A new practical synthesis of germylalkoxydienes, acylgermanes and ethynylgermanes from α,β-unsaturated and α-phenyl acetals

The treatment of alpha,beta-unsaturated acetals 1a-f with LIC-KOR base (equimolar mixture of n-BuLi and tert-BuOK) produces alpha-metalated alkoxy-1,3-dienes that easily react with halotrialkyl-and halotriarylgermanes producing substituted (Z)-alkoxyvinylgermanes 2a-i in good yields. Functionalized dienyl derivatives can be transformed into the corresponding acylgermanes 3a-d under mild acidic hydrolytic conditions. Furthermore, the lithium-potassium mixed reagent promotes the conversion of the a-phenyl acetal 4 into trimethyl(2-phenylethynyl)germane (5).