Synthesis and characterization of new lithiated organogermanium compounds

New (8-methoxy-1-naphthyl)arylgermanes 1a-c are synthesized. The crystal structure of 1b (aryl = mesityl), determined by X-ray diffraction, shows that an intramolecular interaction occurs between the oxygen and germanium atoms, the Ge---O distance being 2.75 Angstrom. The corresponding (diarylgermyl)lithiums R(2)HGeLi are prepared in high yield by hydrogermolysis of tert-butyllithium in THF and are susprisingly stable. Their characterization by H-1, C-13, and Li-7 NMR spectroscopy is reported. Dimetalation of the initial arylgermanes depends upon steric hindrance around the germanium atom and the nature of the organolithium compound RLi. The reaction of 1a or 1c with n-BuLi followed by Mel affords the expected dialkylation product, whereas 1b gives the unexpected iodide 5b due to steric hindrance around the germanium atom.