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

Abstract

An efficient and highly selective reaction of 2‐(2‐bromophenyl)‐5,6,7,8‐tetrahydrobenzo[4,5]thieno[2,3‐d]pyrimidin‐4(3H)‐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(1H)‐one derivatives with only the (E)‐configuration were obtained and stabilized by intramolecular C‐H…O hydrogen bonding for stabilization.