Nanoporous TiO2 modified with an ionic liquid was used for efficient coupling of amines, 1,2-phenylene diamines, 2-aminophenol and 2-aminothiophenol with orthoesters.

Butane-1-sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2-Sultone) was easily prepared via direct ring opening of 1,4-butanesultone with nanomagnetic Fe3O4@SiO2. The prepared reagent was characterized and used for the efficient promotion of the synthesis of barbituric acid and pyrano[2,3-d] pyrimidine derivatives. All reactions were performed under mild and completely heterogeneous reaction conditions affording products in good to high yields. The catalyst is easily isolated from the reaction mixture by magnetic decantation and can be reused at least eight times without significant loss in activity.

In this study, structurally functionalized 1,2,4-triazolo[4,3-a]pyrimidines and pyrido[2,3-d]pyrimidines were synthesized by two non-metal DABCO-based ionic liquids which were compared in catalytic activity in both reactions.

A mild, simple and efficient procedure for the preparation of barbituric acid and pyrano[2,3-d]pyrimidine derivatives in aqueous media is described using 4-(4-propylpiperazine-1-yl)butane-1-sulfonic acid-modified silica-coated magnetic nanoparticles as a novel and reusable catalyst. The catalyst was easily isolated from the reaction mixture by magnetic decantation using an external magnet and reused at least eight times without significant degradation in activity.

In this work, a new nitrogen and sulfur based di-cationic ionic liquid (IL), named 1,4-piperazinium hydrogen sulfate ([H-pi]HSO4), was simply synthesized from the reaction of piperazine with sulfuric acid, and then characterized with a variety of techniques, including Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopies, Thermo-gravimetric analysis (TGA), Scanning Electron Microscope (SEM), and pH analysis. This new ionic liquid was employed as an efficient catalyst for the synthesis of 2,2 '-arylmethylene-bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) and 1,8-dioxooctahydroxanthene derivatives in C2H5OH:H2O media and under solvent-free conditions, respectively. Also, this adequate catalyst was employed for the synthesis of imidazo[1,2-a]pyrimidines and triazolo[4,3-a]pyrimidines via three-component reaction of aldehydes, malononitrile and 2-aminobenzimidazole and/or 3-amino[1,2,4]triazole. The new functionally-structured products, synthesized through these methods, were characterized with IR, H-1 NMR, C-13 NMR and mass spectroscopy. Moreover, the procedures gave the products in good yields and short reaction times as well as reusability of the catalyst.

Succinimidinium hydrogen sulfate, a newly reported Brønsted acidic ionic liquid, is used as an efficient, homogeneous catalyst for synthesis of prospective API (active pharmaceutical ingredients) – 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives. Mild reaction conditions, short reaction times, high yields, and easy work-up of the products and catalyst are some of advantages of this protocol.

TiO2, nanoscale TiO2 and modified nanoscale TiO2 are three forms of metal oxides which have been used for the acceleration of some of the most important types of organic reactions including protection, oxidation and multi-component reactions. All reactions have been carried out under mild and heterogeneous conditions and the products are obtained in high yields in relatively short reaction times. Also, in many cases these catalysts can be recycled and reused for several times without significant decrease in their activity.

A novel hydroxyapatite-encapsulated-alpha-Fe2O3-based Cu(II) organic-inorganic hybrid (interphase) catalyst was prepared. The prepared nanocatalyst provided an efficient, useful and green method for the oxidative amidation of aromatic aldehydes with ammonium hydrochloride and aniline hydrochloride, in short reaction times and good yields. The magnetic nature of the catalyst led to its easy recovery by an external magnetic field and convenient reuse.

Indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidin-4,6-(5H,11H)dione derivatives were synthesized regioselectively in high yields by a three-component reaction of 1,3-indanedione, aromatic aldehydes and 2,6-diaminopyrimidin-4(3H)-one in the presence of 1,2-dimethyl-N-butanesulfonic acid imidazolium hydrogen sulfate ([DMBSI]HSO4) ionic liquid as green and reusable catalyst. This protocol produced the desired products in high yields (87–95%) and short reaction times (3–6 min).

A mild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields.

Different types of nanoparticles are efficiently able to catalyze the synthesis of some of the important organic compounds via multi-component reactions. All reactions are performed under mild conditions and the products are obtained in high yields in short reaction times. On the other hand, these catalysts are recyclable and can be reused in successive trials without significant decrease in their activity.

An efficient synthesis of novel bis(1-(cyclohexylamino)-1-oxoalkyl or aryl) fumarates (4a–k), considering as organic building blocks for natural products and drugs, via the reaction of fumaric acid, various aldehydes and cyclohexyl isocyanide in water using one-pot three-component approach under mild condition and without catalyst is described. This rapid method produced the products in short reaction times (10–15 min) and excellent yields (85–95 %) at room temperature. The structures of the products were deduced from their elemental analyses and spectroscopic data.

Cu(NO3)(2) center dot 3 H2O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO2 and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.

Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields.

ChemInformVolume 41, Issue 46 Heterocyclic Compounds ChemInform Abstract: Vanadium Hydrogen Sulfate Catalyzed Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Bis-(indolyl)methanes. F. Shirini, F. Shirini Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorA. Yahyazadeh, A. Yahyazadeh Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorM. Abedini, M. Abedini Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorD. Imani Langroodi, D. Imani Langroodi Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this author F. Shirini, F. Shirini Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorA. Yahyazadeh, A. Yahyazadeh Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorM. Abedini, M. Abedini Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this authorD. Imani Langroodi, D. Imani Langroodi Dep. Chem., Fac. Sci., Guilan Univ., Rasht, IranSearch for more papers by this author First published: 25 October 2010 https://doi.org/10.1002/chin.201046156Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume41, Issue46November 16, 2010 RelatedInformation

The choice of a method which is used for the functional group transformations depends on its simplicity, high yields of the desired products, short reaction times, low cost of the process and ease of the work-up procedure.Between the several methods available for the protection of aldehydes, acylal formation is often preferred due to the ease of preparation and the stability of the produced 1,1-diacetate towards basic and neutral conditions.