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<p></p><p>Previous studies of the multicomponent reaction using acetone or more complicated ketones with 3-amino-1<i>H</i>-1,2,4-triazole and benzaldehydes opened the door for diastereoselective formation of 4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-<i>a</i>]pyrimidine derivatives as an alternative product type in Biginelli-like condensations. In this work, replacing acetone with cyclohexanone in this transformation led to the formation of two diastereomeric hexahydro[1,2,4]triazolo[1,5-<i>a</i>]quinazolin-9a(4<i>H</i>)-ols formed in 2:1 ratio, which were isolated with diastereomeric excess of 88 and 66%, correspondingly. The reaction proceeds in a one-pot manner at 140°C for 2 h in <i>n</i>-BuOH under microwave irradiation in the presence of <i>p</i>-toluenesulfonic acid as a catalyst. Both diastereomers were characterized using 2D NMR, with full assignment of proton and carbon signals, and further confirmed by X-ray crystallography. Characteristic proton signals for each diastereomer were identified and a plausible mechanism of reaction was proposed based on the stereochemical structures of the products and literature data.</p>

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Stereochemical aspect of a Biginelli-like reaction involving cyclohexanone and 3-amino-1H-1,2,4-triazole

  • 期刊论文

  • 发表日期：

    2025年6月1日

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  • Pavlo V. Mormylo,
  • Maria O. Shyshkina,
  • Nadia M. Kolos,
  • Anastasiia S. Konstantynova,
  • Oleksandr V. Borysov,
  • Mykola Yu. Gorobets

摘要

Previous studies of the multicomponent reaction using acetone or more complicated ketones with 3-amino-1H-1,2,4-triazole and benzaldehydes opened the door for diastereoselective formation of 4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-a]pyrimidine derivatives as an alternative product type in Biginelli-like condensations. In this work, replacing acetone with cyclohexanone in this transformation led to the formation of two diastereomeric hexahydro[1,2,4]triazolo[1,5-a]quinazolin-9a(4H)-ols formed in 2:1 ratio, which were isolated with diastereomeric excess of 88 and 66%, correspondingly. The reaction proceeds in a one-pot manner at 140°C for 2 h in n-BuOH under microwave irradiation in the presence of p-toluenesulfonic acid as a catalyst. Both diastereomers were characterized using 2D NMR, with full assignment of proton and carbon signals, and further confirmed by X-ray crystallography. Characteristic proton signals for each diastereomer were identified and a plausible mechanism of reaction was proposed based on the stereochemical structures of the products and literature data.