1-Vinylpyrrole-2-carbaldehyde oximes: Synthesis, isomerization, and spectral properties

Article abstract of DOI:10.1007/s00706-009-0200-0

The reaction of 1-vinylpyrrole-2-carbaldehydes with hydroxylamine hydrochloride in pyridine or ethanol in the presence of NaHCO₃ or NaOAc affords previously unknown 1-vinylpyrrole-2-carbaldehyde oximes in 95-99% yields. Isomerization of oximes

Full text of DOI:10.1007/s00706-009-0200-0

Monatsh Chem (2009) 140:1475–1480
DOI 10.1007/s00706-009-0200-0
ORIGINAL PAPER
1-Vinylpyrrole-2-carbaldehyde oximes: synthesis, isomerization,
and spectral properties
•
Alexander M. Vasil’tsov Kai Zhang Andrei V. Ivanov Igor A. Ushakov
•
•
•
•
•
•
Andrei V. Afonin Konstantin B. Petrushenko Shayu Li Jin Shi Ma
•
•
Al’bina I. Mikhaleva Boris A. Trofimov Guoqiang Yang
•
Received: 14 January 2009 / Accepted: 11 October 2009 / Published online: 10 November 2009
Ó Springer-Verlag 2009
Abstract The reaction of 1-vinylpyrrole-2-carbaldehydes
with hydroxylamine hydrochloride in pyridine or ethanol in
the presence of NaHCO3 or NaOAc affords previously
unknown 1-vinylpyrrole-2-carbaldehyde oximes in 95–
99% yields. Isomerization of oximes from (E) to (Z) in the
presence of strong acids and the spectral characteristics of
the isomers were studied.
applied in agriculture (the fungicide Fludioxonil [6] and
insecticide Chlorfenapyr [7]) and in medicine (the nonste-
roidal progesterone receptor agonist Tanaproget [8]). They
are also used for the preparation of heterocyclic ensembles
[5]. A notable example of the application of pyrrolecarbal-
dehyde oximes as starting materials is the synthesis of
pyrrolylcarbonitriles, which are important building blocks in
heterocyclic chemistry [5, 9].
Keywords (Z)/(E)-isomers ꢀ Protonation ꢀ Absorption ꢀ
1-Vinylpyrrole-2-carbaldehydes [10, 11] prove to be
highly reactive building blocks in organic synthesis [12].
Being involved in the investigations of chemical properties
of 1-vinylpyrrole-2-carbaldehydes, we have synthesized a
series of 1-vinylpyrrole-2-carbaldehyde oximes. The (E)/
(Z) isomerization of oximes has been known for a long
time [13–18]. In many cases the (Z)- and (E)-isomers of the
oximes show different reactivity [5, 21, 22]. In this paper,
we report the synthesis of 1-vinylpyrrole-2-carbaldehyde
oximes and the study of their (Z)/(E) isomerization as well
as spectral characteristics using 1H and 13C NMR, UV–Vis,
luminescence- and IR techniques.
Fluorescence
Introduction
Oximes and their derivatives have widespread application in
organic synthesis to furnish amines, hydroxylamines,
nitriles, diaza compounds, various heterocyclic compounds
(isoxazoles, isoxazolidines, pyrroles, pyrrolines, benzofu-
rans, imidazoles, pyridines, oxazines, azirines, aziridines,
diaziridines, and palladacycles), as well as metal complexes
[1–4]. Oximes of pyrrole series show a wide spectrum of
biological activity: bactericidal, acaricidal, growth-regulat-
ing, receptor, etc. [5]. A number of oximes are extensively
Results and discussion
We have obtained 1-vinylpyrrole-2-carbaldehyde oximes
from 1-vinylpyrrole-2-carbaldehydes 1a–1e and hydroxyl-
amine hydrochloride by two procedures [5, 19]: in pyridine
(65 °C, 1–1.5 h, method A) and in ethanol in the presence
of NaHCO3 or NaOAc (20–25 °C, 1.5–3 h, method B).
The yields of the oximes 2a–2e are 95–99% (Scheme 1).
Due to considerable solubility of the oxime 2a in water
method B, involving the washing of the crude product with
water, is of limited utility in this case.
A. M. Vasil’tsov ꢀ A. V. Ivanov ꢀ I. A. Ushakov ꢀ
A. V. Afonin ꢀ K. B. Petrushenko ꢀ A. I. Mikhaleva ꢀ
B. A. Trofimov (&)
A.E. Favorsky Irkutsk Institute of Chemistry,
Siberian Branch of the Russian Academy of Sciences,
1 Favorsky St., Irkutsk 664033, Russian Federation
e-mail: boris_trofimov@irioch.irk.ru
K. Zhang ꢀ S. Li ꢀ J. S. Ma ꢀ G. Yang (&)
CAS Key Laboratory of Photochemistry, Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100190,
People’s Republic of China
1
In the H NMR spectra of the oximes 2a–2e, all the
proton signals assigned to the pyrrole moiety, vinyl group
e-mail: gqyang@iccas.ac.cn
123

1476
A. M. Vasil’tsov et al.
R2
Scheme 1
R2
R1
R2
R1
Base
HCl
NH2OH
H
H
+
H
+
-HCl, H2O
R1
N
N
N
N
O
N
OH
HO
1a-1d
(E)-2a-2d
(Z)-2a-2d
Base = Pyridine, NaHCO3/EtOH, or NaOAc/EtOH
Oxime
2a
R1
H
R2
H
Yield (%a)
95
96
99
97
n-Pr
Et
H
2b
Ph
2c
2-Thienyl
H
2d
aIsolated
Base
-HCl, H2O
H
H
HCl
NH2OH
+
N
O
N
N
OH
99%
(E),(Z)-2e
1e
Base = Pyridine, NaHCO3/EtOH, or NaOAc/EtOH
1
and azomethine fragment are doubled due to (Z)/(E)-
isomerism. All the signals of (Z)- and (E)-isomers differ
significantly (up to 0.8 ppm) from each other. The (E)-
isomers of oximes 2a–2e feature low-field resonances of
the azomethine protons [13] (8.1–8.2 ppm) as well as lower
proceeds readily at room temperature. H and 13C NMR
monitoring of this process (CDCl3) allows some of the
regularities (for all compounds and acids used) of (E)- and
(Z)-isomer protonations to be revealed. Successive addition
of an acid to the solution of an (E)/(Z) mixture results in
1
1
values of the coupling constants JC–H for azomethine
protons [20] (164–168 Hz) as compared to the corre-
low field shifts of H NMR signals for (Z)-isomers only,
while those for (E)-isomers 2a–2c and 2e are not shifted at
1
sponding (Z)-isomers (d = 7.5–7.6 ppm, JC–H = 171–
179 Hz).
all and eventually disappear with increasing of the acid
1
concentrations. In the H NMR spectra, the typical signals
The (E)/(Z)-isomer ratios of the oximes 2a–2e depend
on the method of preparation. For example, the oxime 2e
prepared by method A contains 42% of (Z)- and 58% of
(E)-isomer, by method B (with NaHCO3) 16% of (Z)- and
84% of (E)-isomer and by method B (with NaOAc) 36% of
(Z)- and 64% of (E)-isomer. The ratio is not changed on
heating up to 70 °C and is practically invariant with the
nature of the solvent (CDCl3, C2D5OD, C6D6, DMSO-d6)
used for recording the 1H and 13C NMR spectra. At a
higher temperature (above 90 °C), the ratio of the isomers
starts to change. In CCl4 and hexane, the solubility of the
(Z)-isomer of 2c is low, which allows us to isolate this
isomer as an individual compound.
of CH=N protons in protonated (Z)-isomers H?-(Z)-2a to
2c and H?-(Z)-2e are singlets resonated in the region of
8.1–8.2 ppm (see Experimental). These singlets are shifted
by *0.6 ppm towards the low field as compared with
that in unprotonated (Z)-isomers. The disappearance of
(E)-isomer signals and increase in integral intensity of
protonated (Z)-isomers indicate the fact that protonated
(E)-isomers are transformed rapidly and quantitatively into
the corresponding protonated (Z)-isomers. The initial ratio
of (E)- and (Z)-isomers as well as the concentration of acid
in the solution (up to equimolar ratio oxime:acid) do not
affect the process (Scheme 2).
In the 1H NMR spectra, the signals of resinification
products of compounds 2b, 2c and 2e are observed when
the acids were used in concentrations exceeding equimolar
ones.
It has been found that under the action of strong acids
(CF3SO3H, CF3COOH and HCl) (E)/(Z)-isomerization of
1-vinylpyrrole-2-carbaldehyde oximes 2a–2c, and 2e
123

1-Vinylpyrrole-2-carbaldehyde oximes: synthesis, isomerization, and spectral properties
1477
Scheme 2
R2
R1
R2
H
H
H
R1
N
N
N
N
H
OH
HO
H-(Z)-2a-2c
(E),(Z)-2a-2c
H
H
H
N
N
N
N
OH
H
HO
H-(Z)-2e
(E),(Z)-2e
In the case of 1-vinylpyrrole-2-carbaldehyde oxime
(2a), excess HCl leads to the addition of the acid at the
vinyl group to furnish a Markovnikov adduct (Scheme 3).
The UV–Vis and fluorescence emission spectra of pure
(Z)-isomer of 2c in MeCN are shown in Fig. 1 (absorption
kmax = 304 nm; emission kem = 365.5 nm, kex = 304
nm). Unlike the results obtained in DMSO, the equilibrium
of (Z)/(E) isomer 2c [(Z):(E) & 1:1] is easily reached
under heating of pure (Z)-isomer solution in MeCN at
30 °C for 20 h. The UV–Vis and fluorescence emission
spectra of (E)-isomer could be obtained from the difference
spectra of (Z)/(E) mixture (1:1) and (Z) isomer, which are
shown in Fig. 1 (absorption kmax = 310 nm; emission
kem = 375.5 nm).
aldoxime functional moieties, have been obtained and
characterized.
Experimental
IR spectra were recorded on a FT-IR spectrophotometer
(Excalibur HE 3100). 1H and 13C NMR spectra were run on
Bruker DPX-400 and AV-400 instruments; HMDS was
used as internal standard. Spectrophotometric measure-
ments were performed on a Lambda 35 Perkin-Elmer
spectrophotometer. Fluorescence spectra were recorded on
a LS 55 Perkin-Elmer spectrofluorimeter. Elemental anal-
yses (C, H, N, S) were conducted on a ThermoFinnigan
1112 elemental analyzer, and results agreed favorably with
the calculated values.
In the IR spectrum of the (Z)-isomer 2c, the character-
istic absorption bands of oxime (vꢀC¼N = 1,677 cm-1
,
vꢀNꢁO = 955 cm-1
)
and vinyl (vꢀC¼C = 1,636 cm-1
,
1-Vinylpyrrole-2-carbaldehydes 1a–1e were synthesized
by a modified Vilsmeier–Haack reaction [10, 11]. The
reagents were of commercial grade. The solvents were
purified by known procedures [23].
vꢀsðHC¼CHÞ = 913 cm-1, vꢀxð¼CH Þ = 850 cm-1) functional
2
groups are observed, which have been assigned [22].
Stretching vibrations of the OH moieties of the solid
sample appear as a wide band (intermolecular H-bonds,
3,165 cm-1), while in diluted solutions (\10-3 mol dm-3
)
General procedures for synthesis of 1-vinylpyrrole-2-
carbaldehyde oximes.
of CCl4 the formation of monomer with an intensive nar-
row peak at 3,594 cm-1 is observed.
In conclusion, the first representatives of 1-vinylpyrrole-
2-carbaldehyde oximes, promising pyrrole synthons and
building blocks containing simultaneously vinyl and
Method A
A mixture of 0.25 g 1-vinylpyrrole-2-carbaldehyde (1a,
1.1 mmol) and 0.16 g hydroxylamine hydrochloride
Scheme 3
H
H
H
HCl
N
HCl
N
N
N
H
N
N
H
Cl
OH
HO
HO
Cl
Cl
H-(Z)-3
(E),(Z)-2a
H-(Z)-2a
123

1478
A. M. Vasil’tsov et al.
Fig. 1 Normalized UV–Vis
absorption and fluorescence
emission spectra of (Z)- and (E)-
isomers of 2c in MeCN
1.0
0.8
0.6
0.4
0.2
0.0
1.0
Abs of (Z )-2c
Em of (Z )-2c
Abs of (E )-2c
Em of (E )-2c
(2 9 10-5 mol dm-3
)
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
550
Wavelength/nm
(2.2 mmol) in 2.5 cm3 pyridine was heated at 65 °C for
1.5 h, and then cooled to room temperature. The mixture
was diluted with 2.5 cm3 water, extracted with diethyl
ether (4 9 10 cm3) and dried over K2CO3. After the ether
removal, the mixture was distilled in vacuum (3 mmHg,
50 °C, 3 h) from pyridine traces to afford 0.27 g (95%) of
the oxime 2a.
Protonated (Z)-1-vinylpyrrole-2-carbaldehyde oxime
(H?-(Z)-2a)
1H NMR (400.13 MHz, CDCl3): d = 8.21 (s, 1H, CHN),
3
4
7.73 (dd, 1H, H-3, J3–4 = 3.9 Hz, J3–5 = 1.0 Hz), 7.38
(dd, 1H, H-5, 3J4–5 = 2.5 Hz, 4J3–5 = 1.0 Hz), 7.20 (dd, 1H,
HX, 3JB–X = 15.1 Hz, 3JA–X = 8.3 Hz), 6.50 (dd, 1H, H-4,
3J3–4 = 3.9 Hz, 3J4–5 = 2.7 Hz), 5.40 (dd, 1H, HB, 3JX–B
=
2
3
15.1 Hz, JA–B = 1.2 Hz), 5.21 (dd, 1H, HA, JA–X
=
Method B
8.3 Hz, JA–B 1.2 Hz) ppm; 13C NMR (100.61 MHz,
CDCl3): d = 136.95 (C=N), 131.3 (Ca), 128.6 (C-5), 128.4
(C-3), 120.1 (C-2), 113.7 (C-4), 105.2 (Cb) ppm.
2
A mixture of 0.41 g 5-phenyl-1-vinylpyrrole-2-carbalde-
hyde 1c (1.1 mmol), 0.16 g hydroxylamine hydrochloride
(2.2 mmol) and 0.12 g NaHCO3 (1.1 mmol) in 2.5 cm3
ethanol was stirred at room temperature for 2.5 h. Then the
mixture was diluted with 10 cm3 water, the residue was
filtered on a Schott filter, washed with 5 cm3 distilled water
and dried on air to give 0.44 g (99%) of the oxime 2c.
Protonated (Z)-1-(1-chloroethyl)pyrrole-2-
carbaldehyde oxime (3)
1H NMR (400.13 MHz, CDCl3): d = 8.53 (s, 1H, CHN),
1
In the H NMR spectra of the compounds 2a–2e, the
signals of the hydroxyl proton appear as a broad singlet at
8–9 ppm.
3
4
7.76 (dd, 1H, H-3, J3–4 = 3.8 Hz, J3–5 = 1.1 Hz), 7.48
(dd, 1H, H-5, 3J4–5 = 2.6 Hz, 4J3–5 = 1.1 Hz), 6.72 (q, 1H,
3
3
CHCl, J = 6.1 Hz), 6.52 (dd, 1H, H-4, J3–4 = 3.8 Hz,
3J4–5 = 2.6 Hz), 2.14 (d, 3H, CH3, 3J = 6.1 Hz) ppm; 13
C
1-Vinylpyrrole-2-carbaldehyde oxime (2a, C7H8N2O)
Yield 95%, yellowish powder, 50% of (Z)-isomer; m.p.: 65–
90 °C; 1H NMR (400.13 MHz, CDCl3), (E)- ((Z)-): d = 8.10
NMR (100.61 MHz, CDCl3): d = 134.5 (C=N), 129.5
(C-5), 128.6 (C-3), 119.8 (C-2), 114.3 (C-4), 64.9 (CHCl),
25.3 (CH3) ppm.
1
(7.49) (s, 1H, CHN, JC–H = 164.2 Hz (172.7 Hz)), 7.55
(6.80) (dd, 1H, HX, 3JB–X = 15.7 Hz, 3JA–X = 8.6 Hz), 7.15
(7.08) (d, 1H, H-5, 3J4–5 = 2.8 Hz), 6.49 (7.41) (d, 1H, H-3,
4-Ethyl-5-propyl-1-vinylpyrrole-2-carbaldehyde
(1b, C12H17NO)
3
3J3–4 = 3.7 Hz), 6.27 (6.37) (dd, 1H, H-4, J3–4 = 3.7 Hz,
1
Yield 28%, yellow–orange oily liquid; n2D0 = 1.5754; H
3
3J3–5 = 1.7 Hz), 5.20 (5.29) (d, 1H, HB, JA–B = 15.7 Hz),
NMR (400.13 MHz, CDCl3): d = 9.44 (s, 1H, CHO), 7.20
3
4.81 (4.98) (d, 1H, HA, JA–X = 8.9 Hz) ppm; 13C NMR
3
3
(dd, 1H, HX, JB–X = 15.8 Hz, JA–X = 8.6 Hz), 6.85 (s,
1H, H-3), 5.27 (d, 1H, HA, 3JA–X = 8.6 Hz), 5.22 (d, 1H, HB,
3JB–X = 15.9 Hz), 2.61 (m, 2H, CH2CH2CH3), 2.43 (q, 2H,
(100.61 MHz, CDCl3), (E)- ((Z)-): d = 142.96 (135.36)
(C=N), 132.65 (130.20) (Ca), 124.80 (122.45) (C-2), 121.70
(121.18) (C-5), 115.77 (119.63) (C-3), 110.74 (111.12) (C-4),
100.56 (104.04) (Cb) ppm.
3
CH2CH3, J = 7.5 Hz), 1.55 (m, 2H, CH2CH2CH3), 1.18
3
(t, 3H, CH2CH3, J = 7.5 Hz), 0.94 (t, 3H, CH2CH2CH3,
123

1-Vinylpyrrole-2-carbaldehyde oximes: synthesis, isomerization, and spectral properties
1479
3
1H, H-4, J3–4 = 3.9 Hz), 4.97 (5.21) (d, 1H, HA,
3J = 7.3 Hz) ppm; 13C NMR (100.61 MHz, CDCl3):
d = 178.17 (C=O), 140.32 (C-5), 131.63 (Ca), 131.20 (C-2),
126.37 (C-4), 123.28 (C-3), 111.29 (Cb), 26.54
(CH2CH2CH3), 22.54 (CH2CH2CH3), 18.88 (CH2CH3),
14.93 (CH2CH3), 14.03 (CH2CH2CH3) ppm; IR (film):
vꢀ = 3,111, 3,046, 2,946, 2,930, 2,871, 2,861, 2,810, 2,723,
1,671, 1,639, 1,580, 1,530, 1,473, 1,420, 1,380, 1,322, 1,282,
1,241, 1,212, 1,157, 1,126, 1,076, 1,029, 960, 915, 881, 854,
3
3JA–X = 8.3 Hz), 5.13 (5.34) (d, 1H, HB, JB–X
=
15.7 Hz) ppm; 13C NMR (100.61 MHz, CDCl3), (E)- ((Z)-):
d = 143.31 (137.45) (C=N), 126.26 (123.63) (C-2), 132.55
(132.34) (Ci), 137.45 (136.51) (C-5), 127.52 (127.74) (Cp),
129.09 (129.18) (Cm), 128.42 (128.47) (Co), 113.18
(119.35) (C-3), 111.38 (111.22) (C-4), 131.85 (131.47)
(Ca), 112.05 (114.18) (Cb) ppm.
802, 773, 746, 710, 682, 593, 514, 481 cm-1
.
Protonated (Z)-5-phenyl-1-vinylpyrrole-2-
carbaldehyde oxime (H?-(Z)-2c)
4-Ethyl-5-propyl-1-vinylpyrrole-2-carbaldehyde oxime
(2b, C12H18N2O)
Yield 96%, yellow powder, 58% of (Z)-isomer; m.p.: 94–
149 °C (dec.); 1H NMR (400.13 MHz, CDCl3), (E)- ((Z)-):
1H NMR (400.13 MHz, CDCl3): d = 8.27 (s, 1H, CHN),
7.93 (d, 1H, H-3, J3–4 = 4.4 Hz), 7.42–7.26 (m, 5H, Ph),
3
1
d = 8.11 (7.49) (s, 1H, CHN, JC–H = 163.8 Hz
(171.6 Hz)), 6.91 (6.81) (dd, 1H, HX, JB–X = 15.9 Hz,
6.81 (dd, 1H, HX, 3JB–X = 15.7 Hz, 3JA–X = 8.1 Hz), 6.67
3
3
(d, 1H, H-4, J3–4 = 4.4 Hz), 5.67 (dd, 1H, HA,
3JA–X = 8.6 Hz), 6.51 (7.31) (d, 1H, H-3, 3J3–4 = 3.9 Hz),
3JA–X = 8.1 Hz, JA–B = 1.2 Hz), 5.44 (dd, 1H, HB,
2
3
5.22 (5.36) (d, 1H, HA, JA–X = 8.6 Hz), 5.14 (5.23) (d,
2
3JB–X = 15.7 Hz, JA–B = 1.2 Hz) ppm; 13C NMR
3
1H, HB, JB–X = 15.9 Hz), 2.58 (m, 2H, CH2CH2CH3),
(100.61 MHz, CDCl3): d = 143.45 (C-5), 135.51 (C=N),
130.35 (Ci), 129.85 (Ca), 129.12 (Cp), 128.93 (Cm), 128.52
(Co), 126.18 (C-3), 121.46 (C-2), 117.94 (Cb), 113.81 (C-4)
ppm.
2.46 (q, 2H, CH2CH3, 3J = 7.5 Hz), 1.52 (m, 2H,
CH2CH2CH3), 1.18 (t, 3H, CH2CH3, 3J = 7.5 Hz), 0.94 (t,
3H, CH2CH2CH3, 3J = 7.3 Hz) ppm; 13C NMR
(100.61 MHz, CDCl3), (E)- ((Z)-): d = 142.87 (137.11)
(C=N), 133.28 (132.69) (C-5), 131.45 (130.60) (Ca),
124.48 (124.56) (C-4), 123.34 (121.15) (C-2), 111.05
(113.89) (Cb), 26.60 (26.64) (CH2CH2CH3), 23.05 (22.83)
(CH2CH2CH3), 19.00 (19.06) (CH2CH3), 15.39 (15.44)
(CH2CH3), 13.95 (13.95) (CH2CH2CH3) ppm.
(Z)-5-Phenyl-1-vinylpyrrole-2-carbaldehyde oxime
((Z)-2c)
Hexane (15 cm3) was added to a solution of 0.50 g
5-phenyl-1-vinylpyrrole-2-carbaldehyde oxime (2c, 66%
(Z)-isomer) in 2 cm3 diethyl ether under stirring at room
temperature; the residue was filtered on a Schott filter,
washed with 5 cm3 hexane and dried on air to give 0.25 g
of oxime (Z)-2c as orange powder (100% of (Z)-isomer).
m.p.: 135–137 °C (dec.); IR (KBr): vꢀ = 3,165, 3,056,
3,027, 2,978, 2,923, 2,864, 2,784, 1,677, 1,636, 1,607,
1,453, 1,407, 1,321, 1,283, 1,233, 1,170, 955, 913, 849,
Protonated (Z)-4-ethyl-5-propyl-1-vinylpyrrole-2-
carbaldehyde oxime (H?-(Z)-2b)
1H NMR (400.13 MHz, CDCl3): d = 7.93 (s, 1H, CHN),
7.64 (s, 1H, H-3), 6.82 (dd, 1H, HX, JB–X = 15.4 Hz,
3
3
3JA–X = 8.1 Hz), 5.70 (dd, 1H, HA, JA–X = 8.1 Hz,
3
2JA–B = 1.0 Hz), 5.38 (dd, 1H, HB, JB–X = 15.4 Hz,
758, 696, 655, 596 cm-1
.
2JA–B = 1.0 Hz), 2.64 (m, 2H, CH2CH2CH3), 2.48 (q, 2H,
3
CH2CH3, J = 7.3 Hz), 1.56 (m, 2H, CH2CH2CH3), 1.22
5-(2-Thienyl)-1-vinylpyrrole-2-carbaldehyde oxime
(2d, C11H10N2OS)
Yield 97%, orange powder, 84% (Z)-isomer; m.p.: 148–
3
(t, 3H, CH2CH3, J = 7.3 Hz), 0.96 (t, 3H, CH2CH2CH3,
3J = 7.1 Hz) ppm; 13C NMR (100.61 MHz, CDCl3):
d = 145.50 (C-5), 136.19 (C=N), 129.97 (C-4), 128.71
(Ca), 126.58 (C-3), 120.09 (Cb), 118.55 (C-2), 27.17
(CH2CH2CH3), 21.94 (CH2CH2CH3), 18.87 (CH2CH3),
14.44 (CH2CH3), 13.94 (CH2CH2CH3) ppm.
1
180 °C (dec.); H NMR (400.13 MHz, CDCl3), (E)- ((Z)-):
d = 8.16 (7.55) (s, 1H, CHN, 1JC–H = 167.4 Hz (178.5 Hz)),
6.67 (7.47) (d, 1H, H-3, 3J3–4 = 3.9 Hz), 7.28 (7.28) (dd, 1H,
3
H-30, J3 -4 = 5.1 Hz, 3J3 -5 = 1.0 Hz), 7.12 (7.12) (dd, 1 H,
0
0
0
0
3
H-50, J4 -5 = 3.4 Hz, 3J3 -5 = 1.0 Hz), 7.04 (7.04) (dd, 1H,
0
0
0
0
3
H-40, J3 -4 = 5.1 Hz, 3J4 -5 = 3.4 Hz), 6.98 (6.91) (dd, 1H,
0
0
0
0
5-Phenyl-1-vinylpyrrole-2-carbaldehyde oxime
(2c, C13H12N2O)
Yield 99%, orange powder, 66% of (Z)-isomer; m.p.:
3
HX, JB–X = 15.7 Hz, JA–X = 8.6 Hz), 6.38 (6.51) (d, 1H,
3
3
H-4, J3–4 = 3.9 Hz), 5.29 (5.47) (d, 1H, HA, JA–X
3
=
1
85–128 °C (dec.); H NMR (400.13 MHz, CDCl3), (E)-
8.6 Hz), 5.18 (5.35) (d, 1H, HB, 3JB–X = 15.7 Hz) ppm; 13
C
1
((Z)-): d = 8.21 (7.62) (s, 1H, CHN, JC–H = 164.8 Hz
(175.0 Hz)), 7.42–7.26 (7.44–7.29) (m, 5H, Ph), 6.98
NMR (100.61 MHz, CDCl3), (E)- ((Z)-): d = 142.71
(137.00) (C=N), 133.85 (133.85) (C-20), 131.42 (131.28)
(Ca), 130.06 (129.55) (C-5), 127.40 (127.49) (C-40), 126.68
(124.08) (C-2), 126.67 (126.43) (C-50), 125.52 (125.68) (C-
3
(6.80) (dd, 1H, HX, JB–X = 15.7 Hz, JA–X = 8.3 Hz),
3
3
6.66 (7.46) (d, 1H, H-3, J3-4 = 3.9 Hz), 6.29 (6.39) (d,
123

1480
A. M. Vasil’tsov et al.
30), 113.69 (115.85) (Cb), 112.29 (119.17) (C-3), 111.84
(111.32) (C-4) ppm.
National Basic Research Program (2007CB808004) and Presidium of
the Russian Academy of Sciences (project no. 8.20).
4,5-Dihydro-1-vinyl-1H-benz[g]indole-2-carbaldehyde
oxime (2e, C15H14N2O)
Yield 99%, yellow–orange powder, 42% of (Z)-isomer;
References
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1
m.p.: 131–174 °C (dec.); H NMR (400.13 MHz, CDCl3),
1
(E)- ((Z)-): d = 8.17 (7.50) (s, 1H, CHN, JC–H
=
164.7 Hz (173.7 Hz)), 7.20 (7.10) (dd, 1H, HX,
3JB–X = 15.7 Hz, 3JA–X = 8.0 Hz), 7.55 (7.57) (m, 1H, H-
9), 7.20–7.10 (m, 3H, H-6, H-7, H-8), 6.58 (7.36) (s, 1H,
H-3), 5.42 (5.60) (d, 1H, HA, 3JA–X = 8.0 Hz), 5.33 (5.45)
3
(d, 1H, HB, JB–X = 15.7 Hz), 2.60 (2.61) (m, 2H, H-4),
2.90 (2.92) (m, 2H, H-5) ppm; 13C NMR (100.61 MHz,
CDCl3), (E)- ((Z)-): d = 142.7 (137.5) (C=N), 136.9
(136.3) (C-5a), 130.6 (131.4) (C-9b), 126.4 (123.5) (C-2),
132.6 (132.4) (Ca), 128.5 (128.6) (C-7), 128.9 (128.8) (C-
9a), 126.3 (126.4) (C-6), 125.8 (126.2) (C-8), 124.6 (124.0)
(C-3a), 122.3 (122.5) (C-9), 110.6 (117.2) (C-3), 113.8
(115.6) (Cb), 30.6 (29.7) (C-5), 22.2 (22.2) (C-4) ppm.
Protonated (Z)-4,5-dihydro-1-vinyl-1H-benz[g]indole-
2-carbaldehyde oxime (H?-(Z)-2e)
1H NMR (400.13 MHz, CDCl3): d = 8.15 (s, 1H, CHN),
7.79 (m, 1H, H-9), 7.76 (s, 1H, H-3), 7.38–7.30 (m, 3H,
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3
H-6, H-7, H-8), 7.06 (dd, 1H, HX, JB–X = 15.4 Hz,
3
3JA–X = 8.1 Hz), 5.90 (dd, 1H, HA, JA–X = 8.1 Hz,
3
2JA–B = 1.0 Hz), 5.63 (dd, 1H, HB, JB–X = 15.4 Hz,
2JA–B = 1.0 Hz), 3.10 (m, 2H, H-5), 2.95 (m, 2H, H-4)
ppm; 13C NMR (100.61 MHz, CDCl3): d = 140.9 (C-9b),
140.7 (C-5a), 139.6 (C-9a), 136.5 (C=N), 130.6 (Ca), 129.4
(C-7), 127.6 (C-3a), 126.3 (C-6), 125.8 (C-8), 125.1 (C-3),
124.9 (C-9), 120.5 (C-2), 120.3 (Cb), 30.4 (C-5), 21.6 (C-4)
ppm.
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Acknowledgments This work has been carried out under financial
support of the Russian Foundation of Basic Research (Project RFBR-
NNSFC no. 06-03-39003), National Natural Science Foundation of
China (grant nos. 20703049, 20733007, 20573122, 20873165),
123