Rhodium(III)-Catalyzed Dual C-H Activation/Annulation of 1-(2-Pyridinyl)isoquinoline with Internal Alkynes: Synthesis of 1,1'-Biisoquinoline Derivatives

Transition-metal-catalyzed nitrogen directing group-assisted C–H bond functionalization has emerged as an efficient and atom/step-economical strategy to realize the derivatization of various organic compounds. Herein, we have described a new method for the efficient synthesis of 1,1'- biisoquinoline derivatives through Rh(III)-catalyzed dual C-H activation reaction of 1-(2- pyridinyl)isoquinoline, which involves the construction of a new aromatic ring through a cascade CH activation/[2 + 2 + 2] annulation with two internal alkynes. The catalytic system exhibits good substrate compatibility. Electron-withdrawing and electron-donating substituents at different positions on the substrates 1-(2-pyridinyl)isoquinoline or diphenylacetylene enable the catalytic C-H annulation reaction to proceed smoothly. This work has provided a novel approach for the synthesis of 1,1'-biisoquinoline derivatives from the perspective of organic synthesis.