Nitration of 2′-deoxyguanosine by a NO/O2 gas mixture: Identification and characterization of N2-nitro-2′ -deoxyguanosine

Article abstract of DOI:10.1021/ol0300468

(Matrix presented) A gas mixture of NO and O₂ was bubbled into 2′-deoxyguanosine solution at neutral pH and 37°C. A novel nitrated nucleoside was generated in the reaction mixture in addition to 8-nitroguanine, 8-nitroxanthine, 2′-deoxyxanthosine, xanthine, and guanine. The novel nucleoside was identified as N²-nitro-2′-deoxyguanosine by spectrometric data.

Full text of DOI:10.1021/ol0300468

ORGANIC
LETTERS
2
003
Vol. 5, No. 18
173-3176
Nitration of 2′-Deoxyguanosine by a
3
NO/O Gas Mixture: Identification and
2
Characterization of
2
N -Nitro-2′-deoxyguanosine
Masaki Yamada,†,⊥ Toshinori Suzuki, Kenji Kanaori, Kunihiko Tajima,
†,#
‡
‡
§
†
,†,|
Shunji Sakamoto, Tsutomu Kodaki, and Keisuke Makino*
Institute of AdVanced Energy, Kyoto UniVersity, Uji 611-0011, Japan,
Department of Applied Biology and Department of Polymer Science and Engineering,
Kyoto Institute of Technology, Kyoto 606-8585, Japan, and International InnoVation
Center, Kyoto UniVersity, Kyoto 606-8501, Japan
kmak@iae.kyoto-u.ac.jp
Received March 20, 2003
ABSTRACT
2
A gas mixture of NO and O was bubbled into 2′-deoxyguanosine solution at neutral pH and 37 °C. A novel nitrated nucleoside was generated
in the reaction mixture in addition to 8-nitroguanine, 8-nitroxanthine, 2′-deoxyxanthosine, xanthine, and guanine. The novel nucleoside was
2
identified as N -nitro-2′-deoxyguanosine by spectrometric data.
Nitric oxide (NO) is a messenger molecule mediating various
physiological functions. Today inhaled NO is used as a
not unaerobic conditions, suggesting that reactive nitrogen
species generated from the reaction of NO and molecular
1
5
-7
vasodilator for newborns with persistent pulmonary hyper-
oxygen (O
2
) cause the deamination.
Reaction of 2′-
2
tension, despite its clinical risk. However, NO is also a major
deoxyguanosine (dGuo) with NO under aerobic conditions
3
constituent of air pollutant. NO can react with biomolecules
generates 2′-deoxyxanthosine (dXao) as a major deaminated
5
-7
8
such as protein and DNA to exert cytotoxicity and geno-
product and 2′-deoxyoxanosine (dOxo) as a byproduct.
2
Recently, our group has reported that 8-nitroguanine (8-NO -
4
toxicity. Nucleic acid bases are converted to their deami-
nated derivatives by incubation with NO under aerobic but
Gua), which is a product from dGuo by reaction with several
-
reactive nitrogen species such as peroxynitrite (ONOO ) and
†
Institute of Advanced Energy, Kyoto University.
Department of Applied Biology, Kyoto Institute of Technology.
Department of Polymer Science and Engineering, Kyoto Institute of
9-11
nitryl chloride (NO
2
Cl),
is also formed from dGuo by
‡
1
2
§
2
reaction with a gas mixture of NO and O . In the present
Technology.
|
International Innovation Center, Kyoto University.
Current address: Life Science Laboratory, Shimadzu Corporation,
(5) Wink, D. A.; Kasprzak, K. S.; Maragos, C. M.; Elespuru, R. K.;
Misra, M.; Dunams, T. M.; Cebula. T. A.; Koch, W. H.; Andrews, A. W.;
Allen, J. S.; Keefer, L. K. Science 1991, 254, 1001-1003.
(6) Nguyen, T.; Brunson, D.; Crespi, C. L.; Penman, J. S.; Tannenbaum,
S. R. Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 3030-3034.
(7) Caulfield, J. L.; Wishnok, J. S.; Tannenbaum, S. R. J. Biol. Chem.
1998, 273, 12689-12695.
⊥
Nishinokyo-Kuwabaracho Nakagyo-ku, Kyoto 604-8511, Japan.
#
Current address: Biological Engineering Division, 56-786, Mas-
sachusetts Institute of Technology, Cambridge, MA 02139.
(
1) Moncada, S.; Palmer, R. M. J.; Higgs, E. A. Pharmacol. ReV. 1991,
3, 109-142.
2) Weinberger, B.; Laskin, D. L.; Heck, D. E.; Laskin, J. D. Toxicol.
Sci. 2001, 59, 5-16.
3) Finlayson-Pitts, B. J.; Pitts, J. N., Jr. Chemistry of the Upper and
4
(
(8) Suzuki, T.; Yamaoka, R.; Nishi, M.; Ide, H.; Makino, K. J. Am. Chem.
Soc. 1996, 118, 2515-2516.
(
(9) Yermilov, V.; Rubio, J.; Becchi, M.; Friesen, M. D.; Pignatelli, B.;
Ohshima, H. Carcinogenesis 1995, 16, 2045-2050.
Lower Atmosphere: Theory, Experiments, and Applications; Academic
Press: San Diego, 2000.
(10) Chen, H.-J. C.; Chen, Y.-M.; Wang, T.-F.; Wang, K.-S.; Shiea, J.
Chem. Res. Toxicol. 2001, 14, 536-546.
(4) Ohshima, H.; Bartsch, H. Mutat. Res. 1994, 305, 253-264.
1
0.1021/ol0300468 CCC: $25.00 © 2003 American Chemical Society
Published on Web 08/05/2003

study, we report the formation, identification, and charac-
terization of a novel nitrated nucleoside in the reaction of
on the basis of coincidence of their retention time, UV
spectrum (λmax ) 382 nm), and APCI-MS spectrum (nega-
tive, m/z ) 196) with those of the authentic sample.15
dGuo with the gas mixture of NO and O
-NO -Gua, 8-nitroxanthine (8-NO -Xan), dXao, xanthine
Xan), and guanine (Gua).
An aqueous dGuo solution (100 µmol/10 mL) was treated
by the gas mixture of NO (0.5 mL/s) and O (2.0 mL/s) at
2
in addition to
8
2
2
R
An unknown product (termed 1) was eluted at t ) 11.3
(
min showing a UV spectrum with a λmax ) 330 nm (Figure
1, inset). Compound 1 was isolated by preparative RP-HPLC
1
6 1
2
and subjected to structural assignment. H NMR spectrum
of 1 in DMSO-d showed signals for an aromatic proton and
pH 7.4 and 37 °C until 10 mmol of NO was consumed, and
6
the solution was subsequently allowed to stand for 3 h at
room temperature. Figure 1 shows a reversed-phase HPLC
an exchangeable proton with a set of signals derived from
2′-deoxyribose moiety. The C NMR spectrum showed 10
13
13
signals, of which five were in the aromatic region. APCI-
MS (negative) showed a signal at m/z ) 311 as the
-
deprotonated molecular ion [M - H] , which was 45 mass
units greater than that of the starting dGuo. Additionally,
signals at m/z ) 195, 166, and 150 assignable to base
-
-
fragments [Mbase] , [Mbase + H - NO] , and [Mbase + H -
-
NO
2
] , respectively, were observed. High-resolution FAB-
MS (negative) of 1 showed m/z ) 311.0743 for the
deprotonated molecular ion, which agreed with the theoretical
molecular mass for composition C10
IR exhibited absorption bands at 1561 and 1304 cm
attributable to asymmetric and symmetric vibrations of a nitro
11 6 6
H O N within 0.3 mmu.
-
1
17
2
group in a nitramine (-NH-NO ), respectively. Combining
these spectrometric data, we identified 1 as a nitrated
2
derivative of dGuo on the exocyclic amino group, N -nitro-
Figure 1. RP-HPLC chromatogram of the reaction mixture of
dGuo with the gas mixture of NO and O . The inset is the on-line
2
2
2
′-deoxyguanosine (N -NO
2
-dGuo) (Figure 2). We detected
detected UV spectrum of 1.
14
(
RP-HPLC) chromatogram of the reaction mixture. Several
product peaks were detected in addition to void peaks
-
-
including NO
Among the product peaks, a peak with the retention time
) of 5.1 min contained Xan with a small amount of Gua.
The products of t ) 6.8 and 8.5 min were identified as
dXao and 8-NO -Gua, respectively. A peak of t ) 9.6 min
2
and NO
3
and the starting dGuo peak.
(t
R
2
Figure 2. Structure of N -NO
2
-dGuo and its possible acid-base
R
equilibrium. dR stands for 2-deoxyribose. The numbers designate
the atomic position.
2
R
denoted by an asterisk in Figure 1 contained a trace amount
of dOxo overlapped by another unknown product. The
identification of these products was based on their identical
2
only one exchangeable proton signal derived from N -NO
2
-
15
retention times and UV spectra with the authentic samples.
The product of t ) 9.8 min was identified as 8-NO -Xan
dGuo, although two exchangeable proton signals were
expected for this structure. The pH titration of isolated N2
R
2
-
NO
2
-dGuo solution using absorbance at 260 nm showed the
) 2.1 and 9.2.
(
11) Byun J.; Henderson, J. P.; Mueller, D. M.; Heinecke, J. W.
Biochemistry 1999, 38, 2590-2600.
12) Suzuki, T., Yamada, M., Kanaori, K., Tajima, K., Morii, T. and
Makino, K. Nucleic Acids Symp. Ser. 1999, 42, 155-156.
13) Reaction Conditions. dGuo (100 µmol) was dissolved in 10 mL
existence of two acid-base equilibria of pK
a
(
(15) Authentic Samples. Gua and Xan were purchased. dXao and dOxo
were prepared from dGuo by reaction with nitrous acid (see ref 8). 8-NO2-
Gua was synthesized from Gua by reaction with peroxynitrite (see ref 9).
8-NO2-Xan was synthesized from Xan by the treatment with nitric acid
(see ref 10). The samples synthesized were purified by RP-HPLC.
(16) Spectrometric Data of N -Nitro-2′-deoxyguanosine (1). H NMR
(600 MHz, in DMSO-d6 at 30 °C): δ (ppm/TMS) 12.3 (br, 1H, NH), 8.01
(s, 1H, H8), 6.13 (dd, J1′2′ ) 7.1 Hz, J1′2′′ ) 6.7 Hz, 1H, H1′), 5.28 (br, 1H,
3′-OH), 5.02 (br, 1H, 5′-OH), 4.31 (ddd, J3′4′ ) 2.8 Hz, 1H, H3′), 3.78
(ddd, J4′5′ or J4′5′′ ) 2.6 or 4.3 Hz, 1H, H4′), 3.48 (ABX, J5′5′′ ) 40.1 Hz,
2H, H5′, 5′′), 2.51 (ddd, 1H, H2′ or H2′′), 2.16 (ddd, 1H, H2′ or H2′′).
NMR (125 MHz, in DMSO-d6 at 30 °C): δ (ppm/TMS) 155.8, 154.0, 149.3,
137.2 (C8), 118.4, 87.9 (C4′), 83.4 (C1′), 70.7 (C3′), 61.6 (C5′), 39.8 (C2′).
(
of 100 mM sodium phosphate buffer (pH 7.4) in an open vessel. An NO/
O2 gas mixture with flow rates of 0.5 mL/s for NO and 2.0 mL/s for O2
was bubbled into well-stirring dGuo solution at 37 °C. The pH of the
solution was maintained at 7.4 ( 0.4 by the titration of 1 M NaOH
throughout the reaction. NO dose was measured as the moles of NaOH
required to neutralize the solution. The reaction mixture was allowed to
stand for 3 h at room temperature before RP-HPLC analysis. The NO/O2
gas mixture was prepared as follows. NO (99.8%, Kyoto Teisan, Kyoto,
Japan) was passed through soda lime and then mixed with O2 (99.5%, Kyoto
Teisan) at a Y-type connector. The mixed gas was run through a Teflon-
lined tube (5.0 × 200 mm) and bubbled into the dGuo solution by a glass
frit (4.0 × 200 mm, pore size 20-30 µm, Kinoshita Rika, Tokyo, Japan).
2
1
1
3
C
1
13
The signal assignments for H and C resonances were performed by
13
1
13
(
14) HPLC Conditions. RP-HPLC analyses were performed using an
TOCSY, 1H- C HMQC, and H- C HMBC. IR (KBr): 3418, 1688,
-1
octadecylsilane column (ULTORON VX-ODS, 6.0 × 150 mm, particle size
1561, 1520, 1468, 1396, 1304, 1219, 1094, 1063, 943, 781, 725, 642 cm .
5
µm, Shinwa Chemical Industry, Kyoto, Japan) eluted with 100 mM
UV: λmax 272 and 319 nm (pH 1), 266 and 330 nm (pH 7), 244 nm (pH
11). APCI-MS (negative, CH3OH): m/z 311, 200, 195, 186, 166, and 150;
HR-MS (FAB, negative, CH3OH): m/z ) 311.0743 [M - H] (calcd for
C10H11N6O6, 311.0740).
triethylammonium acetate buffer (pH 7.0) containing acetonitrile. The
acetonitrile concentration was increased from 0 to 20% for 20 min in a
linear gradient mode. The flow rate was 1.5 mL/min.
-
3174
Org. Lett., Vol. 5, No. 18, 2003

2
2
At neutral pH, an anion-exchange resin trapped N -NO
2
-
The yield of N -NO
2
-dGuo increased extremely at basic pH.
-dGuo was produced in 32% yield
2
dGuo completely, whereas a cation-exchange resin did not.
At pH 12.5, N -NO
relative to the starting dGuo. The stability of N -NO -dGuo
2
2
Generally, primary nitramines are weak acids.1
7-19
Thus, the
2
acid-base equilibrium of pK
a
) 2.1 is attributable to
was evaluated under physiological and mildly acidic condi-
tions. No decomposition was observed by RP-HPLC when
2
protonation-deprotonation of the nitramino group of N -NO
2
-
2
2
dGuo, indicating that N -NO
2
-dGuo exists as the anionic form
the isolated N -NO
2
-dGuo was incubated at pH 7.4 and 37
2
in neutral solution (Figure 2). In the NMR solvent DMSO-
°C for 1 week. At pH 4.0 and 70 °C, N -NO
2
-dGuo
2
-4
d
6
, N -NO
2
-dGuo may exist as the anion form due to a trace
disappeared with a first-order rate constant of 1.2 × 10
-1 -5 -1
of H O present in the solvent or the sample, thus obscuring
2
s , which was greater than that for dGuo (4.8 × 10 s )
-3 -1
the nitramine proton signal. Under the above reaction
conditions, the yields for each product relative to the starting
dGuo were 0.35% Gua, 0.86% Xan, 1.60% dXao, 0.31%
but smaller than that for dXao (1.0 × 10 s ).
Possible pathways for the formation of the products are
summarized in Scheme 1. Nitration, deamination, and
depurination occur simultaneously in the reaction of dGuo
8
-NO
2
2
-Gua, <0.10% dOxo, 1.33% 8-NO -Xan, and 0.14%
2
20
N -NO
2
-dGuo.
with the NO/O
2′-deoxyguanosine (8-NO
and subsequent depurination. Reportedly, 8-NO
unstable and undergoes depurination, readily releasing
2
gas mixture. dGuo is converted via 8-nitro-
-dGuo) to 8-NO -Gua by nitration
-dGuo is
Figure 3A shows NO dose-dependent changes of the yields
2
2
2
of the nitrated products, N -NO
2
2
-dGuo, 8-NO -Gua, and
2
8
3
2
-NO -Gua with a half-life of less than 3 min at pH 7.4 and
2
1,22
7 °C.
Under the present conditions, almost all 8-NO
-Gua since a
gas mixture of 10 mmol
2
-
dGuo formed would be converted to 8-NO
typical bubbling period of the NO/O
2
2
NO dose is 11 min and a reaction mixture is allowed to stand
for 3 h at room temperature before RP-HPLC analysis. dGuo
is also converted via Gua to 8-NO
subsequent nitration. We confirmed that Gua was nitrated
readily by the NO/O gas mixture, resulting in 8-NO -Gua
2
-Gua by depurination and
2
2
as a major product (data not shown). On the other hand, dGuo
gives rise to dXao by deamination. Analogous to dGuo, dXao
is converted to 8-NO
8-NO -dXao) or via Xan since 8-NO
release 8-NO
form 8-NO -Xan exclusively by the NO/O
not shown). Independently of the formation of these products,
2
-Xan via 8-nitro-2′-deoxyxanthosine
-dXao is unstable to
-Xan and since Xan was nitrated readily to
gas mixture (data
Figure 3. (A) NO dose- and (B) O
2
flow rate-dependence of the
(
2
2
2
2 2
yields for N -NO -dGuo (b), 8-NO -Gua (0), and 8-NO -Xan (4).
2
1
0
2
2
2
8
-NO
s) gas mixture. The yields of all of the nitrated products
increased with increasing NO dose, while the yield of 8-NO
2 2
-Xan, generated from dGuo by the NO/O (0.5/2.0 mL/
2
2
N -NO -dGuo is generated by nitration on the exocyclic
amino group of dGuo and stays as the nucleoside form in
2
-
2
the reaction mixture since N -NO
2
-dGuo is stable.
Xan increased significantly at high doses of NO. Figure 3B
shows changes of the yields at 10 mmol NO dose when the
Several intermediates such as ONOO, ONOONO, NO
2
,
and N
2
O
3
have been proposed in autoxidation of NO until
O
2
flow rate decreased from 2.0 to 0.5 mL/s with the fixed
flow rate of NO (0.5 mL/s). The yields of all the nitrated
products decreased as the O flow decreased. Figure 4 shows
the yields at various pHs, when dGuo was reacted with the
-
23-26
NO
2
is generated finally.
None of these compounds,
however, can be candidates of the reactive intermediates to
2
(
17) Fridman, A. L.; Ivshin, V. P.; Novikov, S. S. Russ. Chem. ReV.
1969, 38, 640-654.
18) Unterhalt, B. In Methoden der Organischen Chemie, Band E16a;
Klamann, D., Ed.; Georg Thieme Verlag: Stuttgart, 1990; pp 1147-1181.
19) Politzer, P.; Sukumar, N.; Jayasuriya, K.; Rnaganathan, S. J. Am.
Chem. Soc. 1988, 110, 3425-3430.
20) Quanitative Procedures. Yields of the products were estimated
from integrated peak areas of the HPLC chromatogram detected at 260,
82, or 400 nm and the molar extinction coefficients (ꢀ). The ꢀ260 values
NO/O
2
(0.5/2.0 mL/s) gas mixture of 10 mmol NO dose.
(
(
(
3
3
-1
-1
3
-1
-1
3
of 7.5 × 10 M cm for Gua, 8.5 × 10 M cm for Xan, 7.8 × 10
-
1
-1
3
-1
-1
M
8
cm for dXao, and 5.1 × 10 M cm for dOxo were used (see ref
and Henle, E. S.; Luo, Y.; Gassmann, W.; Linn, S. J. Biol. Chem. 1996,
3
-1
-1
2
71, 21177-21186). The ꢀ400 of 9.1 × 10 M cm for 8-NO2-Gua and
3 -1 -1
the ꢀ382 of 7.7 × 10 M cm for 8-NO2-Xan were used (see ref 10). The
2
3
-1
-1
ꢀ
260 of N -NO2-dGuo was estimated as 9.5 × 10
M
cm by the
comparison of the integration of H1′ proton signal and the RP-HPLC peak
area detected at 260 nm with those for dGuo. Gua, Xan, and dOxo were
separated and quantified using another HPLC eluent of 100 mM ammonium
formate (pH 6.3) with acetonitrile, while 100 mM triethylammonium acetate
(
pH 7.0) was used as the eluent buffer for the nitrated products and dXao.
(
21) Sodum, R. S.; Fiala, E. S. Chem. Res. Toxicol. 2001, 14, 438-450.
2
Figure 4. pH-dependence of the yields of N -NO
2
-dGuo (b),
(
46.
22) Yermilov, V.; Rubio, J.; Ohshima, H. FEBS Lett. 1995, 376, 536-
2 2
8-NO -Gua (0), and 8-NO -Xan (4). The pHs were maintained
5
within the indicated values ( 0.5.
(23) Bhatia, S.; Hall, J. H., Jr. J. Phys. Chem. 1980, 84, 3255-3259.
(
24) McKee, M. L. J. Am. Chem. Soc. 1995, 117, 1629-1637.
Org. Lett., Vol. 5, No. 18, 2003
3175

Scheme 1. Proposed Pathway for Reaction of dGuo with Gas Mixture of NO and O
2
nitrate dGuo directly, because of low reactivity of these
compounds with dGuo.25-28 Recently, Malhotra and Ross29
have reported that aromatic compounds in liquid nitrogen
equiribilium between the cation radical and the neutral radical
is 3.9. The cation or neutral radical of dGuo (or Gua) reacts
30
with NO
Analogously, dXao (or Xan) is nitrated at the C8 position.
If NO reacts with the cation or neutral radical of dGuo on
its exocyclic amino group, N -NO
Another candidate of the reactive intermediate for the
nitration is dinitrogen pentoxide (N ), since NO can react
2 2 2
at C8 to form 8-NO -dGuo (or 8-NO -Gua).
tetroxide (N
simultaneous passage of NO and O
nitration mechanism as follows. The initial reaction of NO
and O produces ONOO. In the presence of excess NO
O
2 4
), a liquid phase of NO
2
, are nitrated by
2
. They proposed the
2
2
2
-dGuo can be generated.
2
2
,
ONOO leads to nitrate radical (NO
oxidant:
3
), a strong one-electron
2
O
5
3
3
1
with NO
2
to form N
NO + NO f N O
5
2 5
O :
3
2
2
ONOO + (excess NO ) f NO + (excess NO )
2
3
2
2 5
N O , a strong nitrating agent, can nitrate various compounds
NO
cation radicals react with NO
In the present study, NO can be generated because a
relatively large amount of NO would exist in the NO/O
gas mixture. The formation of the nitrated products from
dGuo may be explained by this nitration mechanism as
3
oxidizes the aromatics to give their cation radicals. The
32
including aromatics and amines. The nitration reactions are
2
, forming nitrated aromatics.
+
32
+
believed to be via the nitronium ion (NO
2
). NO
2
may
3
react directly with C8 of dGuo, Gua, dXao, and Xan,
+
2
2
resulting in their 8-nitro derivatives. When NO
2
attacks the
2
2
exocyclic amino group of dGuo, N -NO -dGuo can be
formed.
follows. The NO
3
formed in the NO/O
2
gas mixture reacts
In conclusion, we found a novel nitrated nucleoside, N2-
with dGuo, resulting in a cation radical of dGuo. The cation
radical of dGuo then deprotonates to become the neutral
NO
NO and O
Gua, 8-NO
a major product under basic conditions. Involvement of NO
and N was suggested as the reactive intermediate for the
nitration. The isolated N -NO
physiological conditions. Studies would be required for N -
NO -dGuo on formation and significance in biological
systems.
2
-dGuo, in the reaction of dGuo with a gas mixture of
2
at neutral pH and 37 °C in addition to 8-NO
-Xan, dXao, Xan, and Gua. N -NO -dGuo was
2
2
-
radical of dGuo in neutral solution since the pK
a
of the
2
2
3
(
25) Goldstein, S.; Czapski, G. J. Am. Chem. Soc. 1995, 117, 12078-
2084.
26) Goldstein, S.; Czapski, G. J. Am. Chem. Soc. 1996, 118, 3419-
425.
27) Shafirovich, V.; Cadet, J.; Gasparutto, D.; Dourandin, A.; Geacintov,
N. E. Chem. Res. Toxicol. 2001, 14, 233-241.
28) Spencer, J. P. E.; Whitemen, M.; Jenner, A.; Halliwell, B. Free
Radical Biol. Med. 2000, 28, 1039-1050.
29) Malhotra, R.; Ross, D. S. In Nitration: Recent Laboratory and
2 5
O
1
3
2
(
2
-dGuo was stable under
2
(
2
(
(
Acknowledgment. We thank Dr. M. Nishi (Setsunan
Industrial DeVelopment; ACS Symposium Series 623; American Chemical
University) for acquiring the HR-MS spectrum. This work
was partly supported by Grants-in-Aid for Scientific Research
from the Ministry of Education, Science and Culture, Japan
[to K.M., 11101001, 08458176, 10151219, 10878092,
Society: Washington, DC, 1996; pp 32-41.
(
30) Steeken, S. Chem. ReV. 1989, 89, 503-520.
(31) W a¨ ngberg, I.; Etzkorn, T.; Barnes, I.; Platt, U.; Becker, K. H. J.
Phys. Chem. A 1997, 101, 9694-9698.
(32) Millar, R. W.; Colclough, M. E.; Desai, H.; Golding, P.; Honey, P.
J.; Paul, N. C.; Sanderson, A. J.; Stewart, M. J. In Nitration: Recent
Laboratory and Industrial DeVelopment; ACS Symposium Series 623;
American Chemical Society: Washington, DC, 1996; pp 104-121.
1
2480173].
OL0300468
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Org. Lett., Vol. 5, No. 18, 2003