RSC Advances
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Acknowledgements
The authors wish to thank the National Natural Science Foun-
dation of China (Grant Nos. 21105054 and 21221062) for
nancial support.
References
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obtained. This spectrum was satisfactorily simulated (Fig. 2b)
assuming coupling of the unpaired electron with a Boron
nucleus, two sets of two equivalent hydrogen atoms, a set of
three equivalent hydrogen atoms and a nitrogen atom with
coupling constants (see ESI†) typical of a tolyl boroxy
nitroxide.
7
(
2
3
On this basis, a possible mechanism for the ipso-nitration of
arylboronic acids with iron nitrate is proposed in Scheme 2:
accordingly, under heating conditions Fe(NO3)3 produces
Fe(NO ) and the radical _N O (II) that dimerizes to III, which
4
3
2
3
4
5
6
then decomposes to _N O
2
(IV) releasing oxygen. Radical IV reacts
1
with 4-methylphenylboronic acid (1) to produce the cyclo-
hexadienyl radical V that loses radical _B (OH) (VI) affording the
2
reaction product 2. Reaction of VI with 2 would lead to the
detected boroxynitroxide VII.
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1
In conclusion, we have developed an easy and efficient
ipso-nitration of arylboronic acids with iron nitrate. The
protocol uses readily available arylboronic acids as the start-
ing materials, 0.5 equiv. of iron nitrate as the nitro source,
toluene as the solvent, the reactions are performed under
mild conditions without addition of any additive, and the
corresponding nitration products are obtained in good to
excellent yields. The method could tolerate various functional
groups in the substrates and showed a wide generality.
Therefore, the present method is amenable to nd wide
application in various elds.
4
6, 4715.
7
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1
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9
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1
0 G. K. S. Prakash, C. Panja, T. Mathew, V. Surampudi,
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1
Scheme 2 Possible mechanism for ipso-nitration of arylboronic acids with iron
nitrate.
2
5604 | RSC Adv., 2013, 3, 25602–25604
This journal is ª The Royal Society of Chemistry 2013