Highly Site-Selective Direct C−H Bond Functionalization of Unactivated Arenes with Propargyl α‑Aryl-α-diazoacetates via Scandium Catalysis

Highly chemo- and regio-selective C–H bond functionalization of unactivated arenes with propargyl α-aryl-α-diazoacetates is developed using scandium catalysis. Variety of unactivated, mildly deactivated and electronically activated arenes are functionalized using this protocol. We have explored the novel combination of scandium triflate and propargyl α-aryl-α-diazoacetate as catalyst-reagent system for the effective C–H bond functionalization. The protocol avoids the use of expensive catalysts and practicality of the protocol has been demonstrated by the gram scale synthesis of very useful α-diarylacetates including antispasmodic drug-adephenine.