Synthesis and characterization of a novel N-F reagent derived from the ethano-Tr?ger's base: 1JFN coupling constants as a signature for the N-F bond

Article abstract of DOI:10.1039/c5cc08375c

Methylation of 2,8-dimethyl-6H,12H-5,11-ethanodibenzo[b,f][1,5]-diazocine (ethano-Tr?ger's base) with methyl iodide followed by ion metathesis and fluorination with N-fluoro-2,3,4,5,6-pentachloropyridinium triflate affords a new electrophilic N-F reagent, that is more reactive than Selectfluor. 2D ¹⁹F-¹⁵N HMQC experiments provide ¹J_NF coupling constants which are diagnostic for the N-F functional group.

Full text of DOI:10.1039/c5cc08375c

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: R. Pereira, J.
Wolstenhulme, G. Sandford, T. D. W. Claridge, V. Gouverneur and J. Cvengros, Chem. Commun., 2015,
DOI: 10.1039/C5CC08375C.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/chemcomm

Please do not adjust margins
ChemComm
Page 1 of 4
View Article Online
DOI: 10.1039/C5CC08375C
Chemical Communications
COMMUNICATION
Synthesis and Characterization of a Novel N-F Reagent derived
1
from the Ethano-Tröger’s Base: JFN Coupling Constant as
Signature for the N-F Bond
Received 00th January 20xx,
Accepted 00th January 20xx
Raul Pereira,a,b Jamie Wolstenhulme,a Graham Sandford,c Timothy D. W. Claridge,a
DOI: 10.1039/x0xx00000x
Véronique Gouverneura* and Jan Cvengroš b
*
www.rsc.org/
alternative scaffolds amenable to double N-quaternization.
The Tröger's base
(TB)11 and its analogues are attractive
Methylation of 2,8-dimethyl-6H,12H-5,11-ethanodibenzo[b,f][1,5]-
diazocine (Ethano-Tröger’s base) with methyl iodide followed by
ion metathesis and fluorination with N-fluoro-2,3,4,5,6-
pentachloropyridinium triflate affords a new electrophilic N–F
reagent, that is more reactive than Selectfluor. 2D 19F-15N HSQC
1
candidates for transformation into N–F reagents, due to their
C2 symmetry, and concave Λ-shape. In our hands, the
methylene-bridged TB proved unstable towards F+
electrophiles,12 so we focused our efforts on the synthesis and
1
experiments provide JNF coupling constants which are diagnostic
characterization of the N–F reagent
2 derived from the
for the N–F functional group.
ethylene-bridged Tröger’s base 313 (ETB = 2,8-dimethyl-
6H,12H-5,11-ethanodibenzo[b,f][1,5]-diazocine). ETB is readily
available by reacting TB with dibromoethane and Li2CO3 in
DMF. In this report, we disclose the synthesis and
The progress made in recent years in the field of modern
organofluorine chemistry indicates that the nature of the
fluorine source is critical for a particular fluorination process to
succeed.1 This observation stands true for nucleophilic and
electrophilic fluorination, and this independently of the
activation manifold applied to induce C-F bond formation.
Much research has therefore focused on the development of
new reagents for late stage fluorination.2 The appearance of
safe and easy to handle N–F reagents2d,3 has revolutionized the
field of electrophilic fluorination by providing an alternative to
F2, XeF2,4 perchloryl fluoride5 or O–F reagents, such as
characterization of 2 along with a preliminary study on
reactivity. For the first time, 2D 19F-15N Heteronuclear
Multiple-Quantum Correlation (HMQC) experiments were
1
and known N–F reagents. The resulting JNF
performed on
2
coupling constants constitute a new signature for the N–F
functional group.
2c,
7
trifluoromethyl hypofluorite,6 acyl2b,
and perfluoroacyl
hypofluorites.8 The preparation, properties and reactivity of N-
fluoro electrophilic fluorinating agents have been discussed in
authoritative reviews.9 In this category, Selectfluor
bis(tetrafluoroborate) and its analogues, constitute a series of
doubly quaternized N-fluoro-1,4-bicyclo[2.2.2]octane reagents
of remarkable stability and relatively low toxicity. Our own
work has concentrated on the development of chiral
Selectfluor bis(triflate)10 featuring the stereogenicity elements
on the DABCO core, and more recently as a corollary to this,
the development of new chiral N–F reagents derived from
Figure 1 Structures of the methylene- and ethylene-bridged
Tröger’s bases
1
and
3, and of the N–F reagent
2.
The synthesis of
2
was investigated with a study in racemic
series. Modifying a literature procedure, the treatment of (±)-
ETB with a large excess of methyl iodide in a mixture of
MeOH/CH2Cl2 afforded the desired monoquaternized iodide
salt,14 which was then subjected to ion metathesis with AgOTf
to afford 4 isolated in 70% yield over two steps (Scheme 1).
Scheme 1 Synthesis of the monoquaternized salt 4.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 4
View Article Online
DOI: 10.1039/C5CC08375C
COMMUNICATION
Journal Name
Table 1. Optimization for the fluorination of 4a
place when a solution of
2
in acetonitrile was left at room
temperature for eight hours or more. As a result, the reagent
is best prepared immediately before use. Therefore, the
optimized procedure for the synthesis of
2 consists of treating
a solution of 4 (43 mg, 0.1 mmol, 1 equiv) in dry CH3CN (1 mL)
with
a
slurry of N-fluoro-2,3,4,5,6-pentachloropyridinium
(1 equiv) in dry CH3CN (1 mL) at – 35 oC. The resulting
triflate
7
solution is composed of the novel N–F reagent
equimolar amount of 2,3,4,5,6-pentachloropyridine.
The relative instability and the difficulties encountered upon
isolation and purification of did not allow for analysis of a
single crystal by X-ray crystallography. The theoretical and
experimentally measured HR-ESI spectra of are in excellent
2 and an
No.
1
F Source
XeF2
Equiv Temp. [oC]
Conversion [%]b
2
1
1
2
2
2
2
2
1
1
1
1
40
80
0
0c
0
2
XeF2
d,e
2
3
F2
-35
-35
-35
-10
0
agreement showing a parent peak at m/z 149.0917 and m/z
149.0918, respectively. To help characterize the N-F bond in
particular, we performed 1D 19F NMR and 2D 19F-15N
d,f
4
F2
0
0c
d,g
5
F2
d,e
6
F2
0
heteronuclear correlation experiments with 2 (Figure 2). From
this, we observe a 14N/15N one-bond isotope shift15 Δδ equal to
0.27ppm. Similar experiments were performed with
d,e
7
F2
0c
0
8
5h
6i
7j
7j
25
Selectfluor bis(tetrafluoroborate)
analogues and ; for completeness, we also performed these
measurements on the N-fluoropyridiniums 10 and 11. All
5 and the two chiral
9
25
0
8
9
10
11
25
55
> 95
6, 7,
- 35
a
of the N-F reagents in this NMR study, as expected, do exhibit
the characteristic one-bond isotope shift (See ESI for further
details). Table 2 assembles the 19F and 15N chemical shifts for
these compounds. Nitrogen chemical shifts clearly reflect the
differing hybridization states of the nitrogen in the [NF]2+ and
[NF]+ compound groups, but otherwise exhibit little variation
within each series. The 19F chemical shifts show a more
Conditions:
4 (0.1 mol, 1 equiv), fluorine donor (1 equiv),
CH3CN (0.05 M). Conversion measured by 19F NMR with
respect to triflate as internal standard. Degradation of the in
b
c
d
situ formed N-F reagent. F2 (10% in N2). Reaction with
e
NaOTf (1 equiv). f Reaction with HOTf (1 equiv). g Reaction with
h
NaBF4 (1 equiv).
bicyclo[2.2.2]octane bis(tetrafluoroborate) [Selectfluor bis-
(tetrafluoroborate)].
triflate. j
5: 1-Chloromethyl-4-fluoro-1,4-diazonia-
I
6:
N-Fluoro-2,6-dichloropyridinium
: N-Fluoro-2,3,4,5,6-pentachloropyridinium triflate.
pronounced difference for compound
2 specifically, which
7
exhibited a very high shift of +103 ppm for the N-F group. This
is well above the corresponding signals recorded for
Selectfluor bis(triflate) and its derivatives, and the [NF]+
reagents that typically range from 30 ppm to 50 ppm,2d, 10 as
considered further below.
The validation and optimization of the critical fluorination
step was carried out with
. The reaction was monitored by 19
4
F
NMR spectroscopy (Table 1). XeF2, F2 and a series of
commercially available N–F reagents were tested for their
ability to transfer fluorine onto 4; these experiments also gave
information on relative reactivity. XeF2 and F2 are atom
economical reagents, and have the advantage to facilitate
post-fluorination purification since no organic co-product is
produced upon fluorine transfer. Regrettably, we found that
these reagents were not suitable for the synthesis of 2. XeF2
did not react at room temperature or led to decomposition at
40 oC or 80 oC. Similarly, F2 (10 % in N2) led to decomposition at
o
o
0 C, or returned unreacted starting material at -10 C or -35
oC. No fluorine transfer took place upon treatment of
with
one equivalent of Selectfluor bis(tetrafluoroborate) (1-chloro-
methyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetra-
fluoroborate) or N-fluoro-2,6-dichloropyridinium triflate in
4
5
6
acetonitrile at room temperature, suggesting that these known
N–F reagents would be less reactive than 2. Pleasingly, the
more
reactive
N-fluoro-2,3,4,5,6-pentachloropyridinium
when the reaction was performed at
Figure 2. 2D 19F-15N HMQC of
2 N
(0.1 mM) in CD3CN at 298K. 15
triflate
7
gave 55% of 2
(60.8 MHz) &19F (565.2 MHz). 19F 1Δδ(14N-15N) = 0.27 ppm.
ambient temperature. Significant improvement was observed
o
when the reaction temperature was lowered to -35 C. Under
these conditions, the pyridinium salt fully transferred F+ on to
2. Stability studies indicate that decomposition was taking
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 3 of 4
View Article Online
DOI: 10.1039/C5CC08375C
Journal Name
COMMUNICATION
1
Table 2
constants for
19F NMR (565.2 MHz, CD3CN, 298K).
.
19F and 15N Chemical shifts, and JFN coupling related reagents; for the dicationic [NF]2+ type reagents, this
2, 5-11. 2 is more reactive than Selectfluor
15N NMR (60.8 MHz, CD3CN, 298K) and trend would suggest that
and could therefore serve as a reagent to prepare Selectfluor
from its monoquaternized precursor. Experimentally, we
found that fluorine transfer from
minutes at room temperature in acetonitrile (Scheme 2).
We probed next the ability of
to transfer F+ onto
2 to 12 was complete after 5
2
substrates other than the Selectfluor precursor 12. Scheme 3
presents selected fluorination processes, and compare the
reaction conditions and yields with data obtained from the
literature for Selectfluor bis(tetrafluoroborate) 5 20
available for N-fluoro-2,3,4,5,6-pentachloropyridinium triflate
7 3c
The fluorination reactions of benzene, fluorobenzene and
anisole were successful and overall required shorter reaction
times with compared to . The ortho-para ratios of the
,
and when
.
2
5
fluorinated products of anisole and fluorobenzene by 2 and 5
are similar suggesting a similar mode of reactivity. The
[NF]2+ Reagent
19F NMR (ppm)
15N NMR (ppm)
1JFN (Hz)a
[NF]+ Reagent
19F NMR (ppm)
15N NMR (ppm)
1JFN (Hz)a
2
5
8
9
reactivity profile of N–F reagents
Styrene derivatives underwent fluorination in the presence of
and acetic acid giving the products of fluoroacetoxylation in
good yields. Additional experiments demonstrate that the
ethylene-bridged Tröger based reagent does not react with
less activated alkenes, for example cyclohexene. This result
7 and 2 is more similar.
+103.6 +48.1
+36.7
+182
90
+36.0
+183
91
+188
70
+177
85
2
7
6
10
11
2
+46.2
+253
140
+30.2
+256
145
+46.9
+260
130
+15.9
+259
125
defines the limitation of the novel N-F reagent
reactivity.
2 in term of
a
Although not determined, the sign of these coupling
constants are expected to be negative due to the negative
magnetogyric ratio of 15N. The chemical shifts are relative to
external NH3 (15N) and CFCl3 (19F) at 0.0 ppm.
1
We also measured JFN couplings constants to further
characterise the N-F bond (Table 2). In the literature,
experimental measurements of two-bond 19F-15N spin-spin
coupling constants across N-H…F hydrogen bonds (2hJFN) are
available, due primarily to the work of Limbach and co-
workers.16 These have also been reported for complexes with
F-H…N and N-H+…F hydrogen bonds.17 The directly recorded
1JFN coupling constant of
5 is in agreement with a literature
precedent.18 To the best of our knowledge, the values of the
other reagents reported here are the first measurements of
1JFN coupling constants of electrophilic N–F reagents. These
magnitudes principally reflect the nitrogen hybridization state
in the two compound classes, increasing with greater s-
character. We note compound
2
shows the smallest 1JFN value,
although the limited data set makes meaningful comparisons
difficult.
Scheme 2. Fluorine transfer from 2 to 12
a
Scheme 3. A) Fluorination of arenes: Arene (4 equiv),
2 (1.5
b
equiv), CH3CN. Data from reference 3c; substrate (excess),
7
(1.0 equiv) in CH2Cl2. Data from reference 20; arene (2.8
c
d
5 ( 1.4 equiv), TfOH (3 mL) in refluxing CH2Cl2. Data
equiv),
from reference 3c; substrate (co-solvent),
7
( 1 equiv), CH2Cl2.e
Yields determined by 19F NMR spectroscopy using 1-fluoro-4-
nitrobenzene as internal standard. B) Fluorination of styrenes:
styrene (1 mmol, 1 equiv), 2 (1 equiv), CH3COOH (0.04 M), 10
°C, 30 mins. Yields refer to product isolated after silica gel
chromatography.
With regard to the notably greater fluorine chemical shift of 2,
previous studies19 have suggested that 19F NMR shifts of N-F
reagents correlate with reactivity for a series of structurally
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 4
View Article Online
DOI: 10.1039/C5CC08375C
COMMUNICATION
Journal Name
5
6
(a) D. H. R. Barton, A. K. Ganguly, R. H. Hesse, S. N. Loo and
M. M. Pechet, Chem. Commun., 1968, 14, 806-808; (b) W. A.
Sheppard, Tetrahedron Lett., 1969, 10, 83-84.
(a) D. H. R. Barton, L. S. Godinho, R. H. Hesse and M. M.
Pechet, Chem. Commun., 1968, 14, 804-806; (b) M. J. Robins
and S. R. Naik, J. Chem. Soc., Chem. Commun., 1972, 18-19;
(c) M. J. Fifolt, R. T. Olczak, R. F. Mundhenke and J. F. Bieron,
J. Org. Chem., 1985, 50, 4576-4582.
(a) O. Lerman and S. Rozen, J. Org. Chem., 1983, 48, 724-727;
(b) S. Rozen, A. Hagooly and R. Harduf, J. Org. Chem., 2001,
66, 7464-7468; (c) I. Vints, J. Gatenyo and S. Rozen, J. Org.
Chem., 2013, 78, 11794-11797.
In summary, we have prepared and characterized the novel
N–F reagent
2 derived from the ethylene-bridged Tröger base.
This reagent was found to be a competent F+ source, more
reactive than Selectfluor, and of similar reactivity to
pentachloropyridinium triflate. Moreover, we present the first
1J(F-N) coupling constants for eight N–F reagents inclusive of
2, a
set of data serving as a new signature for the N–F bond. This
study opens the door towards asymmetric fluorination since
the ethylene-bridged Tröger's base is a chiral molecule.
7
8
9
(a) S. Rozen and Y. Menahem, J. Fluorine Chem., 1980, 16
19-31; (b) S. Rozen and D. Hebel, J. Org. Chem., 1990, 55
2621-2623.
(a) A. G. Gilicinski, G. P. Pez, R. G. Syvret and G. S. Lal, J.
Fluorine Chem., 1992, 59, 157-162; (b) G. S. Lal, G. P. Pez and
R. G. Syvret, Chem. Rev., 1996, 96, 1737-1756; (c) J. Baudoux
and D. Cahard, in Organic Reactions, John Wiley & Sons, Inc.,
2004, vol. 69, pp. 1–326; (d) P. T. Nyffeler, S. G. Durón, M. D.
Burkart, S. P. Vincent and C.H. Wong, Angew. Chem. Int. Ed.,
2005, 44, 192-212.
,
,
The financial support from the Swiss National Science
Foundation
(Doc.Mobility
project
P1EZP2_155528),
AstraZeneca (J.W.) and the EPSRC (J.W.) is gratefully
acknowledged. R.P. thanks the ETH for a PhD finishing
scholarship. VG holds a Royal Society Wolfson Merit Award
(2013-2018).
Notes and references
10 J. R. Wolstenhulme, J. Rosenqvist, O. Lozano, J. Ilupeju, N.
Wurz, K. M. Engle, G. W. Pidgeon, P. R. Moore, G. Sandford
and V. Gouverneur, Angew. Chem. Int. Ed., 2013, 52, 9796-
9800.
11 (a) J. Tröger, Journal für Praktische Chemie, 1887, 36, 225-
245; (b) Ö. V. Rúnarsson, J. Artacho and K. Wärnmark, Eur. J.
Org. Chem., 2012, 7015-7041.
12 Fe X, Yang, M. Yang, Q, Yang, Y, Xianjin, Y, Mingjie, Y,
Quahang, Chinese Patent, 2011, CN20101120193 20100309.
13 (a) Y. Hamada and S. Mukai, Tetrahedron: Asymmetry, 1996,
1
(a) T. Furuya, A. S. Kamlet and T. Ritter, Nature, 2011, 473,
470-477; (b) C. Hollingworth and V. Gouverneur, Chem.
Commun., 2012, 48, 2929-2942; (c) M. Tredwell and V.
Gouverneur, Angew. Chem. Int. Ed., 2012, 51, 11426-11437;
(d) T. Liang, C. N. Neumann and T. Ritter, Angew. Chem. Int.
Ed., 2013, 52, 8214-8264; (e) M. G. Campbell and T. Ritter,
Org. Process Res. Dev., 2014, 18, 474-480; (f) M. G. Campbell
and T. Ritter, Chem. Rev., 2015, 115, 612-633; (g) C. N.
7, 2671-2674; (b) R. Pereira, E. Otth and J. Cvengroš, Eur. J.
Org. Chem., 2015, 1674-1679.
14 D. A. Lenev, D. G. Golovanov, K. A. Lyssenko and R. G.
Kostyanovsky, Tetrahedron: Asymmetry, 2006, 17, 2191-
2194.
15 (a) H. Batiz-Hernandez and R. A. Bernheim, Prog. Nucl.
Magn. Reson. Spectrosc., 1967, 3, 63-85; (b) C. J. Jameson
Neumann and T. Ritter, Angew. Chem. Int. Ed., 2015, 54
3216-3221.
,
2
(a) W. J. Middleton, J. Org. Chem., 1975, 40, 574-578; (b) S.
Rozen, O. Lerman and M. Kol, J. Chem. Soc., Chem. Commun.,
1981, 443-444; (c) M. Kol, S. Rozen and E. Appelman, J. Am.
Chem. Soc., 1991, 113, 2648-2651; (d) R. E. Banks, S. N.
Mohialdinkhaffaf, G. S. Lal, I. Sharif and R. G. Syvret, J. Chem.
and H. J. Osten, J. Am. Chem. Soc., 1985, 107, 4158-4161; (c)
,
P. E. Hansen, Prog. Nucl. Magn. Reson. Spectrosc., 1988, 20
207-255.
Soc. Chem. Comm., 1992, 8, 595-596; (e) G. S. Lal, G. P. Pez,
16 (a) I. G. Shenderovich, P. M. Tolstoy, N. S. Golubev, S. N.
Smirnov, G. S. Denisov and H.H. Limbach, J. Am. Chem. Soc.,
2003, 125, 11710-11720; (b) M. Pietrzak, A. C. Try, B.
Andrioletti, J. L. Sessler, P. Anzenbacher and H.H. Limbach,
Angew. Chem. Int. Ed., 2008, 47, 1123-1126; (c) I. Alkorta, J.
Elguero, H.H. Limbach, I. G. Shenderovich and T. Winkler,
Magn. Reson. Chem., 2009, 47, 585-592.
17 (a) H. Fritz, T. Winkler and W. Küng, Helv. Chim. Acta., 1975,
58, 1822-1824; (b) J. E. Del Bene, S. A. Perera, R. J. Bartlett,
M. Yáñez, O. Mó, J. Elguero and I. Alkorta, J. Phys. Chem. A,
2003, 107, 3121-3125; (c) M. T. Scerba, C. M. Leavitt, M. E.
Diener, A. F. DeBlase, T. L. Guasco, M. A. Siegler, N. Bair, M.
A. Johnson and T. Lectka, J. Org. Chem., 2011, 76, 7975-7984.
18 K.K. Laali, A. Jamalian and C. Zhao, Tetrahedron Lett., 2014,
55, 6643-6646.
R. J. Pesaresi, F. M. Prozonic and H. Cheng, J. Org. Chem.,
1999, 64, 7048-7054; (f) T. Furuya, H. M. Kaiser and T. Ritter,
Angew. Chem. Int. Ed., 2008, 47, 5993-5996; (g) A.
L’Heureux, F. Beaulieu, C. Bennett, D. R. Bill, S. Clayton, F.
LaFlamme, M. Mirmehrabi, S. Tadayon, D. Tovell and M.
Couturier, J. Org. Chem., 2010, 75, 3401-3411; (h) E. Lee, A.
S. Kamlet, D. C. Powers, C. N. Neumann, G. B. Boursalian, T.
Furuya, D. C. Choi, J. M. Hooker and T. Ritter, Science, 2011,
334, 639-642; (i) P. Tang, W. Wang and T. Ritter, J. Am.
Chem. Soc., 2011, 133, 11482-11484; (j) S. J. Ryan, S. D.
Schimler, D. C. Bland and M. S. Sanford, Org Lett, 2015, 17
,
1866-1869; (k) K. M. Engle, L. Pfeifer, G. W. Pidgeon, G. T.
Giuffredi, A. L. Thompson, R. S. Paton, J. M. Brown and V.
Gouverneur, Chem. Sci., 2015, 6, 5293-5302.
(a) T. Umemoto, K. Kawada and K. Tomita, Tetrahedron Lett.,
1986, 27, 4465-4468; (b) T. Umemoto and K. Tomita,
Tetrahedron Lett., 1986, 27, 3271-3274; (c) T. Umemoto, S.
Fukami, G. Tomizawa, K. Harasawa, K. Kawada and K. Tomita,
J. Am. Chem. Soc., 1990, 112, 8563-8575; (d) R. E. Banks, J.
Fluorine Chem., 1998, 87, 1-17.
3
4
19 T. Umemoto, K. Harasawa, G. Tomizawa, K. Kawada and K.
Tomita, J. Fluorine Chem., 1991, 53, 369-377.
20 T. Shamma, H. Buchholz, G. K. S. Prakash and G. A. Olah, Isr.
J. Chem., 1999, 39, 207-210.
(a) M. Zupan and A. Pollak, J. Org. Chem., 1975, 40, 3794-
3796; (b) M. A. Tius, Tetrahedron, 1995, 51, 6605-6634; (c)
M. Zupan, J. Iskra and S. Stavber, J. Org. Chem., 1998, 63
878-880.
,
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins