Br[C:2]1[CH:3]=[C:4]([CH:7]=[CH:8][C:9]=1[F:10])[CH:5]=[O:6].[S:11]1[CH:15]=[CH:14][CH:13]=[C:12]1B(O)O.C(=O)([O-])[O-].[Na+].[Na+].O>COCCOC.[Pd].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>[F:10][C:9]1[CH:8]=[CH:7][C:4]([CH:5]=[O:6])=[CH:3][C:2]=1[C:12]1[S:11][CH:15]=[CH:14][CH:13]=1Ex-20A: A solution of 3-bromo-4-flouro-benzaldehyde (5.0 g, 24.6 mmol) and thiophene-2-boronic acid (4.7 g, 37.0 mmol) in ethylene glycol dimethyl ether (100 mL) was stirred at room temperature under nitrogen for 15 min. Then tetrakis(triphenylphosphine)-palladium(0) (2.8 g, 2.42 mmol) and a sodium carbonate solution (2 M, 33 mL) were added, and the resulting mixture was refluxed under nitrogen overnight. Upon cooling to room temperature the reaction was poured into water (100 mL) and extracted with ethyl acetate (2×100 mL). The organic phase was dried over magnesium sulfate, and the solvent was removed under reduced pressure. Silica gel chromatography (hexane/ethyl acetate, 1:1) gave 4.8 g (95%) of the desired 4-fluoro-3-(thiophen-2-yl)-benzaldehyde product as a yellow oil. 1H-NMR (300 MHz, CDCl3) δ 10.0 (s, 1H), 8.18 (dd, 1H, J=7.3 and 2.4 Hz), 7.80 (m, 1H), 7.56 (dd, 1H, J=3.7 and 1.7 Hz), 7.44 (d, 1H, J=5.1 Hz), 7.36 (m, 1H), 7.16 (dd, 1H, J=5.1 and 3.7 Hz).
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