Table 1. Optimization of the Reaction Conditions^a.

entry	solvent	2a (mmol)	T (°C)	yieldb (%)
1	DMF	0.2	90	55
2	DMSO	0.2	90	35
3	EtOH	0.2	90	27
4	Acetone	0.2	90	49
5	EA	0.2	90	31
6	DCE	0.2	90	24
7	CH3CN	0.2	90	82
8	1,4-dioxane	0.2	90	57
9	Toluene	0.2	90	63
10	THF	0.2	90	50
11	n-hexane	0.2	90	48
12	CH3CN	0.2	70	68
13	CH3CN	0.2	110	81
14	CH3CN	0.3	90	86
15	CH3CN	0.4	90	93

^aAll reactions were performed with 1a (0.2 mmol) and 2a in solvent (2.0 mL) under an air atmosphere at 90 °C for 9 h.

^bIsolated yield. DMF = N,N-dimethylformamide, DMSO = dimethylsulfoxide, EA = ethyl acetate, DCE = 1,2-dichloroethane, and THF = tetrahydrofuran.