New inorganic-organic hybrid materials based on polyoxovanadates: [Morp]6[VO4cV14O32(OH)6]‚2H2O, [HMTA-H][HMTA-CH2OH]2[H5V10O28]‚6H2O (original) (raw)
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Catalysis Today, 2012
In this paper we report on the first mesoporous catalyst based on SBA-15 incorporating simultaneously basic and acid functions able to promote the Friedländer reaction between 2-aminoaryl ketones and ethyl acetoacetate leading to quinolines 1 with high yields. From 2-aminobenzophenone (3a) it is possible to prepare quinoline 1a with the highest selectivity (86%) as compared with other mesoporous acidic catalysts. In contrast, the reaction catalyzed by amine-grafted SBA-15 yielded selectively (98%) the corresponding quinolone 2a in accordance with our previous results. Experimental results have been justified by theoretical calculations as function of the stability of reaction intermediate species, which could be involved in the process.
ChemCatChem, 2009
The quinoline ring [1] is present in a number of natural [2] and synthetic products often exhibiting interesting pharmacological activities or physical properties. [3, 4] Different synthetic approaches for the preparation of quinolines have been reported; the Friedländer reaction (FR) being one of the simplest and most efficient methods. [5] FR is a base-or acid-catalyzed condensation of an aromatic 2-amino-substituted carbonyl compound (aldehyde or ketone) with a carbonyl derivative containing a reactive a-methylene group followed by cyclodehydration (Scheme 1). Generally, the annulation takes place by heating aqueous or ethanolic solutions of the reactants at reflux in the presence of bases or acids, or by heating at temperatures of 150-220 8C in the absence of any catalyst. [6] Numerous studies have been undertaken with the aim of developing new catalysts operating under milder conditions. [5] Concerning green chemistry, replacement of homogeneous catalysts with heterogeneous catalysts for the production of fine chemicals in industrial processes, remains a very active research area. FRs have been catalyzed by several heterogeneous catalysts, such as Al 2 O 3 , [7] H 2 SO 4 /SiO 2 , [8] NaHSO 4 /SiO 2 , [9] HClO 4 / SiO 2 , [10] silica gel-supported phosphomolybdic acid, [11] KAIA C H T U N G T R E N N U N G (SO 4) 2 •12 H 2 O/SiO 2 [12] and sulfonated cellulose. [13] Although the acid or base-promoted FR has been extensively studied with o-aminoaryl aldehydes, [5] the base-catalyzed reactions starting from the corresponding o-aminoaryl ketones [b] D.
Current Catalysis, 2015
A new, efficient and green methodology for obtaining quinolines based on the use of tungstophosphoric acid included in a polymeric matrix of polyacrylamide is proposed (APTPOL60). The methodology involves the formation of polysubstituted quinoline compounds using a variety of 2-aminoaryl ketones and -dicarbonyl compounds, in absolute ethanol as reaction solvent, and a temperature of 78 ºC. The catalyst efficiency is not compromised after its successive use in reactions, and no leaching was observed. Seven examples of quinolone derivatives were obtained with excellent yields (89%-99%). This is the first report about the use of a heteropolyacid included in a polymeric matrix as recyclable catalyst in the Friedländer synthesis of quinoline derivatives (molecules with biological activity potential).
South African journal of chemistry, 2011
Different Keggin type heteropoly acids (HPAs) and supported ones on solids with different nature and textural properties were used in the Friedländer reaction in order to obtain quinoline derivatives. This conversion has been preceded by tungstophosphoric acid supported on silica, KSF and activated carbon as optimized catalysts in high yields and short reaction times. The general applicability of this method is demonstrated by using various substrates including ketones, b-ketoesters and b-diketones. For most substrates the reaction worked well. These catalysts were found to be reusable and considerable catalytic activity could still be achieved after the fourth run.
Different Keggin type heteropoly acids (HPAs) and supported ones on solids with different nature and textural properties were used in the Friedländer reaction in order to obtain quinoline derivatives. This conversion has been preceded by tungstophosphoric acid supported on silica, KSF and activated carbon as optimized catalysts in high yields and short reaction times. The general applicability of this method is demonstrated by using various substrates including ketones, b-ketoesters and b-diketones. For most substrates the reaction worked well. These catalysts were found to be reusable and considerable catalytic activity could still be achieved after the fourth run.
Journal of combinatorial chemistry 12, 100–10 (2010)
An efficient and practical method has been manifested for the diversity-oriented synthesis of quinolines via Friedländer annulation reaction for the generation of a wide range of structurally interesting and pharmacologically significant compounds by using ceric ammonium nitrate as a catalyst (10 mol %) at ambient temperature in 45 min. A variety of functional groups are introduced at various positions of the quinoline moiety, and further the diversity of the core skeleton was expanded at R 1 and R 2 positions by the synthesis of various hybrids. Initial screening of the compounds for cytotoxicity against a series of cancer cell lines showed promising results. Figure 1. Some biologically active quinolines.
The scope and limitations of metal salt Lewis acid catalysts were examined for the selectivity control for the formation of Friedländer and non-Friedländer product during the reaction involving 2-aminobenzophenone and ethyl acetoacetate. From a pool of metal halides, tetrafluoroborates, perchlorates, and triflates used as catalyst, In(OTf)3 emerged as the most effective catalyst for selective/exclusive formation of the Friedländer product. The generality of the In(OTf)3-catalysed Friedländer reaction was demonstrated by the reaction of differently substituted 2-aminoarylketones with various carbonyl compounds containing active methylene group (e.g., β- ketoesters, cyclic/acyclic β-diketones, cyclic/acylic ketones, and aryl/heteroaryl methyl ketones) under solvent-free conditions affording the desired quinolines in 75-92% yields.
An efficient and practical method has been manifested for the diversity-oriented synthesis of quinolines via Friedländer annulation reaction for the generation of a wide range of structurally interesting and pharmacologically significant compounds by using ceric ammonium nitrate as a catalyst (10 mol %) at ambient temperature in 45 min. A variety of functional groups are introduced at various positions of the quinoline moiety, and further the diversity of the core skeleton was expanded at R 1 and R 2 positions by the synthesis of various hybrids. Initial screening of the compounds for cytotoxicity against a series of cancer cell lines showed promising results. Figure 1. Some biologically active quinolines.