Table 1.

Optimization of the reaction conditions^a.

Entry	Solvent	Temperature	Time, h	Yield, %
1	MeCN	reflux	0.5	15
2	MeCN	reflux	3	22
4	MeCN	reflux	6	18
5	MeCN	rt	3	13
6	MeCN	rt	12	44
7	MeCN	rt	24	62
8	MeCN	rt	48	61
9	dioxane	rt	24	54
10	toluene	rt	24	49
11	CH2Cl2	rt	24	51

^aReaction conditions: 3a (0.37 g, 1 mmol), CDI (0.49 g, 3 mmol), DBU (0.17 g, 1.1 mmol), solvent (7 mL).