Imidazolium
zwitterionic molten salt (4-(3-methylimidazolium)butane
sulfonate) has been an efficient and useful organocatalyst for a one-pot
three-component reaction of 4-hydroxycoumarin, aldehydes, and thiols
to synthesize 4-hydroxy-3-thiomethylcoumarin derivatives by the ball-milling
technique. This mechanochemical way has taken the reactions over the
conventional grinding method to provide good to excellent yields of
the corresponding products in a very short time. All the reactions
were carried out under neat conditions, and the coumarin derivatives
were obtained without performing any column chromatography. The protocol
is beneficial because of mild conditions, a wide substrate scope,
product scalability, and the easy product isolation technique. In
addition, the present method is also applicable for gram-scale synthesis
and shows lower E-factors. The biological activities of the synthesized
products are very promising, and the antimicrobial activities have
been studied for some randomly taken synthesized compounds.