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References and notes
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1. Hocart, S. J.; Jain, R.; Murphy, W. A.; Taylor, J. E.;
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D. H. J. Med. Chem. 1999, 42, 1863–1871.
3. Hruby, V. J. Nature Rev. DrugDis. 2002, 1, 847–858.
4. Jain, R.; Singh, J.; Perlman, J. H.; Gershengorn, M. C.
Bioorg. Med. Chem. 2002, 10, 189–194.
20. The observation of exclusive s(N-1) alkylation of N-a-
Boc-L-histidine was authenticated as follows: Histidine
derivatives 2a–f were subjected to acidic hydrolysis with
CF3CO2H (10% solution in DCM) for 30min. A solution
of 1-alkyl-L-histidine trifluoroacetate salt in water was
applied to an ion-exchange column (Dowex 50 · 2–200,
H+ form). The column waseluted with water until the
eluent wasneutral to pH paper. The modified amino acid
5. Perlman, J. H.; Colson, A.-O.; Jain, R.; Czyzewski, B.;
Cohen, L. A.; Osman, R.; Gershengorn, M. C. Biochem-
istry 1997, 36, 15670–15676.
wasthen eluted with 25% NH OH solution. Evaporation
4
of the solvent provided free 1-alkyl-L-histidines, and their
spectroscopic data and physical properties were found
to be identical upon comparison to earlier reported data.
Jain, R.; Cohen, L. A. Tetrahedron 1996, 52, 5363–
5370.
6. Faden, A. I.; Labroo, V. M.; Cohen, L. A. J. Neurotrauma
1993, 10, 101–108.
7. Jain, R.; Cohen, L. A. Tetrahedron 1996, 52, 5363–5370.
8. Jain, R.; Cohen, L. A.; El-Kadi, N. A.; King, M. M.
Tetrahedron 1997, 53, 2365–2370.
21. 1-Propyl-L-histidine was synthesized from N-a-(tert-
butoxycarbonyl)-1-propyl-L-histidine 2c using the proce-
dure reported in Ref. 20. Spectral data: Yield: 95%; 1H
NMR (D2O): d 0.91 (t, 3H, J = 7.2Hz), 1.90 (m, 2H), 3.03
(m, 2H), 3.91 (t, 2H, J = 7.1Hz), 4.04 (m, 1H), 6.92 (s,
1H), 7.66 (s, 1H); APCI MS m/z 198 (M+1); analysis for
C9H15N3O2 (197.2), calcd, C, 54.81; H, 7.67; N,
9. Jain, R.; Cohen, L. A.; King, M. M. Tetrahedron 1997, 53,
4539–4548.
10. Jain, R.; Avramovitch, B.; Cohen, L. A. Tetrahedron 1998,
54, 3235–3242.
11. Narayanan, S.; Suryanarayana, V.; Jain, R. Bioorg. Med.
Chem. Lett. 2001, 11, 1133–1136.
12. Jain, R.; Suryanaryana, V.; Jain, M.; Kaur, N.; Singh, S.;
Singh, P. P. Bioorg. Med. Chem. Lett. 2002, 12,
1701–1704.
25
21.30; found, C, 54.97; H, 7.51; N, 21.53; ½aꢀD À30.1 (c
1, H2O).
22. Spectral data of N-a-(tert-butoxycarbonyl)-1-propyl-L-his-
13. Chandna, P.; Nayyar, A.; Jain, R. Synth. Commun. 2003,
33, 2925–2933.
1
tidine 2c. Yield: 75%; H NMR (CD3OD): d 0.86 (t, 3H,
J = 7.3Hz), 1.39 (s, 9H), 1.78 (m, 2H), 3.07 (m, 2H), 3.91
(t, 2H, J = 7.0Hz), 4.10 (m, 1H), 6.90 (s, 1H), 7.98 (s, 1H);
APCI MS m/z 298 (M+1); analysis for C14H23N3O4
(297.4), calcd, C, 56.55; H, 7.80; N, 14.13; found, C,
14. Bodanszky, M.; Bodanszky, A. In The Practice of Peptide
Synthesis, Springer Lab Manual, 2nd ed.; Springer Verlag,
Berlin. 1994; p 17.
15. (a) Giegel, D. A.; Massey, V.; Williams, C. H. J. Biol.
Chem. 1987, 262, 5705–5710; (b) Bambal, R.; Hanzlik, R.
P. J. Org. Chem. 1994, 59, 729–732.
16. (a) Jones, J. H.; Rathbone, D. L.; Wyatt, P. B. Synthesis,
1987, 1110–1113; (b) Fletcher, A. R.; Jones, J. H.;
Ramage, W. I.; Stachulski, A. V. J. Chem. Soc., Perkin
Trans. 1, 1979, 2261–2267.
17. Thaisrivongs, S.; Blinn, J. R.; Pals, D. T.; Turner, S. R.
J. Med. Chem. 1991, 24, 1276–1282.
25
56.34; H, 7.99; N, 14.51; ½aꢀD +13.5 (c 1, CH3OH).
23. Spectral data of N-a-(tert-butoxycarbonyl)-1-isopropyl-L-
histidine 2d. Yield: 71%; 1H NMR (CD3OD): d 1.43 (s,
9H), 1.58 (d, 6H, J = 6.6Hz), 2.96 (m, 2H), 4.06 (m, 1H),
4.10 (m, 1H), 6.80 (s, 1H), 8.02 (s, 1H); APCI MS m/z 298
(M+1); analysis for C14H23N3O4 (297.4), calcd, C, 56.55;
H, 7.80; N, 14.13; found, C, 56.87; H, 7.65; N, 13.88;
25
½aꢀD +17.6 (c 1, CH3OH).