La2O3 as a very effective double‌-functional catalyst for the production of 2-amino-4-aryl-4H-pyrans and Pyrazolopyranopyrimidines

Authors

• Alireza Kohzadian * ¹
• Rohollah Fathollahi ²
• Mostafa Karami ²
• Esmail Korani ³
• Abdolkarim Zare ⁴

1. Department of Chemistry, Faculty of Sciences, Ilam Branch, Technical and Vocational University (TVU), Ilam, Iran
2. Department of Chemistry, Payame Noor University, PO Box 19395-3697 Tehran, Iran
3. Department of Chemistry, North Tehran Branch, Islamic Azad University, Tehran, Iran
4. Department of Chemistry, Payame Noor University, PO Box 19395-3697, Tehran, Iran

Abstract

Lanthanum (III) oxide (La₂O₃) was applied as an efficient bifunctional catalyst to develop a new methodology in the production of 2-amino-4-aryl-4H-pyrans and pyrazolopyranopyrimidines in the absence of solvent. In both synthetic protocol, due to the dual functionality of lanthanum­ (III) oxide (i.e. having basic and acidic Lewis sites), it was very useful and general, and plausible mechanisms were presented in support of this generality and high capability. The current protocol featured environmentally friendly conditions, the ability to recycle and reuse the heterogeneous catalyst up to 6 times, providing products in short times with high yields, easy work-up and no need for difficult steps of catalyst synthesis by using a commercially available catalyst, which makes it an appealing route for the preparation of these derivatives.

Graphical Abstract

Keywords

• Solvent-free conditions
• 2-amino-4-aryl-4H-pyrans
• Dual-functional catalyst
• Lanthanum(III) oxide
• Multi-component reaction
• One-pot
• Pyrazolopyranopyrimidines