Oxidation of the inert sp C-H bonds of tetrahydroisoquinolines through C-H activation relay (): construction of functionalized isoquinolin-1-ones

A TBN/O 2 -initiated oxidation of the relatively inert 3,4-C-H bonds of THIQs was accomplished, in which the existence of an α-phosphoric ester group is crucial to enable dioxygen trapping and intramolecular HAT (C-H activation relay, CHAR ), realizing the synthesis of a series of isoquinolin-1-ones in high yields. The mechanistic study confirmed that the formation of the 3,4-double bond is mediated by the CHAR process. This work provides a new strategy to achieve remote C-H bond activation. An unprecedented functionalization of the 3,4-C-H bonds of THIQs was realized by CHAR , accomplishing the shift of radical center from the active position to the inert position.