Communications
Bioconjugate Chem., Vol. 21, No. 7, 2010 1133
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Conjugation with Nε-Boc-L-lysine, Synthesis of 7. Activated
ester 6a (11 mg, 12 µmol), Boc-lysine (6 mg, 24 µmol), and
DIEA (4.3 µL, 24 µmol) were suspended in dry acetonitrile (5
mL) and stirred for 1 h under nitrogen. Solvent was removed,
and the residue was chromatographed (silica, CH2Cl2/MeOH,
9:1 then 8:2, 7:3) affording 7 (9.5 mg, 76%) as green solid. A
solution of activated ester 6b (6.0 µmol) was added to Boc-
lysine (3 mg, 12 µmol) solution in 0.1 M NaHCO3 (1 mL, pH
) 8.3). After 15 min, the resulting mixture was acidified with
2 M HCl and extracted with AcOEt. Subsequent chromatogra-
phy (silica, CH2Cl2/MeOH, 7:3) afforded 7 as green solid (4
1
mg, 63%). H NMR (500 MHz, CDCl3) 1.26-1.46 (m, 4H),
1.39 (s, 9H), 1.55-1.65 (m, 2H), 1.70-1.80 (m, 2H), 2.25-240
(m, 2H), 2.46-2.54 (m, 2H), 3.12-3.18 (m, 2H), 3.34 (s, 3H),
3.52-3.55 (m, 2H), 3.50-3.53 (m, 2H), 3.60-3.66 (m, 4H),
3.68-3.71 (m, 2H), 3.82 (t, 2H), 3.95-4.02 (m, 3H), 4.10-4.16
(m, 2H), 5.83 (s, 1H), 6.83-6.97 (m, 6H), 7.05 (s, 1H), 7.22
(s, 1H), 7.29-7.40 (m, 6H), 7.90-8.05 (m, 8H). 13C NMR (100
MHz, CDCl3) δ: 173.2, 172.8, 161.1, 160.8, 157.8, 156.1, 145.2,
145.1, 142.9, 118.6, 114.7, 114.6, 71.8, 70.8, 70.5, 70.4, 69.5,
67.5, 66.6, 59.0, 28.5. HRMS (ESI) calcd for C56H65BF2N6O11Na
[M + Na+]+: 1069.4670, found 1069.5371. IR (KBr disk) cm-1:
1475, 1506, 1603, 1657, 3055.
(12) Hall, M. J., Allen, L. T., and O’Shea, D. F. (2006) PET
modulated fluorescent sensing from the BF2 chelated azadipyr-
romethene platform. Org. Biomol. Chem. 4, 776–80.
(13) McDonnell, S. O., and O’Shea, D. F. (2006) Near-infrared
sensing properties of dimethlyamino-substituted BF2-azadipyr-
romethenes. Org. Lett. 8, 3493–6.
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and Pharr, J. S. (2007) Visible fluorescence chemosensor for
saxitoxin. J. Org. Chem. 72, 2187–91.
(15) Loudet, A., Bandichhor, R., Wu, L., and Burgess, K. (2008)
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ACKNOWLEDGMENT
We would like to thank Science Foundation Ireland and The
Irish Research Council for Science, Engineering and Technology
for financial support. Thanks to Dr. F. Paradisi for helpful
discussions and Marco Grossi for technical assistance.
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Gallagher, W. M., and O’Shea, D. F. (2005) Supramolecular
photonic therapeutic agents. J. Am. Chem. Soc. 127, 16360–1.
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M., Killoran, J., and O’Shea, D. F. (2005) A potent nonporphyrin
class of photodynamic therapeutic agent: cellular localisation,
cytotoxic potential and influence of hypoxia. Br. J. Cancer 92,
1702–10.
Supporting Information Available: Conjugation experi-
mental procedures, UV-visible and fluorescence spectra, NMR
spectra, MALDI-TOF data. This material is available free of
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BC100051P