An Efficient Four-Component, One-Pot Synthesis of 6-Amino-4-Aryl-3- Methyl-2,4-Dihydropyrano[2,3-C]Pyrazole-5-Carbonitriles Under Phase- Transfer Catalyst

Abstract

A series of 6-amino-4-aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles (5a-5j) were synthesized by four-component one-pot reaction of methyl acetoacetate (or ethyl acetoacetate), hydrazine hydrate, arylaldehydes and malononitrile in the presence of phase transfer catalyst. A highest yield of product was obtained while using 30 mol % of HDBAC as a catalyst.

Synthesis and Application of Nano Vanadium‐Oxo Pyridiniumporphyrazinato Sulfonic Acid for Synthesizing Pyrazole and Dihydropyrano[2,3]pyrazole Derivatives

“…This condensation has been developed using some catalysts such as basic ionic liquids, triethylamine, L-proline, hexadecyl dimethyl benzyl ammonium chloride (HDBAC), γ-alumina, piperidine, Amberlyst A21, and per-6-amino-b-cyclodextrin. [54][55][56][57][58][59][60][61] However, these methods mainly possess some limitations that may cause difficult workup procedures, severe reaction conditions, and slowed reaction times or lead to moderate yields.…”

“…Moreover, the four‐component, one‐pot synthesis of various pyranopyrazoles has been achieved, which includes the condensation of hydrazines, aldehydes, ethyl acetoacetate, and malononitrile. This condensation has been developed using some catalysts such as basic ionic liquids, triethylamine, L‐proline, hexadecyl dimethyl benzyl ammonium chloride (HDBAC), γ‐alumina, piperidine, Amberlyst A21, and per‐6‐amino‐b‐cyclodextrin [54–61] …”

Copper‐catalyzed multicomponent green reaction approach: Synthesis of dihydropyrano [2,3‐c] pyrazoles and evaluation of their anti‐cancer activity

“…per-6-amino-β-cyclodextrin [22], hexadecyl dimethyl benzyl ammonium chloride [23], basic ionic liquids [24], disulfonic acid imidazolium chloroaluminate [25], meglumine [26], and sodium benzoate [27], while only a few methods involving heterogeneous catalysts, such as amberlyst A21 [28], γ-alumina [29], SnO 2 QDs [30], and CeCl 3 [31]. In addition, pyrazoles were synthesized under catalyst-free conditions also; however they needed a high temperature [32].…”

“…Recently, the synthesis of pyranopyrazole derivatives has been published [19]. However, most of the protocols were developed using nitrogenous‐based toxic catalysts, for example, trirthylamine [20], piperidine [21], per‐6‐amino‐β‐cyclodextrin [22], hexadecyl dimethyl benzyl ammonium chloride [23], basic ionic liquids [24], disulfonic acid imidazolium chloroaluminate [25], meglumine [26], and sodium benzoate [27], while only a few methods involving heterogeneous catalysts, such as amberlyst A21 [28], γ‐alumina [29], SnO 2 QDs [30], and CeCl 3 [31]. In addition, pyrazoles were synthesized under catalyst‐free conditions also; however they needed a high temperature [32].…”

Catalytic application of 1-(carboxymethyl)pyridinium iodide on the synthesis of pyranopyrazole derivatives

“…Several catalysts have been introduced for the synthesis of pyranopyrazoles, including imidazole [13], per-6-amino-b-cyclodextrin [14], phase transfer catalyst (HDBAC) [15], organocatalysts (MDOs) [16], D,L-Proline [17], hexa decyl tri methyl ammonium bromide (HTMAB) [18], disulfonic acid imidazolium chloroaluminate {[Dsim]AlCl 4 } [19], gamma-Alumina [20], magnetic Fe 3 O 4 nanoparticles [21] and isonicotinic acid [22]. Therefore, considerable attention has been focused on the development of new protocols for the preparation of these compounds.…”