Mechanochemical Access to 2,4-Diaroyl-5-aminothiazoles from β-Ketothioamides at Room Temperature

A mechanochemical approach to hitherto unreported 2,4-diaroyl-5-aminothiazoles via formal [3 + 2] heteroannulation of β-ketothioamides with 3-(hydroxyimino) chromane-2,4-diones has been developed utilizing SiO2-assisted hand grinding in a mortar with pestle at room temperature within 10 min. The reaction proceeds via C(sp2)–S bond formation/dehydrative intramolecular cyclization cascade. This strategy is distinguished by safe and easily accessible substrates, metal-free mild conditions, broad substrate scope, and wide functional group compatibility. Control experiments, DFT, and HRMS studies validated the proposed mechanism.