Photocatalytic Germylation via Direct Hydrogen Atom Transfer

An innovative visible-light-driven direct hydrogen atom transfer (d-HAT) of Ge–H bond has been developed, wherein the photoexcited 9,10-phenanthraquinone (PC_HAT9) serves as an efficient photocatalyst for the generation of germanium-centered radicals from germanium hydrides including Ph₃GeH, ⁿBu₃GeH, and Ph₂GeH₂. By employing hypervalent iodine reagents as SOMOphiles, this protocol facilitates streamlined germylation through a mechanism involving germyl radical addition followed by β-cleavage of a carboxyl radical to yield a diverse array of ethynyl-, vinyl-, nitrile-, and phenyl-functionalized germanes. The methodological leap signifies a noteworthy departure from the previous photocatalytic indirect hydrogen atom transfer (i-HAT) relying on combined usage of PC_SET with abstractors, which not only advances the methodology for creating germanium radicals in a photocatalytic fashion but also provides access to structurally novel and pharmaceutically promising organogermanium compounds that are difficult to synthesize by routine methods.