Annulative Coupling of β‐Ketosulfoxonium Ylides and β‐Ketothioamides: Access to Thiazolines and Thiazolidin‐4‐Ones

A catalyst‐ and additive‐free one‐step protocol for synthesizing thiazolines and thiazolidin‐4‐ones, utilizing the annulative coupling between β‐ketosulfoxonium ylides and β‐ketothioamides has been described. The dual functionalization of β‐ketosulfoxonium ylides through S‐alkylation and intramolecular N‐cyclization leads to the generation of both C−S and C−N bonds. The developed synthetic methods facilitate the synthesis of diverse functionalized thiazolines and thiazolidin‐4‐one derivatives, validated through large‐scale reactions.