Table 3. Optimization of Reaction Conditions for Indoline 5a^a.

entry	base	solvent	yield (%)b
1	K2CO3	THF	26
2	Cs2CO3	THF	65
3	KOtBu	THF	31
4	Na2CO3	THF	52
5	Cs2CO3	CH2Cl2	77
6	Cs2CO3	CH3CN	74
7	Cs2CO3	Et2O	48

^aReaction conditions: 1a (0.15 mmol), 4a (0.1 mmol), and base (0.2 mmol) were reacted at room temperature.

^bIsolated yield based on 4a.