Cl[C:2]1[CH:7]=[CH:6][C:5]([CH2:8][C:9](O)=O)=[CH:4][CH:3]=1.C1N=CN(C(N2C=NC=C2)=O)C=1.CC(C1C=CC(F)=CC=1O)=O.[C:35](=O)([O-:37])[O-:36].[K+].[K+]>CN(C=O)C.CN(C1C=CN=CC=1)C.O>[O:37]1[C:6]2[CH:7]=[CH:2][CH:3]=[CH:4][C:5]=2[CH:8]=[CH:9][C:35]1=[O:36]
A solution of 4-chlorophenylacetic acid (11.05 g, 64.8 mmol) in DMF (100 mL) was treated with CDI (13.13 g, 81 mmol) in several portions over about 15 minutes and the mixture was stirred until gas evolution had ceased. 4-Fluoro-2-hydroxyacetophenone (5.0 g, 32.4 mmol) was added followed by potassium carbonate (15.7 g, 113.6 mmol) and 4-DMAP (about 1 g). The reaction mixture was warmed at about 80° C. for about 10 h then cooled to room temperature. Water (200 mL) was added and the aqueous layer was extracted with ethyl acetate. The combined organic layer was concentrated and the crude product was purified by flash chromatography (ethyl acetate/hexanes) to give a yield of about 3.5 g (38%) of a benzopyranone intermediate.
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