Visible-light promoted serendipitous synthesis of 3,5-diaryl-1,2,4-thiadiazoles via oxidative dimerization of thiobenzamides

Abstract

In the present manuscript, we report serendipitous synthesis of 3,5-diaryl-1,2,4-thiadiazoles with the aid of a household compact fluorescent lamp (CFL). In presence of α-bromo-β-diketone, thiobenzamides undergo oxidative dimerization to generate corresponding 3,5-diaryl-1,2,4-thiadiazoles in excellent yields in just 5 min instead of expected 2-aryl-4-methyl-5-acylthiazoles. Inhibition of the reaction by free radical scavenger (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) indicates that the dimerization takes place through a free radical process. The synthetic value of the developed protocol was established by synthesizing over eleven diverse 1,2,4-thiadiazoles in a shorter duration with exceptionally high purity and simple work-up procedure under environment benign additive-free conditions.

GRAPHICAL ABSTRACT

KEYWORDS:

• α-bromo-β-diketone
• thiobenzamides
• oxidative cyclization
• thiadiazoles
• CFL light

Acknowledgement

We are thankful to the Council of Scientific and Industrial Research, India for providing financial assistance (SRF) to Mona Hooda.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Council of Scientific and Industrial Research, India.