Sodium Carbonate-Promoted Formation of 5-Amino-1,2,4-thiadiazoles and 5-Amino-1,2,4-selenadiazoles with Elemental Sulfur and Selenium.

Abstract

Sodium carbonate-promoted facile synthesis of 5-amino-1,2,4-thiadiazoles and 5-amino-1,2,4-selenadiazoles with elemental sulfur and selenium, respectively, was developed. This method was carried out with O2 in the air as the green oxidant, and it has several advantages, including low cost, low toxicity, and stable sulfur and selenium sources, good to excellent yields with water as the sole byproduct, simple operation, and a broad substrate scope. Preliminary mechanistic studies indicate that the formation of the 1,2,4-thiadiazole ring and the 1,2,4-selenadiazole ring undergoes different processes.