10.1002/ejoc.201601339
European Journal of Organic Chemistry
COMMUNICATION
understand the role of HFIP in this reaction, 5a was independently
prepared.[20] When a solution of 5a in i-PrOH was stirred and the
solvent evaporated, the 5a decomposed back to 1a. The reaction
was followed using in situ ATR-IR spectroscopy and no evident
change was observed during stirring, hence decomposition must
occur during evaporation. When a solution of 5a in HFIP was
stirred at room temperature, in situ ATR-IR spectroscopy clearly
showed the formation of 2a and after removing the solvent by
evaporation 2a was obtained quantitatively (Figure 3). Contrary to
the acid co-catalyzed HNO3-mediated oxidation in dioxane,[19] the
signal for N2O (at 2236 cm-1 in the IR spectra) was not observed
(Figure 3), This could be attributed to the lower reaction
temperature and highly polar and ionizing nature of HFIP.
Unfortunately, the fate of nitrite part of 5a could not be elucidated
from the ATR-IR spectra of reaction mixture. As could be seen
from the enlarged region of the N=O around 1600 cm-1 there is an
overlap of signals of N=O with those of benzaldehyde (See fig. 5
in SI).
Acknowledgements
The financial support of the Slovenian Research Agency (P1-
0134 and Young Researcher Program) is greatly appreciated.
The authors are grateful to the Slovenian NMR Centre at the
National Institute of Chemistry. This work was also supported by
COST Action CM1205 CARISMA (Catalytic Routines for Small
Molecule Activation).
Keywords: alcohols • nitric acid • oxidation • perfluorinated
solvents• template catalysis
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Experimental Section
One mmol of 1 was dissolved in 1.0 mL of 1,1,1,3,3,3-hexafluoro-2-
propanol (HFIP) and then 10 mol% 65 % HNO3 was added. A balloon filled
with molecular oxygen was attached to the round bottle flask containing
the reaction mixture. Reaction mixture was stirred for 22 h at room
temperature. Once completed the reaction solution was washed with brine.
The organic phase was removed and dried with Na2SO4 and the solvent
evaporated under reduced pressure.
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