Synthesis, characterization and the crystal structures of novel achiral and chiral α-ferrocenyl α-aminophosphine oxides

Novel achiral α-ferrocenyl α-aminophosphine oxides (2a–2e) have been prepared by the reaction of ferrocenylaldimines (1a–1e) with Ph2PLi at room temperature in 63–92% yield. Similarly, starting from l-phenylalaninol derived ferrocenylaldimine (3), the corresponding (S,S)-phosphine oxide (4) and its (R,S)-diastereomer (5) were isolated by fractional crystallization in 41% and 16% yield, respectively. All the achiral and chiral α-aminophosphine oxides were air-stable and easily accessible. They were fully characterized by elemental analysis, 1H NMR, 31P NMR and IR spectra. In addition, structures of 2e and 4 have been determined by X-ray single-crystal analysis.