Screening of the catalysts for the asymmetric alkylation of N-methylindole 3a with α,β-unsaturated 2-acyl imidazole 4a^a.

Entry	Cat.	Solvent/T (°C)	T (h)	% Yb	% eec
1	1a	CH2Cl2/25	3	90	65
2d	1a	CH2Cl2/25	4	92	60
3e	1a	CH2Cl2/25	5	88	58
4	1a	CH2Cl2/5	10	91	73
5	1b	CH2Cl2/5	10	98	79
6	1c	CH2Cl2/5	15	90	69
7	1d	CH2Cl2/5	12	87	57
8	1e	CH2Cl2/5	10	99	85
9	1f	CH2Cl2/5	10	94	71
10	1e	CH2Cl2/−15	24	95	90
11	1e	ClCH2CH2Cl/−15	24	97	93
12	1e	CH3Cl/−15	24	96	91
13	1e	CH3CN/−15	20	92	95
14	1e	CH3CN/−25	48	91	97.5

^aReaction conditions: 3a (0.45 mmol), 4a (0.3 mmol), 1 (5 mol%), 4 Å MS (100 mg) and solvent (3 mL), under argon.

^bIsolated yield.

^cDetermined by chiral-phase HPLC.

^dWithout 4 Å MS.

^eWithout 4 Å MS, under air.