83 mg of 1-(3-chloropyrido[2,3-b]pyrazin-6-yl)-3-ethylurea (0.33 mmol), 99 mg of 4-cyclohexylaniline (0.55 mmol), 30 mg of sodium tert-butoxide (0.30 mmol), 29 mg of tris(dibenzylideneacetone)dipalladium(0) (0.03 mmol) and 68 mg of 2-(dicyclohexylphosphanyl)biphenyl (0.19 mmol) were initially charged in 1.5 ml of dried toluene. The reaction mixture was heated to 100° C. under nitrogen in a microwave (100 watt) for 30 minutes. The solvent was removed under reduced pressure and the crude product was purified by column chromatography on silica gel (dichloromethane/methanol eluent). This gave a yellow solid.
