Table 2.

Examination of steric effect on enantioselectivity^a.

Entry	R	er	Charton value	△△G≠ (kcal K−1 mol−1)b
1	OMe	88.06:11.94	0.36	1.16
2	OEt	96.0:4.0	0.48	1.85
3	Ph	96.52:3.48	0.57	1.93
4	Me	92.42:7.58	0.52	1.46
5	Et	94.02:5.98	0.56	1.60
6	nBu	95.45:4.55	0.68	1.77
7	iPr	96.66:3.34	0.76	1.96
8	Cl	18.32:81.68	0.55	0.87
9	Br	16.95:83.05	0.65	0.93

^aReaction conditions: 1 (0.1 mmol), CuCl (10 mol%), L1 (15 mol%), (R)-CPA (0.1 mmol), toluene (2.0 mL), 20 °C for 36 h. Yields of isolated products, er values were determined by chiral HPLC.

^bΔΔG^≠ = RTln(er), R = 0.001986 kcal K⁻¹ mol⁻¹, T = 293.15 K.