CC1(C)C(C)(C)OB([C:9]2[CH:10]=[N:11][CH:12]=[C:13]([CH:19]=2)[C:14]([O:16][CH2:17][CH3:18])=[O:15])O1.Br[C:22]1[O:26][C:25]([CH:27]=[O:28])=[CH:24][CH:23]=1.C([O-])([O-])=O.[Cs+].[Cs+]>O.O1CCOCC1.O.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.Cl[Pd]Cl.[Fe+2]>[CH:27]([C:25]1[O:26][C:22]([C:9]2[CH:10]=[N:11][CH:12]=[C:13]([CH:19]=2)[C:14]([O:16][CH2:17][CH3:18])=[O:15])=[CH:23][CH:24]=1)=[O:28]A solution of ethyl 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)nicotinate (570 mg, 2.06 mmol), 5-bromofuran-2-carbaldehyde (300 mg, 1.71 mmol), Cs2CO3 (1.125 g, 3.46 mmol) and PdCl2(dppf) (65 mg, 0.09 mmol) in H2O/dioxane (5%, 10 mL) was heated at reflux for 15 min. The reaction mixture was cooled to rt and diluted with H2O (100 mL). The resulting precipitate was collected by filtration to yield the desired ethyl 5-(5-formylfuran-2-yl)nicotinate (420 mg). LCMS (ES): m/z 246 [M+1]+.
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