TABLE 1.

Optimization of the reaction conditions ^a .

Entry	Base (eq.)	Cat	Solvent	t	Yield/% b	ee/% c
1	K2CO3 (2.0)	4a	Toluene	12 h	72	58
2	K2CO3 (2.0)	4b	Toluene	12 h	78	58
3	K2CO3 (2.0)	4c	Toluene	12 h	78	55
4	K2CO3 (2.0)	4d	Toluene	5 h	76	46
5	K2CO3 (2.0)	4e	Toluene	2 day	75	−32
6	K2CO3 (2.0)	4f	Toluene	12 h	70	70
7	K2CO3 (2.0)	4g	Toluene	1 day	80	65
8	K2CO3 (2.0)	4h	Toluene	3 day	75	69
9	K2CO3 (2.0)	4i	Toluene	2 day	75	69
10	Cs2CO3 (2.0)	4f	Toluene	5 h	63	38
11	K3PO4 (2.0)	4f	Toluene	18 h	80	67
12	NaOH (2.0)	4f	Toluene	12 h	56	71
13 d	K2CO3 (2.0)	4f	Toluene	7 day	77	76
14	K2CO3 (1.0)	4f	Toluene	12 h	85	75
15	K2CO3 (0.1)	4f	Toluene	12 h	80	74
16	K2CO3 (0.1)	4f	PhCF3	2.5 day	65	68
17	K2CO3 (0.1)	4f	PhCl	2 day	88	71
18	K2CO3 (0.1)	4f	PhF	2.5 day	72	68
19	K2CO3 (0.1)	4f	THF	2.5 day	74	59
20	K2CO3 (0.1)	4f	2-Me-THF	2 day	78	65
21	K2CO3 (0.1)	4f	Mesitylene	1 day	89	80
22 e	K2CO3 (0.1)	4f	Mesitylene	2.5 day	88	80
23	‒	4f	Mesitylene	1 day	ND	‒

^a Unless otherwise noted, the reaction was performed with 0.10 mmol of 1a, 0.20 mmol of 2, catalyst 4 (5 mol%), and base in 1.0 mL solvent.

^b Isolated yield.

^c Determined by chiral HPLC analysis.

^d 0°C.

^e 4f (1 mol%) was used.