Optimized experimental conditions for the synthesis of PBIs 3.

Entry	R	Experimental conditions	Product, yield (%)
1		1 + 2a (2.1 eq.) + imidazole (10 eq.), 95 °C, 2 h	3a, 91%a
		1 + 2a (2 eq.) + imidazole (17 eq.), 110 °C, 4 h	3a, 74%a
2		1 + 2b (2 eq.) + imidazole (17 eq.), 95 °C, 3 h	3b, 92%a
3		1 + 2c (2.3 eq.) + imidazole (17 eq.), 95 °C, 3 h	3c, 95%
4		1 + 2d (2 eq.) + imidazole (17 eq.), 95 °C, 3 h	3d, 89%
5		1 + 2d (2 eq.) + imidazole (17 eq.), 110 °C, 48 h	4, 39%
6		1 + 2e (2.2 eq.) + imidazole (17 eq.), 95 °C, 3 h	3e, 92%
7		1 + 2f (2 eq.) + imidazole (17 eq.), 95 °C, 3 h	3f, 88%
8		1 + 2g (2 eq.) + imidazole (17 eq.), 95 °C, 3 h	3g, 73%
9		1 + 2h (10 eq.), 100 °C, 30 min	3h, 98%
10		1 + 2i (10 eq.), 100 °C, 30 min	3i, 96%
11		1 + 2j (2.5 eq.), EtOH, 100 °C, 2 days	3j, 74%
12		1 + 2k (10 eq.), 100 °C, 1 h	3k, 77%
13		1 + 2l (10 eq.), 100 °C, 1 h	3l, 84%
14		1 + 2m (101 eq.), 600 W, 1 h 40 minb	3m, 96%

^aReported in the literature [ref. 16].

^bBy microwave irradiation.