[NH:1]1[C:5]([C:6]2[CH:7]=[C:8]([C:12]3[C:13]([OH:18])=[CH:14][CH:15]=[CH:16][CH:17]=3)[CH:9]=[CH:10][CH:11]=2)=[N:4][N:3]=[N:2]1.[N+:19]([O-])([OH:21])=[O:20].O>C(O)C>[N+:19]([C:14]1[CH:15]=[CH:16][CH:17]=[C:12]([C:8]2[CH:9]=[CH:10][CH:11]=[C:6]([C:5]3[NH:1][N:2]=[N:3][N:4]=3)[CH:7]=2)[C:13]=1[OH:18])([O-:21])=[O:20]3′-(1H-Tetrazol-5-yl)-biphenyl-2-ol 8d (3.5 g, 14.7 mmol) was dissolved in 145 mL of ethanol under argon atmosphere. Fuming nitric acid (0.565 mL, 13.2 mmol) was added dropwise at 35° C. After the reaction mixture was reacted at room temperature for 1 hour, 150 mL of water was added. After standing overnight, the mixture was filtered. The filter cake was washed with 100 mL of water and dissolved in 500 mL of ethyl acetate and 250 mL of water. The separated organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate. The mixture was purified by silica gel column chromatography to obtain the title compound 3-nitro-3′-(1H-tetrazol-5-yl)-biphenyl-2-ol 8e (1 g, yield 27.0%) as a yellow solid.
Wird geladen…