ZnO-beta zeolite: as an effective and reusable heterogeneous catalyst for the one-pot synthesis of polyhydroquinolines

Abstract

ZnO-beta zeolite, an inexpensive and mild catalyst, has been used for the synthesis of polyhydroquinolines in excellent yields from the one-pot four-component condensation of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in ethanol at room temperature. The remarkable advantages offered by this method are a green catalyst, mild reaction conditions, simple work-up procedures, much faster reactions, and excellent yield of products. Furthermore, the catalyst could be reused several times keeping its initial activity in recycled reactions.

Green biosynthesis and characterization of zinc oxide nanoparticles usingCorymbia citriodoraleaf extract and their photocatalytic activity

“…Zinc oxide (ZnO) is a well-known n-type semiconductor with a band gap of 3.37 eV and excitation binding energy of 60 meV, hence is considered as one of the best photocatalysts to degradation of pollutant in water (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). In order to enhance the photocatalytic property of ZnO, nano-sized ZnO have been synthesized to increase the surface area and enhance the photocatalytic activity.…”

Microwave Assisted One‐Pot Multicomponent Synthesis Using ZnO‐β Zeolite Nanoparticle: An Easy Access to 7‐Benzodioxolo[4,5‐b]xanthene‐dione and 4‐Oxo‐tetrahydroindole Scaffolds

“…The Brønsted acid sites of the β‐zeolite have been tuned by altering the metal cations for preparing the modified catalysts with acidity suitable for diverse trans‐esterification reactions . Interestingly, β‐zeolite modified with zinc oxide (ZnO) is an efficient catalyst for a variety of bioactive moieties like 5‐arylidene‐2,4‐thiazolidinedione, quinoxaline derivatives, benzothiazole, tetrahydrobenzo[b]pyrans, and polyhydroquinoline …”

Multicomponent synthesis of novel hybrid PHQ-fatty acids

“…[12][13][14] The method for synthesis of PHQs involves a multicomponent Hantzsch reaction of an aldehyde with cyclic 1,3-diketone, ethyl acetoacetate, and ammonia acetate in an acid catalyst. 4,15 Alternatively, the Hantzsch reaction for the synthesis of polyhydroquinolines was recently studied using crosslinked poly (AMPS-co-AA), 16 magnetic Fe 3 O 4 nanoparticles, 17 Brönsted ionic liquid, 18 [TBA] 2 [W 6 O 19 ], 19 visible light irradiation in ethyl-L-lactate-water, 20 microwave irradiation, 21 organocatalysts, 22 ZnO-beta zeolite, 23 p-TSA 24 and vanadium dodecylamino phosphate. 25 However, these methods suffer from drawbacks, such as the use of complex metal catalysts, the use of expensive reagents, difficult workup, corrosion problems, effluent pollution and nonrecoverable catalysts.…”