Table 1.

Catalyst and solvent screening.

Entrya	Catalyst	Solvent	Time (h)	Yieldb (%)	eec (%)
1	5	toluene	1	98	63
2	6	toluene	2.5	>99	30
3	7a	toluene	0.5	92	46
4	7b	toluene	0.5	63	40
5	7c	toluene	0.5	79	52
6	8a	toluene	0.5	72	41
7	8b	toluene	0.5	96	43
8	8c	toluene	0.5	90	31
9	8d	toluene	0.5	95	25
10	9a	toluene	0.5	71	41
11	9b	toluene	0.5	94	41
12	5	DCM	2.5	42	65
13	5	hexane	1	>99	6
14	5	THF	4	85	79
15	5	CHCl3	2	50	65
16	5	dioxane	4	90	75
17	5	TBME	1	92	57
18	5	EtOAc	2	49	65
19	5	MeCN	1	81	55
20	5	Et2O	3	28	57

^aUnless stated otherwise, all reactions were performed with 0.10 mmol trans-chalcone and 0.20 mmol naphthalene-1-thiol in 0.5 mL of solvent, in the presence of 2 mol % organocatalyst at rt. ^bIsolated yields. ^cDetermined by chiral HPLC analysis, AD-H column, hexane/isopropanol (99:1), 0.8 mL/min, 220 nm.