Abstract
Novel nano-ordered 1,1,3,3-tetramethylguanidine-functionalized melamine (Melamine@TMG) organocatalyst was prepared and adequately identified by various techniques including FTIR, EDX, XRD and SEM spectroscopic or microscopic methods as well as TGA and DTG analytical methods. The Melamine@TMG, as an effective multifunctional organocatalyst, was found to promote smoothly the three-component synthesis of 1,2,4-triazoloquinazolinone derivatives using cyclic dimedone, 3-amino-1,2,4-triazole and different benzaldehyde derivatives in EtOH at 40 °C. This practical method afforded the desired products in high to excellent yields (86–99%) and short reaction times (10–25 min). The main advantages of this new method are the use of heterogeneous multifunctional nanocatalyst, simple work-up procedure with no need for chromatographic purification, highly selective conversion of substrates and recyclability of the catalyst, which could be used in five consecutive runs with only a small decrease in its activity.
Highlights
The discovery of efficient catalytic systems for synthetic chemical reactions is a milestone and key principle in green and sustainable chemistry, which has emerged as an active area of research
We hereby report a green approach for the synthesis of 1,2,4-triazoloquinazolinones catalyzed by the 1,1,3,3-tetramethylguanidine superbase[79] anchored onto melamine (Melamine@TMG, 1) as a novel nano-ordered multifunctional and heterogeneous organocatalyst (Scheme 1)
The efficiency of the Melamine@TMG nanocatalyst was examined in the synthesis of 1,2,4-triazoloquinazolinones
Summary
The discovery of efficient catalytic systems for synthetic chemical reactions is a milestone and key principle in green and sustainable chemistry, which has emerged as an active area of research. Preparation of nano-ordered multifunctional Melamine@TMG organocatalyst and its application for the three-component synthesis of 1,2,4-triazoloquinazolinones 5a–j. Among various reported procedures for the synthesis of 1,2,4-triazoloquinazolinone derivatives, the three-component reaction of enolizable 1,3-dicarbonyls, 3-amino-1,2,4-triazole, and aldehydes/ketones has been known as the most beneficial method in terms of obtained yield, selectivity and green chemistry principles[51,56,57,58,59,60,61,62,63,64,65,66].
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