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<p>Conventional routes for pyrano[2,3-c]pyrazole synthesis typically rely on metal nanoparticles or metal salts, which are expensive and require complex handling. In this work, pyrano[2,3-c]pyrazoles were synthesized via a one-pot four-component reaction (4-CR) of substituted benzaldehydes, malononitrile, phenyl hydrazine, and ethyl acetoacetate using microporous zeolites (H-Y, Hβ, H-MOR, H-ZSM-5) and mesoporous (Al-MCM-41) catalyst. Zeolite p-Hβ (H-BEA) demonstrated high catalytic efficiency, and a detailed evaluation revealed that the Si/Al ratio, acidity, surface area, and pore structure significantly influence catalytic activity. The performance of p-Hβ was further enhanced through controlled desilication in the presence of cationic surfactant, 6-bromo hexyl trimethyl ammonium bromide treatment leading to increased surface area, porosity, and improved accessibility of active sites in resultant micro-meso composite of zeolite HZβ. The HZβ catalyst has been found to exhibit superior activity, delivering up to 93% product yield under optimized solvent-free conditions (10 wt% catalyst, 100&#xa0;°C, 60&#xa0;min). The catalyst was successfully reused up to five cycles, and the solvent-free protocol provides an environmentally benign approach for pyrano[2,3-c]pyrazole synthesis. The HZβ zeolite was further utilized for the synthesis of a series of pyrazole derivatives, including two novel derivatives, which were comprehensively characterized.</p> Graphical abstract <p></p>

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Cationic surfactant assisted post modification of microporous Hβ zeolite and its catalytic application for the sustainable synthesis of pyrano[2,3-c]pyrazoles

  • 期刊论文

  • 发表日期：

    2026年3月12日

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  • Bilal Mansuri,
  • Aayushi Lodhi,
  • Ajay Dalai,
  • Kalpana Maheria

摘要

Conventional routes for pyrano[2,3-c]pyrazole synthesis typically rely on metal nanoparticles or metal salts, which are expensive and require complex handling. In this work, pyrano[2,3-c]pyrazoles were synthesized via a one-pot four-component reaction (4-CR) of substituted benzaldehydes, malononitrile, phenyl hydrazine, and ethyl acetoacetate using microporous zeolites (H-Y, Hβ, H-MOR, H-ZSM-5) and mesoporous (Al-MCM-41) catalyst. Zeolite p-Hβ (H-BEA) demonstrated high catalytic efficiency, and a detailed evaluation revealed that the Si/Al ratio, acidity, surface area, and pore structure significantly influence catalytic activity. The performance of p-Hβ was further enhanced through controlled desilication in the presence of cationic surfactant, 6-bromo hexyl trimethyl ammonium bromide treatment leading to increased surface area, porosity, and improved accessibility of active sites in resultant micro-meso composite of zeolite HZβ. The HZβ catalyst has been found to exhibit superior activity, delivering up to 93% product yield under optimized solvent-free conditions (10 wt% catalyst, 100 °C, 60 min). The catalyst was successfully reused up to five cycles, and the solvent-free protocol provides an environmentally benign approach for pyrano[2,3-c]pyrazole synthesis. The HZβ zeolite was further utilized for the synthesis of a series of pyrazole derivatives, including two novel derivatives, which were comprehensively characterized.

Graphical abstract