Scheme 2. Substrate Scope of 2,3-Disubstituted Pyrimido[1,2-b]indazoles a,b a Reaction conditions: 1 (1.2 mmol), I 2 (1.0 mmol) in DMSO (4 mL) at 100 °C for 1 h, and then 2 (1.2 mmol), 3a (1.0 mmol), and FeCl 3 (1.5 mmol) were added to react at 100 °C for 5 h. b Isolated yields.