Table 1.

Optimization of reaction conditions for synthesis of compound 1 to 8.

Entry	Base	Solvent	T (°C)	t (h)	Yielda (%)
1	Pyridine	Toluene	110	12	39
2	K2CO3	Toluene	110	12	32
3	NaOH	Toluene	110	12	45
4	KOH	Toluene	110	12	53
5	Cs2CO3	Toluene	110	12	74
6	Cs2CO3	DMSO	110	12	40
7	Cs2CO3	DCM	40	12	Trace
8	Cs2CO3	THF	60	12	20
9	Cs2CO3	Toluene	25	12	Trace
10	Cs2CO3	Toluene	60	12	29
11	Cs2CO3	Toluene	110	18	91
12	Cs2CO3	Toluene	110	24	94

Reaction conditions: ethyl 4-bromobenzoate (1 mmol), piperonyl alcohol (1.1 mmol), Cs₂CO₃ (1 mmol), and toluene (5 mL).

^aIsolated yields.