Background:
The various industrial processes have diverse effect on environment through pollution. In view of these observations, some environmentally benign synthetically protocols have developed under green chemistry. For rapid and sustainable synthesis the microwave irradiation (MI) has gained popularity as a powerful tool compared to conventional synthesis. The present study describes the synthesis of novel substituted 1, 3-diaryl-2-propene-1-one derivative using alumina supported K3PO4-MWI combination.
Objective:
Chalcones are the important compounds and widely spread in nature such as in fruits, vegetables, tea, spices etc. The 2’-hydroxy derivative of chalcones play an important role in synthesis of bioactive compounds. The present communication deals with a convenient and rapid synthesis of 1, 3-diaryl-2-propene-1-one under the support of alumia-tripotassium phosphate and microwave irradiation. Our efforts are focused on the introduction of typical and easier route for synthesis of title compounds using microwave. All synthesized chalcones have been screened and evaluated for the antioxidant activity by DPPH and nitric oxide radical scavenging. Some of these compounds found to be more potent scavengers and may lead to the development of new class of antioxidants.
Method:
The α, β-unsaturated carbonyl functionality contain two electrophilic centers allowing them to undergo addition and cyclisation reaction with different nucleophiles. In the literature survey, we found that Chalcones were synthesized using tripotassium phosphate catalyst under refluxing by conventional method. A novel method for the synthesis of 1, 3-diaryl-2-propene-1-one via Claisen –Schmidt has been introduced by reacting substituted 2’- hydroxyl acetonaphthones with substituted aromatic aldehydes under the support of basic alumina –tripotassium phosphate via microwave radiations. Formation of corresponding Chalcones was confirmed by spectral studies followed by their screening for antioxidant activity. The scavenging activity is expressed in terms of % inhibition and IC50 value (μg/ml).
Results:
The structures of newly synthesized Chalcones were confirmed and in good agreement with obtained spectral analysis such as IR, NMR, Mass and elemental analysis. Commercially available basic alumina and tripotassium phosphate in combination of microwave were utilized and found to be effective, convenient route for the synthesis of 1, 3-diaryl-2-propene-1-one derivatives with desirable yields in short reaction time (5-12 min). The results of antioxidant activity revealed that the IC50 value for compounds 3a, 3d, 3e, 3f, 3g, 3h, 3j, 3l and 3nare lower than that of standard ascorbic acid to scavenge DPPH radical. This indicates that these compounds are more significant scavenger in comparison with standard drug. On the other hand the compounds 3a, 3b, 3c, 3d, 3g, 3l and 3n are more potent scavenger for NO free radical.
Conclusion:
We have introduced an efficient, ecofriendly, simple and fast microwave assisted method using basic alumina-tripotassium phosphate for synthesis of 1, 3-diaryl-2-propene-1-one derivatives. Microwave irradiation provides an effective way for the preparation of Chalcones in terms of several advantages as simple procedure, short reaction time, milder reaction condition, cleaner reaction and excellent yield. The scavenging activity of chalcones against DPPH and NO free radicals showed excellent properties of antioxidants.
