Structure-Modified Germatranes for Pd-Catalyzed Biaryl Synthesis

Germanium, a member of 14th group that falls between Si and Sn, has remained considerably ignored as a nucleophile for a long time. Compared with other forms of Ge-containing nucleophiles, germatranes are structure-defined, easily accessible, and stabilized nucleophilic fragments, but they fail to meet the need of high reactivity and facile introducing to organics. Herein, we report a modified structure of germatranes, whose cross-coupling reactivity is greatly improved. The structure can be easily constructed from inexpensive industrial GeO₂, and corresponding Ge-Cl and Ge-H can also be obtained after facile transformations. Moreover, Ar-Ge can be effectively synthesized either from Grignard reagents or Pd-catalyzed germylation of aryl halides.