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TCI Practical Example: Chemoselective Reduction of Nitro Group Using Diboronic Acid

We are proud to present the selective reduction of nitro groups from trans-4-nitrostilbene to trans-4-aminostilbene using diboronic acid and 4,4'-bipyridyl.

Used Chemicals

• trans-4-Nitrostilbene [N0549]
• Diboronic Acid [T2953]
• 4,4'-Bipyridyl [B0469]
• DMF

Procedure

To a solution of trans-4-nitrostilbene (1.13 g, 5.00 mmol), diboronic acid (1.34 g, 15.0 mmol, 3.0 eq.) in DMF (30 mL) was added 4,4'-bipyridyl (3.9 mg, 0.025 mmol, 0.50 mol%) at r.t. and the mixture was stirred at the same temperature for 1 hour. The reaction mixture was diluted by 1 mol/L NaHCO₃ aq. (100 mL) and the resulting solid was filtered off. The solid was purified by column chromatography (dichloromethane：hexane = 0:1 - 4:1 on silica gel) to give trans-4-aminostilbene as a yellow solid (891 mg, 91% yield).

Experimenter’s Comments

The reaction mixture was monitored by UPLC.

Analytical Data

trans-4-Aminostilbene

¹H NMR (270 MHz, CDCl₃); δ 7.47 (d, 2H, J = 7.0 Hz), 7.38-7.30 (m, 4H), 7.21 (t, 1H, J = 7.0 Hz), 7.03 (d, 1H, J = 15 Hz), 6.91 (d, 1H, J = 15 Hz), 6.63 (d, 2H, J = 8.6 Hz), 3.75 (brs, 2H).

Lead Reference

• Metal-Free, Rapid, and Highly Chemoselective Reduction of Aromatic Nitro Compounds at Room Temperature
• • M. Jang, T. Lim, B. Y. Park, M. S. Han, J. Org. Chem. 2022, 87, 910.