Synthesis of 2-aryl- and 2-hetaryl-4-6-dinitroindoles from 2,4,6- trinitrotoluene

Article abstract of DOI:10.1055/s-1999-3643

A general preparative method for the synthesis of the previously unknown substituted indoles 2-aryl- and 2-hetaryl-4,6-dinitroindoles from 2,4,6- trinitrotoluene (TNT) has been elaborated. The presented procedure involves condensation of TNT with aromatic and heteroaromatic aldehydes to give the corresponding (E)-stilbenes 1(a-k) and their heterocyclic analogues followed by regiospecific nucleophilic susbtitution of the ortho-nitro group in 1(a-k) with the azido group under the action of NaN₃. The thermolysis of the azides 2)a-k) leads to 2-aryl- or 2-hetaryl-4,6-dinitroindoles 3(a-k).

Full text of DOI:10.1055/s-1999-3643

PAPER
2065
Synthesis of 2-Aryl- and 2-Hetaryl-4,6-dinitroindoles from
2,4,6-Trinitrotoluene
Vladimir V. Rozhkov,a Alexander M. Kuvshinov,a Valentina I. Gulevskaya,a Ivan I. Chervin,b
Svyatoslav A. Sheveleva*
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp., 47, 117913, Moscow, Russia
Fax +7(095)1355328; E-mail: shevelev@cacr.ioc.ac.ru
bN. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, ul. Kosygina, 4, 117977, Moscow, Russia
Received 11 May 1999; revised 28 July 1999
Table 1 Yields and Mps of Stilbenes 1(a–k)
Abstract: A general preparative method for the synthesis of the pre-
viously unknown substituted indoles 2-aryl- and 2-hetaryl-4,6-dini-
Producta
Yieldd
(%)
Mp
(°C)
troindoles from 2,4,6-trinitrotoluene (TNT) has been elaborated.
The presented procedure involves condensation of TNT with aro-
matic and heteroaromatic aldehydes to give the corresponding (E)-
stilbenes 1(a-k) and their heterocyclic analogues followed by re-
giospecific nucleophilic substitution of the ortho-nitro group in 1(a-
k) with the azido group under the action of NaN3. The thermolysis
of the azides 2(a-k) leads to 2-aryl- or 2-hetaryl-4,6-dinitroindoles
3(a-k).
1a
1b
1c
1d
1e
1f
1g
1h
1i
81
60
67
79
50
51
81
73
75
67
158.5 (EtOH)b
176–177 (EtOH)c
161–162 (AcOH)
159–160 (AcOH)
190–191 (EtOH)
131–133 (AcOH)
135–136 (AcOH)
171–173 (EtOH)
200–202 (EtOH)
242–243(EtOH)
Key words: 2,4,6-trinitrotoluene, aromatic aldehydes, (E)-stil-
benes, aromatic nucleophilic substitution, aromatic azides, 4,6-dini-
troindoles
1k
a Satisfactory microanalyses obtained: C 0.25; H 0.28; N 0.33.
b Lit.,4 mp 156°C (AcOH).
The present paper is part of a research project directed to-
wards the utilization of the explosive 2,4,6-trinitrotoluene
(TNT)1 as a readily available multipurpose starting mate-
rial for the synthesis of various valuable products, along
with structures possessing previously unknown combina-
tions of functional substituents. To fit our goal, we have
set the task of synthesising a new type of indole derivative
that could be used as a basis in the search for novel bio-
active compounds, and in combinatorial synthesis. It
should be pointed out that natural and synthetic indole de-
rivatives attract widespread attention as potential pharma-
cologically and agrochemically important compounds.2
It has been reported in a number of old papers3-7 that TNT
undergoes condensation with benzaldehyde and its deriv-
atives to give the corresponding stilbenes [1-(2,4,6-trini-
trophenyl)-2-arylethenes], the configuration of which has
not been elucidated. We have found a general method of
condensation of TNT with aromatic aldehydes by boiling
under reflux in benzene with a catalytic amount of a sec-
ondary aliphatic amine (piperidine, morpholine, or dieth-
ylamine) (Scheme). Under such conditions the
condensation reaction occurred not only with benzalde-
hyde derivatives but also with heteroaromatic aldehydes,
and iso-phthalaldehyde with the formation of the bis-stil-
bene 1k. As this takes place, the corresponding stilbenes
and their heteroaromatic analogues 1(a-k) can be obtained
with satisfactory yields (Scheme, Table 1), and all pos-
sessed (E) - configuration.
Lit.,5 mp 168–169°C (AcOH), lit.,6 mp 167–168°C (AcOH).
c
d The yields refer to isolated products without further optimization.
giospecific. Only one of the ortho-nitro groups is substi-
tuted with the azido group to give the previously unknown
(E)-1-(2-azido-4,6-dinitrophenyl)-2-arylethenes 2(a-k)
with high yields (Schemes, Table 2). It is conceivable that
the substitution of only one ortho-nitro group is associated
with the significant rotation of one of the nitro groups rel-
ative to the plane of the benzene ring.8 According to quan-
tum-chemical calculations (AM1), with full optimization
of the geometric parameters the dihedral angle between
the nitro group and the plane of an aromatic ring is ap-
proximately 60o. Considering the fact that the ortho-nitro
group can be selectively substituted regardless of the elec-
tronic effects of the substituents in the arylvinyl fragment,
the selectivity of this reaction is probably controlled by
the steric effect of this fragment. Literature analysis9 and
further literature on nitrosubstitution show that for the
first time we are faced with an interesting effect of such a
fragment.
Azides 2(a-k) are stable compounds. They, as well as the
stilbenes 1(a-k), can be easily crystallized from EtOH, i-
PrOH, or MeCN. Some of the azides 2(a-k) even melt
without decomposition. The molecular structures of stil-
benes 1(a-k) and azides 2(a-k) were confirmed by IR (Ta-
ble 2) and 1H NMR spectroscopy (3J = 16.6 Hz
unambiguously determined their (E)-configuration)(Ta-
ble 3), as well as mass spectrometry and elemental analy-
sis (Table 2).
We have examined the interaction of stilbenes 1(a-k) with
various nucleophilic reagents and found that the reaction
of 1(a-k) with NaN3 in DMF at room temperature is re-
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2066
V. V. Rozhkov et al.
PAPER
Ar
Ar
Me
O2N
NO2
O2N
NO2
O2N
N3
+ArCHO
+NaN3
∆
(Amine)
−H2O
in DMF
−NaNO2
−N2
NO2
NO2
1a-i
NO2
2a-i
NO2
Hc
Ar
Ha
O
Amine =
Et2NH,
,
O2N
N
N
H
N
H
Hb
H
3a-i
H3
H2
H1
H2
H1
H1
H2
O
O
(c),
(d),
(a),
(b),
H4
N
(e),
Ar = H3
MeO
O2N
H3
Me
H2
H3
(g),
H2
H3
(f),
(h),
(i)
H1
(Et)2N
N
N
H1
S
H1
O
Me
NO2
OHC
CHO
O2N
NO2
Me
O2N
+
O2N
NO2
+NaN3
NO2
in DMF
−NaNO2
(Piperidine)
NO2
−H2O
1k
NO2
NO2
NO2
NO2
Hc
O2N
N3
Ha
N3
∆
H1
−2N2
O2N
N
N
H
NO2
H
NO2
NO2
Hb
H2
H3
2k
3k
Scheme
The presence of the azido group ortho to the double bond In conclusion, we have developed an efficient preparative
suggested the formation of indoles.10 Actually, the ther- methodology for the synthesis of a novel type of indoles,
molysis of azides 2(a-k) in nitrobenzene or ethylene gly- i.e. 2-aryl(hetaryl)-4,6-dinitroindoles from TNT. It must
col at 160-170 °C resulted in the formation of 2-aryl and be noted that 4,6-dinitroindoles with C-substituents in po-
2-hetaryl-4,6-dinitroindoles 3(a-k) with high yields.
sition 2 and with position 3 vacant were hitherto un-
known.
We have also studied the photolysis of azide 2b as an ex-
ample. Photolysis of azide 2b occurred at room tempera-
ture in benzene, and led to the corresponding indole 3b
with 80% yield.
Mps were measured on a Boetius apparatus and are uncorrected. IR
spectra were recorded with a Perkin-Elmer spectrometer. Mass
spectra were recorded on MS-30 (Kratos) spectrometer using elec-
tron ionization technique. All reactions were monitored by TLC
Synthesis 1999, No. 12, 2065–2070 ISSN 0039-7881 © Thieme Stuttgart · New York

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Synthesis of 2-Aryl- and 2-Hetaryl-4,6-dinitroindoles from 2,4,6-Trinitrotoluene
2067
Table 2 Yields, Mps, IR and MS Data of Azides 2(a–k) and Indoles 3(a–k).
Pro-
Mpb
(°C)
(MeCN)
Yielde
(%)
IR (KBr)
MS (EI)
m/z (%)
Pro-
ductc (°C)
(Pyridine)
Mpd
Yielde IR (KBr)
(%)
MS (EI)
m/z (%)
ducta
v (cm–1)
v (cm–1)
2a
138
81
3100, 2150,
2110, 1625,
1530, 1300,
1340
283(79), 193(21),
79(17), 164(20),
36(20), 105(100),
88(24), 76(11)
3a
289–290
81
3340, 1600, [M+, 283 (100)],
1620, 1590,
1520, 1470,
1380, 300,
1070, 900.
253(29), 238(23),
191(83), 180(10),
163(14), 139(30),
57(9)
2b
136–137 60
2150, 2120,
1610, 1580,
1540, 1520,
1340, 1310,
1260, 1180,
1100, 1020,
960, 800, 720
313(95), 267(26),
237(18), 221(100),
206(40), 165(14),
133(21), 100(12),
59(22)
3b
264–266
83
3339, 1609, [M+, 313 (95)],
1590, 1510,
1350, 1300,
1067, 800,
740
267(26), 37(18),
221(100), 209(19),
206(40), 165(14),
133(21), 100(13)
2c
171
dec.
67
79
50
2120, 2130,
1580, 1530,
1510, 1320,
1340, 1120,
910, 800, 710
327 (86), 311(17),
297(22), 235(100),
251(10), 281(39),
177(6), 149(25),
69(11)
3c
>360
85
84
3440, 1610,
1590, 1500,
1490, 1340,
1300, 1140,
1120, 920,
800, 710
[M+, 327 (86)],
311(17), 297(22),
235(78), 223(11),
193(8), 149(25),
69(10)
2d
178
dec.
3095, 2150,
1525, 1350,
1305, 1170,
970, 900,
328 (100), 298(14),
282(12), 236(53),
190(14), 186(100),
178(12), 163(17),
77(11)
3d
338–339
3360, 3080, [M+, 328(100)],
1620, 1590,
1520, 1480,
1350, 1300,
1060, 810,
740.
298(14), 282(11),
252(8), 236(53),
190(14), 178(12),
163(17), 77(11)
815, 740
2e
2f
138
dec.
2140, 2120,
1590, 1540,
1350, 1340,
1300, 1160,
980, 800, 720
284 (93), 268(13),
254(13), 192(100),
164(18), 105(25),
79(37), 69(12), 52(58)
3e
3f
268–270
312–313
75
81
3350, 1610, [M+, 284 (93)],
1580, 1470,
1370, 1340,
1070, 740
268(13), 254(13),
208(19), 92(100),
180(17), 105(25),
79(37), 52(58)
131–133 51
2160, 2120,
1620, 1580,
1540, 1380,
1340, 1160,
1020, 960, 800, 83(41), 75(41)
760
[M+, 301 (23)],
273(83), 227(35),
181(95), 151(38),
126(57), 102(20),
3280, 1620, [M+, 273 (85)],
1520, 1480,
1380, 1340,
1280, 1060,
940, 820,
740
257(7), 227(32),
197(15), 181(72),
169(15), 151(19),
140(10), 126(14)
2g
2h
177
dec.
78
3110, 2150,
2120, 1615,
1580, 1530,
1365, 1340,
1200, 1170,
965, 815, 740
[M+, 317(15)],
289(45), 259(10),
243(16), 213(12),
197(100), 169(25),
145(13), 121(13),
88(20)
3g
3h
317–318
279–280
87
82
3370, 3010, [M+, 289 (53)],
1600, 1590,
1480, 1350,
1200, 1000,
810, 710
244(12), 214(9),
197(100), 169(10),
145(13), 110(8),
69(19), 62(22)
192–194 92
2140, 2120
1630, 1570,
1540, 1340,
1300, 1170,
970, 820, 750
[M+, 382(30)],
354(40), 339(100),
247(29), 218(26),
162(29), 91(31)
3320, 3000, [M+, 354(49)],
1605, 1590,
1500, 1470,
1340, 1280,
1200, 1150,
1060, 1000,
920, 800, 740
339(100), 324(11),
247(14), 218(12),
91(18)
+
2i
147–148 70
2140, 2120,
1610, 1580,
1530, 1410,
1370, 1330,
1280, 1100,
820, 740
301(98), 284(13),
255(23), 225(25),
210(15), 209(100),
140(39), 124(60),
109(49)
3i
303–305
80
3240, 3160, [M , 301(60)],
1580, 1510,
1340, 1300,
1160, 1060,
1000, 810
271(42),
255(63), 209(100),
139(44), 104(53),
99(33), 77(39)
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V. V. Rozhkov et al.
PAPER
Table 2 (continued)
Pro-
Mpb
(°C)
(MeCN)
Yielde
(%)
IR (KBr)
MS (EI)
m/z (%)
Pro-
ductc (°C)
(Pyridine)
Mpd
Yielde IR (KBr)
(%)
MS (EI)
m/z (%)
ducta
v (cm–1)
v (cm–1)
2k
162
dec.
73
3090, 2120,
1535, 1350,
1300, 1170,
1095, 970,
488(54), 458(20),
396(100), 304(82),
240(12), 151(7),
3k
>360
71
3360, 3100,
1580, 1500,
1340, 1290
1000, 800
[M+, 488 (100)],
396(34), 304(22),
139(16), 137(24),
77(9), 59(19),
91(17), 58(23), 45(49)
895, 820, 740
57(18), 55(30)
aSatisfactory microanalyses obtained: C 0.20; H 0.45; N 0.28.
bCompounds 2a, 2b, 2d were recrystallized from EtOH.
cSatisfactory microanalyses obtained: C 0.18; H 0.40; N 0.27.
dCompound 3a was recrystallized from acetone and 3b from PriOH.
eThe yields refer to isolated products without further optimization.
Table 3 1H NMR Data of Stilbenes 1(a–k), Azides 2(a–k) and Indoles 3(a–k)
Prod-
uct
Hpic
(Ha), (Hb)
d/ppm
HC=CHb
(Hc)c
d/ppm
4Jab
Hz
Other Groups
d/ppm
a
1a
1b
9.10
9.06
6.79
6.86
7.47
7.35
7.41 and 7.58 (m, 5 H, Harom, ABB’CC’spectrum)
3.85 (s, 3 H, MeO), 7.0 (m, 2H, Harom, AA’BB’spectrum), 7.58 (m, 2
H, Harom, AA’BB’spectrum)
1c
9.06
9.12
6.82
6.95
7.35
7.73
6.07 (s, 2 H, CH2), 6.89 (d, 1 H, 3J = 8.1, H3), 7.06 (dd, 1 H, 3J = 8.1,
4J = 1.7, H2), 7.24 (d, 1 H, 4J = 1.7, H1)
1d
7.76 (t, 1 H, 3J = 8.1, H3), 8.03 (ddd, 1 H, 3J = 8.1, 4J = 2.4, 4J = 1.0,
H2 OR H4), 8.21 (ddd, 1 H, 3J = 8.1, 4J = 2.4, 4J = 1.0, H2 OR H4), 8.42 (t,
1 H, 4J = 2.4, H1)
1e
1f
9.16
9.07
9.06
9.05
6.78
6.79
7.01
6.75
7.83
7.27
7.18
7.05
7.57 (m, 2 H, Hpyridine, AA’BB’spectrum), 8.64 (m, 2 H, Hpyridine
AA’BB’spectrum)
,
,
6.59 (dd, 1 H, 3J = 3.4, 3J = 2.0, H2), 6.74 (d, 1 H, 3J = 3.4, H3), 7.71
(d, 1 H, 3J = 2.0, H1)
1g
1h
7.12 (dd, 1 H, 3J = 5.0, 3J = 3.7, H2), 7.36 (dd, 1 H, 3J = 3.7, 4J = 1.0
H1), 7.65 (dd, 1 H, 3J = 5.0, 4J = 1.0, H3)
1.14 (t, 6 H, 3J = 7.1, Me), 3.41 (q, 4 H, 3J = 7.1, CH2), 6.69(m, 2 H,
Harom, AA’BB’ spectrum), 7.39 (m, 2 H, Harom, AA’BB’ spectrum)
1i
9.04
9.12
6.67
6.83
6.92
7.58
2.5 (s, 3 H, Me), 3.77 (s, 3 H, NMe), 8.02 (s, 1 H, H1)
1k
7.49 (t, 1 H, 4J = 8.1, H1), 7.68 (dd, 2 H, 4J = 8.1, 3J = 2.0, H2), 7.82 (t,
1 H, 3J = 2.0, H3)
2a
2b
(8.32)
(8.35)
(8.55)
7.16
7.01
7.59
7.32
2.1
2.0
7.35 and 7.46 (m, 5 H, Harom, ABB'CC' spectrum)
(8.44)
(8.46)
(8.47)
3.85 (s, 3 H, MeO), 7.0 (m, 2 H, Harom, AA'BB' spectrum), 7.58 (m, 2
H, Harom, AA'BB' spectrum)
2c
(8.36)
(8.53)
7.04
7.44
7.3
2.4
2.0
6.07 (s, 2 H, CH2), 6.89 (d, 1 H, 3J = 8.1, H3), 7.06 (dd, 1 H, 3J = 8.1,
4J = 1.7, H2), 7.24 (d, 1 H, 4J = 1.7, H1)
2d
7.50
7.76 (t, 1 H, 3J = 8.1, H3), 8.12 (ddd, 1 H, 3J = 8.1, 4J = 2.4, 4J = 1.0,
H2 OR H4), 8.25 (ddd, 1 H, 3J = 8.1, 4J = 2.4, 4J = 1.0, H2 OR H4), 8.28 (t,
1 H, 4J = 2.4, H1)
2e
2f
(8.46)
(8.39)
(8.53)
(8.46)
7.28
6.97
7.46
7.4
2.1
2.4
7.57 (m, 2 H, Hpyridine, AA'BB' spectrum), 8.64 (m, 2 H, Hpyridine
AA'BB' spectrum)
,
6.59 (dd, 1 H, 3J = 3.4, 3J = 2.0, H2), 6.74 (d, 1 H, 3J = 3.4, H3), 7.71 (d,
1 H, 3J = 2.0, H )
1
Synthesis 1999, No. 12, 2065–2070 ISSN 0039-7881 © Thieme Stuttgart · New York

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Synthesis of 2-Aryl- and 2-Hetaryl-4,6-dinitroindoles from 2,4,6-Trinitrotoluene
2069
Table 3 (Continued)
Prod-
uct
Hpic
(Ha), (Hb)
δ/ppm
HC=CHb
(Hc)c
δ/ppm
4Jab
Hz
Other Groups
δ/ppm
a
2g
2h
(8.31)
(8.25)
(8.52)
6.79
6.79
7.53
2.2
2.2
7.12 (dd, 1 H, 3J = 5.0, 3J = 3.7), H2, 7.39 (dd, 1 H, 3J = 3.7, 4J = 1.0,
H1), 7.65 (dd, 1H, 3J = 5.0, 4J = 1.0, H3)
(8.49)
7.25
1.12 (t, 3 H, 3J = 7.1, Me), 3.40 (q, 2 H, 3J=7.1,CH2), 6.70 (m, 2 H,
Harom, AA’BB’ spectrum), 7.41 (m, 2H, Harom, AA’BB’ spectrum)
2i
(8.26)
(8.43)
(8.48)
(8.50)
6.35
7.28
7.17
7.38
2.2
2.4
2.50 (s, 3 H, Me), 3.23(s, 3 H, NMe), 8.00 (s, 1 H, H1)
2k
7.52 (t, 1 H, 4J = 8.1, H1), 7.68 (dd, 2 H, 4J = 8.1, 3J = 2.0, H2), 7.91 (t,
1 H, 3J = 2.0, H3)
3a
3b
(8.28)
(8.48)
(8.45)
(8.70)
(7.33)
(7.51)
2.0
2.0
7.48 and 7.84 (m, 5 H, Harom, ABB'CC' spectrum)
3.85 (s, 3 H, MeO), 7.12 (m, 2 H, Harom, AA'BB' spectrum), 7.97 (m, 2
H, Harom, AA'BB' spectrum)
3c
(8.42)
(8.56)
(8.65)
(8.71)
(7.45)
(7.82)
2.0
2.2
6.13 (s, 2 H, CH2), 7.07 (d, 1 H, 3J = 7.4, H3), 7.51 (dd, 1 H, 3J = 7.4,
4J = 1.7, H2), 7.52 (s, 1 H, 4J = 1.7, H1)
3d
7.81 (t, 1 H, 3J = 8.1, H2), 8.31 (ddd, 1 H, 3J= 8.1, 4J = 2.1, 4J = 1.0,
H2 OR H4), 8.52 (ddd, 1 H, 3J = 8.1, 4J = 1.8, 4J = 1.0, H2 OR H4), 8.82
(dd, 1 H, 4J = 2.1, 4J = 1.8, H4)
3e
3f
(8.58)
(7.96)
(8.28)
(8.41)
(8.7)
(7.77)
(7.32)
(7.09)
(7.41)
2.0
2.0
2.1
2.2
7.94 (m, 2 H, Hpyridine, AA'BB' spectrum), 8.74 (m, 2 H, Hpyridine
AA'BB' spectrum)
,
(8.41)
(8.47)
(8.71)
6.75 (dd, 1 H, 3J = 3.4, 3J = 1.7, H2), 7.30 (d, 1 H, 3J = 3.4, H1), 8.63
(d, 1 H, 3J = 1.7, H3)
3g
3h
7.20 (dd, 1 H, 3J = 5.0, 3J = 3.7, H2), 7.67 (dd, 1 H, 3J = 3.7, 4J = 1.0,
H1), 7.76 (dd, 1 H, 3J = 5.0, 4J = 1.0, H3)
(t, 3H, 3J = 7.1, Me), 3.45(q, 2 H, 3J = 7.1, CH2), 6,72 (m, 2 H, Harom
AA’BB spectrum), 7.85 (m, 2 H, Harom, AA’BB spectrum)
,
3i
(8.27)
(8.57)
(8.51)
(8.60)
(6.98)
(7.77)
2.2
2.2
2.39 (s, 3 H, Me), 3.85(s, 3 H, NMe), 8.11 (s, 1 H, H1)
3k
7.75 (t, 1 H, 4J = 8.1, H1), 8.10 (dd, 2 H, H2, 4J = 8.1, 3J = 1.8, H2), 8.72
(t, 1 H, 3J = 1.8, H3)
aStilbenes 1(a–k) and azides 2(a–k), except 2d and 2h in acetone-d6. All other compounds were in DMSO-d6.
bDoublet, 3JHH,trans = 16.6 Hz.
cDoublet, 5Jac = 0.7 Hz.
using Silufol precoated aluminiun plates which were visualized
with ultraviolet light. 1H NMR spectra were measured on a Bruker
WM-400 spectrometer. Chemical shifts are reported in ppm down-
field from TMS using the δ scale. Organic solvents and reagents
were purified by the accepted literature procedures. For all new
compounds satisfactory microanalyses were obtained.
mixture was stirred at r.t. until full conversion of the starting mate-
rial, ca 6 h (TLC). The mixture was then poured into cold water (200
mL) and the precipitate was filtered off and recrystallized.
Indoles 3(a-k); General Procedure
Azide 2 (1g) in nitrobenzene (50 mL) or ethylene glycol was heated
with rigorous stirring for 1 h at 160-165 °C. The solvent (nitroben-
zene) was evaporated in vacuo, the solid residue was washed with
hexane, filtered off and recrystallized. In the case of ethylene gly-
col, the mixture was poured into cold water and the precipitate was
filtered off and recrystallized.
Stilbenes 1(a-k); General Procedure
TNT (10.0 mmol) and an aromatic aldehyde (a-k) (10.1 mmol)
were dissolved in benzene (50 mL), a catalytic amount of an amine
(5 drops) was added and the mixture was refluxed until the disap-
pearance of the starting material, ca 6 h (TLC). The solvent was then
evaporated under reduced pressure, and the solid residue was re-
crystallized from an appropriate solvent.
Photolysis of Azide 2b
Azide 2b (0.5g) was dissolved in benzene (50 mL) and irradiated
with UV light (H.P. mercury lamp, without filter, r.t.) for ca. 8 h, un-
til full conversion of the starting azide (TLC) was achieved. The
precipitate was filtered off and recrystallized from i-PrOH.
Azides 2(a-k); General Procedure
Stilbene 1(a-k) (10.0 mmol) was dissolved in dried DMF (20 mL)
and NaN3 (10.1 mmol) was then added in one portion. The reaction
Synthesis 1999, No. 12, 2065–2070 ISSN 0039-7881 © Thieme Stuttgart · New York

2070
V. V. Rozhkov et al.
PAPER
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Acknowledgement
We thank the International Science and Technology Center (Project
# 419-98) for financial support.
(7) Splitter, J. S.; Calvin, M. J. Org. Chem. 1955, 20, 1086.
(8) Benedetti, F.; Marshall, D. R.; Stirling, Ch. J. M.; Leng, J. L.
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References
(9) Terrier, F. Nucleophilic Aromatic Displacement: The
Influence of the Nitro Group; VCH: Weinheim, 1991.
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(1) Tartakovsky, V. A.; Shevelev, S. A.; Dutov, M. D.; Shakhnes,
A. K.; Rusanov, A. L.; Komarova, L. G.; Andrievsky, A. M.
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Article Identifier:
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Synthesis 1999, No. 12, 2065–2070 ISSN 0039-7881 © Thieme Stuttgart · New York