Synthesis of Thioureas, Thioamides, and Aza-Heterocycles via Dimethyl-Sulfoxide-Promoted Oxidative Condensation of Sulfur, Malonic Acids, and Amines

Malonic acid and derivatives have been well-known to undergo monodecarboxylation under relatively mild conditions and have been exclusively used as a C₂ synthon. We report herein their new application as a C₁ synthon via double decarboxylation promoted by sulfur and dimethyl sulfoxide. In the presence of amines as nucleophiles, a wide range of thioureas and thioamides as well as N-heterocycles were obtained in good to excellent yields under mild heating conditions.