2. Scope of Substrates Using (R)-3a or (R)-3b .

entry	(R)-3	2: R, Ar	4	anti/syn	ee (%)
1	3b	2b: 4-FC6H4, Ph	4ab	>95/5	98
2	3b	2c: 4-ClC6H4, Ph	4ac	>95/5	98
3	3b	2d: 4-BrC6H4, Ph	4ad	>95/5	98
4	3a	2d	4ad	>95/5	98
5	3a	2d	4ad	>95/5	98
6	3a	2e: 4-CF3C6H4, Ph	4ae	>95/5	99
7	3a	2f: 4-MeC6H4, Ph	4af	94/6	99
8	3b	2g: 3-MeC6H4, Ph	4ag	>95/5	91
9	3a	2h: 3-FC6H4, Ph	4ah	91/9	92
10	3a	2i: 2-FC6H4, Ph	4ai	>95/5	99
11	3b	2j: 2-naphthyl, Ph	4aj	>95/5	98
12	3b	2k: 2-thiophenyl, Ph	4ak	83/17	92
13	3b	2l: Ph, 4-BrC6H4	4al	94/6	99
14	3b	2m: Ph, 4-MeC6H4	4am	93/7	95
15	3a	2n: cyclohexyl, Ph	4an	87/13	29, 18
16	3a	2a: Ph, Ph	4ca	73/27	90, 81

^aReaction conditions: 1a (0.20 mmol), 2 (0.30 mmol), and (R)-3 (5 mol %) in Et₂O (2 mL, 0.1 M) under a nitrogen atmosphere at 0 °C for 4 h unless otherwise specified.

^bDiastereomeric mixtures were formed quantitatively, and the diastereomeric ratio (anti/syn) was determined by ¹H NMR measurements after short path silica-gel column chromatography.

^cThe enantiomeric excess was determined by HPLC analysis using a chiral stationary phase column.

^dGram-scale experiment: 1a (2.0 mmol), 2d (3.0 mmol), and (R)-3a (2.5 mol %, 0.05 mmol) in Et₂O (20 mL, 0.1 M).

^eFor 12 h.

^fA 63% combined yield of diastereoisomers.

^gUse 1c (0.20 mmol) instead of 1a for 16 h.