Germanium enolates

Kobayashi prepared a novel germanium-containing polymer, poly(germanium enolate), by reaction of a divalent germanium compound, germylene, with a cyclic a, -unsaturated ketone in the presence of a catalytic amount of a lithium compound (Scheme 11.65) [91[. 

Shoda, S., Iwata, S., Yajima, K., Yagi, K., Ohnishi, Y. and Kobayashi, S. (1997) Synthesis of germanium enolate polymers from germylene monomers. Tetrahedron 53,15281-15295. 

Aldol reactions Enolates are formed from a-bromo carbonyl compounds on reaction with germanium (prepared in situ from Gel and K). The aldol reaction is jyn-selective. 

The a-germylated ester (164) reacts with a number of aldehydes and acetals in the presence of Lewis acid to give, regioselectively, the y-products (Scheme 55). In that sense the germanium-masked di-enolate behaves like the siloxy dienes in their regioselection. 

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