Reactions of cyclotrigermane and germylenes with carbonyl compounds: Cycloadducts and oligomers

Reactions of germylenes, generated by thermolysis of cyclotrigermanes, or of bulky germylenes, with various α‐dicarbonyl compounds are described. They proceed through a radical pathway, as confirmed by ESR measurements, to give different types of compounds. In the reaction of (Mes₂Ge)₃ with fluorenone, formation of the 2:1 ketone/germylene cycloadduct and of the oxadigermetane, resulting from a transient digermene, occurred. In the case of acenaphthene quinone, we observed the first example of cycloaddition between a digermene and an α‐diketone. The X‐ray crystal structure of the product shows a drastically distorted six‐membered ring system. The formation of oligomeric adducts was observed with parabenzoquinone. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 125–132, 1999