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Iodination of BOC protected phenylglycinol

SyntheticPage 612

Submitted: July 10, 2013, published: July 15, 2013

Authors

Nikola P. Chmel (N.Chmel@warwick.ac.uk)

Pratik Gurnani (pratik.gurnani@warwick.ac.uk)

A contribution from 

Reaction Scheme

Chemicals

(R)-tert-butyl 2-hydroxy-1-phenylethylcarbamate (Prepared in house, see page 611)
Imidazole (Aldrich)
Triphenylphosphine (Aldrich)
THF (Distilled over potassium)
Iodine (Acros)

Procedure

(R)-tert-butyl 2-hydroxy-1-phenylethylcarbamate (1.0 g, 4.2 mmol) was dissolved in dry THF (50 ml) under argon and cooled in an ice/water bath. Imidazole (1.06 g, 15.6 mmol), triphenylphosphine (2.91 g, 11.1 mmol) and iodine (2.72 g, 10.7 mmol) were added in that order. The resulting mixure was stirred for 1 h at 0°C and then at ambient temperature for 2 d. The reaction was quenched with a saturated solution of sodium thiosulphate (40 ml) and brine (40 ml). The aqueous layer was extracted with DCM (30 ml) and the combined organic layers were dried over anhydrous magnesium suphate. The solvents were removed under reduced pressure and the residue was purified on silica using DCM as eluent. Yield 0.85 g (58%).

Author Comments

Although yield was modest it worked well and reproducibly.

Data

Elemental analysis found (calculated for C13H18NO2) %: 45.50 (44.97), H 5.35 (5.23), N 4.01 (4.03).

1H NMR (400 MHz, 298 K, CDCl3) δH 7.40 – 7.21 (5H, m, Ph), 5.04 (1H, s, NH), 4.78 (1H, s br, CH), 3.59 – 3.40 (2H, m, CH2), 1.43 (9H, s, tBu).

13C NMR (100 MHz, 298 K, CDCl3) δC 128.90, 128.17, 126.38 (Ph), 55.46 (CH), 28.48 (CH3), 12.33 (CH2).

MS (ESI+) m/z 370.0 ([M+Na]+)

IR (cm-1) ν 3354, 3009, 2981, 1688, 1521, 1453, 1417, 1392, 1368, 1351, 1333, 1316, 1279, 1247, 1155, 1123, 1079, 1044, 1020, 914, 877, 842, 758, 742, 698, 658.

Lead Reference

D. L. J. Clive, J. Peng, S. P. Fletcher, V. E. Ziffle and D. Wingert, Journal of Organic Chemistry, 2008, 73, 2330-2344. http://dx.doi.org/10.1021/jo7026307

Other References

R. Caputo, E. Cassano, L. Longobardo and G. Palumbo, Tetrahedron Letters, 1995, 36, 167-168.http://dx.doi.org/10.1016/0040-4039(94)02202-M

Supplementary Information

Keywords

aromatics/arenes, esters, Iodination, substitution