Table 3.

Synthesis of highly substituted 1H-imidazo[1,2-b]pyrazoles^a.

Entry	R1	R2	R3CHO	R4NC	Product	Yieldb (%)
1	H	COOEt	2a	3a	46	54
2	H	COOEt	2b	3b	47	56
3	Me	CN	2a	3a	48	79
4	Me	CN	2c	3c	49	57
5	Me	COOEt	2a	3a	50	74
6	Me	COOEt	2i	3b	51	59

^aReaction conditions: 4b–d (0.50 mmol), 5 (0.55 mmol), ethanol (0.5 mL), MW (10 min; 4b: 150 °C, 4c,d: 120 °C; 150 W), then water (0.5 mL), 2a–c,i (0.55 mmol), TFA (0.10 mmol), 3a–c (0.55 mmol), room temperature, 10–60 min. ^bIsolated yield after simple filtration.