Reactions of bis(tetrazole)phenylenes. Surprising formation of vinyl compounds from alkyl halides

Article abstract of DOI:10.1016/j.tet.2005.05.013

The reactions of 1,2-bis(tetrazol-5-yl)benzene (1), 1,3-bis(tetrazol-5-yl) benzene (2), 1,4-bis(tetrazol-5-yl)benzene (3), 1,2-(Bu₃SnN ₄C)₂C₆H₄ (4), 1,3-(Bu ₃SnN₄C)₂C<

Full text of DOI:10.1016/j.tet.2005.05.013

Tetrahedron 61 (2005) 7002–7011
Reactions of bis(tetrazole)phenylenes. Surprising formation of
vinyl compounds from alkyl halides
a
Adrienne Fleming,a Fintan Kelleher,a Mary F. Mahon,b John McGinleya,c, and Vipa Prajapati
*
aDepartment of Applied Science and Advanced Smart Materials Research Center, Institute of Technology, Tallaght, Dublin 24, Ireland
bDepartment of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, England
cDepartment of Chemistry, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
Received 4 February 2005; revised 25 April 2005; accepted 5 May 2005
Available online 6 June 2005
Abstract—The reactions of 1,2-bis(tetrazol-5-yl)benzene (1), 1,3-bis(tetrazol-5-yl)benzene (2), 1,4-bis(tetrazol-5-yl)benzene (3), 1,2-
(Bu3SnN4C)2C6H4 (4), 1,3-(Bu3SnN4C)2C6H4 (5) and 1,4-(Bu3SnN4C)2C6H4 (6) with 1,2-dibromoethane were carried out by two different
methods in order to synthesise pendant alkyl halide derivatives of the parent bis-tetrazoles. This lead to the formation of several alkyl halide
derivatives, substituted at either N1 or N2 on the tetrazole ring, as well as the surprising formation of several vinyl derivatives. The crystal
structures of both 1,2-[(2-vinyl)tetrazol-5-yl)]benzene (1-N,2-N0) (1b) and 1,3-bis[(2-bromoethyl)tetrazol-5-yl]benzene (2-N,2-N0) (5d) are
discussed.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
Tetrazoles have roles in coordination chemistry as ligands,
in medicinal chemistry as metabolically stable surrogates
for carboxylic acids and in materials science applications,
including photography and explosives.1,2 The synthesis of
tetrazoles from the cycloaddition reaction between a nitrile
and an azide is well documented.1–6 The three main
synthetic approaches towards this type of transformation
involve the use of tin azides,4,5 strong Lewis acids,7 and
employment of acidic media.8 Our interest in tetrazoles
surrounds their potential as precursors in the formation of
new functionalised poly-tetrazoles which can be used in
other areas of chemistry, for example—sensors or molecular
recognition. In this paper, we report our initial findings
regarding the addition of pendant alkyl halide arms of some
bis-tetrazoles. Earlier investigations by Molloy et al.
revealed the formation of bis-tetrazole derivatives either
with pendant alkyl halide arms or with a cyclophane
structure.5 In our hands, syntheses have yielded not only bis-
tetrazole derivatives with pendant alkyl halide arms but
also, and rather surprisingly, bis-tetrazole derivatives with
pendant vinyl arms. The crystal structure of one such
derivative is presented herein and discussed.
The reaction of 1,2-(Bu3SnN4C)2C6H4 (4) with 1,2-
dibromoethane has been shown to form either a cyclophane
or bis(bromoalkyltetrazolyl)benzenes, depending on the
ratio of the dibromoethane employed in the reaction.5 When
using a 10-fold excess, the cyclophane was obtained; a
larger excess (25:1) resulted in the formation of the
bis(bromoalkyltetrazolyl)benzenes, either the 2-N, 2-N0- or
the 1-N,2-N0- isomer, with the 2-N, 2-N0-isomer predomi-
nating in a ratio of 3:1. Butler and Fleming have also
synthesised bis(bromoalkyltetrazolyl)benzenes from
N-unsubstituted tetrazoles and dihaloalkanes in the presence
of Et3N with the 2-N, 2-N0-isomer again predominating.9
Our strategy was to use both of these approaches to obtain
sufficient quantities of the 2-N,2-N0-isomer of various
bis(bromoalkyltetrazolyl)benzenes with a view to sub-
sequently generating derivatised tetra-tetrazole marcocycles.
The reaction of either 1,2-bis[tetrazol-5-yl]benzene (1), 1,3-
bis[tetrazol-5-yl]benzene (2) or 1,4-bis[tetrazol-5-yl]ben-
zene (3) with Et3N and 1,2-dibromoethane in methanol at
reflux temperature for 24 h (see Scheme 1) yielded four
spots by TLC; the largest spot, in all cases, being the starting
bis-tetrazole. In all reactions undertaken, on average, 50%
of the starting bis-tetrazole was uniformly recovered. Our
initial belief was that both the 2-N, 2-N0- and the 1-N, 2-N0-
isomers of the bis(bromoethyltetrazolyl)benzene and the
cyclophane had formed in the reaction, based solely on
Keywords: Tetrazole; Organotin; X-ray; Vinyl; NMR.
*
Corresponding author. Tel.: C353 1 708 4615; fax: C353 1 708 3815;
e-mail: john.mcginley@nuim.ie
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.05.013

A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
7003
Scheme 1.
published results in the literature,5,9 and that longer reaction
time would increase the yields of the three products.
Unfortunately, increasing the reaction time, in some cases
up to 120 h, did not improve the yield in any instance.
Column chromatography, using a hexane/ethyl acetate
mixture as eluent, separated the products. 1H and 13C
NMR spectra were obtained for all samples. The isomeric
2-N, 2-N0- and the 1-N, 2-N0-derivatives should be readily
distinguishable from their respective 1H and 13C NMR
spectra, as described by Molloy et al.5
The reaction of 1,2-(Bu3SnN4C)2C6H4 (4), 1,3-(Bu3SnN4-
C)2C6H4 (5) or 1,4-(Bu3SnN4C)2C6H4 (6) with 1,2-
dibromoethane forms either a cyclophane or bis(bromo-
alkyltetrazolyl)benzenes, depending on the ratio of the
dibromoethane employed in the reaction.5 In all the
reactions that we tried, no evidence for a cyclophane was
detected. Generally, four products were obtained from each
reaction, with compounds a, b and c always being present
(see Scheme 2) and either d or e being the remaining
product. In these reactions also, not all the starting bis-
tetrazole was consumed in the reaction, with the largest spot
by TLC being the starting tin tetrazole. What is intriguing is
the presence of vinyl groups in these products as well as
Surprisingly, all three products showed the distinct signal
pattern for the presence of vinyl groups, while in the cases of
1c, 2c and 3c, the presence of a bromoalkyl group was also
observed. The formation of the vinyl group must be due to
the presence of unreacted triethylamine abstracting HBr
from the initially formed alkylbromo compound in all cases,
although no sign of this initial bis-alkylbromotetrazole
derivative was observed by TLC. Thus, the three products
formed were the symmetrical 2-N,2-N0-bis(vinyl)-deriva-
tive, the unsymmetrical 1-N,2-N0-bis(vinyl)-derivative and
the 2-N,2-N0-vinyl-bromoethyl-derivative. No obvious
reason was apparent for the difference between these results
and those published previously by Butler and Fleming.9
Crystals of compound 1b, suitable for an X-ray diffraction
study, were obtained from chloroform and the X-ray
structure obtained confirmed the presence of the pendant
vinyl groups (see Fig. 1). It is notable that in the molecule
the two tetrazole rings are not co-planar with each other, the
angle between the least-squares planes of these two rings
being 87.98.
Figure 1. Molecular structure of 1b, showing the labelling scheme used.
Ellipsoids are represented at 30% probability.

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A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
Scheme 2.
those products already discussed above. In the previous set
of reactions, described above, it was easier to rationalise the
presence of the vinyl group as a result of excess base being
present, resulting from not all the starting bis-tetrazole being
consumed in the reaction.
azobisisobutyronitrile (AIBN) or UV irradiation in tolu-
ene).10,11 On that basis, we believe that this pathway, though
plausible, is not a possibility. The final plausible explanation
is that the bromide ion formed in the first displacement acts
as a base in 1,2-dibromoethane, as there is no solvent
present to solvate the ion. It immediately abstracts a
hydrogen from the product containing the bromoethyl arm
resulting in a negative charge residing on the carbon atom.
Loss of bromide ion removes the negative charge and also
results in the formation of the vinyl group. Of the three
possible routes, this final route appears the most plausible.
There are three ‘plausible’ explanations for the formation of
the N-vinyl compound in the absence of triethylamine. First,
it is a thermal elimination (pyrolysis) of the hydrogen
halide. This is unlikely as the reaction temperature is only
120 8C, and the fact that not all the bromoethyl arms are
converted to vinyl groups would rule this out as a
possibility. Secondly, the tributyltin bromide by-product
under the reaction conditions produces the tributyltin
radical, which then abstracts a bromide radical with
subsequent loss of a proton to give the vinyl. While this
appears plausible, the reaction conditions are very mild
(120 8C reflux) compared to those published in the literature
(for example, in the presence of a catalytic amount of
Despite our best endeavours, we were unable to grow
suitable crystals of any of the a or b compounds but we did
manage to grow suitable crystals of 5d. The X-ray structure
for this compound has been previously published5 but this
compound 5d is a different polymorph. The major
difference between the two sets of structural data is that
the structure already published showed that the crystal was

A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
7005
proximate pairs of such rings in the supramolecular array
˚
being 3.36 A. The tetrazoles based on C1 are also involved
in p-stacking with each other. In this case an interplane
˚
distance of 3.36 A is observed between said rings in closest
˚
lattice neighbours. The closest Br/Br distance of 3.854 A
mitigates against the presence of any significant bromine–
bromine interactions.
Crystallographic data for the structural analysis on 1b and
5d have been deposited with the Cambridge Crystal-
lographic Data Centre, CCDC No. 261954 and 261955,
respectively. Copies of this information may be obtained
free of charge from deposit@ccdc.cam.ac.uk or www:http://
www.ccdc.cam.ac.uk
3. Conclusions
Figure 2. Molecular structure of 5d, showing the labelling scheme used.
Ellipsoids are represented at 30% probability.
The reactions of either 1,n-(HN4C)2C6H4 or 1,n-(Bu3SnN4-
C)2C6H4 (nZ2, 3, 4) with 1,2-dibromoethane yields
compounds containing pendant bromoethyl or vinyl groups
with substitution occurring at either 1-N,2-N0 or 2-N,2-N0,
respectively. This is not in agreement with previously
published work in this area. The next objective is to improve
the reaction yields with a view to attaining our goal of
synthesising tetra-tetrazole macrocycles.
monoclinic in the C2/c space group whereas in this case the
structure is triclinic in the P-1 space group. This difference
manifests itself in the orientation of the pendant bromoethyl
arms. In the previously reported structure,5 the pendant
bromoethyl arms are pointing in opposite directions relative
to the central phenyl ring, whereas in 5d, the pendant
bromoethyl arms are directed in the same direction (see
Fig. 2).
The tetrazole rings and the phenyl ring are almost co-planar,
with both bromoethyl arms on the same face of the phenyl
ring. The packing diagram (see Fig. 3) illustrates this feature
to greater effect. Here, distinct channels of bis-tetrazole
units are evident with intermolecular interactions between
adjacent units. Analysis of the supramolecular array reveals
the presence of slipped p-stacking between the phenyl ring
and the tetrazole based on C8, the distance between most
4. Experimental
1H and 13C NMR (d ppm; J Hz) spectra were recorded on a
JOEL JNM-LA300 FT-NMR spectrometer using saturated
CDCl3 solutions with Me4Si reference, unless indicated
otherwise, with resolutions of 0.18 Hz and 0.01 ppm,
respectively. Infrared spectra (cmK1) were recorded as
KBr discs or liquid films between KBr plates using a Nicolet
Figure 3. Partial packing diagram for structure 5d, to illustrate the relative orientation of the pendant groups on the tetrazole rings and the p-stacking
interactions.

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A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
Impact 410 FT-IR. All uv/vis spectra were recorded on a
Shimadzu UV-160A spectrometer. Melting points were
measured with a Stuart Scientific melting point apparatus
(SMP1) without correction. Microanalysis was carried out
at the Microanalytical Laboratory of University College,
Dublin. Standard Schlenk techniques were used throughout.
dried to give a white solid. Recrystallisation from ethanol
gave white needle-like crystals (14.55 g, 68% yield), mp
234–236 8C. Analysis: dH (300 MHz, d6-DMSO): 7.85 (2H,
dd, aromatic-H), 7.91 (2H, d, aromatic-H); dC (300 MHz,
d6-DMSO): 124.5 (2 i-C6H4), 130.8 (2 C2-C6H4), 131.3 (2
C1-C6H4), 155.5 (2 CN4).
Compounds 2 and 3 were also prepared by the same
methodology.
4.1. Syntheses
1,2-(Bu3SnN4C)2C6H4 (4), 1,3-(Bu3SnN4C)2C6H4 (5) and
1,4-(Bu3SnN4C)2C6H4 (6) were prepared as described
previously.4 1,2-Bis(tetrazol-5-yl)benzene (1), 1,3-bis(tetra-
zol-5-yl)benzene (2) and 1,4-bis(tetrazol-5-yl)benzene (3)
were prepared by a different method to that of Molloy et al.5
but the analytical data in all cases were the same. All other
reagents were commercially obtained and used without
further purification. CAUTION. Owing to their potentially
explosive nature, all preparations of and subsequent
reactions with organotin azides were conducted under an
inert atmosphere behind a rigid safety screen.
4.1.2. 1,3-Bis(tetrazol-5-yl)benzene (2)5 Recrystallisation
from ethanol gave white needle-like solid (67.5% yield), mp
268–270 8C. Analysis: dH (300 MHz, d6-DMSO): 7.86 (1H,
t, H1), 8.24 (2H, dd, H2), 8.78 (1H, s, H3); dC (300 MHz, d6-
DMSO): 125.3 (C1–C6H4), 125.7 (2i–C6H4), 129.3 (2C2–
C6H4), 130.8 (C3–C6H4), 155.5 (2 CN4).
4.1.3. 1,4-Bis(tetrazol-5-yl)benzene (3)5 Recrystallisation
from ethanol gave white needle-like solid (69.7% yield), mp
291–294 8C. Analysis: dH (300 MHz, d6-DMSO): 8.27 (4H,
6, H1); dC (300 MHz, d6-DMSO): 126.7 (2i-C6H4), 127.9
(2C1–C6H4), 155.5 (2CN4).
The numbering scheme for the 1,2-, 1,3- and 1,4-bis-
tetrazoles are shown in the figures below and all NMR
assignments are based on these diagrams (Figs. 4–6).
4.2. Synthesis of compounds 1a, 1b and 1c
4.1.1. 1,2-Bis(tetrazol-5-yl)benzene (1)5 A suspension of
1,2-dicyanobenzene (12.8 g, 0.10 mol), sodium azide
(14.3 g, 0.22 mol), ammonium chloride (11.76 g,
0.22 mol) and lithium chloride (3.0 g, 0.07 mol) in anhy-
drous dimethylformamide (100 ml) was stirred at 110 8C for
10 h. After this time, the solution was cooled and the
insoluble salts were removed by filtration. The solvent was
then evaporated under reduced pressure and the residue was
dissolved in deionised water (200 ml) and acidified with
concentrated HCl (3 ml), to initiate precipitation. The
product was filtered, washed with water (3!40 ml) and
1,2-Bis[tetrazol-5-yl]benzene (1), (1.0 g, 4.7 mmol) was
dissolved in methanol (30 ml), and to the stirred solution
was added triethylamine (3.0 ml, 2.8 mmol). The resulting
solution was heated to reflux for half an hour, and to the hot
solution was added 1,2-dibromoethane (2.6 g, 1.4 mmol).
The reaction mixture was then heated to reflux for a further
24 h. After cooling, the solvent was removed under reduced
pressure to afford the mixture of isomers 1a, 1b and 1c.
These isomers were separated by column chromatography
on silica gel (initially at the ratio of hexane–ethyl acetate
80:20, followed by the ratio 60:40).
Figure 4. Labelling scheme used for central core in the 1,2-bis(tetrazole) derivatives.

A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
7007
Figure 5. Labelling scheme used for central core in the 1,3-bis(tetrazole) derivatives.
4.2.1. 1,2-Bis[(2-vinyl)tetrazol-5-yl]benzene (2-N,2-N0)
(1a). White solid. Analysis: Found: C, 54.52; H, 3.96; N,
42.35. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 13.8%. Mp 95–98 8C; nmax (KBr) 3150, 3090, 2910,
1610, 1648, 1490, 1102, 986, 910, 800 cmK1; dH: 5.25 [dd,
JgemZ1.8 Hz, N1CH]CH2], 5.88 [dd, 1H, Htrans, JcisZ
0
13.9 Hz, JgemZ1.3 Hz, N2 CH]CH2], 6.59 [dd, 1H, Hgem
,
JtransZ15.5 Hz, JcisZ8.8 Hz, N1CH]CH2], 7.30 [dd, 1H,
0
Hgem, JtransZ15.5 Hz, JcisZ8.8 Hz, N2 CH]CH2], 7.53 [d,
1H, JZ6.5 Hz, H1–C6H4], 7.62 [t, 1H, JZ6.5 Hz, H2–
C6H4], 7.78 [t, 1H, JZ6.5 Hz, H3–C6H4], 8.41 [d, 1H, JZ
2Hcis
,
JtransZ8.8 Hz, JgemZ1.8 Hz, N2CH]CH2,
0
N2 CH]CH2], 6.35 [dd, 2Htrans, JcisZ15.5 Hz, Jgem
Z
,
6.5 Hz, H4–C6H4]; dC: 109.3 [CH2], 109.5 [CH2], 122.5 [i-
0
0
1.6 Hz, N2CH]CH2, N2 CH]CH2], 7.59 [dd, 2Hgem
C6H4], 125.6 [CHN2 ], 127.0 [i0-C6H4], 128.8 [CHN1],
JtransZ15.5 Hz,
JcisZ8.8 Hz,
N2CH]CH2,
129.6 [C1–C6H4], 130.9 [C2–C6H4], 131.6 [C3–C6H4],
0
0
N2 CH]CH2], 7.65 [d, 2H, JZ6.6 Hz, H1-C6H4], 7.85 [d,
2H, JZ6.5 Hz, H2–C6H4]; dC: 29.6 [CH2], 109.9 [i-C6H4],
130.6 [C1–C6H4], 134.8 [C2–C6H4], 164.2 [CN4].
132.0 [C4–C6H4], 152.6 [N1CN4], 162.4 [N2 CN4].
4.2.3. 1,2-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (2-N,2-N0) (1c). White solid. Ana-
lysis: Found: C, 41.76; H, 3.45; N, 32.35. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 8.1%. Mp
102–104 8C; nmax (KBr) 3150, 3100, 2890, 1755, 1650,
4.2.2. 1,2-Bis[(2-vinyl)tetrazol-5-yl)]benzene (1-N,2-N0)
(1b). White solid. Analysis: Found: C, 54.45; H, 4.01; N,
42.29. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 10.5%. Mp 110–112 8C; nmax (KBr) 3169, 3109,
1648, 1459, 1210, 1175, 1005, 996, 907, 746, 650 cmK1
;
2910, 2896, 1615, 1589, 1475, 1090, 956, 910, 779 cmK1
;
dH: 3.66 [t, 2H, JZ6.6 Hz, CH2Br], 4.38 [t, 2H, JZ6.6 Hz,
NCH2], 5.27 [dd, 1H, Hcis, JtransZ8.8 Hz, JgemZ1.5 Hz,
dH: 5.04 [dd, 1H, Hcis, JtransZ8.8 Hz, JgemZ1.5 Hz,
N1CH]CH2], 5.25 [dd, 1H, Hcis, JtransZ8.6 Hz, Jgem
Z
NCH]CH2], 5.88 [dd, 1H, Htrans, JcisZ15.4 Hz, Jgem
Z
0
1.6 Hz, N2 CH]CH2], 5.78 [dd, 1H, Htrans, JcisZ15.5 Hz,
1.6 Hz, NCH]CH2], 7.35 [dd, 1H, Hgem, JtransZ15.5 Hz,
Figure 6. Labelling scheme used for central core in the 1,4-bis(tetrazole) derivatives.

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A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
JcisZ8.6 Hz, NCH]CH2], 7.54 [d, 1H, JZ7.0 Hz, H1-
C6H4], 7.62 [t, 1H, JZ7.0 Hz, H2–C6H4], 7.71 [d, 1H, JZ
6.5 Hz, H3–C6H4], 8.37 [t, 1H, JZ6.5 Hz, H4–C6H4]; dC:
27.0 [CH2Br], 48.6 [CH2N], 109.4 [CH2], 122.5 [i-C6H4],
126.9 [i0-C6H4], 128.7 [C1–C6H4], 129.2 [CHN], 129.6 [C2–
C6H4], 130.8 [C3–C6H4], 131.9 [C4–C6H4], 162.6 [CN4].
[C1–C6H4], 127.8 [i-C6H4], 129.1 [C2–C6H4], 129.5 [CHN],
129.8 [C3–C6H4], 164.2 [CN4].
4.4. Synthesis of compounds 3a, 3b and 3c
These compounds were prepared by the same general
method from 1,4-bis[tetrazol-5-yl]benzene (3), triethyl-
amine and 1,2-dibromoethane resulting in a mixture of 3a,
3b and 3c which were individually isolated by column
chromatography on silica gel as previously described.
4.3. Synthesis of compounds 2a, 2b and 2c
These compounds were prepared by the same general
method from 1,3-bis[tetrazol-5-yl]benzene (2), triethyl-
amine and 1,2-dibromoethane, resulting in a mixture of
2a, 2b and 2c which were isolated from each other by
column chromatography on silica gel as described
previously.
4.4.1. 1,4-Bis[(2-vinyl)tetrazol-5-yl]benzene (2-N,2-N0)
(3a). White solid. Analysis: Found: C, 54.36; H, 4.18; N,
42.08. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 12.8%. Mp 124–126 8C; nmax (KBr) 3148, 3108,
2910, 2894, 1690, 1650, 1429, 1150, 1005, 990, 913,
810 cmK1; dH: 5.44 [dd, 2H, Hcis, JtransZ9.7 Hz, Jgem
1.6 Hz, NCH]CH2], 6.32 [dd, 2H, Htrans, JcisZ15.5 Hz,
JgemZ1.2 Hz, NCH]CH2], 7.56 [dd, 2H, Hgem, Jtrans
Z
4.3.1. 1,3-Bis[(2-vinyl)tetrazol-5-yl]benzene (2-N,2-N0)
(2a). White solid. Analysis: Found: C, 54.23; H, 3.69; N,
42.45. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 15.6%. Mp 112–116 8C; nmax (KBr) 3124, 3100,
2921, 2848, 1699, 1649, 1458, 1213, 1182, 1003, 905, 910,
Z
12.2 Hz, JcisZ8.8 Hz, NCH]CH2], 7.81 [s, 4H, C6H4]; dC:
108.9 [CH2], 127.5 [C1–C6H4], 129.0 [i-C6H4], 129.8
[CHN], 164.3 [CN4].
738 cmK1; dH: 5.43 [dd, 2H, Hcis, JtransZ8.8 Hz, Jgem
1.6 Hz, NCH]CH2], 6.33 [dd, 2H, Htrans, JcisZ15.5 Hz,
JgemZ1.6 Hz, NCH]CH2], 7.62 [dd, 2H, Hgem, Jtrans
Z
4.4.2. 1,4-Bis[(2-vinyl)tetrazol-5-yl]benzene (1-N,2-N0)
(3b). White solid. Analysis: Found: C, 54.26; H, 3.56; N,
42.33. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 11.6%. Mp 116–120 8C; nmax (KBr) 3105, 3089,
Z
15.5 Hz, JcisZ8.8 Hz, NCH]CH2], 7.66 [t, 1H, JZ7.0 Hz,
H1-C6H4], 8.34 [d, 2H, JZ7.0 Hz, H2-C6H4], 9.03 [s, 1H,
H3-C6H4]; dC: 108.8 [CH2], 125.6 [C1–C6H4], 127.8 [i-
C6H4], 129.1 [C2–C6H4], 129.6 [CHN], 129.8 [C3–C6H4],
164.2 [CN4].
2928, 2890, 1603, 1567, 1470, 1096, 980, 905, 803 cmK1
;
dH: 5.47 [dd, 1H, Hcis, JtransZ8.8 Hz, JgemZ1.5 Hz,
N1CH]CH2], 5.51 [dd, 1H, Hcis, JtransZ8.6 Hz, Jgem
Z
0
1.5 Hz, N2 CH]CH2], 6.27 [dd, 1H, Htrans, JcisZ15.5 Hz,
4.3.2. 1,3-Bis[(2-vinyl)tetrazol-5-yl]benzene (1-N,2-N0)
(2b). White solid. Analysis: Found: C, 54.26; H, 3.85; N,
42.32. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 10.2%. Mp 120–122 8C; nmax (KBr) 3179, 3067,
2897, 1605, 1596, 1470, 1105, 998, 905, 805 cmK1; dH:
JgemZ1.6 Hz, N1CH]CH2], 6.33 [dd, 1H, Htrans, JcisZ
0
15.4 Hz, JgemZ1.3 Hz, N2 CH]CH2], 7.12 [dd, 1H, Hgem
,
JtransZ15.5 Hz, JcisZ8.7 Hz, N1CH]CH2], 7.59 [dd, 1H,
0
Hgem, JtransZ15.4 Hz, JcisZ8.8 Hz, N2 CH]CH2], 7.89 [d,
2H, JZ8.2 Hz, H2-C6H4], 8.42 [d, 2H, JZ8.2 Hz, H1-
C6H4]; dC: 109.2 [CH2], 111.8 [CH2], 125.4 [i-C6H4], 126.0
5.46 [dd, 1H, Hcis
N1CH]CH2], 5.52 [dd, 1H, Hcis, JtransZ8.8 Hz, Jgem
, JtransZ8.8 Hz, JgemZ1.6 Hz,
[i0-C6H4], 127.9 [C1–C6H4], 128.2 [C2–C6H4], 129.9
Z
20
0
[CHN2 ], 133.1 [CHN1], 152.4 [CN4], 163.6 [CN4].
1.6 Hz, N CH]CH2], 6.27 [dd, 1H, Htrans, JcisZ13.2 Hz,
JgemZ1.6 Hz, N1CH]CH2], 6.32 [dd, 1H, Htrans, JcisZ
0
13.6 Hz, JgemZ1.6 Hz, N2 CH]CH2], 7.15 [dd, 1H, Hgem
,
4.4.3. 1,4-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl))]benzene (2-N,2-N0) (3c). White solid.
Analysis: Found: C, 41.44; H, 3.36; N, 32.45. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 9.8%. Mp
128–130 8C; nmax (KBr) 3128, 3094, 2905, 1610, 1548,
1460, 1238, 1100, 1003, 960, 838, 610 cmK1; dH: 3.94 [t, 2H,
JtransZ15.4 Hz, JcisZ8.8 Hz, N1CH]CH2], 7.59 [dd, 1H,
0
Hgem, JtransZ15.7 Hz, JcisZ8.8 Hz, N2 CH]CH2], 7.75 [t,
1H, JZ7.7 Hz, H2–C6H4], 7.87 [d, 1H, JZ7.4 Hz, H1–
C6H4], 8.45 [d, 1H, JZ7.2 Hz, H3–C6H4], 8.55 [s, 1H, H4–
C6H4]; dC: 109.3 [CH2], 111.8 [CH2], 124.4 [i-C6H4], 125.0
[i0-C6H4], 126.0 [C3–0C6H4], 127.6 [C2–C6H4], 128.4 [C1–
C6H4], 130.0 [CHN2 ], 131.2 [CHN1], 135.2 [C4–C6H4],
152.4 [CN4], 163.6 [CN4].
JZ6.6 Hz, CH2Br], 5.08 [t, 2H, JZ6.6 Hz, CH2N2], 5.45 [dd,
0
1H, Hcis, JtransZ8.8 Hz, JgemZ1.6 Hz, N2 CH]CH2], 6.31
0
[dd, 1H, Htrans, JcisZ15.6 Hz, JgemZ1.5 Hz, N2 CH]CH2],
7.58 [dd, 1H, Hgem
, JtransZ15.5 Hz, JcisZ8.8 Hz,
0
N2 CH]CH2], 8.30 [d, 2H, JZ8.8 Hz, C1–C6H4], 8.34 [d,
2H, JZ8.8 Hz, C2–C6H4]; dC: 27.0 [CH2Br], 54.1 [CH2N],
108.8 [CH2], 127.5 [C1–C6H4], 127.7 [C2–C6H4], 128.8
[i-C6H4], 129.1 [i0-C6H4], 129.8 [CHN], 164.8 [CN4].
4.3.3. 1,3-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (2-N,2-N0) (2c). White solid. Ana-
lysis: Found: C, 41.68; H, 3.33; N, 32.46. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 8.3%. Mp
104–106 8C; nmax (KBr) 3150, 3100, 2890, 1755, 1650,
1459, 1210, 1175, 1005, 907, 746, 650 cmK1; dH: 3.80 [t,
2H, JZ6.6 Hz, CH2Br], 4.95 [t, 2H, JZ6.6 Hz, CH2N2],
4.5. Synthesis of compounds 4a, 4b, 4c and 4e
5.29 [dd, 1H, Hcis
,
JtransZ9.0 Hz, JgemZ1.6 Hz,
1,2-Bis[2-(tributylstannyl)tetrazol-5-yl]benzene (4) (1.0 g,
1.25 mmol) was heated to 120 C in 1,2-dibromoethane
(5.5 ml) for 24 h. A viscous solution resulted which, on
cooling, yielded a mixture of 4a, 4b, 4c and 4e. These were
individually isolated by column chromatography on silica
gel as previously described.
0
o
N2 CH]CH2], 6.18 [dd, 1H, Htrans, JcisZ15.9 Hz, Jgem
Z
0
1.6 Hz, N2 CH]CH2], 7.45 [dd, 1H, Hgem, JtransZ15.9 Hz,
0
JcisZ9.1 Hz, N2 CH]CH2], 7.53 [d, 2H, JZ8.4 Hz, H2–
C6H4], 8.18 [t, 1H, JZ7.9 Hz, H1–C6H4], 8.85 [s, 1H, H3–
C6H4]; dC: 27.0 [CH2Br], 54.1 [CH2N2], 109.1 [CH2], 125.6

A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
7009
4.5.1. 1,2-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (2-N,2-N0) (4a). White solid.
Analysis: Found: C, 41.69; H, 3.42; N, 32.08. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 10.6%. Mp
102–104 8C; nmax (KBr) 3100, 3098, 2954, 2879, 1605,
6.5 Hz, H4–C6H4]; dC: 109.3 [CH2], 109.5 [CH2], 122.5
20
[i-C6H4], 125.6 [CHN ], 127.0 [i0-C6H4], 128.8 [CHN1],
129.6 [C1–C6H4], 130.9 [C2–C6H4], 131.6 [C3–C6H4],
132.0 [C4–C6H4], 152.6 [CN4], 162.4 [CN4].
1545, 1460, 1256, 1100, 1010, 990, 905, 850, 602 cmK1
;
4.6. Synthesis of compounds 5a, 5b, 5c and 5d
dH: 3.66 [t, 2H, JZ6.6 Hz, CH2Br], 4.38 [t, 2H, JZ6.6 Hz,
N2CH2], 5.27 [dd, 1H, Hcis, JtransZ8.8 Hz, JgemZ1.5 Hz,
These compounds were prepared by the same method as
above but using 1,3-bis[2-(tributylstannyl)tetrazol-5-
yl]benzene (5) instead. A viscous solution resulted again
which, on cooling, yielded a mixture of 5a, 5b, 5c and 5d.
These were isolated by column chromatography on silica
gel as previously described.
0
N2 CH]CH2], 5.88 [dd, 1H, Htrans, JcisZ15.4 Hz, Jgem
Z
2
0
1.6 Hz, N CH]CH2], 7.35 [dd, 1H, Hgem, JtransZ15.5 Hz,
2
1
0
JcisZ8.6 Hz, N CH]CH2], 7.54 [d, 1H, JZ7.0 Hz, H –
C6H4], 7.62 [t, 1H, JZ7.0 Hz, H2–C6H4], 7.71 [t, 1H, JZ
6.5 Hz, H3–C6H4], 8.37 [d, 1H, JZ6.5 Hz, H4–C6H4]; dC:
27.0 [CH2Br], 48.6 [CH2N], 109.4 [CH2], 122.5 [i-C6H4],
126.9 [i0-C6H4], 128.7 [C1–C6H4], 129.2 [CHN], 129.6 [C2–
C6H4], 130.8 [C3–C6H4], 131.9 [C4–C6H4], 162.6 [CN4].
4.6.1. 1,3-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (2-N,2-N0) (5a). White solid.
Analysis: Found: C, 41.45; H, 3.55; N, 32.25. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 11.8%. Mp
104–106 8C; nmax (KBr) 3150, 3100, 2890, 1755, 1650,
1459, 1210, 1175, 1005, 907, 746, 650 cmK1; dH: 3.93 [t,
2H, JZ6.6 Hz, CH2Br], 5.08 [t, 2H, JZ6.6 Hz, CH2N2],
4.5.2. 1,2-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (1-N,2-N0) (4b). White solid.
Analysis: Found: C, 41.89; H, 3.36; N, 32.42. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 10.2%. Mp
108–112 8C; nmax (KBr) 3100, 3098, 2954, 2879, 1605,
5.44 [dd, 1H, Hcis
N2 CH]CH2], 6.33 [dd, 1H, Htrans, JcisZ15.7 Hz, Jgem
, JtransZ9.0 Hz, JgemZ1.7 Hz,
1545, 1460, 1256, 1100, 1010, 990, 905, 850, 602 cmK1
;
0
Z
0
dH: 3.92 [t, 2H, JZ6.6 Hz, CH2Br], 4.92 [t, 2H, JZ6.6 Hz,
1.6 Hz, N2 CH]CH2], 7.58 [dd, 1H, Hgem, JtransZ17.9 Hz,
CH2N1], 5.50 [dd, 1H, Hcis, JtransZ8.6 Hz, JgemZ1.5 Hz,
0
JcisZ7.7 Hz, N2 CH]CH2], 7.63 [d, 2H, JZ8.4 Hz, H2–
C6H4], 8.39 [t, 1H, JZ7.9 Hz, H1–C6H4], 8.99 [s, 1H, H3–
C6H4]; dC: 27.0 [CH2Br], 54.2 [CH2N2], 109.1 [CH2], 125.6
[C1–C6H4], 127.5 [i-C6H4], 129.0 [C2–C6H4], 129.5 [CHN],
130.0 [C3–C6H4], 164.2 [CN4].
0
N2 CH]CH2], 6.28 [dd, 1H, Htrans, JcisZ15.4 Hz, Jgem
Z
0
1.3 Hz, N2 CH]CH2], 7.15 [dd, 1H, Hgem, JtransZ15.3 Hz,
0
JcisZ8.6 Hz, N2 CH]CH2], 7.61 [d, 1H, JZ7.0 Hz, H1–
C6H4], 7.69 [t, 1H, JZ7.0 Hz, H2–C6H4], 7.78 [t, 1H, JZ
7.0 Hz, H3–C6H4], 8.38 [d, 1H, JZ7.0 Hz, H4–C6H4]; dC:
27.0 [CH2Br], 54.0 [CH2N1], 112.0 [CH2], 123.4 [i-C6H4],
126.1 [0i0-C6H4], 127.5 [C1–C6H4], 129.8 [C2–C6H4], 130.2
[CHN2 ], 132.2 [C3–C6H4], 132.3 [C4–C6H4], 152.6 [CN4],
162.4 [CN4].
4.6.2. 1,3-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (1-N,2-N0) (5b). White solid.
Analysis: Found: C, 41.54; H, 3.34; N, 32.48. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 9.8%. Mp
99–100 8C; nmax (KBr) 3104, 3098, 2950, 1605, 1540, 1463,
1250, 1110, 1005, 998, 905, 856 cmK1; dH: 3.90 [t, 2H, JZ
4.5.3. 1,2-Bis[(2-bromoethyl)tetrazol-5-yl]benzene (1-
N,2-N0) (4c). White solid. Analysis: Found: C, 33.50; H,
2.96; N, 26.25. Calcd for C12H12N8Br2: C, 33.70; H, 2.81;
N, 26.10. Yield: 8.3%. Mp 124–126 8C; nmax (KBr) 3099,
6.6 Hz, CH2Br], 4.86 [t, 2H, JZ6.6 Hz, CH2N1], 5.49 [dd,
0
1H, Hcis, JtransZ8.8 Hz, JgemZ1.7 Hz, N2 CH]CH2], 6.28
0
[dd, 1H, Htrans, JcisZ15.3 Hz, JgemZ1.8 Hz, N2 CH]CH2],
3087, 2850, 1543, 1460, 1276, 1090, 1005, 830, 605 cmK1
;
7.15 [dd, 1H, Hgem, JtransZ15.4 Hz, JcisZ8.8 Hz,
dH: 3.70 [t, 2H, JZ6.6 Hz, CH2Br], 3.74 [t, 2H, JZ6.6 Hz,
0
N2 CH]CH2], 7.71 [t, 1H, JZ7.9 Hz, H1–C6H4], 7.84 [d,
1H, JZ8.4 Hz, H2–C6H4], 8.42 [d, 1H, JZ8.4 Hz, H3–
C6H4], 8.53 [s, 1H, H4–C6H4]; dC: 27.1 [CH2Br], 54.3
[CH2N1], 111.9 [CH2], 125.2 [i-C6H4], 126.0 [i0-C6H4],
CH2Br], 4.42 [t, 2H, JZ6.6 Hz, CH2N1], 4.89 [t, 2H, JZ
0
6.6 Hz, CH2N2 ], 7.61 [d, 1H, JZ7.0 Hz, H1–C6H4], 7.69 [t,
1H, JZ7.0 Hz, H2–C6H4], 7.78 [t, 1H, JZ7.0 Hz, H3–
C6H4], 8.38 [d, 1H, JZ7.0 Hz, H4–C6H4]; dC: 27.2
0
127.4 [C3–C6H4], 127.6 [C2–C6H4], 129.9 [C1–C6H4],
[CH2Br], 48.9 [CH2N], 54.4 [CH2N2 ], 122.7 [i-C6H4],
127.5 [i0-C6H4], 129.8 [C1–C6H4], 131.0 [C2–C6H4], 132.2
[C3–C6H4], 132.3 [C4–C6H4], 154.8 [CN4], 163.6 [CN4].
0
130.2 [CHN2 ], 133.8 [C4–C6H4], 156.4 [CN4], 162.6
[CN4].
4.5.4. 1,2-Bis[(2-vinyl)tetrazol-5-yl]benzene (1-N,2-N0)
(4e). White solid. Analysis: Found: C, 54.33; H, 3.99; N,
42.35. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 6.4%. Mp 92–94 8C. nmax (KBr) 3169, 3109, 2910,
2896, 1615, 1589, 1475, 1090, 956, 910, 779 cmK1; dH:
4.6.3. 1,3-Bis[(2-bromoethyl)tetrazol-5-yl]benzene (1-
N,2-N0) (5c). White solid. Analysis: Found: C, 33.86; H,
3.01; N, 26.35. Calcd for C12H12N8Br2: C, 33.70; H, 2.81;
N, 26.10. Yield: 7.6%. Mp 130–132 8C; nmax (Nujol) (KBr)
3109, 3086, 2910, 2850, 1545, 1456, 1270, 1105, 1003, 850,
715, 615 cmK1; dH: 3.87 [t, 2H, JZ6.6 Hz, CH2Br], 3.95 [t,
5.04 [dd, 1H, Hcis
N1CH]CH2], 5.25 [dd, 1H, Hcis, JtransZ8.6 Hz, Jgem
, JtransZ8.8 Hz, JgemZ1.5 Hz,
Z
2H, JZ6.6 Hz, CH2Br], 4.87 [t, 2H, JZ6.6 Hz, CH2N1],
0
0
1.6 Hz, N2 CH]CH2], 5.78 [dd, 1H, Htrans, JcisZ15.5 Hz,
5.10 [t, 2H, JZ6.6 Hz, CH2N2 ], 7.83 [t, 1H, JZ7.9 Hz, H1–
C6H4], 7.88 [d, 1H, JZ8.4 Hz, H2–C6H4], 8.42 [d, 1H, JZ
JgemZ1.8 Hz, N1CH]CH2], 5.88 [dd, 1H, Htrans, JcisZ
0
13.9 Hz, JgemZ1.3 Hz, N2 CH]CH2], 6.59 [dd, 1H, Hgem
,
8.4 Hz, H3–C6H4], 8.51 [s, 1H, H4–C6H4]; dC: 27.6
0
JtransZ15.5 Hz, JcisZ8.8 Hz, N1CH]CH2], 7.30 [dd, 1H,
[CH2Br], 27.9 [CH2Br], 49.0 [CH2N1], 54.2 [CH2N2 ],
0
Hgem, JtransZ15.5 Hz, JcisZ8.8 Hz, N2 CH]CH2], 7.53 [d,
1H, JZ6.5 Hz, H1–C6H4], 7.62 [t, 1H, JZ6.5 Hz, H2–
C6H4], 7.78 [t, 1H, JZ6.5 Hz, H3–C6H4], 8.41 [d, 1H, JZ
124.6 [i-C6H4], 125.0 [i0-C6H4], 127.4 [C1–C6H4], 128.6
0
[C2–C6H4], 129.9 [C2 –C6H4], 130.2 [C3–C6H4], 154.5
[CN4], 164.4 [CN4].

7010
A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
4.6.4. 1,3-Bis[(2-bromoethyl)tetrazol-5-yl]benzene (2-
N,2-N0) (5d). White solid. Analysis: Found: C, 33.58; H,
2.98; N, 26.25. Calcd for C12H12N8Br2: C, 33.70; H, 2.81;
N, 26.10. Yield: 6.3%. Mp 118–122 8C; nmax (KBr) 3109,
3086, 2910, 2850, 1545, 1456, 1270, 1105, 1003, 850, 715,
615 cmK1; dH: 3.94 [t, 4H, JZ6.6 Hz, CH2Br], 5.09 [t, 4H,
JZ6.6 Hz, CH2N], 7.64 [t, 1H, JZ7.9 Hz, H1–C6H4], 8.29
[d, 2H, JZ8.4 Hz, H2–C6H4], 8.94 [s, 1H, H3–C6H4]; dC:
27.7 [CH2Br], 54.1 [CH2N], 125.4 [i-C6H4], 128.0 [C1–
C6H4], 128.8 [C2–C6H4], 129.6 [C3–C6H4], 164.9 [CN4].
130.2 [C1–C6H4], 132.8 [C2–C6H4], 156.3 [CN4], 164.1
[CN4].
4.7.4. 1,4-Bis[(2-vinyl)tetrazol-5-yl]benzene (1-N,2-N0)
(6e). White solid. Analysis: Found: C, 54.08; H, 3.49; N,
42.28. Calcd for C12H10N8: C, 54.13; H, 3.76; N, 42.10.
Yield: 7.3%. Mp 116–120 8C; nmax (KBr) 3099, 3089, 2928,
2894, 1610, 1568, 1475, 1106, 1008, 980, 905, 810 cmK1
;
dH: 5.49 [dd, 1H, Hcis, JtransZ8.8 Hz, JgemZ1.5 Hz,
N1CH]CH2], 5.52 [dd, 1H, Hcis, JtransZ8.8 Hz, Jgem
Z
0
1.5 Hz, N2 CH]CH2], 6.29 [dd, 1H, Htrans, JcisZ15.5 Hz,
JgemZ1.6 Hz, N1CH]CH2], 6.36 [dd, 1H, Htrans, JcisZ
4.7. Synthesis of compounds 6a, 6b, 6c and 6e
0
15.5 Hz, JgemZ1.5 Hz, N2 CH]CH2], 7.11 [dd, 1H, Hgem
,
JtransZ15.5 Hz, JcisZ8.6 Hz, N1CH]CH2], 7.35 [dd, 1H,
These compounds were prepared by the same method from
1,4-bis[2-(tributylstannyl)tetrazol-5-yl]benzene (6) and 1,2-
dibromoethane. A viscous solution resulted again which, on
cooling, yielded a mixture of 6a, 6b, 6c and 6e. These were
isolated by column chromatography on silica gel as
previously described.
0
Hgem, JtransZ15.5 Hz, JcisZ8.8 Hz, N2 CH]CH2], 7.90 [d,
2H, JZ8.2 Hz, H2–C6H4], 8.43 [d, 2H, JZ8.2 Hz, H1–
C6H4]; dC: 109.3 [CH2], 111.9 [CH2], 125.4 [i-C6H4], 126.1
[i0-C6H4], 127.9 [C1–C6H4], 128.2 [C2–C6H4], 129.9
0
[CHN2 ], 133.1 [CHN1], 152.0 [CN4], 165.0 [CN4].
4.8. X-ray crystallography
4.7.1. 1,4-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (2-N,2-N0) (6a). White solid.
Analysis: Found: C, 41.69; H, 3.39; N, 32.05. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 10.9%. Mp
128–130 8C; nmax (KBr) 3128, 3094, 2905, 1610, 1548,
1460, 1238, 1100, 1003, 960, 838, 610 cmK1; dH: 3.94 [t,
2H, JZ6.6 Hz, CH2Br], 5.08 [t, 2H, JZ6.6 Hz, CH2N2],
Suitable crystals of 1b and 5d for X-ray study were obtained
by recrystallisation from chloroform and acetonitrile
solutions, respectively. Crystallographic details are given
below. In each case, refinement was full-matrix least-
squares on F2. Data for compounds 1b and 5d were
collected at room temperature on an Enraf–Nonius CAD4
diffractometer. In both cases, data were corrected for Lp and
absorption. Hydrogen atoms were added at calculated
positions. Software used was SHELXS86,12 SHELXL9713
and ORTEX.14
5.45 [dd, 1H, Hcis
N2 CH]CH2], 6.33 [dd, 1H, Htrans, JcisZ15.7 Hz, Jgem
, JtransZ8.6 Hz, JgemZ1.5 Hz,
0
Z
0
1.6 Hz, N2 CH]CH2], 7.58 [dd, 1H, Hgem, JtransZ15.5 Hz,
0
JcisZ8.8 Hz, N2 CH]CH2], 8.30 [d, 2H, JZ8.8 Hz, C1–
C6H4], 8.33 [d, 2H, JZ8.8 Hz, C1–C6H4]; dC: 26.9 [CH2Br],
54.3 [CH2N2], 108.8 [CH2], 127.6 [C1–C6H4], 127.9 [C2–
20
4.8.1. Compound 1b. Crystal data: C12H10N8, MZ266.28,
C6H4], 128.8 [i-C6H4], 129.1 [i0-C6H4], 129.8 [CHN ],
˚
3
˚
orthorhombic, aZ12.9010(3) A, bZ12.9580(3) A, cZ
164.8 [CN4].
˚
˚
7.5620(2) A, UZ4264.15(5) A , space group P212121,
ZZ4, m(Mo Ka)Z0.095 mmK1. Crystallographic measure-
ments were made at 150(2) K on a Nonius kappaCCD
diffractometer in the range 4.14!q!27.428. The solution
of the structure (SHELXS86) and refinement (SHELXL97)
converged to a conventional [i.e., based on 2775F data with
FoO4s(Fo)] R1Z0.0393 and wR2Z0.0836. Goodness of
fitZ1.019. CCDC No. 261954.
4.7.2. 1,4-Bis[((2-bromoethyl)tetrazol-5-yl)((2-vinyl)
tetrazol-50-yl)]benzene (1-N,2-N0) (6b). White solid.
Analysis: Found: C, 41.69; H, 3.28; N, 32.11. Calcd for
C12H11N8Br: C, 41.50; H, 3.17; N, 32.28. Yield: 10.1%. Mp
122–126 8C; nmax (Nujol) (KBr) 3128, 3094, 2905, 1610,
1548, 1460, 1238, 1100, 1003, 960, 838, 610 cmK1; dH:
3.94 [t, 2H, JZ6.6 Hz, CH2Br], 5.10 [t, 2H, JZ6.6 Hz,
CH2N1], 5.52 [dd, 1H, Hcis, JtransZ8.6 Hz, JgemZ1.5 Hz,
4.8.2. Compound 5d. Crystal data: C12H12Br2N8,
˚
0
N2 CH]CH2], 6.27 [dd, 1H, Htrans, JcisZ15.4 Hz, Jgem
Z
˚
MZ428.12, triclinic, aZ6.5230(4) A, bZ9.7510(6) A,
0
1.3 Hz, N2 CH]CH2], 7.14 [dd, 1H, Hgem, JtransZ15.3 Hz,
˚
cZ12.7850(9) A, aZ88.149(3)8, bZ75.839(3)8, gZ
0
JcisZ8.6 Hz, N2 CH]CH2], 7.88 [d, 2H, JZ8.8 Hz, C1-
C6H4], 8.38 [d, 2H, JZ8.8 Hz, C2–C6H4]; dC: 26.9 [CH2Br],
3
˚
84.759(2)8, UZ785.15(9) A , space group P-1 (No. 2),
ZZ2, m(Mo Ka)Z5.172 mmK1. Crystallographic measure-
ments were made at 150(2) K on a Nonius kappaCCD
diffractometer in the range 3.70!q!27.578. The solution
of the structure (SHELXS86) and refinement (SHELXL97)
converged to a conventional [i.e., based on 2441F data with
FoO4s(Fo)] R1Z0.0498 and wR2Z0.1044. Goodness of
fitZ1.029. CCDC No. 261955.
54.2 [CH2N1], 111.8 [CH2], 125.1 [i-C6H4], 126.1 [i0-C6H4],
0
127.6 [C1-C6H4], 129.8 [C2–C6H4], 130.2 [CHN2 ], 152.4
[CN4], 164.2 [CN4].
4.7.3. 1,4-Bis[(2-bromoethyl)tetrazol-5-yl]benzene (1-
N,2-N0) (6c). White solid. Analysis: Found: C, 33.33; H,
2.74; N, 26.08. Calcd for C12H12N8Br2: C, 33.70; H, 2.81;
N, 26.10. Yield: 8.1%. Mp 156–160 8C; nmax (KBr) 3105,
3090, 2897, 1543, 1459, 1225, 1108, 1010, 897, 776,
609 cmK1; dH: 3.92 [t, 2H, JZ6.6 Hz, CH2Br], 3.94 [t, 2H,
Acknowledgements
JZ6.6 Hz, CH2Br], 4.38 [t, 2H, JZ6.6 Hz, CH2N1], 5.07 [t,
We would like to thank Prof. D. Cunningham and Dr. B. A.
Murray for useful discussions. VP would like to thank the
Postgraduate R&D Skills programme (Technological Sector
Research, Strand III) for financial assistance.
0
2H, JZ6.6 Hz, CH2N2 ], 8.15 [d, 2H, JZ8.8 Hz, H1-C6H4],
8.22 [d, 2H, JZ8.8 Hz, H2–C6H4]. dC: 27.7 [CH2Br], 54.2
20
[CH2 N1], 54.4 [CH2N ], 116.8 [i-C6H4], 117.0 [i0-C6H4],

A. Fleming et al. / Tetrahedron 61 (2005) 7002–7011
7011
8. Koguro, K.; Oga, T.; Mitsui, S.; Orita, R. Synthesis 1998,
910.
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