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<p>An environmentally benign and highly efficient synthetic protocol has been established for the preparation of new dihydrotetrazolo[1,5-<i>a</i>]thiazolo[4,5-<i>d</i>]pyrimidine-6(<i>4H</i>)-thione derivatives via a one-pot, three-component condensation of rhodanine, 5-aminotetrazole, and various aromatic aldehydes catalyzed by a recoverable Fe(III)–porphyrin complex. Comprehensive characterization of the catalytic products was performed using FT-IR, <sup>1</sup>H-NMR, <sup>13</sup>C-NMR, and micro-elemental analyses, confirming their proposed structures. The optimized catalytic system, operating in an ethanol–water (3:1, v/v) medium at 80&#xa0;°C, afforded the desired products in excellent yields (91–97%) within short reaction times (10–25&#xa0;min). Systematic optimization studies revealed that increasing the catalyst loading from 3 mmol to 10 mmol% significantly improved the product yield (from 14 to 97%) and reduced the reaction time, identifying 10 mmol% as the optimal catalyst dosage. Comparative screening demonstrated that the Fe(III)–porphyrin catalyst markedly outperformed other Lewis acids, bases, and ionic liquid catalysts, including FeCl<sub>3</sub>·6H<sub>2</sub>O, Fe(OTf)<sub>3</sub>, Mg(OTf)<sub>2</sub>, and ZnBr<sub>2</sub>, which achieved superior conversion efficiency and selectivity under mild conditions. Hot filtration experiments confirmed that the catalytic process proceeds predominantly via a homogeneous mechanism, as the reaction continued to progress even after the catalyst was removed. The Fe(III)–porphyrin catalyst exhibited excellent stability and could be reused for at least five consecutive cycles without significant loss of activity. This green and high-yielding methodology not only minimizes solvent waste but also highlights the potential of Fe(III)–porphyrin complexes as robust, recyclable, and eco-friendly catalysts for the sustainable synthesis of pharmacologically significant heterocycles.</p>

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Recoverable Fe(III)–porphyrin complex using a rapid, highly yielded, and green synthesis of dihydrotetrazolo[1,5-a]thiazolo[4,5-d]pyrimidine-6(4H)-thione derivatives

  • 期刊论文

  • 发表日期：

    2025年12月2日

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  • Mohamed Shaker S. Adam,
  • Ahmed Khalil,
  • Mostafa Y. Nassar,
  • Mohammed A. Alkhalifah,
  • Thomas Nady A. Eskander,
  • Mahmoud Abd El Aleem Ali Ali El-Remaily

摘要

An environmentally benign and highly efficient synthetic protocol has been established for the preparation of new dihydrotetrazolo[1,5-a]thiazolo[4,5-d]pyrimidine-6(4H)-thione derivatives via a one-pot, three-component condensation of rhodanine, 5-aminotetrazole, and various aromatic aldehydes catalyzed by a recoverable Fe(III)–porphyrin complex. Comprehensive characterization of the catalytic products was performed using FT-IR, 1H-NMR, 13C-NMR, and micro-elemental analyses, confirming their proposed structures. The optimized catalytic system, operating in an ethanol–water (3:1, v/v) medium at 80 °C, afforded the desired products in excellent yields (91–97%) within short reaction times (10–25 min). Systematic optimization studies revealed that increasing the catalyst loading from 3 mmol to 10 mmol% significantly improved the product yield (from 14 to 97%) and reduced the reaction time, identifying 10 mmol% as the optimal catalyst dosage. Comparative screening demonstrated that the Fe(III)–porphyrin catalyst markedly outperformed other Lewis acids, bases, and ionic liquid catalysts, including FeCl3·6H2O, Fe(OTf)3, Mg(OTf)2, and ZnBr2, which achieved superior conversion efficiency and selectivity under mild conditions. Hot filtration experiments confirmed that the catalytic process proceeds predominantly via a homogeneous mechanism, as the reaction continued to progress even after the catalyst was removed. The Fe(III)–porphyrin catalyst exhibited excellent stability and could be reused for at least five consecutive cycles without significant loss of activity. This green and high-yielding methodology not only minimizes solvent waste but also highlights the potential of Fe(III)–porphyrin complexes as robust, recyclable, and eco-friendly catalysts for the sustainable synthesis of pharmacologically significant heterocycles.