Preparation of Thiazole-2-thiones through TBPB-Promoted Oxidative Cascade Cyclization of Enaminones with Elemental Sulfur.

An unprecedented method for the construction of thiazole-2-thiones via an oxidative cascade cyclization strategy is described. The novel protocol involves the simultaneous formation of two C-S bonds and a C═S bond on the structure of enaminones in a single operation through a cascade of C(sp2)-H/C(sp3)-H bond sulfurations and C(sp3)-H bond thiocarbonylation. This transformation allows for the efficient synthesis of thiazole-2-thiones with broad tolerance in moderate to excellent yields from simple enaminones with elemental sulfur.