Access to thiazoles via [3+2] cycloaddition of 1,2,3-thiadiazoles with isonitriles

Sulfur-containing heterocycles are important structural units that could be commonly found in pharmaceuticals and functional molecules. Herein, we report a cycloaddition of 1,2,3-thiadiazoles with isonitriles to obtain 4,5-disubstituted thiazoles that are not easily attainable by traditional methods. This work is the first example of the cycloaddition of thioketenes with isonitriles in the presence of base, wherein no competitive carbon nucleophilic cyclization was observed and sulfur nucleophilic cyclization resulted in the formation of thiazoles. We expect this protocol to offer a new idea for the preparation of sulfur-containing aromatic heterocycles through the cyclization of thioketenes with dipoles or their equivalents.