A green, facile, and one-pot synthesis of 2-amino-4H-pyran derivatives using tungstate sulfuric acid as a solid acid catalyst

2-Amino-4H-pyran-3-carbonitriles and 2-amino-4H-pyran-3-carboxylate derivatives were synthesized under mild conditions in the presence of tungstate sulfuric acid (TSA) as a recyclable solid acid catalyst. Catalytic condensation between 3-acetylcoumarin, aromatic aldehydes, and malononitrile or ethyl cyanoacetate gave the 2-amino-4H-pyran derivatives. Tungstate sulfuric acid is a low-cost, nontoxic, and reusable catalyst, which does not require very high temperatures and good to excellent yields were obtained in all cases. The catalyst can be reused for many times without significant loss of its activity.

Automated summary

In this study, 2-amino-4H-pyran derivatives were synthesized using tungstate sulfuric acid as a recyclable solid acid catalyst, demonstrating good to excellent yields under mild conditions. The catalyst proved to be low-cost, non-toxic, and reusable, with the ability to maintain its activity over multiple cycles of use.