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. 2023 Oct 21;13(1):18009.
doi: 10.1038/s41598-023-45352-4.

An acid-based DES as a novel catalyst for the synthesis of pyranopyrimidines

Arezo Monem  1 , Davood Habibi  2 , Hadis Goudarzi  1
Affiliations

An acid-based DES as a novel catalyst for the synthesis of pyranopyrimidines

Arezo Monem et al. Sci Rep. .

Abstract

Deep eutectic solvents have countless advantages over normal solvents, and in addition to complying with the principles of green chemistry, depending on their nature, they can also act as catalysts. The use of deep eutectic solvents as acid catalysts has several advantages such as non-toxicity, a catalytic effect similar to or higher than the acid itself, and the possibility of recovery and reuse without significant loss of activity. In this project, A novel deep eutectic solvent (MTPPBr-PCAT-DES) was prepared from a one-to-one mole ratio of methyltriphenyl-phosphonium bromide (MTPPBr) and 3,4-dihydroxybenzoic acid (PCAT = protocatechuic acid) and characterized by various techniques such as FT-IR, TGA/DTA, densitometer, eutectic point, 1H NMR, 13C NMR and 31P NMR. Then, it was used as a novel and capable catalyst for the synthesis of pyranopyrimidines from the multicomponent condensation reaction of barbituric acid, 4-hydroxycoumarin, and aromatic aldehydes in mild conditions, short reaction times, and high yields.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Scheme 1
Scheme 1
Synthesis of MTPPBr–PCAT–DES as a novel DES.
Scheme 2
Scheme 2
Synthesis of 2(a-l) by MTPPBr–PCAT–DES.
Figure 1
Figure 1
The FT-IR spectra of (a), (b), (c), and (d).
Figure 2
Figure 2
The 1H NMR of MTPPBr.
Figure 3
Figure 3
The 1H NMR of PCAT.
Figure 4
Figure 4
The 1H NMR of MTPPBr–PCAT–DES.
Figure 5
Figure 5
The 13C NMR of MTPPBr–PCAT–DES.
Figure 6
Figure 6
The 31P NMR of MTPPBr–PCAT–DES.
Figure 7
Figure 7
The TGA–DTA curve of MTPPBr–PCAT.
Figure 8
Figure 8
The eutectic points phase diagram of MTPPBr–PCAT–DES.
Scheme 3
Scheme 3
Synthesis of 2h by the novel DES catalyst.
Scheme 4
Scheme 4
Proposed mechanism for the synthesis of 2(a-l).
Figure 9
Figure 9
Reusability of the MTPPBr–PCAT–DES catalyst in four consecutive reaction runs.
Figure 10
Figure 10
The 1H NMR of recovered catalyst.
Figure 11
Figure 11
The 13C NMR of recovered catalyst.
Figure 12
Figure 12
The 31P NMR of recovered catalyst.
See this image and copyright information in PMC

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