A General Synthetic Method for 1,1′-Bis(diacetylene-group)-Connected Ferrocene and π-Electronic System

In contrast to the facile synthon ethynylferrocene for diacetylene ferrocene (Fc) derivatives, 1,1'-diethynylferrocene for the corresponding 1,1'-bis(diacetylene-group)-connected Fc derivatives is extremely difficult to handle under ordinary conditions, giving rise to spontaneous self-polymerization. Under modified Eglinton oxidative coupling conditions, it has been possible to generate 1,1'-diethynylferrocene in situ readily from a trimethylsilyl-protected precursor and to react it with other terminal acetylenes. The present tandem reactions could provide a general synthetic method for an extended pi-electronic conjugation system of 1,1'-bis(diacetylene-group)-connected Fe derivatives, of which the chemistry has been scarcely developed.