Research on the Tandem Reaction via Chloropalladation/Heck Cross Coupling of o-(Alkynyl)styrenes with Pd/O₂

Abstract

An economic and environmental synthestic method for 3-chloroindenes from o-(alkynyl)styrenes through tandem reactions including choropalladation/Heck cross coupling in Pd/O 2 system was reported. Taking green dioxygen as sole oxidant and LiCl as chlorine source, 13 functionalized 3-chloroindenes could be synthesized in moderate to high yield without the addition of CuCl 2

LiCl-Mediated and Palladium-Catalyzed Oxidative Cyclization of Furan–Ynes via Dearomatizing Alkoxyalkenylation of Furan

“…During this process, alkynes could react with various nucleophiles and generate diverse vinylpalladium species, which are prone to Heck-type insertion with alkenes (Scheme a) . Since Lu’s seminal reports of 1,6-enyne cyclization initiated by chloropalladation, , this type of cyclization has been extensively developed by Zhang, Liu, Volla, Qiu, Liu, and Sridharan . Mechanistically, chloropalladation-initiated enyne cyclization falls into two groups: redox–neutral cyclization , and oxidative cyclization. ,− These chloropalladation-initiated oxidative cyclization reactions of enynes are mostly focused on enynes with activated alkene units.…”

“…Since Lu’s seminal reports of 1,6-enyne cyclization initiated by chloropalladation, , this type of cyclization has been extensively developed by Zhang, Liu, Volla, Qiu, Liu, and Sridharan . Mechanistically, chloropalladation-initiated enyne cyclization falls into two groups: redox–neutral cyclization , and oxidative cyclization. ,− These chloropalladation-initiated oxidative cyclization reactions of enynes are mostly focused on enynes with activated alkene units. Due to inherent nucleophilicity and inferior oxidative resistance of electron-rich alkenes; however, chloropalladation-initiated oxidative cyclization of enynes with unactivated electron-rich alkene units, such as furan, remains significantly underexplored.…”