Table 2. Substrate scope ^a .

4/ent-4	R1	R2	R3	Yield b (%)	ee c (%)
4a	OEt	Ph	Ph	61	98
4b	OEt	4-FC6H4	Ph	64	99
4c	OEt	4-ClC6H4	Ph	55	99
4d	OEt	4-MeC6H4	Ph	63	93
4e	OEt	4-MeOC6H4	Ph	67	97
4f	OEt	2-Thienyl	Ph	61	91
4g	OEt	Ph	4-FC6H4	60	98
4h	OEt	Ph	4-ClC6H4	61	97
4i	OEt	Ph	3-ClC6H4	69	97
4j	OEt	Ph	4-MeC6H4	73	99
4k	OEt	Ph	2-MeC6H4	49	95
4l	OEt	Ph	4-MeOC6H4	39	96
4m	OEt	Ph	2-Thienyl	50	97
4n	OMe	Ph	Ph	58	97
4o	Me	Ph	Ph	50	96
ent-4a	OEt	Ph	Ph	69	96
ent-4b	OEt	4-FC6H4	Ph	63	97
ent-4c	OEt	4-ClC6H4	Ph	51	95
ent-4d	OEt	4-MeC6H4	Ph	64	98
ent-4e	OEt	4-MeOC6H4	Ph	66	95
ent-4f	OEt	2-Thienyl	Ph	59	96
ent-4h	OEt	Ph	4-ClC6H4	60	97
ent-4k	OEt	Ph	2-MeC6H4	50	96

^aReaction conditions: 0.5 mmol of 1, 0.5 mmol of 2, 1 mol% of I (entry 1–17) or II, 1.0 mmol of 3 and 30 mol% of DBU (0.1 M in CH₂Cl₂).

^bYield of isolated product after column chromatography.

^cEnantiomeric excess of the major diastereomer determined by HPLC analysis on a chiral stationary phase.