Nanocatalytic one-pot, four-component synthesis of some new triheterocyclic compounds consisting of pyrazole, pyran, and pyrimidinone rings

Abstract

A new series of triheterocyclic compounds containing pyrazole, pyran, and pyrimidinone rings was synthesized via a one-pot condensation of ethylacetoacetate, hydrazine hydrate, barbituric acid, and aromatic aldehydes in the presence of catalytic amounts of titanium dioxide nanowires. Various functional groups were well tolerated under the optimized reaction conditions. Synthesis of 5 using TiO 2 nanowiresEthylacetoacetate (0.13 mL, 1 mmol) and TiO 2 NWs (10 mol%) were added to a solution of hydrazine hydrate (96%, 0.05 mL, 1 mmol) in H 2 O/EtOH (5 mL, 50/50) over 20 min. Then, Scheme 2 Suggested mechanism for the synthesis of triheterocyclic compounds 5 using TiO 2 NWs as the catalyst.

β‐Alanine‐functionalized magnetic graphene oxide quantum dots: an efficient and recyclable heterogeneous basic catalyst for the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione and 2,3‐dihydroquinazolin‐4(1H)‐one derivatives

“…As depicted in Scheme 2, GO was first prepared by the modified Hummers method as previously reported. [ 62,63 ] In the next step, GOQDs were synthesized by a simple process using freshly synthesized GO. GO was treated with DMF and heated at 250 °C for 6 hr.…”

“…This result combined with the TEM analysis clearly confirmed the successful synthesis of GOQDs. [ 62 ] The peak at 1161 cm −1 in Figures 1c and 2d can be attributed to the stretching vibration of the amino C–N bond formed by amidation or amination of the GOQDs sheets with the β‐alanine group. In addition, the characteristic stretching vibrations shown at 3235 and 3236 cm −1 in the spectra of the β‐alanine‐functionalized GO (Figure 1c) and the Fe 3 O 4 @GOQDs‐ N ‐(β‐alanine) (Figure 1d), respectively, correspond to the N–H bond stretching vibration.…”

Multiwalled carbon nanotubes/guanidine/Ni (II): A new and effective organometallic catalyst for the green synthesis of pyrazolopyranopyrimidines

“…[12][13][14] In this point of view, one of the best methods for the synthesis of pyrazolopyranopyrimidines is four-component condensation of ethyl acetoacetate, hydrazine hydrate, barbituric acid, and arylaldehyde. A few numbers of catalysts have been released for the synthesis of these compounds such as Fe 3 O 4 /cellulose, [15] TiO 2 nanowires, [16] meglumine, [17] DABCO, [18] HPA-FHNTs, [19] multiwalled carbon nanotubes (MWCNTs)/COOH, [20] ChCl:urea, [21] and MNPs@DABCO + Cl − . [22] Recently, the design of new pathways for the synthesis of these kinds of heterocycles has been considered because the efficiency of some reported procedures comes down with low yield of products, long reaction times, low rates, harsh reaction conditions, and tedious workup procedures.…”

Sulfonic acid‐functionalized Fe3O4‐supported magnetized graphene oxide quantum dots: A novel organic‐inorganic nanocomposite as an efficient and recyclable nanocatalyst for the synthesis of dihydropyrano[2,3‐c]pyrazole and 4H‐chromene derivatives

“…Also, MNPs have attracted much research interests as highly active supports for preparation of various supported nanocatalysts which can be easily separated from the mixture reaction simply by using an external magnetic field. [ 5 ] Among the heterogeneous catalysts, several nanoparticles (NPs) have received great interest due to their high catalytic activity and interesting physical and chemical properties such as nontoxicity, reusability, long‐term stability and high surface area. [ 6 ] Despite these advantages, such small particles suffer from tedious recycling and separation from the reaction mixtures by filtration or expensive ultracentrifugation that has limited their application.…”