Germylene Reactions with Quinones Shed Light on Germylene Phenone Equilibria

Ge[CH(SiMe<INF>3</INF>)<INF>2</INF>]<INF>2</INF> (<BO>1</BO>) and Ge[N(SiMe<INF>3</INF>)<INF>2</INF>]<INF>2</INF> (<BO>2</BO>) react with anthraquinone and naphthoquinone in a 2:1 ratio to form five-membered rings with the carbonyl oxygens and the ortho carbons of the adjacent aromatic ring. The reaction with 1,4-diacetylbenzene proceeds in a similar fashion with <BO>1</BO>; however no reaction is observed with <BO>2</BO>. Compounds <BO>1</BO> and <BO>2</BO> react with 1,2-diacetylbenzene to yield a novel bicyclo species. In a previous report describing equilibria between <BO>1</BO> and phenones, it appeared that <BO>2</BO> did not undergo reaction to generate the five-membered ring with the accompanying formation of a conjugated triene. However, these quinone results indicate that an equilibrium can exist between <BO>2</BO> and a phenone moiety. In the reaction with quinones, a second equivalent of germylene effectively traps the conjugated triene by undergoing a 1,4-addition reaction. Unlike the initial triene formation, this second insertion is irreversible.