Synthesis of pyrrole disulfides via umpolung of β-ketothioamides.

A Na 2 CO 3 -promoted reaction of β-ketothioamides (KTAs) and cyanoacetates was developed for the synthesis of pyrrole disulfides using air as a green oxidant. This protocol features a broad substrate scope and mild reaction conditions. Preliminary mechanistic studies indicate that the reaction involves a tandem unusual umpolung of KTAs, N -cyclization, tautomerization and oxidative coupling process.