Synthesis and Characterization of Chalcones and Their New Pyrazolines Derivatives

Abstract

Chalcones are open-chain flavonoids and considered to be the precursor of isoflavonoids and flavonoids which consist of two aromatic rings that linked by a three carbons consisting of a α, β-unsaturated carbonyl system. Besides, chalcones display a wide range of biological activities such as antibacterial, anticancer and antioxidant activity. In this study, the synthesis of several chalcones and their pyrazoline derivatives namely (E)-1-(5-methylfuran-2-yl)-3-phenylprop-2-en-1-one, (E)-3-(4-bromophenyl)-1-(5-methylfuran-2-yl)prop-2-en-1-one, (E)-1-(5-methylfuran-2-yl)-3-(p-tolyl)prop-2-en-1-one, 1-(5-(5-methylfuran-2-yl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one, 1-(3-(4-bromophenyl)-5-(5-methylfuran-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one and 1-(5-(5-methylfuran-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one has been carried out. These targeted compounds were synthesized via Claisen-Schmidt condensation of the respective aldehydes and ketones under basic condition to give the corresponding chalcones, (E)-1-(5-methylfuran-2-yl)-3-phenylprop-2-en-1-one, (E)-3-(4-bromophenyl)-1-(5-methylfuran-2-yl)prop-2-en-1-one, and (E)-1-(5-methylfuran-2-yl)-3-(p-tolyl)prop-2-en-1-one which were obtained as yellow precipitate with a percentage yield 76.98 %, 38.55 % and 66.33 % respectively. The pyrazoline derivatives which were 1-(5-(5-methylfuran-2-yl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one, 1-(3-(4-bromophenyl)-5-(5-methylfuran-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one and 1-(5-(5-methylfuran-2-yl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)ethan-1-one were synthesized from (E)-1-(5-methylfuran-2-yl)-3-phenylprop-2-en-1-one, (E)-3-(4-bromophenyl)-1-(5-methylfuran-2-yl)prop-2-en-1-one, and (E)-1-(5-methylfuran-2-yl)-3-(p-tolyl)prop-2-en-1-one respectively with hydrazine hydrate in acetic acid. All pyrazoline derivatives obtain as white powder with a percentage yield of 40.29 %, 51.60% and 52.84 % respectively. The structures were confirmed spectroscopically by ATR-FTIR and ¹H NMR.