Site-Selective C(sp)-H and Switchable C(sp)-H/C(sp)-H Functionalization Enabled by Electron-Deficient Cp*Ir(III) Catalyst and Photosensitizer.

A site-selective functionalization of a C(sp)-H bond was achieved in the presence of an intrinsically more reactive C(sp)-H bond by controlling the orientation of a directing group via a photo-induced E/Z isomerization of an oxime ether. By combining E/Z isomerization and an electron deficient Cp*Ir(III) catalyst, the scope of oxime ethers in C(sp)-H functionalization was successfully expanded. Based on this strategy, the order of C-H activation was switchable and successive C(sp)-H/C(sp)-H and C(sp)-H/C(sp)-H double functionalizations were accomplished to construct densely functionalized structures.