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Chapter 6
Arg + CHα Lys), 4.0-4.6 (m, 3H, CH-CH 2 Fmoc), 5.16 (s, 2H, CH 2 Z group), 6.40 (sb, 2H,
NH), 7.2-7.4 (m, 9H, aromatic CH tosyl + CH Fmoc + CH Z group), 7.4-7.6 (m, 2H, CH
aromatic Fmoc group), 7.7-7.8 (m, 5H, aromatic CH tosyl + CH Fmoc + CH Z group). 13 C
NMR (75 MHz, CDCl 3 ): δ(ppm) 21.3, 22.6, 22.9, 26.6, 28.4, 29.4, 32.4, 40.3, 40.7, 47.1,
50.3, 51.5, 63.7, 67.0, 77.1, 79.7, 119.2, 124.6, 126.0, 126.8, 127.1, 127.3, 127.5, 127.7,
129.1, 129.3, 133.3, 134.3, 140.8, 141.2, 141.9, 143.7, 156.4, 156.6, 156.7, 156.8, 172.0.
HRMS (ESI-MS, positive ions): calcd m/z for C 47 H 58 ClN 6 O 10 S (MH + ): 933.36237; found
m/z: 933.36298.
N α -Boc-L-Lysψ-(N ω -2-Cl-Z)-L-Lys-(N α -Fmoc)-(N ω -2-Cl-Z)-OH
(L-Lys-L-Lys
submonomer). The synthesis and characterization of the submonomer of has already been
already reported 31 . HRMS (ESI-MS, positive ions): calcd m/z for C 48 H 56 Cl 2 N 4 O 10 Na (MNa + ):
941.32712; found m/z: 941.32703.
6.4.3 PNA and peptide synthesis
The NLS peptide 1 and the achiral PNA 2 were synthesized by standard Boc-SPPS protocols
on a ABI 433A synthesizer, following the procedures provided from the company, whereas
modified PNA 3 (with or without the N-terminal proline) was synthesized by submonomeric
strategy 31 . The syntheses were performed on 25 mg of a preloaded Boc-Gly-MBHA-PS resin
(loading 0.2 mmol/g). The synthetic cycle for the synthesis of modified PNA 3 were the
following: Boc deprotection by neat TFA (added of 5% m-cresol), coupling of the desired
chiral submonomer by using HATU/DIEA, Fmoc removal by piperidine/NMP (20%) and
carboxymethyl-Z-adenine, carboxymethyl-O-benzyl-guanine or carboxymethyl-thymine
coupling by using DIC/DhBtOH. In all cases an aminoethoxyethoxyacetyl (AEEA) spacer
and rhodamine B were coupled to the growing chains before the cleavage. The peptide and
the PNAs were cleaved from the resin by using a 1:3 TFMSA/TFA mixture (10% thioanisole
+ 10% m-cresol) and precipitated by Et 2 O. HPLC analyses of the crude products were carried
out by LC/MS by using an analytical C18 column (3x250 mm, 5 µm, flow 0.5 ml/min),
gradient elution from 100% H 2 O (0.2% HCOOH, eluent A) to 100% CH 3 CN (0.2%HCOOH,
eluent B) in 30 min. MS acquisition in the positive ion mode, capillary voltage 3kV, cone
voltage 30V, full scan acquisition from 150 to 1500 m/z. HPLC purifications of the crude
products were carried out on a semipreparative Jupiter (Phenomenex) C18 column
(10x300mm, 5 µm, flow 4 ml/min), gradient elution from 100% H 2 O (0.1% TFA, eluent A) to
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