4-[(Dimethylamino)methylene]-2-ferrocenyl-5-oxo-4,5-dihydrofuran-3-carboxaldehyde: Synthesis, spectral characterization and single crystal X-ray analysis

The title compound 4-[(dimethylamino)methylene]-2-ferrocenyl-5-oxo-4,5-dihydrofuran-3-carboxaldehyde was synthesized by reacting 3-ferrocenoylpropionic acid with Vilsmeier reagent. This result is rather unexpected, since 3-aroylpropanoic acids under these conditions usually give the corresponding 2-aryl-4-chloro-3-formylfurans. 3-Ferrocenoylpropanoic acid is not the only 3-aroylpropanoic acid that exhibit an unusual behavior under the same conditions: 3-thenoylpropanoic acid gave 4-[(dimethylamino)-methylene]-2-(2-thienyl)-5-oxo-4,5-dihydrofuran-3-carboxaldehyde and 4-[(dimethylamino)methylene]-2-(2-thienyl-5-formyl)-5-oxo-4,5-dihydrofuran-3-carboxaldehyde, whereas 3-(4-methoxybenzoyl)propanoic acid yielded 4-[(dimethylamino)methylene]-2-(4-methoxyphenyl)-5-oxo-4,5-dihydrofuran-3-carboxaldehyde and 2-(4-methoxyphenyl)-5-chloro-furan-3,4-dicarboxaldehyde. Single crystal X-ray analysis was successfully performed for 4-[(dimethylamino)methylene]-2-ferrocenyl-5-oxo-4,5-dihydrofuran-3-carboxaldehyde and 4-[(dimethylamino)methylene]-2-(2-thienyl)-5-oxo-4,5-dihydrofuran-3-carboxaldehyde and their structures were compared.

Graphical abstractFrom 3-ferrocenoylpropionic acid and Vilsmeier reagent compound 4-[(dimethylamino)methylene]-2-ferrocenyl-5-oxo-4,5-dihydrofuran-3-carboxaldehyde was synthesized. Under the same conditions electron-rich 3-aroylpropanoic acids, 3-thenoylpropanoic and 3-(4-methoxybenzoyl)propanoic acid gave similar products. This result is rather unexpected, since 3-aroylpropanoic acids under these conditions usually give the corresponding 2-aryl-4-chloro-3-formylfurans. Single crystal X-ray analysis was successfully performed for 4-[(dimethylamino)methylene]-2-ferrocenyl-5-oxo-4,5-dihydrofuran-3-carboxaldehyde and 4-[(dimethylamino)-methylene]-2-(2-thienyl)-5-oxo-4,5-dihydrofuran-3-carboxaldehyde.Figure optionsDownload full-size imageDownload as PowerPoint slide