Synthesis of the first 1,3-disubstituted 1,3-butadienyl heteroannular bridged [4]ferrocenophane

An unusual heteroannular cyclization of methyl 4-(((1′-(trimethylsilyl)ethynyl)ferrocenyl)ethynyl)benzoate (11) under the basic desilylation condition yielded 1,1′-(l-methoxy-3-(4′-(methoxycarbonyl)phenyl)-1,3-butadienylene)ferrocene (7), the first reported 1,3-disubstituted 1,3-butadienyl heteroannular bridged [4]ferrocenophane. Compound 7 has been characterized by elemental analysis, IR spectra, 1H NMR spectroscopy and X-ray diffraction analysis. The electrochemical behavior has been investigated by cyclic voltammetry. The DFT calculation results of 7 are also reported.

Graphical abstractAn unusual heteroannular cyclization of methyl 4-(((1′-(trimethylsilyl)ethynyl)ferrocenyl)ethynyl)benzoate (11) under the basic desilylation condition yielded 1,1′-(l-methoxy-3-(4′-(methoxycarbonyl)phenyl)-1,3-butadienylene)ferrocene (7), the first reported 1,3-disubstituted 1,3-butadienyl heteroannular bridged [4]ferrocenophane. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Unusual transannular cyclization of 1′-trimethylsilylethynyl alkynylferrocene. ► Desilylation of the 1,1′-bis(alkynyl)ferrocene leads to [4]ferrocenophane. ► Structure and electrochemistry of 1,3-disubstituted butadienyl [4]ferrocenophane.