Formation and reactions of lithium pyridinylcarbonyl tetracarbonylferrate

Abstract

The reaction of phenyllithium-pyridine intermediate, 1-lithio-2-phenyl-1,2-dihyropyridine, with pentacarbonyliron gave an anionic pyridinylcarbonyl iron complex. Although the isolation of the complex was unsuccessful, the structure of the complex was elucidated by means of infrared, 1H and 13C NMR spectroscopy and by its reaction with various reagents. The complex was found to be formed even at -65*C, but decomposed at elevated temperatures. The hydrolysis of the pyridinylcarbonyl iron complex gave a new aldehyde, 2-phenyl-5-pyridinecarboxaldehyde. Different mole ratios of reactants affected the formation of the pyridinylcarbonyl iron complex. The pyridinylcarbonyl iron complex was treated with methyl iodide, dimethyl sulfate, benzyl bromide, ethyl iodide, n-propyl iodide and isopropyl iodide. The corresponding ketones were obtained from the reactions of the complex with methyl iodide, dimethyl sulfate and benzyl bromide. However, no corresponding ketones were obtained with ethyl iodide, n-propyl iodide and isopropyl iodide. The pyridinylcarbonyl iron complex was found to react violently with aromatic nitro compounds to give 6-phenylnicotinanilides in good yields. However, no corresponding amides were obtained from the reaction with nitromethane or 1-nitropentane.