Synthesis of thiophene-pyrazole conjugates as potent antimicrobial and radical scavengers

• Main Authors: Malledevarapura Gurumurthy Prabhudeva, Nagamallu Renuka, Kariyappa Ajay Kumar
• Format: Article
• Language: English
• Published: Growing Science 2018-08-01
• Series: Current Chemistry Letters
• Subjects: Antimicrobial; Antioxidant; Chalcone; Cyclocondensation; Radical scavengers
• Online Access: http://www.growingscience.com/ccl/Vol7/ccl_2018_8.pdf

The current study presents the synthesis of thiophene-appended pyrazoles through 3+2 annulations of chalcones <b>3</b>(<b>a</b>-<b>g</b>)with aryl hydrazine hydrochlorides <b>4</b>(<b>a</b>-<b>d</b>) in acetic acid (30%) under reflux conditions produced the thiophene-pyrazole hybrids <b>5</b>(<b>a</b>-<b>g</b>) in good yields. Structures of synthesized new pyrazoles were confirmed by spectral studies, and elemental analysis. Further, preliminary biological evaluation studies show that compounds <b>5b</b> and <b>5f</b> having chloro substitution only in the thiophene ring exhibited excellent inhibition (12.5-25.0 µg/mL) against all the tested organisms in comparison with that of the standard. Compounds, <b>5a</b>, <b>5c</b> and <b>5g</b> having electronegative chloro substitutions each in the aromatic and thiophene rings showed excellent (12.423-31.213 µg mL^-1) DPPH radical scavenging potencies. The synthesis of pyrazoline derivatives and the efficacy of some of the synthesized molecules as antimicrobial and antioxidant agents validate the significance of this study.