Visible‐Light‐Induced C−H Silylation of Azauracils with Hydrosilanes

A C–H silylation of azauracils was developed via the combination of organic photoredox and hydrogen atom transfer (HAT) catalysis. Using 1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene (4CzIPN) as the photocatalyst, quinuclidine as the HAT catalyst, and silanes as the silyl radical sources, a variety of silylated azauracils were synthesized in 43‐87% yields. Moreover, pyrazinone, cinnolinone, and chromone were also compatible with this catalytic system. The reaction is suitable for late‐stage functionalization of drugs and complex molecules, and the transformation can be easily scaled up to the gram level. Mechanistic studies suggest that the silylation reaction is likely to proceed through a radical mechanism.