Chiral N-phosphonyl imine chemistry: Asymmetric addition of ketone-derived enolates for the synthesis of β-amino ketones

New chiral N-phosphonyl imines have been synthesized in good yields under convenient reaction conditions. These chiral N-phosphonyl imines can serve as efficient electrophiles for asymmetric addition reactions with lithium ketone enolates. Good chemical yields and excellent diastereoselectivities were obtained for twelve examples. The N-1-naphthyl group of the chiral auxiliary was found to be superior to its benzyl counterpart in controlling the diastereoselectivity for this reaction. The chiral auxiliary can be readily removed by treatment with aqueous HBr in methanol at room temperature to give free β-amino ketones in high yields.