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Chemistry
DOI: 10.21070/acopen.10.2025.10794
Published: 2025-04-05

Synthesis , characterization , a Cytotoxicity study of a New [(6S)-6-(2-hydroxyphenyl)-5-methoxy-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carbonitrile]


Sintesis, karakterisasi, studi Sitotoksisitas dari [(6S) -6-(2-hidroksifenil) -5-metoksi-2-tioxo-1,2,3,6-tetrahidropirimidin-4-karbonitril] Baru

Department of Pharmaceutical Chemistry, College of Pharmacy, University of Thi-Qar, 64001, Thi-Qar
Iraq

(*) Corresponding Author

Dihydropyrimidine Thiourea Spectra Cyanoacetate 1H-NMR

Abstract

General Background: The development of heterocyclic compounds, particularly dihydropyrimidine derivatives, has garnered considerable interest due to their broad pharmacological potential. Specific Background: Among these, thioxo-dihydropyrimidines have demonstrated significant bioactivity, including anticancer and antimicrobial properties. Knowledge Gap: However, efficient synthesis methods and biocompatibility assessments for novel thioxo-dihydropyrimidines remain limited. Aims: This study aims to synthesize and characterize a new compound, [(6S)-6-(2-hydroxyphenyl)-5-methoxy-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carbonitrile], and evaluate its cytotoxic potential on human red blood cells. Results: The compound was synthesized via a one-pot multi-component reaction using 2-hydroxybenzaldehyde, methyl cyanoacetate, and thiourea with ferric (III) chloride and HCl in ethanol, yielding 80% of a light golden solid (m.p. 222–224°C). Characterization was confirmed through FT-IR, ¹H-NMR, and MS analysis. Cytotoxicity tests showed the compound to be non-toxic at tested concentrations (0.1–0.5 mg/mL), as evidenced by minimal hemolytic activity. Novelty: This study presents a novel synthetic route for a thioxo-dihydropyrimidine derivative with confirmed structural integrity and biocompatibility. Implications: These findings highlight the potential of this compound as a safe scaffold for future drug development, especially in therapeutic applications requiring low cytotoxic profiles.

Highlights:

  1. Thioxo-dihydropyrimidines show promise in biomedical applications.
  2. Synthesized novel compound; confirmed structure; non-toxic to red blood cells.
  3. Potential safe scaffold for future drug development.

Keywards: Dihydropyrimidine , Thiourea, Spectra, Cyanoacetate, 1H-NMR

lntroduction

Nitrogen is one of the atoms in heterocyclic compounds referred to as dihydropyrimidines (DHPMs) and their derivatives. Their varied biological functions have garnered interest in medicinal chemistry in recent decades [1,2] as antibacterial[3] ,antihypertensive agents, anti-inflammatory, antitumor, antiviral, anticancer [4,5,6] , antioxidant and calcium channel antagonism/inhibition[7,8].

The first citation pertaining to the synthesis of (3,4-dihydropyrimidin-2-(1H)-one) was reported by P. Biginelli [9,10], it involved the acid-catalyzed cyclocondensation of a urea or thioureae (1), aromatic aldehyde (2), and a beta-keto ester (3) (Scheme1).

Figure 1.

Scheme 1

In addition, ILs such as [bmim][FeCl4][11] and [bmim] copper(II) acetyl lactones linked to BF4[12] were used to synthesis[ 3,4-dihydropyrimidin-2(1H)-one] . Recently, (1-sulfonylpyridinium chloride) has also been used in a greatly altered version of Biginelli's reaction [13].

Methods

Expermental

The method for preparing [(6S)-6-(2-hydroxyphenyl)-5-methoxy-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carbonitrile] [14]. A 100 ml round bottom flask (RBF) was filled with (25 ml )of ethanol and (0.015 mol) of thiourea. To obtain a clear solution, the flask was warmed to a specified temperature. After then, it was let to cool to room temperature. The aforementioned combination was combined with (25 mol) of hydrated ferric chloride, (0.01 mol) of methyl cyanoacetate, and (0.01 mol) of 2-hydroxybenzaldehyde utilizing HCl as a catalyst. After that, the mixture was stirred at the reflux temperature for seven to twenty-four hours (Scheme 2). Methanol: chlorine was employed using TLC to monitor the progress of the reaction. By carbonizing the solid and then recrystallizing it from a suitable solvent (ethanol), the pure material was produced. It has (m. p= 222-224°C) and an 80% yield pure product of light golden solid.

Figure 2.

Scheme 2

Cytotoxicity test

It was made with varying doses of the chemical (0.1, 0.3, and 0.5 mg/ml). In an Eppendorf tube, the chemical was first serially diluted with phosphate-buffered salt, with a complete volume of (0.8 ml ) for each dilution. The required amount of human purple blood cells become delivered to each tube until the full quantity was (1 ml). The combination turned into then incubated at 37°C for 30 minutes. A fantastic control box for tap water and a poor manipulate box for salt have been additionally blanketed within the test. The system become repeated two times to make certain that the red blood cells were absolutely damaged down [15,16].

Results and Discussion

According to the literature, the condensation of β-ketoesters, aldehydes and ureas/thioureas in catalyse the Biginelli reaction, which produces [3,4-dihydropyrimidin-2(1H)-ones/thiols].The reaction is more effective in an acidic environment because of its higher specificity [14].

Figure 3.

Thiourea and aldehyde condensation is the first possible mechanism for this reaction (Scheme 3). This results in an imine intermediate that serves as a nucleophilic reagent when the ketoester enol is added. The ketone carbonyl that is formed then goes under a condensation reaction with the NH2 of the urea. The cyclized final is product is the outcome of this[17,18].

Figure 4.

Scheme 3

FT-IR data :New absorption bands were detected at (3101.54), (2993.52), (3419.22), (1411.89), (1240.56), and (2240.4) cm-1 of the material in the spectra of KBr disc. The groups that make up these bands are (C-H) aromatic,(C-H) aliphatic, (OH), (C=C), (O-C) and () groups respectively. There are peaks in two (N-H) groups at (3224.8,3348.4)cm-1. The stretching bands at [(1627.92) cm-1, (C=N)], [(1056.99 ) cm-1 (C=S)], and [(2350 ) cm-1 (SH)] [19,20,21] demonstrate that the molecule is in a tautomeric form.

The novel Compound has more than a tautomeric state as shown below(Scheme 4).

Figure 5.

Scheme 4

1H NMR spectra, Tetramethylsilane (TMS) turned into used as the inner general for protons inside the solvent d6-DMSO as a way to document the proton NMR information for the synthesised compounds on a 500 MHz NMR spectrophotometer (Bruker). The predicted structures have been regular with the range of protons and their chemical shifts (δ ppm) in the NMR spectra.

The 1H NMR spectra data gave additional support for the composition of the compound ,the spectra exhibit peaks at (3.33),(4.45),(7.27-7.56),(9.35-9.95) , (10.06) ppm to (3H,S, OCH3),(H,S,-C-H),(4H,m, Ar-H),(H,S,-NH),(H,S,OH) respectively [22.23] .The1H-NMR spectra of the compound are included in Table(1).

Comp. -OCH3- aliphatic ppm C4-H ring ppm Aromatic protons ppm -OH ppm -N1H-SO-N2H ppm
d 3.33 4.45 7.27-7.56 10.06 9.35, 9.95
Table 1.

Table(1)

Mass spectral analysis

The molecular ion peak [M0] at m/z 261was found in agreement with molecular weight of are shown in (Scheme 4).

Figure 6.

Scheme 4

Cytotoxicity test

This exam is the initial stage in choosing whether to continue or halt the work. Red blood cells and their lysis effect temperature, incubation duration and medication concentration. At doses of ( 0.1, 0.3, and 0.5 mg/ml), the chemical was shown to be non-toxic to human red blood cells.

Conclusion

The effective synthesis of [(6S)-6-(2-hydroxyphenyl)-5-methoxy-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carbonitrile] has been performed. A variety of experimental methods are utilised, including NMR spectra (1H-NMR), infrared spectra (FT-IR), and mass spectrometry. The synthesised chemical was evaluated and shown to be non-toxic to human red blood cells.

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