Synthesis of Thio and Selenoethers of Cyclic β-Hydroxy Carbonyls and Amino Uracils: A Metal-Free Regioselective I2 /DMSO Mediated Reaction

Abstract

A simple and practical method has been developed using I2/DMSO for the construction of C−S and C−Se bonds in pharmaceutically important cyclic β-hydroxy carbonyls such as 4-hydroxy-6-methyl-2H-pyran-2-one, 4-hydroxy-1-methylquinolin-2(1H)-one, quinoline-2,4-diol and heterocyclic enamines such as amino uracil and amino pyrazole derivatives under mild reaction conditions. A series of thio and seleno ethers have been synthesized directly from thiols and selenols in the presence of in situ iodonium ion generated from the I2/DMSO combination in good to very good yields. This metal-free dehydrogenative C−S and C−Se coupling reaction goes via C(sp2)-H bond activation and works under conventional as well as microwave heating. Under microwave conditions, reactions complete within 15 minutes with very good yields.