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. 2025 May 31;15(1):19139.
doi: 10.1038/s41598-025-03630-3.

Preparation, characterization, and application of a valine-malonic acid based-DES as a potent catalyst for the green synthesis of thiazolopyrimidines

Nastaran Dehnokhalaji  1 , Davood Habibi  2 , Arezo Monem  1 , Afagh Ranjbaran  1
Affiliations

Preparation, characterization, and application of a valine-malonic acid based-DES as a potent catalyst for the green synthesis of thiazolopyrimidines

Nastaran Dehnokhalaji et al. Sci Rep. .

Abstract

Based on the eutectic point phase diagram, a novel natural deep eutectic solvent (VAL/MAL-DES) was prepared by a mixture of one mole of valine (VAL) and one mole of malonic acid (MAL), and characterized by the eutectic points, FT-IR, 1HNMR, TGA/DTA and densitometer techniques. Then, it was used as a novel and capable catalyst for the green synthesis of thiazolo[3,2-a]pyrimidines via a one-pot four-component condensation reaction of 4-hydroxycoumarin, 2-amino-6-methylbenzothiazole, morpholine, and aldehydes at 80 °C with high yield and short reaction time.

Keywords: Homogeneous catalysis; Malonic acid; Multicomponent reactions; Natural deep eutectic solvent; Valine.

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Conflict of interest statement

Declarations. Competing interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Scheme 1
Scheme 1
Preparation of VAL/MAL-DES.
Scheme 2
Scheme 2
Synthesis of 2(a-j) by VAL/MAL-DES.
Fig. 1
Fig. 1
The eutectic points phase diagram of VAL/MAL-DES.
Fig. 2
Fig. 2
The FT-IR spectra of (a), (b), (c), and (d).
Fig. 3
Fig. 3
The 1HNMR of VAL/MAL-DES. aThe 1HNMR spectrum (250 MHz, DMSO-d6) of VAL. bThe 1HNMR spectrum (250 MHz, DMSO-d6) of MAL. cThe 1HNMR spectrum (250 MHz, DMSO-d6) of VAL/MAL-DES.
Fig. 3
Fig. 3
The 1HNMR of VAL/MAL-DES. aThe 1HNMR spectrum (250 MHz, DMSO-d6) of VAL. bThe 1HNMR spectrum (250 MHz, DMSO-d6) of MAL. cThe 1HNMR spectrum (250 MHz, DMSO-d6) of VAL/MAL-DES.
Fig. 4
Fig. 4
The TGA-DTA patterns of VAL/MAL-DES.
Scheme 3
Scheme 3
Synthesis of 2g by the VAL/MAL-DES catalyst.
Scheme 4
Scheme 4
Proposed mechanism for the synthesis of 2(a- j).
Fig. 5
Fig. 5
Reusability of the VAL/MAL-DES catalyst in four-consecutive reaction runs.
See this image and copyright information in PMC

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