Ferrocenyl and pyridyl methylenepyrans as potential precursors of organometallic electron-rich extended bipyrans: Synthesis, characterization and crystal structure

Ferrocenyl and pyridyl methylenepyrans were obtained from a Wittig reaction between a pyran phosphorane and ferrocenyl or pyridyl-aldehydes. The nucleophilic nature of the exocyclic C–C bond allowed the formylation of these compounds by a Vilsmeier type reaction. All the new products were characterized by IR spectroscopy, 1H and 13C NMR spectroscopy, mass spectroscopy and (or) elemental analysis. Electrochemistry of representative compounds 2, 10 and 13 was undertaken. In addition, a crystal structure of the ferrocenylpyranylidene aldehyde 5 was described, and the pyrylium character of this compound was specified.