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TCI Practical Example: Regioselective Iodination Using Iodine and Silver Nitrate

We are proud to present the ortho-selective iodination of the aryl boronic acid using iodine and silver nitrate.

Used Chemicals

• 3-Benzyloxyphenylboronic Acid [B3056]
• Iodine [I0604]
• Silver(I) Nitrate
• Ethanol

Procedure

To the ethanol (4.5 mL) solution of 3-benzyloxyphenylboronic acid (342 mg, 1.50 mmol) and silver(I) nitrate (280 mg, 1.65 mmol, 1.1 eq.), iodine (381 mg, 1.50 mmol, 1.0 eq.) in ethanol (7 mL) was added at room temperature. The mixture was stirred for 2 hours. The suspension was filtered and the filtrate was diluted with ethyl acetate (30 mL) and washed with water (30 mL) and brine (30 mL). The organic layer was dried over sodium sulfate and filtered. The solvent was removed under reduced pressure and the residue was purified by column chromatography (ethyl acetate:hexane = 1:4 on silica gel) to give 2-iodo-5-benzyloxyphenylboronic acid as a white solid (483 mg, 91%).

Experimenter’s Comments

Silver salt precipitated as the reaction proceeded.
The reaction mixture was monitored by UPLC.

Analytical Data

2-Iodo-5-benzyloxyphenylboronic Acid

¹H NMR (270 MHz, CDCl₃); δ 8.22 (s, 2H), 7.60 (d, 1H, J = 8.6 Hz), 7.47-7.31 (m, 5H), 6.90 (d, 1H, J = 3.5 Hz), 6.76 (dd, 1H, J = 8.6, 3.0 Hz), 5.08 (s, 2H).

Lead Reference

• Mild Silver (I)-Mediated Regioselective Iodination and Bromination of Arylboronic Acids
• • R, M. Al-Zoubi, D. G. Hall, Org. Lett. 2010, 12, 2480.