SYNTHESIS OF PEPTIDE HYDROXAMIC ACIDS
b+7 = 798.3883 (calcd m/z = 798.3880 for C35H56N7O14), b+6 =
685.3042 (calcd m/z = 685.3039 for C29H45N6O13), b+5 = 614.2673
(calcd m/z = 614.2668 for C26H40N5O12), b+3 = 356.1816 (calcd
m/z = 356.1816 for C16H26N3O6).
Yield 98%
Melting point 95–97 ꢀC (lit. [24] 103–104 ꢀC)
1H NMR (CDCl3) 500 MHz: d = 1.43 (9H s); d = 2.81 (4H s); d = 2.96
(1H dd, J3 = 4.47 Hz, J2 = 17.48 Hz); d = 3.13 (1H dd, J3 = 4.67 Hz,
J2 = 17.39 Hz); d = 5.00 (1H m); d = 5.18 (2H m); d = 5.58 (1H d,
J3 = 9.0 Hz); d = 7.34 (5H m).
Rt1 36.6 min, Rt2 30.2 min, Yield of purified peptide 31%
Synthesis of Asp Derivative – Boc-Asp-EDA-Fmoc
Boc-Asp(OBzl)EDA-Z
The Boc-Asp-EDA-Fmoc was synthesized according to scheme
shown in Figure 2.
The synthetic procedure was similar to that described by Anderson
[25]. To the solution of Boc-Asp(OBzl)-ONSu (0.005 mol, 2.1g) in THF
(35 ml) and DIEA (0.01 mol, 1,73 ml), the Z-EDA-H*HCl (0.005 mol,
1.15 g) was added. After 1 h at room temperature, the product
was precipitated from the solution by adding 100 ml of water.
After filtration, the precipitate was washed with 10% sodium
bicarbonate, water, 1M hydrochloric acid, water and finally dried
in vacuo.
Z-EDA-Boc
Z-EDA-Boc was obtained from Boc-EDA-H. Synthesis of Boc-EDA-H
has been previously described in the literature by Reschel et al.
[22]. Boc-EDA-H (0.027 mol, 4.26 g) was dissolved in the mixture
of 46 ml 1 M aqueous sodium carbonate and 125 ml acetone. To
a stirred solution, benzyloxycarbonyl chloride (0.027mol, 3.8ml)
was added dropewise. The reaction was allowed to proceed for
24 h. The partially precipitated product was filtered. The filtrate
was extracted with ethyl acetate. The solvent was removed in
vacuo, and the next batch of product was isolated by crystallization
from the mixture of water and acetone.
Yield: 71%
1H NMR (CDCl3) 500 Hz : d = 1.42 (9H,s), d = 2.7 (1H dd,
J3 = 5.96 Hz, J2 = 17.1 Hz), d = 3.04 (1H dd, J3 = 4.6 Hz, J2 = 17.2),
d = 3.34 (4H m), d = 4.45 (1H s), d = 5.08 (4H m), d = 5,21 (1H s),
d = 5.52 (1H s), d = 6.71 (1H s), d = 7.32 (10H m).
Boc-Asp-EDA-H
Yield 51%
Melting point: 168–170.1 ꢀC (lit. 169–172 ꢀC)
The protecting groups (Z and Bzl) were removed by hydrogenation
in the presence of 10% Pd on C in the mixture of isopropanol/
methanol (5 : 5 v : v) under atmospheric pressure. The substrate
Boc-Asp(OBzl)-EDA-Z (0.012 mol, 6 g) was dissolved at 40 ꢀC in
the 80 ml of solvent. After 3 h of hydrogenation, the catalyst
was filtered off, and the solvent was removed in vacuo. The
product was used for further synthesis without purification.
Yield 85%
1H NMR(CDCl3) 500 MHz: d = 1.43 (9H, s); d = 3.26(4H, m);
d = 4.79 (0.87, br-s); d = 5.08 (2.76H, s); d = 7.31(5H, m).
Z-EDA*HCl
In 50 ml THF, 0.013 mol (3.82 g) of Z-EDA-Boc was dissolved. The
dry HCl gas was bubbled through solution for 1 h. Then the
product was isolated by filtration, washed with diethyl ether
and dried in vacuo.
ESI-MS: [M + H]+ = 276.1625 (calcd 2716.1554 for C11H21N3O5)
Yield 87%
Boc-Asp-EDA-Fmoc
Melting point 122.1–124.8 ꢀC (lit. 123–124 ꢀC)
1H NMR (D2O) 500 Hz d = 3.18 (2H t, J3 = 5.88 Hz), d = 3.5 (2H t,
J3 = 5.69 Hz), d = 5.19 (2H s), d = 7.49 (5H m).
The protection of amino group with 9-fluorenylmethyloxycarbonyl
was performed according modified procedure given by Paquet
[26]. Boc-Asp-EDA-H (0.008 mol, 2.2g) and DIEA (0.008 mol,
1.4 ml) were dissolved in mixture of water (10 ml) and acetone
(34 ml). The mixture was heated until substrate dissolved. After
cooling the solution to room temperature Fmoc-OSu (0.008 mol,
2.7 g) was added. The reaction mixture was stirred overnight, and
then the acetone was removed in vacuo. The product was precip-
itated by addition of 1M solution of KHSO4 to pH= 2, filtered off,
washed with water and dried.
Boc-Asp(OBzl)-ONSu
Synthesis of N-hydroxysuccinimide ester was performed accord-
ing to Anderson et al. [23] using DCC as a coupling reagent.
Boc-Asp-OH (0.03 mol, 10 g) and N-hydroxysuccinimide
(0.03 mol, 3.57 g) were dissolved in dioxane (60 ml). The solution
was cooled to 5 ꢀC, and then the DCC (0.03 mol, 4.76 ml) was
added. The solution was stirred at 0 ꢀC for 24 h. Next, the solvent
was removed in vacuo, and the crude product was precipitated by
addition of pentane. The product was used for further synthesis
without purification.
Yield 92%
Melting point 153–155 ꢀC
ESI-MS: [M + H]+ = 498.2170 (calcd 498.2235 for C26H32N3O7)
1H NMR (DMSO-d6) 500M Hz d = 1.37 (9H s), d = 2.44 (1H dd
J2 = 16.87, J3 = 8.04 Hz), d = 2.62 (1,41H dd J2 = 16.87 J3 = 5.09 Hz),
d = 3.04 (2H m), d = 3.1 (2H m), d = 4.21 (2H m), d = 4.29 (2H m),
d = 6.93 (1H d J3 = 8.03 Hz), d = 7.24 (1H t J3 = 5.32 Hz), d = 7.33
(2H m), d = 7.41 (2H m), d = 7.67 (2H m), d = 7.88 (2H m),
d = 12.06 (0.66H br-s).
Derivatization of Trityl ChemMatrixW Resin
Derivatization of ChemMatrixW support, shown in Figure 3, was
performed according to Bauer’s procedure [27] developed
previously for a cross-linked polystyrene Wang resin.
A sample of ChemMatrixW resin (100 mg) was suspended in
DCM (2 ml) for about 30 min. Then the solution of 2% SOCl2 in
DCM was added (3 ml). The reaction was allowed to proceed for
Figure 2. Scheme of synthesis of Boc-Asp-EDA-Fmoc.
J. Pept. Sci. 2013; 19: 9–15 Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/jpepsci
Cal, Marta
