Table 1.

Optimization of the reaction conditions for the synthesis of compound 7a.

entry	cat	solv	conditions	yield (%) 6aa	yield (%) 7aa
1	K2CO3	DMF	MW, 80 °C, 20 min	25	63
2	K2CO3	DMF	MW, 90 °C, 10 min	7	78
3	K2CO3	DMF	MW, 110 °C, 10 min	—	89
4	DBU	DMF	MW, 90 °C, 10 min	—	76
5	DBU	DMF	MW, 110 °C, 10 min	—	87
6	DIPA	DMF	MW, 90 °C, 10 min	—	71
7	DIPA	DMF	MW, 110 °C, 10 min	—	83
8	—	DMF	MW, 90 °C, 10 min	7	77
9	—	DMF	MW, 110 °C, 10 min	—	85
10	—	DMF	MW, 110 °C, 20 min	—	95
11	—	TFE	MW, 90 °C, 10 min	12	23
12	—	TFE	MW, 110 °C, 10 min	30	40
13	—	TFE	MW, 110 °C, 20 min	32	51
14	—	MeCN	MW, 90 °C, 10 min	—	—
15	—	THF	MW, 90 °C, 10 min	—	—
16	—	EtOH	MW, 90 °C, 10 min	—	12
17	—	EtOH	MW, 110 °C, 10 min	10	15

^aYield (%) based on the integral of the HPLC peaks detected at 254 nm. MW = microwave irradiation. Reaction conditions: 5a (0.1 mmol), additive (2.0 eq.) in DMF (1.0 mL) under microwave irradiation.