Beilstein J. Org. Chem. 2015, 11, 469–472.
Protected substrate 3 showed conversion to diphosphate 4 added and the mixture was stirred and solids were collected by
after 91 h of reaction, however, we were unable to precipitate centrifugation as described above. When all pyrophosphate had
this material after removal of excess pyrophosphate ions been removed from the supernatant layer (determined by
(Scheme 4). We believe the isopropylidene protecting group 31P NMR spectroscopy), sodium iodide in acetone (5 mL,
decreases the polarity of diphosphate 4 to such an extent that it 0.1 M) was added in order to precipitate the NDP product. The
remains soluble even after the addition of excess sodium iodide mixture was stirred for 30 minutes at 0 °C and then centrifuged
and acetone.
at 4,000 rpm for 10 minutes. The precipitated NDP was washed
with acetone (2 × 2 mL) in order to remove remaining sodium
iodide and dried in a vacuum desiccator to yield a white solid.
Supporting Information
Supporting Information File 1
Experimental procedures for the preparation of 5’-tosylates
and their 1H and 13C NMR spectra, and 31P and 1H NMR
spectra of NDPs.
Scheme 4: Attempted use of an isopropylidene-protected 5’-tosylnu-
cleoside.
Conclusion
PPN pyrophosphate is a convenient, effective reagent for the
preparation of NDPs from 5’-tosylnucleosides. Post-reaction
removal of PPN cations and elimination of excess pyrophos-
phate followed by isolation of polar NDPs as sodium salts can
be readily achieved through selective precipitation.
Acknowledgements
This work was supported by the Jenny and Antti Wihuri Foun-
dation (H.J.K), Durham University (H.L.B.) and the Royal
Society (chromatography system).
Experimental
General procedure for the synthesis of NDPs
2a–d
References
1. Hodgson, D. R. W.; Schröder, M. Chem. Soc. Rev. 2011, 40,
2. Korhonen, H. J.; Conway, L. P.; Hodgson, D. R. W.
Curr. Opin. Chem. Biol. 2014, 21, 63–72.
PPN pyrophosphate was prepared as described previously [11]
and was dried in a vacuum desiccator over P2O5 (we have also
found freeze-drying to be effective in other experiments), then
dissolved in dry acetonitrile, and stored over activated 4 Å
molecular sieves. Tosylated nucleoside 1a–d (0.18 mmol) and
PPN pyrophosphate (0.36 mmol) in dry acetonitrile (0.8 mL)
were stirred at 30 °C under an inert atmosphere. The reaction
progress was monitored by 31P NMR spectroscopy until no
further reaction was observed. Sodium iodide (0.149 g) was
dissolved into 9:1 acetone/water (10 mL) and the solution was
added dropwise with stirring to the crude reaction mixture
which had been transferred to a centrifuge tube. The solution
was mixed for 30 minutes at 0 °C and then centrifuged at
4,000 rpm for 10 minutes. The supernatant was removed by a
pipette and the solid residue was dissolved in TEAB buffer
(3 mL, 0.1 M, pH 8.0) [4]. Sodium iodide in acetone (5 mL,
0.1 M) was added slowly to the solution and the mixture was
stirred for 30 minutes at 0 °C. Solids were collected by centrifu-
gation at 4,000 rpm for 10 minutes, and the liquid layer was
analysed by 31P NMR spectroscopy to ensure that selective
removal of inorganic pyrophosphate had been achieved. In
cases where pyrophosphate ions were still present, an addition-
al small volume (<1 mL) of sodium iodide in acetone was
3. Lee, S. E.; Elphick, L. M.; Anderson, A. A.; Bonnac, L.; Child, E. S.;
Mann, D. J.; Gouverneur, V. Bioorg. Med. Chem. Lett. 2009, 19,
4. Williams, D. M.; Harris, V. H. Phosphorus methods in nucleotide
chemistry. In Organophosphorus Reagents: a Practical Approach in
Chemistry; Murphy, P. J., Ed.; Oxford University Press: Oxford, 2004;
pp 237–272.
5. Caton-Williams, J.; Lin, L.; Smith, M.; Huang, Z. Chem. Commun.
6. Cremosnik, G. S.; Hofer, A.; Jessen, H. J. Angew. Chem., Int. Ed.
7. Jessen, H. J.; Ahmed, N.; Hofer, A. Org. Biomol. Chem. 2014, 12,
8. Mohamady, S.; Desoky, A.; Taylor, S. D. Org. Lett. 2012, 14, 402–405.
9. Ravalico, F.; Messina, I.; Berberian, M. V.; James, S. L.; Migaud, M. E.;
Vyle, J. S. Org. Biomol. Chem. 2011, 9, 6496–6497.
10.Strenkowska, M.; Wanat, P.; Ziemniak, M.; Jemielity, J.; Kowalska, J.
11.Korhonen, H. J.; Bolt, H. L.; Vicente-Gines, L.; Perks, D. C.;
Hodgson, D. R. W. Phosphorus, Sulfur Silicon Relat. Elem., in press.
12.Ludwig, J. Acta Biochim. Biophys. Hung. 1981, 16, 131–133.
471