Photo-oxidative Ruthenium(II)-Catalyzed Formal [3+2] Heterocyclization of Thioamides to Thiadiazoles

An operationally simple and sustainable one-pot photo-oxidative formal [3 + 2] heterocyclization of beta-ketothioamides with aryldiazonium salts catalyzed by Ru(bpy)(3)Cl-2 has been realized to provide 2,4-disubstituted 5-imino-1,2,3-thiadiazoles in good to high yields under mild reaction conditions for the first time. The reaction proceeded via an a-phenylhydrazone adduct of thioamides leading to 1,2,3-thiadiazoles via N-S bond formation at room temperature. Notably, the products possess Z-stereochemistry with regard to the exocyclic C = N double bond at the 5-position of the ring.

Automated summary

An operationally simple and sustainable one-pot photo-oxidative formal [3 + 2] heterocyclization of beta-ketothioamides with aryldiazonium salts catalyzed by Ru(bpy)(3)Cl-2 has been realized to provide 2,4-disubstituted 5-imino-1,2,3-thiadiazoles in good to high yields under mild reaction conditions for the first time. The reaction proceeded via an a-phenylhydrazone adduct of thioamides leading to 1,2,3-thiadiazoles via N-S bond formation at room temperature. Notably, the products possess Z-stereochemistry with regard to the exocyclic C = N double bond at the 5-position of the ring.