Access to Fully Alkylated Germanes by B(C6F5)3-Catalyzed Transfer Hydrogermylation of Alkenes.

Various cyclohexa-2,5-dien-1-yl-substituted germanes are shown to serve as easy-to-handle surrogates of hydrogermanes, including gaseous MeGeH3 and Me2GeH2. The Ge-H functional group is liberated by treatment with catalytic amounts of B(C6F5)3 and participates in situ in the B(C6F5)3-catalyzed hydrogermylation of alkenes. The range of suitable alkenes is broad, and the overall procedure provides a convenient access to tetraalkyl-substituted germanes at room temperature. Transfer hydrogermylation of internal alkynes works equally well and selectively forms the trans or cis diastereomer depending on the electronic bias of the C≡C bond.