[OH:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:8]([C:12]([OH:14])=O)=[CH:7][CH:6]=[CH:5]2.S(Cl)(Cl)=O.[CH3:19][O:20][C:21]1[CH:27]=[CH:26][C:25]([O:28][CH3:29])=[CH:24][C:22]=1[NH2:23].C(N(CC)CC)C.Cl>O.C1COCC1>[CH3:19][O:20][C:21]1[CH:27]=[CH:26][C:25]([O:28][CH3:29])=[CH:24][C:22]=1[NH:23][C:12]([C:8]1[C:9]2[C:4](=[CH:3][C:2]([OH:1])=[CH:11][CH:10]=2)[CH:5]=[CH:6][CH:7]=1)=[O:14]A mixture of 6-hydroxy-1-naphthoic acid (5.0 g, 26.6 mmol) and thionyl chloride (20 mL) was refluxed for 1 h. The volatiles were then removed under vacuum. The residue was dissolved in THF (20 mL) and added into a cold (0° C.) solution of 2,5-dimethoxyaniline (4.06 g, 26.6 mmol), triethylamine (10 mL, 71.8 mmol) and THF (100 mL). The mixture was stirred for 30 min, poured into water, acidified with HCl (2N) and extracted with EtOAc. The organic extracts were dried over MgSO4. Evaporation and purification by flash chromatography (hexanes/EtOAc 1/1) gave a tan solid (8.2 g, 95% yield, m.p. 165-166° C.); MS m/e 324 (M+H)+.
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