Addition of the germene Mes2Ge=CR2 to 1,4-naphthoquinone yields a singular o-quinodimethane which gives Diels-Alder reactions at room temperature and reacts cleanly with oxygen to form an endoperoxide.

Germenes Mes 2 GedCR 2 1a (Mes = 2,4,6-trimethylphenyl; CR 2 = fluorenylidene) and Mes 2 GedCR 0 2 1b (CR 0 2 =2,7-di-tert-butylfluorenylidene) react with 1,4-benzoquinone and 2,3,5,6-tetramethyl-1,4-benzoquinone to give compounds 3a, 3b, and 5a, containing a 1,4-cyclohexadiene unit as central ring. Upon prolonged storage in diethyl ether or THF solution, compounds 3a and 3b undergo a double 1,3-hydrogen shift, leading to their structural isomers 4a and 4b. Theoretical calculations performed on the model compound H 2 GedCH 2 1H postulate that the first steps of its reaction with 1,4-benzoquinone are a double [2þ2] cycloaddition between the GedC and CdO double bonds, leading to a transient dispiro compound containing two oxagermetane rings, followed by its isomerization to derivative 3H. Between 1a and 9,10anthraquinone, a double [2þ4] cycloaddition is observed involving the oxygens and the ortho-carbon atoms of one adjacent aromatic ring system, to generate the dioxadigermabenzopyrene derivative 2a.