Table 1.

Optimizing the stereo effect of chiral N-phosphonyl imines^a

entry	substrate	auxiliary	reaction time	drb,c
1	5a		>8.5 h	100:42
2	5b		>8.5 h	100:15
3	5c		8 h	>99:1

^aReaction conditions: 0.57 mmol imine, 1.15 mmol methyl-2-bromo acetate, 1.20 mmol LiHMDS 14 mL solvent, −78 °C.

^bDiastereoselectivities were determined by ³¹P-NMR analysis of crude products.

^c>99:1 means only one isomer was observed by ³¹P NMR.