Abstract
A bis-chalcone has been synthesized by reaction of 3-acetyl-2,5-dimethylthiophene and terephthalaldehyde in ethanolic NaOH at room temperature: (2E,2′E)-3,3-(1,4-phenylene)bis[1-(2,5-dimethyl-3-thienyl)prop-2-en-1-one] (3) was obtained in high yield. The structure of this compound was established by elemental analysis, IR, 1H NMR, 13C NMR and EI-MS spectral analysis.
Aldol condensations are important in organic synthesis, providing a good way to form α,β-unsaturated ketones known as chalcone [1]. Naturally occurring as well as synthetic chalcones are important for their biological activities. Compounds with α,β-unsaturated ketones have become of much interest in recent years on account of their antioxidant [2], antibacterial [3], antidepressant [4], antihypertensive [5] and anti-inflammatory activity [6].
They are also intermediates in the biosynthesis of flavonoids, which are substances widespread in plants and with an array of biological activities. Chalcones are also intermediates in the synthesis of flavones and cyclization of chalcones can give rise to other heterocyclic compounds such as pyrazoles and oxazoles. In view of these observations, author has synthesized a novel bis-chalcone.
A solution of 3-acetyl-2,5-dimethylthiophene (4.14 mL, 0.029 mol) and terephthalaldehyde (2 g, 0.014 mol) in ethanolic solution of NaOH (6 g in 10 mL of ethanol) was stirred for 20 h at room temperature. The solution was poured into ice cold water of pH~2 (pH adjusted by HCl). The solid was separated and dissolved in CH2Cl2, washed with saturated solution of NaHCO3 and evaporated to dryness. The residual was recrystallized from methanol/chloroform.
Dark yellow solid (Chloroform); Yield: 78%; m.p. 194-195 °C.
EI-MS m/z (rel. int.%): 407 (40) [M+1]+, 255 (70), 153 (45).
IR (KBr) vmax cm-1: 3050 (Ar-H), 2914 (C-H), 1648 (C=O), 1585 (C=C).
1H NMR (DMSO-d6) (δ/ppm): 7.71 (d, 2H, J = 15.6 Hz, C=CH), 7.30 (d, 2H, J = 15.6 Hz, CO=CH), 7.64 (s, 4H, Ar-H), 7.09 (s, 2H, thiophene-H), 1.61 (s, CH3).
13C NMR (DMSO-d6) (δ/ppm): 186.09, 147.77, 142.36, 136.77, 136.47, 135.46, 130.21, 125.76, 15.98, 15.07.
Anal. calc. for C24H22O2S2: C, 70.91, H, 5.41, S, 15.57, Found: C, 70. 86, H, 5.35, S, 15.52.
Supplementary materials
Supplementary File 1Supplementary File 2Supplementary File 3Acknowledgements
The authors would like to thank the Chemistry Department, King Abdul Aziz University, Jeddah, Saudi Arabia for providing the research facilities.
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