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

A simple and practical method has been developed using I-2/DMSO for the construction of C-S and C-Se bonds in pharmaceutically important cyclic beta-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 I-2/DMSO combination in good to very good yields. This metal-free dehydrogenative C-S and C-Se coupling reaction goes via C(sp(2))-H bond activation and works under conventional as well as microwave heating. Under microwave conditions, reactions complete within 15 minutes with very good yields.