Green Synthesis of Bis(pyrazol‐5‐ole) and Pyrazolopyranopyrimidine Derivatives through Mechanochemistry Using Chitosan as a Biodegradable Catalyst

Abstract

Grinding assisted, simple and green route for the synthesis of bis(pyrazol-5-ole) and pyrazolopyranopyrimidine using chitosan as a biodegradable catalyst is developed. This protocol offers selective synthesis of bis(pyrazol-5-ole) and pyrazolopyranopyrimidine without any side product with excellent yield and shorter duration. Moreover, this method provides metal-free synthesis and put forward easy separation in gram scale synthesis which makes the protocol sustainable. The recyclability of the catalyst is also simple and carried upto eight consecutive runs. In addition, SEM images and powder XRD of fresh and recycled catalysts are also compared.

Guanidine Hydrochloride Catalyzed One‐Pot Multi‐Component Synthesis of Pyrazolopyranopyrimidine

“…Various methodologies have been reported for the synthesis of pyrazolopyranopyrimidine including the use of ultrasonication and a heterogeneous catalyst such as porphyrininitiated amine-functionalized PolyBCMO dendritic polymer as a sonocatalyst, [29] 1-deoxy-1-(methylamino)-D-glucitol, [30] magnetic nanoparticle supported silica bonded n-propyl-4-aza-1azoniabicyclo[2.2.2]octane chloride (MNPs@DABACO + ClÀ ), [31] Multiwalled carbon nanotube/guanidine/Ni(II), [32] oxidized nanoparticle (OMWCNTs), [33] TEDA/IMIZ-BAIL@UiO-66, [34] TiO 2 NWs, [35] β-cyclodextrin, [36] DABCO, [37] SDS, [38] SBAÀ PRÀ SO 3 H, [39] Diamine@GO, [40] Chitosan, [41] [BBSA-DBU][HSO 4 ], [42] Cu 2 + @MSNsÀ (CO 2 À ) 2 , [43] HPAÀ FÀ HNTs, [44] Fe 3 O 4 /cellulose nanocomposite, [45] ChCl : Urea, etc. [46] Although numerous methodologies are already mentioned in the literature, they show a varying degree of success, and many have limitations and shortcomings, which include expensive reagents, harmful chemicals, extremely higher reaction temperature, less yield, increased duration of reaction, poor catalyst recovery, etc.…”

“…Various methodologies have been reported for the synthesis of pyrazolopyranopyrimidine including the use of ultrasonication and a heterogeneous catalyst such as porphyrin‐initiated amine‐functionalized PolyBCMO dendritic polymer as a sonocatalyst, [29] 1‐deoxy‐1‐(methylamino)‐D‐glucitol, [30] magnetic nanoparticle supported silica bonded n‐propyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane chloride (MNPs@DABACO+Cl−), [31] Multiwalled carbon nanotube/guanidine/Ni(II), [32] oxidized nanoparticle (OMWCNTs), [33] TEDA/IMIZ‐BAIL@UiO‐66, [34] TiO 2 NWs, [35] β‐cyclodextrin, [36] DABCO, [37] SDS, [38] SBA−PR−SO 3 H, [39] Diamine@GO, [40] Chitosan, [41] [BBSA‐DBU][HSO 4 ], [42] Cu 2 + @MSNs−(CO 2 − ) 2 , [43] HPA−F−HNTs, [44] Fe 3 O 4 /cellulose nanocomposite, [45] ChCl : Urea, etc [46] …”

Fluorinated and Non-Fluorinated 1,4-Diarylpyrazoles via MnO2-Mediated Mechanochemical Deacylative Oxidation of 5-Acylpyrazolines

“…Several interesting applications of mechanochemistry in the synthesis of pharmaceutically-relevant N -containing compounds, such as Dantrolene (muscle relaxant), Tolbutamide (antidiabetic), and Axitinib (anticancer), have been reported [ 22 , 23 , 24 ]. Furthermore, the presented technique has been successfully applied for preparation of pyrazoles, mainly via condensation reactions starting with 1,3-dicarbonyls [ 25 , 26 , 27 , 28 , 29 , 30 ], chalcones [ 31 ], or enaminones [ 32 ], and appropriate hydrazine derivatives. Notably, to the best of our knowledge, no mechanochemical nitrile imine (3 + 2)-cycloadditions leading to pyrazoles have been reported.…”

NiFe2O4@B,N,F-tridoped CeO2 (NFTDNC): a mesoporous nanocatalyst in the synthesis of pyrazolopyranopyrimidine and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives and as an adsorbent

“…It makes the process benign by curtailing the amount of solvent, cost and energy during the reaction. 33 Among various discovered and synthesized heterocyclic systems, fused nitrogen-containing heterocycles are ubiquitous. [34][35][36][37] The single molecular structure encompassing different heterocyclic nuclei has enhanced biological activity and pharmacological properties leading to continuous refinement in their synthesis.…”