Table 1. Optimization of the Reaction Conditions for the Model Reaction^a.

entry	solvent	promoter	t (°C)	time (h)	yieldb (%)
1	CH3CN		reflux	12	nr
2	CH3CN	AgOTf	reflux	12	nr
3	CH3CN	Cu(OTf)2	reflux	12	nr
4	CH3CN	K2CO3	reflux	12	33
5	CH3CN	Cs2CO3	reflux	12	62
6	1,4-dioxane	Cs2CO3	reflux	12	68
7	1,4-dioxane	t-BuOK	reflux	12	complex
8	CH3CN	DBU	reflux	12	82
9	1,4-dioxane	DBU	reflux	12	nr
10	acetonec	DBU	reflux	12	90
11	EtOH	DBU	reflux	12	12
12	acetone	DABCO	reflux	12	nr
13	acetone	Et3N	reflux	12	nr
14	acetone	DBU	reflux	8	85
15	acetone	DBU	reflux	16	89

^aReaction conditions: 1a (1.1 mmol), 3a (1.0 mmol), base (2.0 mmol), solvent (15 mL).

^bIsolated yield based on 3a. nr = no reaction.

^cBold entry indicates the best condition.