Hydrochloric Acid → [1,1'-Biphenyl]-3,4-diamine, 4'-chloro-

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Reaction Conditions

Reaction Steps

To a solution of 5-chloro-2-nitroaniline (2 g, 11.59 mmol) in dioxane (100 ml) and water (10 ml) was added (4-chlorophenyl)boronic acid (3.6 g, 23.02 mmol), K3PO4 (5.01 g, 23.18 mmol) and Pd(PPh3)4 (0.7 g, 0.58 mmol) with stirring for 4 h at 95° C. maintained with an inert atmosphere of nitrogen. Then the resulting mixture was concentrated under vacuum to give a residue, which was purified by a silica gel column with 2% to 5% ethyl acetate in petroleum ether to afford 4-(4-chlorophenyl)-2-nitroaniline as a yellow solid (2.0 g, 69%). Next, to a solution of 5-(4-chlorophenyl)-2-nitroaniline (300 mg, 1.21 mmol) in ethanol (10 ml) was added hydrogen chloride (0.5 ml, 3.63 mmol) and Zn powder (800 mg, 12.3 mmol) in portions at room temperature and stirred for 2 h at 85° C. The resulting mixture was concentrated under vacuum to give a residue and dissolved in water (100 ml), adjusted to pH 8 with aqueous sodium bicarbonate. The mixture was extracted with ethyl acetate (3×100 ml) and dried and concentrated under vacuum to give a residue, which was purified by a silica gel column with 10% to 20% ethyl acetate in petroleum ether to produce 4-(4-chlorophenyl)benzene-1,2-diamine as an off-white solid (200 mg, 76%). Finally, a solution of 4-(4-chlorophenyl)benzene-1,2-diamine (150 mg, 0.69 mmol) in heptafluorobutanoic acid (2 ml) was stirred for 8 h at 120° C. Then the reaction was quenched with water (50 ml), adjusted to pH 7 with sodium bicarbonate and extracted with ethyl acetate(3×100 ml). The combined organic layers were dried over anhydrous magnesium sulfate and concentrated under vacuum to give a residue, which was purified by a silica gel column with 5% to 10% ethyl acetate in petroleum ether to produce 6-(4-chlorophenyl)-2-(heptafluoropropyl)-1H-1,3-benzodiazole as a white solid (49.5 mg, 18%).

Provenance & Evidence