Br[C:2]1[C:10]([CH3:11])=[CH:9][C:5]2[N:6]=[CH:7][O:8][C:4]=2[CH:3]=1.[NH2:12][C:13]1[CH:18]=[CH:17][C:16](B2OC(C)(C)C(C)(C)O2)=[CH:15][N:14]=1.[O-]P([O-])([O-])=O.[K+].[K+].[K+]>C(#N)C.O1CCOCC1.O.CC(P(C(C)(C)C)C1C=CC(N(C)C)=CC=1)(C)C.CC(P(C(C)(C)C)C1C=CC(N(C)C)=CC=1)(C)C.Cl[Pd]Cl>[CH3:11][C:10]1[C:2]([C:16]2[CH:17]=[CH:18][C:13]([NH2:12])=[N:14][CH:15]=2)=[CH:3][C:4]2[O:8][CH:7]=[N:6][C:5]=2[CH:9]=1A mixture of 6-bromo-5-methybenzoxazole (43) (91 mg, 0.43 mmol), 2-aminopyridine-5-boronic acid pinacol ester (11) (220 mg, 1 mmol), Bis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium (II) (A-Phos) (30 mg) and K3PO4 (127 mg, 0.6 mmol) in 1.5 ml ACN, 1.5 ml dioxane, 0.5 ml H2O was bubbled with argon before heated at 85° C. for 2 h. After cooling down to r.t., the reaction mixture was taken up in EA, washed with aq. NaHCO3 and brine, dried over Na2SO4, concentrated to dryness. The resulting red solid was dissolved in DCM and subjected to silica gel column purification using 0-100% B (A: hexane; B: EA) to furnish 79.9 mg 5-(5-methylbenzoxazol-6-yl)-2-pyridylamine (44) as orange solid (yield: 82.5%, purity>90%)
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