[Br:1][C:2]1[N:3]=[C:4]2[CH2:12][CH2:11][C:10](=[O:13])[NH:9][C:5]2=[N:6][C:7]=1[Cl:8].Br[CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][C:21]([O:23][CH2:24][CH3:25])=[O:22].C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C.O>[Br:1][C:2]1[N:3]=[C:4]2[CH2:12][CH2:11][C:10](=[O:13])[N:9]([CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][C:21]([O:23][CH2:24][CH3:25])=[O:22])[C:5]2=[N:6][C:7]=1[Cl:8]A solution of 2-bromo-3-chloro-7,8-dihydro-5H-pyrido[2,3-b]pyrazin-6-one (Intermediate J) (3.9 g, 14.86 mmol) and ethyl 7-bromoheptanoate (7.05 g, 29.7 mmol) in DMF (75 ml) under nitrogen was treated with potassium carbonate (10.27 g, 74.3 mmol) and the resultant solution was stirred at room temperature for 96 hours. The mixture was diluted with water and extracted with EtOAc (×2). The combined organic extracts were washed with water, brine, dried (MgSO4) and concentrated in vacuo. Purification of the crude product by chromatography on silica eluting with 0-60% EtOAc/iso-hexane 0-60% afforded the title compound;
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