C(OC(=O)[CH:5]([C:15]1[CH:20]=[CH:19][C:18]([O:21][CH3:22])=[CH:17][C:16]=1[Cl:23])[C:6]([C:8]1[CH:13]=[N:12][C:11]([CH3:14])=[CH:10][N:9]=1)=[O:7])C.[Cl-].[Na+].O.CS(C)=O>C(OCC)(=O)C>[Cl:23][C:16]1[CH:17]=[C:18]([O:21][CH3:22])[CH:19]=[CH:20][C:15]=1[CH2:5][C:6]([C:8]1[CH:13]=[N:12][C:11]([CH3:14])=[CH:10][N:9]=1)=[O:7]A mixture of 2-(2-chloro-4-methoxy-phenyl)-3-(5-methyl-pyrazin-2-yl)-3-oxo-propionic acid ethyl ester (700 mg, 2 mmol), sodium chloride (130 mg), water (55 mg) and DMSO (10 mL) was heated for 5 h to 140° C. Upon cooling, the reaction mixture was taken up in ethyl acetate and washed (water, brine). The organic layer was dried (Na2SO4), and the solvent was evaporated. Purification of the residue by column chromatography (silica gel, heptane:ethyl acetate=100:0-80:20) gave the title compound (370 mg, 67%). 1H NMR (300 MHz, CDCl3) 9.13 (1H, s), 8.54 (1H, s), 7.18 (1H, d), 6.97 (1H, d), 6.70 (1H, dd), 4.57 (2H, s), 3.80 (3H, s), 2.68 (3H, s); MS (m/e)=277.0 [MH+].
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