Synthesis of α-Alkenyl α,β-Unsaturated Ketones via Dehydrogermylation of Oxagermacycles with Regeneration of the Germanium(II) Species

The synthesis of α-alkenyl α,β-unsaturated ketones using germanium(II) salts is reported. Oxagermacycles derived from α,β-unsaturated ketones with germanium(II) salts and aldehydes can be transformed into α-alkenyl α,β-unsaturated ketones. Ammonium salts promoted the elimination of Ge(II) species to afford the two classes of α-alkenyl α,β-unsaturated ketones in good yields. The α-alkenyl α,β-unsaturated ketones are precursors for multisubstituted heterocycles.