Tandem Synthesis of 1,2,3-Thiadiazoles with 3,4-Dichloroisothiazoles and Hydrazines under External Oxidant- and Sulfur-Free Conditions.

1,2,3-Thiadiazoles are among the most important heterocyclic motifs, with wide applications in natural products and medicinal chemistry. Herein, we disclose a tandem reaction for the synthesis of structurally diverse 1,2,3-thiadiazoles from 3,4-dichloroisothiazol-5-ketones and hydrazines. This method is characterized by mild external oxidant- and sulter-free reaction conditions, a broad substrate scope, and easy purification.