Iodine

Used Chemicals

• 3-Benzyloxyphenylboronic Acid (contains varying amounts of Anhydride) [B3056]
• Iodine [I0604]
• Silver(I) Nitrate
• Ethanol

Procedure

To a solution of 3-benzyloxyphenylboronic acid (342 mg, 1.50 mmol) and silver(I) nitrate (280 mg, 1.65 mmol, 1.1 eq.) in ethanol (4.5 mL) was added iodine (381 mg, 1.50 mmol, 1.0 eq.) in ethanol (7 mL) at rt and 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 salts 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.

Used Chemicals

• 2-Phenylethyl Alcohol [P0084]
• Iodine [I0604]
• Triphenylphosphine (= PPh₃) [T0519]
• Imidazole [I0001]
• Dichloromethane

Procedure

To a mixture of iodine (0.416 g, 1.63 mmol), PPh₃ (0.416 g, 1.64 mmol) and Imidazole (0.223 g, 3.27 mmol) in CH₂Cl₂ (3.3 mL) at 0 ºC was added a solution of 2-phenylethyl alcohol (0.196 mL, 1.64 mmol) in CH₂Cl₂ (3.3 mL). The reaction mixture was stirred at 0 ºC for 1 h. The reaction mixture was added aqueous solution (10 mL) of sodium thiosulfate pentahydrate (2.0 g, 8.19 mmol) and then extracted by CH₂Cl₂. The organic layer was dried over Na₂SO₄ and concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:ethyl acetate = 9:1) to give (2-iodoethyl)benzene (0.360 g, 95% yield) as a colorless liquid.

Experimenter’s Comments

The reaction mixture was monitored by TLC (hexane:ethyl acetate= 9:1, Rf = 0.6).

Analytical Data

¹H NMR (400 MHz, CDCl₃); δ 7.33-7.17 (m, 5H), 3.34 (t, 2H, J = 7.6 Hz), 3.17 (t, 2H, J = 7.6 Hz).

¹³C NMR (101 MHz, CDCl₃); δ 140.6, 128.6, 128.3, 126.8, 40.3, 5.62.

Lead Reference

• The Prins Cascade Cyclization Reaction for the Synthesis of Angularly-Fused Tetrahydropyran and Piperidine Derivatives
• B. V. S. Reddy, H. Kumar, P. Borkar, J. S. Yadav, B. Sridhar, Eur. J. Org. Chem. 2013, 2013, 1993.

References

• 1)Molecular Iodine Catalyzed Selective Acetylation of Alcohols with Vinyl Acetate
  • J. W. J. Bosco, A. Agrahari, A. K. Saikia, Tetrahedron Lett. 2006, 47, 4065.
• 2)Molecular Iodine in Isopropenyl Acetate (IPA): A Highly Efficient Catalyst for the Acetylation of Alcohols, Amines and Phenols under Solvent Free Conditions
  • N. Ahmed, J. E. van Lier, Tetrahedron Lett. 2006, 47, 5345.
• 3)Protection for the Hydroxyl Group, Including 1,2- and 1,3-Diols
  • P. G. M. Wuts, in Greene’s Protective Groups in Organic Synthesis, 5th ed., ed. by P. G. M. Wuts, John Wiley & Sons, Inc., Hoboken, New Jersey, 2014, Chap. 2, 17.

Reference

• Protection for the Hydroxyl Group, Including 1,2- and 1,3-Diols
  • P. G. M. Wuts, in Greene’s Protective Groups in Organic Synthesis, 5th ed., ed. by P. G. M. Wuts, John Wiley & Sons, Inc., Hoboken, New Jersey, 2014, Chap. 2, 17.