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BOC deprotection of an aminophenylethyl methanesulfonate using hydrochloric acid; (R)-2-amino-2-phenylethyl methanesulfonate

SyntheticPage 608
DOI: 10.1039/SP608
Submitted Jul 10, 2013, published Jul 12, 2013
Nikola P. Chmel (N.Chmel@warwick.ac.uk), Pratik Gurnani (pratik.gurnani@warwick.ac.uk)
A contribution from Scott group, Warwick University
Reaction Scheme: <img src="/images/empty.gif" alt="" /><img src="/images/empty.gif" alt="" />BOC deprotection of an aminophenylethyl methanesulfonate using hydrochloric acid<img src="/images/empty.gif" alt="" /><img src="/images/empty.gif" alt="" />

Chemicals Used

(R)-2-(tert-butoxycarbonylamino)-2-phenylethyl methanesulfonate (Prepared in house, See Page 607)
HCl (4M)
Dioxane (Fisher Scientific)

Procedure

A solution of HCl (10 ml, 4 M) was added to a solution of (R)-2-(tert-butoxycarbonylamino)-2-phenylethyl methanesulfonate (2.5 g, 7.9 mmol) in dioxane (10 ml) and was stirred for 1 h. The volatiles were removed under reduced pressure and the residue was recrystallised from acetonitrile/diethyl ether. Yield 1.28 g (65%).

Author's Comments

Derivatives with combinations of different leaving groups, (iodine, methane sulfonate) and amine protecting groups( BOC-anhydride, phthalic anhydride) as well as no protecting groups were synthesised. See page 607, 608, 609, 610,610, 611, 612 and 613 for more detail on phenyl glycinol and pages 614 and 615 for more detail on (S)- Alaninol.

Data

1H NMR (400 MHz, 298 K, CD3CN) δH 7.63 (2H, dd, 3JHH = 7.5 Hz, 4JHH = 1.7 Hz, Ph), 7.52 – 7.42 (3H, m, Ph), 4.80 – 4.68 (2H, m, CH2), 4.58 (1H, dd, 3JHH = 9.8 Hz, 3JHH = 3.5 Hz, CH), 3.20 (3H, s, SO3CH3).

13C NMR (100 MHz, 298 K, CD3CN) δC 130.65, 130.07, 128.99 (Ph), 70.05 (CH), 55.26 (CH2), 38.22 (SO3CH3),

MS (ESI+) m/z 198.9 ([M-NH2·HCl]+), 215.9 ([M-Cl]+)

MS (ESI-) m/z 248.9 ([M-H]-)

IR (cm-1) ν 2962, 2804, 2658, 2578, 2494, 2037, 1595, 1518, 1456, 1410, 1380, 1347, 1268, 1205, 1180, 1126, 1068, 1033, 992, 950, 919, 860, 831, 787, 759, 739, 695.

Lead Reference

K. Higashiura, H. Morino, H. Matsuura, Y. Toyomaki and K. Ienaga, Journal of the Chemical Society-Perkin Transactions 1, 1989, 1479-1481. http://dx.doi.org/10.1039/p19890001479

Supplementary Information

HNMR (HNMR.jcamp)
13C NMR (13CNMR.jcamp)

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Keywords: amines, aromatics/arenes, BOC, deprotection, sulfonate