Et3B Induced Stereoselective Radical Addition of Ph3GeH to Carbon–Carbon Multiple Bonds and Its Application to Isomerization of Olefins

Triphenylgermane easily adds to acetylenes or terminal olefins in the presence of Et3B to give alkenyltriphenylgermane or alkyltriphenylgermane respectively under excellent control of regio- and stereoselectivities. While Et3B catalyzed addition of Ph3GeH to 1-dodecyne at −78 °C affords (Z)-1-triphenygermyl-1-dodecene exclusively, the addition of Ph3GeH at 60 °C provides (E)-1-triphenylgermyl-1-dodecene as a single product. The triphenylgermyl radical is also effective to isomerize Z-olefins into their thermodynamically more stable E-isomers.