Rh(iii)-catalyzed sp 3 /sp 2 -C-H heteroarylations via cascade C-H activation and cyclization.

The development of an efficient strategy for facile access to quinoline-based bis-heterocycles holds paramount importance in medicinal chemistry. Herein, we describe a unified approach for accessing 8-(indol-3-yl)methyl-quinolines by integrating Cp*Rh(iii)-catalyzed C(sp 3 )-H bond activation of 8-methylquinolines followed by nucleophilic cyclization with o -ethynylaniline derivatives. Remarkably, methoxybiaryl ynones under similar catalytic conditions delivered quinoline tethered spiro[5.5]enone scaffolds via a dearomative 6 -endo-dig C-cyclization. Moreover, leveraging this method for C8(sp 2 )-H bond activation of quinoline- N -oxide furnished biologically relevant oxindolyl-quinolines. This reaction proceeds via C(sp 2 )-H bond activation, regioselective alkyne insertion, oxygen-atom-transfer (OAT) and intramolecular nucleophilic cyclization in a cascade manner. One C-C, one C-N and one C[double bond, length as m-dash]O bond were created with concomitant formation of a quaternary center.