A Highly Selective Synthesis of (E)‐11‐Arylidenebenzo [4′,5′] thieno [2′,3′ : 4,5] Pyrimido [2,1‐a] Isoindol‐13(1H)‐ones via Copper‐Catalyzed Sonogashira Coupling and Hydroamination

An efficient and highly selective reaction of 2‐(2‐bromophenyl)‐5,6,7,8‐tetrahydrobenzo [4,5] thieno[2,3‐ d ]pyrimidin‐4(3 H )‐one and terminal alkyne has been developed under palladium‐free conditions by CuI‐catalyzed sequential Sonogashira coupling reaction and 5‐exo‐dig hydroamination reaction. A series of 11‐arylidene‐2,3,4,11‐tetrahydrobenzo [4′,5′]thieno [2′,3′ : 4,5]pyrimido [2,1‐ a ]isoindol‐13(1 H )‐one derivatives with only the (E) ‐configuration were obtained.