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Chapter 3
added and the mixture was stirred at room temperature for 3 hour. THF was evaporated and
the product was precipitated as a white solid at pH= 7.5, filtered and dried under vacuum.
Yield: 75%. 1 H-NMR (300MHz , DMSO-d 6 ): δ (ppm) 7.97 (bs, 1H, N-Hη arginine side
chain), 7.64 (d, 2H, J(H,H)= 8 Hz, CH aromatic tosyl group), 7.29 (d, 2H, J(H,H) = 8 Hz, CH
aromatic tosyl group), 7.18 (bs, 1H, N η -H arginine side chain), 6.99 (bs, 1H, NH-Boc), 3.29-
3.05 (m, 5H, C(2)Hα + Glyψ CH 2 CH 2 ), 2.79-2.69 (m, 2H, CH 2 arginine side chain), 2.34 (s,
3H, CH 3 tosyl group), 1.73-1.40 (m, 4H, CH 2 arginine side chain), 1.38 (s, 9H, CH 3 Boc
group). 13 C-NMR ( 75 MHz, DMSO-d 6 ): δ (ppm) 170.8, 156.8, 155.5, 141.6, 140.8, 128.9,
125.4, 77.9, 61.0, 45.9, 37.1, 28.0, 27.2, 25.0, 20.7. ESI-MS (CH 3 OH, positive ions):
calculated m/z: 472.6 (MH + ), 494.6 (MNa + ), 510.7 (MK + ), found: 472.4, 494.4, 510.4
N α -Boc-Glyψ-[D-Arg-(N α -Fmoc)-(N ω -Tosyl)]-OH. Bis(trimethylsilyl)acetamide (BTSA)
(0.21ml, 0.86 mmol) and DIPEA ( 0.05ml, 0.29 mmol) were added to N α -Boc-Glyψ-[D-Arg-
(N ω -Tosyl)]-OH (0.14g, 0.29 mmol) suspended in DCM (15 ml), with exclusion of humidity
by a CaCl 2 drying tube. When the solution was nearly clear (10-15 min were usually
required), FmocCl (0.1g, 0.58 mmol) was added and the mixture was stirred for 2 hours at
room temperature. Methanol (1 ml ) was carefully added and the mixture was stirred for an
additional 15 min, diluted with 15 ml of DCM, washed with 1M potassium hydrogen sulphate
(3 times) and brine (3 times), dried over magnesium sulfate and evaporated to dryness. The
residue was purified by flash chromatography (dichlomethane:methanol = 9:1) and the
product was obtained as a white foam. Yield: 38%. 1 H NMR (300MHz, DMSO-d 6 ):(some
signals are splitted due to presence of rotamers) δ (ppm) 7.92-7.82 (m, 2H, CH aromatic
Fmoc group), 7.70-7.59 (m, 4H CH aromatic tosyl group + CH aromatic Fmoc group), 7.45-
7.18 (m, 6H CH aromatic Fmoc group + CH aromatic tosyl group), 4.33-4.00 (m, 3H CH 2 CH
Fmoc), 3.31 (bs, 1H, C(2)-Hα), 3.14-2.87 (m, 6H, CH 2 arginine side chain + Glyψ CH 2 CH 2 ),
2.30 (s, 3H, CH 3 tosyl group), 1.66-1.38 (m, 13H, CH 2 arginine side chain + CH 3 Boc group).
13 C-NMR (75 MHz, DMSO-d 6 ,): δ(ppm) 175.0, 156.7, 155.9, 155.5, 143.8, 141.7, 140.8,
140.5, 128.8, 127.5, 127.1, 126.9, 125.4, 125.0, 119.9, 77.3, 66.4, 60.8, 48.3, 46.6, 45.2, 29.9,
28.1, 26.6, 20.7. ESI-MS (CH 3 OH, positive ions): calculated m/z: 694.81 (MH + ), 716.81
(MNa + ), 732.9 (MK + )found: 694.5, 716.4, 732.4.
N α -Boc-[L-Argψ-(N ω -Tosyl)]-Gly methyl ester. N α -Boc-L-Arg-N ω -Tosyl-aldehyde (686.7
mg, 1.66 mmol) and Gly-OMe•HCl (250.8 mg, 2.00 mmol) were dissolved in MeOH (20 ml).
The reaction mixture was cooled to 0° C with an ice bath and NaBH 3 CN (132.1 mg, 2.00
mmol), and acetic acid (144 µl, 2.00 mmol) were added to the stirred solution. The reaction
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