Table 2.

Substrate scope.

entrya	R		yield (%)b	dr (syn/anti)c	ee (%)d
1	Cyclohexyl	3c	77	11:1	92
2	i-Pr	3d	79	7.1:1	90
3	CH(CH2CH3)2	3e	67	5.2:1	88
4	CH2CH(CH3)2	3f	86	3.7:1	87
5	n-Butyl	3g	56	3.9:1	87
6	CH2CH2Ph	3h	72	2.6:1	84
7		3i	84	3.6:1	88
8e	t-Butyl	3j	51	15:1	−75
9e		3k	66	19:1	−74
10e		3l	57	16:1	−72
11e,f	C6H5	3m	65	1.7:1	−92
12f	p-ClC6H4	3n	59	1.8:1	91
13f		3o	59	1.6:1	87

^aReactions performed using 0.2 mmol 1b, 2.0 equiv aldehyde, 0.025 g 4 Å molecular sieves, 20% (S, S)-2b or (R,R)-2a, and 40% Et₂Zn in THF (0.4 M) at 0 °C for 48 h.

^bIsolated Yield.

^cDetermined by 1H NMR of crude reaction mixture.

^dDetermined by chiral HPLC analysis

^e20 mol% (R,R)-3a was used.

^fRun for 72 h at −15 °C