One-pot, four-component synthesis of pyrano[2,3-c]pyrazoles catalyzed by sodium benzoate in aqueous medium

Abstract

An efficient, green, and facile four-component reaction for the preparation of pyrano [2,3-c]pyrazole derivatives through the condensation reaction of aryl aldehydes, ethyl acetoacetate, malononitrile, and hydrazine hydrate or phenyl hydrazine in the presence of commercially available organocatalyst sodium benzoate under aqueous condition is reported. The products are produced with high yields and in shorter reaction times. It also is mild, safe, green and environmental friendly.

A highly efficient and sustainable synthesis of dihydropyrano[2,3-c]pyrazoles using polystyrene-supported p-toluenesulfonic acid as reusable catalyst

“…The previously reported methods include catalysts, such as heteropolyacids, cocamidopropyl betaine, triethyl ammonium bromide, piperazine, piperidine, polyphosphoric acid supported on Ni 0.5 Zn 0.5 Fe 2 O 4 nanoparticles, disulphonic acid imidazolium chloroaluminate, sodium benzoate, and per-6-amino-β-cyclodextrin (Chavan, Babar, Hoval, & Bandgar, 2011;Kanagaraj & Pitchumani, 2010;Kiyani, Samimi, Ghorbani, & Esmaieli, 2013;Kumar et al, 2013;Moeinpour & Khojastehnezhad, 2014;Moosavi-Zare et al, 2013;Peng, Song, & Dou, 2006;Tamaddon & Alizadeh, 2014;Vasuki & Kumaravel, 2008). Most of these synthetic protocols reported suffer from high catalyst loading, prolonged reaction time, harsh reaction conditions, poor recyclability, and low yields.…”

Green Synthetic Approaches for Biologically Relevant 2-amino-4H-pyrans and 2-amino-4H-pyran-Annulated Heterocycles in Aqueous Media∗

“…Furthermore, these compounds also have been identified as vasodilators, hypotensive, hypoglycemic [97,[100][101][102], and some compounds have been demonstrated an affinity toward A1 and A2a adenosine receptors [103,104]. Scheme 10 illustrates the synthesis of 2-amino-4-substituted pyrano[2,3-c]pyrazole-3-carbonitriles 19 in aqueous media using microwave irradiation [106] or catalysts such as imidazole [107], sodium benzoate [108], CTACl [109], and γ-alumina [110]. Thus, development of environment-friendly and efficacious procedures for the synthesis of pyranopyrazoles in water is of significant interest.…”

Synthesis and Pharmacological Activities of Pyrano[2,3-d]pyrimidine and Pyrano[2,3-d]pyrimidine-5-one Derivatives as New Fused Heterocyclic Systems

“…Compound has been prepared by fourcomponent one-pot reaction [29] and three-component onepot reaction [30] (Scheme 1).…”