Cooperative Activating Effect of Tertiary Amine/DMSO on Elemental Sulfur: Direct Access to Thioaurones from 2′-Nitrochalcones under Mild Conditions

A new mode for the activation of elemental sulfur is reported. In the presence of both DMSO and a tertiary aliphatic amine (triethylamine or N-methylpiperidine), this element reacts directly with a wide range of 2'-nitrochalcones 1 to provide the corresponding thioaurones 2 in high yields even at room temperature and in the absence of transition metal catalyst.