Me₃SiCl-Catalyzed Electrophilic Thiocyanation/Cyclization of Alkynylbenzoates to Synthesize 4-Thiocyanatoisocourmarins

A metal-free and regioselective electrophilic thiocyanation/cyclization of alkynylbenzoates has been developed to afford series of thiocyanato-containing isocourmarins catalyzed by Me₃SiCl. Tandem thiocyanation/6-endo cyclization of alkynylbenzoates was achieved using N-thiocyanatosuccinimide (NTS). A wide scope of substrates and functional groups have been tolerated with moderate to excellent yield up to 98%. The mild reaction conditions make this protocol more practical to access isocourmarins bearing a thiocyanato group with diverse transformations.