Base-mediated one-pot synthesis of 3,4,5,6-tetrahydro-4-substituted benzo[h]quinazoline-2(1H)-thione derivatives and evaluation of their antioxidant activity

ABSTRACT

One-pot three-component Beginelli-like reactions of a ketone 1, an aryl aldehyde 2, and thiourea 3 in the presence of sodium hydroxide are described. In this reaction, 3,4,5,6-tertrahydro-4-substituted quinazoline-2(1H)-thione derivatives 4a–h were obtained in good yields (73–85%). The compound 4a has been characterized by single crystal X-ray analysis. All the synthesized compounds 4a–h and 5a–b were screened for their in vitro antioxidant activity. Compounds 4c, 4e, and 4h have exhibited an excellent than the standard ascorbic acid. Compounds 4d, 4f, and 4g have also shown good activity. Remaining compounds show moderate antioxidant activity.

GRAPHICAL ABSTRACT

KEYWORDS:

• α-Tetralone
• aldehyde
• antioxidant activity
• IC₅₀ value
• quinazoline-2(1H)-thione
• thiourea

Acknowledgments

We are thankful to the DST-SERB, UGC-BSR New Delhi for a research grant. K. Prabhakaran thanks DST-SERB, New Delhi for financial support. We are also grateful to DST New Delhi for support under “DST-FIST” program.

Additional information

Funding

This work was supported by the Department of Science and Technology, New Delhi [Grant Number SB/FT/CS-004/2012, dated 24/05/2013]