Br[C:2]1[N:3]=[CH:4][C:5]([NH2:13])=[N:6][C:7]=1[C:8]1[O:9][CH:10]=[CH:11][CH:12]=1.[CH:14]([O:16]CCCC)=[CH2:15].C([O-])(=O)C.[K+].C1(P(C2C=CC=CC=2)CCCP(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.Cl.C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C.O.ClCCl.C([O-])(=O)C.[Pd+2].C([O-])(=O)C>[NH2:13][C:5]1[N:6]=[C:7]([C:8]2[O:9][CH:10]=[CH:11][CH:12]=2)[C:2]([C:14](=[O:16])[CH3:15])=[N:3][CH:4]=1To a stirred solution of 5-bromo-6-(2-furyl)pyrazin-2-amine (Preparation 2, 1.5 g, 6.3 mmol) in a mixture of DMF (16 mL) and water (4 mL) was added butyl vinyl ether (4.10 mL, 31.5 mmol), potassium acetate (3.80 mL, 7.56 mmol), 1,3-bis-(diphenylphosphino)propane (0.172 g, 0.416 mmol) and palladium(II) acetate (42.0 mg, 0.189 mmol)1. The mixture was subjected to three cycles of evacuation-backfilling with argon and heated at 122° C. under microwave irradiation. After 4 h, the mixture was cooled to room temperature and hydrolyzed by adding of HCl 2N (30 mL) for 30 min. The mixture was then neutralized with a saturated solution of potassium carbonate and diluted with dichloromethane. The organic layer was separated, dried (Na2SO4) and evaporated. The residue was purified by silica gel flash chromatography (2% methanol in dichloromethane). Concentration in vacuo of the product-rich fractions provided the titled compound as a pale-yellow solid (0.77 g, 60%). 1K. S. A. Vallin, M. Larhed, A. Hallberg, J. Org. Chem., 2001, 66, 4340.
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