[CH:1]([C:3]1[S:7][C:6](B(O)O)=[CH:5][C:4]=1[CH3:11])=[O:2].Br[C:13]1[CH:18]=[CH:17][C:16]([Cl:19])=[CH:15][N:14]=1.C([O-])([O-])=O.[Na+].[Na+]>CN(C=O)C>[Cl:19][C:16]1[CH:17]=[CH:18][C:13]([C:6]2[S:7][C:3]([CH:1]=[O:2])=[C:4]([CH3:11])[CH:5]=2)=[N:14][CH:15]=1To a degassed solution of 5-formyl-4-methylthiophen-2-ylboronic acid (2.21 g, 13.0 mmol, commercially available), 2-bromo-5-chloropyridine (2.00 g, 10.4 mmol, commercially available) and 2 N Na2CO3 (10.4 mL, 20.8 mmol) in DMF (70.2 mL) was added PdCl2dppf (0.380 g, 0.520 mmol); the flask degassed and heated to 80° C. for 2.0 h. Upon cooling, the reaction mixture was diluted with water (100 mL) and extracted with EtOAc (3×75 ml). The combined organic layers were washed with brine, dried over anhydrous Na2SO4, concentrated and purified by flash chromatography (silica gel, CH2Cl2:EtOAc, 100:0 to 0:100) to afford 2.01 g of the title compound as a yellow solid: 1H NMR (500 MHz, DMSO-d6) δ 9.96 (1H, s), 8.57 (1H, s), 7.98 (2H, s), 7.75 (1H, s), 2.49 (3H, s).HPLC retention time: 3.158 min; LCMS (ES): m/z 238 [M+H]+.
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