Table 1. Copper-Catalyzed Asymmetric Addition of Styrene-Derived Nucleophiles to Imines: Effect of Reaction Parameters^a.

entry	variation from the “standard conditions”	yield of 3 (dr)	ee of 3	yield of 4
1	none	95% (3:1)	99% ee (99% ee)b	1.5%
2	L1 instead of L6	9% (1:1)	95% ee (99% ee)	85%
3	L2 instead of L6	<5%	n.d.	65%
4	L3 instead of L6	<5%c	n.d.	20%
5	L4 instead of L6	56% (1:1)	86% ee (83% ee)	35%
6	L5 instead of L6	46% (1:1)	78% ee (70% ee)	54%
7	no t-BuOH	41% (3:1)	99% ee (99% ee)	31%
8	2b instead of 2a	5%d	n.d.	36%
9	2c instead of 2a	6%e	n.d.	<10%

^aReaction conditions: 1 (0.2 mmol), 2 (0.1 mmol), Cu(OAc)₂ (5 mol %), L (6 mol %), t-BuOH (2 equiv), (MeO)₂MeSiH (5 equiv), THF (0.5 M), rt, 12 h. Yields were determined by ¹H NMR spectroscopic analysis using 1,3,5-trimethoxybenzene as the internal standard. Enantiomeric excess values were determined by chiral HPLC analysis.

^bThe ee of the minor diastereomer is shown in parentheses.

^c30% conv. of 2a.

^d41% conv. of 2b.

^e12% conv. of 2c.