Iridium-Catalyzed Silafluorene Synthesis

Significance

An iridium-catalyzed [2+2+2] cyclo­addition of silicon-bridged diynes leads to the formation of silafluorene derivatives. Although requiring elevated temperatures, the reaction proceeds without the strongly basic and/or reducing conditions that have previously been used to synthesize silafluorenes. The authors report that the reaction also occurs with rhodium catalysis, but in lower yields. Unsubstituted terminal alkynes lead to a significantly lower yield in the one example presented by the authors.