 1,8-dioxooctahydroxanthene derivatives has been successfully developed by treatment of β-naphthol or dimedone with aldehydes under mild conditions in the presence of a pentafluorophenyl ammonium triflate(PFPAT) organocatalyst.These catalytic condensation reactions represent green chemical processes and the PFPAT organocatalyst is air-stable,cost-effective,easy to handle,and easily removed from the reaction mixtures.     

Solvent-Free Condensation of Methyl Pyridinium and Quinolinium Salts with Aldehydes Catalyzed by DBU

Methylpyridinium and methylquinolinium salts were condensed under solvent-free conditions with aromatic aldehydes in the presence of 1,8-diazabicyclo[5.4.]undec-7-ene (DBU) as catalyst, by grinding at room temperature. The products are dyes or useful intermediates. The DBU can be easily recycled and reused.     

Nanorod vanadatesulfuric acid (VSA NRs)-catalyzed green synthesis of hexahydroacridine-1,8-diones in solvent-free conditions

Nanorod vanadatesulfuric acid (VSA NRs), as a novel, recyclable and eco-benign catalyst, was used for an efficient synthesis of hexahydroacridine-1,8-diones using 1,3-cyclohexanedione derivatives, aldehydes and ammonium acetate or aniline under solvent-free conditions. VSA was prepared by the reaction of high-purity chlorosulfonic acid and sodium metavanadate. The present method offers some advantages over conventional ones, such as simple procedure and work-up, short reaction times, high yields, stability and reusability of the catalyst and simple purification of the products. Also, some greenness aspects of this method were investigated and compared with data from previous reports.     

Neat synthesis of octahydroxanthene-1,8-diones,catalyzed by silicotungstic acid as an efficient reusable inorganic catalyst

In this article, the first use of silicotungstic acid (H₄SiW₁₂O₄₀) as a catalyst for the synthesis of octahydroxanthene-1,8-diones by the reaction of 5,5-dimethylcyclohexane-1,3-dione (dimedone) with various aldehydes under thermal solvent-free conditions is described. The obtained results showed that the catalyst has a high catalytic activity, and the desired products were obtained in high yields. Moreover, the catalyst was found to be reusable, and a considerable catalytic activity still could be achieved after the fifth run. Easy work-up and avoidance of using harmful organic solvents are the other advantages of this simple procedure.     

Tungstophosphoric acid nanoparticles supported on polyamic acid: A mild and recoverable heterogeneous catalyst for the selective synthesis of mono and bulky bis(1,8-dioxooctahydroxanthene)s under solvent-free conditions

A series of 1,8-dioxooctahydroxanthene derivatives and some crowded bis(1,8-dioxooctahdroxanthene) were selectively synthesized using tungstophosphoric acid nanoparticles supported on polyamic acid (TPA/PAA) as a new catalyst in solvent-free conditions. The high purity products were isolated and catalyst was easily separated in simple work-up and was recycled several times without loss of reactivity under the described reaction conditions. The reaction is characterized by short reaction time, high efficiency and environmentally friendly reaction conditions.