Table 3.

Asymmetric addition of lithium enolates of different 2-bromoacetates onto N,N-diisopropylphosphonyl benzaldimine^a

Entry	R	Product	Yield(%)b	drc,d
1	Ethyl		78	99.4:0.6
2	Isopropyl		77	>99:1
3	tert-Butyl		74	>99:1

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

^bIsolated yield of the pure product.

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

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