Reactions of 1-cyanoimidazole and 1-cyanobenzimidazole with aliphatic alcohols

Article abstract of DOI:10.1023/A:1020852418320

Alkyl imidazole-1-carboximidates and alkyl benzimidazole-1-carboximidates were synthesized by reaction of 1-cyanoimidazole and 1-cyanobenzimidazole with aliphatic alcohols. The reaction time and the product yield depend on the structure of the alcohol.

Full text of DOI:10.1023/A:1020852418320

Russian Journal of General Chemistry, Vol. 72, No. 8, 2002, pp. 1286 1288. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 8, 2002,
pp. 1369 1371.
Original Russian Text Copyright
2002 by Purygin, Pan’kov, Belyakova, Labazova.
Reactions of 1-Cyanoimidazole and 1-Cyanobenzimidazole
with Aliphatic Alcohols
P. P. Purygin, S. V. Pan’kov, N. A. Belyakova, and O. N. Labazova
Samara State University, Samara, Russia
Received December 14, 2000
Abstract Alkyl imidazole-1-carboximidates and alkyl benzimidazole-1-carboximidates were synthesized
by reaction of 1-cyanoimidazole and 1-cyanobenzimidazole with aliphatic alcohols. The reaction time and the
product yield depend on the structure of the alcohol.
We previously described the reactions of 1-cyano-
benzimidazole with amines, which led to formation of
benzimidazole-1-carboxamidines [1]. The present
communication reports on the results of our study
of the reactions of 1-cyanoimidazole (I) and 1-cyano-
benzimidazole (II) with a series of aliphatic alcohols.
Cyanoazoles I and II reacted with excess anhydrous
alcohols III X at 64 65 C to give alkyl azole-1-
carboximidates XI XXVI:
presume that the reaction of cyanoazoles I and II with
aliphatic alcohols III X occurs as nucleophilic
addition at the cyano group. The structure of imidates
XI XXVI was proved by the H NMR and IR spectra
(Table 1) and elemental analyses (Tables 2, 3). The IR
1
spectra of XI XXVI lack cyano group absorption at
1
2295 2265 cm , but a strong band appears in the
1
region 1700 1670 cm , which corresponds to stretch-
ing vibrations of the newly formed C N bond.
1
A narrow medium-intensity band at 3300 3240 cm
NH
belongs to stretching vibrations of the N H bond in
the imino group. Absorption bands in the range from
64 65 C
Ht C N + ROH
I, II III X
Ht C OR,
1
XI XXVI
3160 to 3020 cm are typical of heterocyclic C H
1
bond vibrations, and bands at 2990 2840 cm arise
I, XI XVIII, Ht = 1-imidazolyl; II, XIX XXVI, Ht =
1-benzimidazolyl; III, XI, XIX, R = Me; IV, XII, XX,
R = Et; V, XIII, XXI, R = Pr; VI, XIV, XXII, R = i-Pr;
VII, XV, XXIII, R = Bu; VIII, XVI, XXIV, R = i-Bu; IX,
XVII, XXV, R = t-Bu; X, XVIII, XXVI, R = iso-C5H11.
from stretching vibrations of aliphatic C H bonds.
The H NMR spectra of XI XXVI (Table 1) contain
characteristic signals from alkyl protons, protons of
the imidazole or benzimidazole ring, and the NH
1
proton at
6.19 6.31 ppm; the latter appears as a
broadened singlet.
Cyanoazoles I and II readily react with primary
alcohols III V, VII, VIII, and X. The reactions take
2 3 h, and the corresponding alkyl azole-1-carbox-
imidates are formed in more than 80% yield. The
structure of the hydrocarbon radical in primary
alcohols has no appreciable effect on the reaction rate
and product yield. The rate of the reaction of cyano-
azoles I and II with secondary and tertiary alcohols
VI and IX is lower by a factor of 5 10, and the yields
of the products do not exceed 20%. The conversion
of the substrates in the reactions with 2-propanol (VI)
does not reach 20%, and with tert-butyl alcohol (IX)
it is as low as 10%. Azolecarboximidates XI XXVI
are colorless crystalline or oily substances, which
decompose on prolonged storage (for 3 4 weeks) as
follows from the IR spectral data.
EXPERIMENTAL
The IR spectra were measured on an IKS-29 spec-
trophotometer in KBr or in thin films on KBr support.
1
The H NMR spectra were recorded on a Bruker WP-
200SI instrument at 200.13 MHz in DMSO-d6 using
TMS as internal reference. The purity of the products
was checked, and the progress of reactions was
monitored by TLC on Silufol UV-254 plates; acetone
and acetone petroleum ether (1:1) were used as
eluents; spots were detected under UV light.
Alkyl imidazole-1-carboximidates XI XVIII
(general procedure). Preliminarily sublimed 1-cyano-
imidazole, 0.063 g, was dissolved in 6 ml of the cor-
responding anhydrous alcohol. The solution was
heated for several hours on a water bath at 64 65 C,
and excess alcohol was removed under reduced pres-
Taking into account published data on alcoholysis
of nitriles [2] and cyanic acid esters [3 6], we
1070-3632/02/7208-1286$27.00 2002 MAIK Nauka/Interperiodica

REACTIONS OF 1-CYANOIMIDAZOLE AND 1-CYANOBENZIMIDAZOLE
1287
Table 1. IR and 1H NMR spectra of alkyl azole-1-carboximidates XI XXVI
IR spectrum,
IR spectrum,
1
1
, cm
, cm
Comp.
no.
Comp.
no.
1H NMR spectrum, , ppm
1H NMR spectrum, , ppm
N H C N
N H C N
XI
3260 1700 3.64 s (3H, CH3O), 6.23 br.s (1H, XX
NH), 6.82 s, 7.45 s (2H, 4-H, 5-H),
8.86 s (1H, 2-H)
3270 1680 1.13 t (3H, CH3, J 6.6 Hz), 3.89 q
(2H, CH2O, J 5.6 Hz), 6.19 br.s
3260 1670 1.19 t (3H, CH3, J 7.00 Hz), 3.95 q
(2H, CH2O, J 5.88 Hz), 6.30 br.s
(1H, NH), 7.11 m (2H, 5-H, 6-H),
7.51 d, 7.55 d (2H, 4-H, 7-H, J 1.8
Hz), 8.46 s (1H, 2-H)
XII
(1H, NH), 7.00 s, 7.62 s (2H, 4-H, XXI
5-H), 8.88 s (1H, 2-H)
3260 1680 0.74 t (3H, CH3, J 7.7 Hz), 1.50 m
(2H, CH2), 3.99 t (2H, CH2O, J 6.1
Hz), 6.23 br.s (1H, NH), 6.91 s,
3250 1680 0.78 t (3H, CH3, J 8.0 Hz), 1.58 m
(2H, CH2), 4.01 t (2H, CH2O, J 6.2
Hz), 6.25 br.s (1H, NH), 7.11 m
(2H, 5-H, 6-H), 7.51 d, 7.54 d (2H,
4-H, 7-H, J 1.8 Hz), 8.42 s (1H,
2-H)
XIII
7.55 s (2H, 4-H, 5-H), 8.15 s (1H,
2-H)
XXII
3240 1670
XIV
XV
3270 1670
XXIII
3260 1670 0.73 t (3H, CH3, J 7.3 Hz), 1.23 m
(2H, CH2), 1.49 m (2H, CH2), 4.07 t
(2H, CH2O, J 6.6 Hz), 6.31 br.s
(1H, NH), 7.11 m (2H, 5-H, 6-H),
7.50 d, 7.54 d (2H, 4-H, 7-H, J 1.7
Hz), 8.45 s (1H, 2-H)
3280 1690 0.73 t (3H, CH3, J 7.3 Hz), 1.26 m
(2H, CH2), 1.48 m (2H, CH2), 4.05 t
(2H, CH2O, J 6.5 Hz), 6.25 br.s
(1H, NH), 6.79 s, 7.48 s (2H, 4-H,
5-H), 8.37 s (1H, 2-H)
XV
XVI
3290 1700 0.75 d (6H, 2 CH3, J 6.6 Hz),
1.84 m (1H, CH), 3.82 d (2H,
CH2O, J 6.5 Hz), 6.25 br.s (1H,
NH), 6.83 s, 7.50 s (2H, 4-H,
5-H), 8.00 s (1H, 2-H)
XXIV
3275 1670 0.79 d (6H, 2 CH3, J 6.7 Hz),
1.92 m (1H, CH), 3.88 d (2H, CH2O,
J 6.5 Hz), 6.23 br.s (1H, NH),
7.12 m (2H, 5-H ,6-H), 7.51 d,
7.55 d (2H, 4-H, 7-H, J 1.7 Hz),
8.50 s (1H, 2-H)
XVII
3300 1675
XVIII 3270 1680 0.68 d (6H, 2 CH3, J 7.7 Hz),
XXV
3300 1670
1.25 m (1H, CH), 1.49 m (2H, CH2), XXVI
4.00 t (2H, CH2O, J 7.3 Hz,),
6.66 br.s (1H, NH), 7.44 s, 7.62 s
3270 1675 0.72 d (6H, 2 CH3, J 6.6 Hz),
1.21 m (1H, CH), 1.46 m (2H, CH2),
4.10 t (2H, CH2O, J 6.3 Hz), 6.26
br.s (1H, NH), 7.13 m (2H, 5-H,
6-H), 7.50 d, 7.54 d (2H, 4-H, 7-H,
J 1.7 Hz), 8.47 s (1H, 2-H)
(2H, 4-H, 5-H), 8.09 s (1H, 2-H)
XIX
3240 1680 3.76 s (3H, CH3O), 7.13 m (2H,
5-H, 6-H), 7.50 d, 7.53 d (2H, 4-H,
7-H, J 1.7 Hz), 8.41 s (1H, 2-H)
Table 2. Reaction times and yields, melting points or TLC data, and elemental analyses of alkyl imidazole-1-carbox-
imidates XI XVIII
Found, %
Calculated, %
Comp.
no.
mp,
(Rfa)
C
Reaction time, h
Yield, %
Formula
C
H
C
H
XI
XII
3 3.5
2.5 3
2.5 3
11
2 2.5
2 2.5
17 18
2 2.5
85
88
86
18
78
85
10
64
(0.25)
68 69
(0.32)
(0.27)
(0.30)
(0.40)
(0.32)
(0.36)
47.96
51.74
54.87
5.69
6.54
7.31
C5H7N3O
C6H9N3O
C7H11N3O
47.99
51.79
54.89
5.64
6.52
7.24
XIII
XIV
XV
XVI
XVII
XVIII
57.43
57.39
7.89
7.90
C8H13N3O
C8H13N3O
57.46
57.46
7.84
7.84
59.57
8.41
C9H15N3O
59.64
8.34
a
For oily products; eluent acetone petroleum ether, 1:1.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002

1288
PURYGIN et al.
Table 3. Reaction times and yields, melting points or TLC data, and elemental analyses of alkyl benzimidazole-1-carbox-
imidates XIX XXVI
Found, %
Calculated, %
Comp.
no.
mp,
(Rfa)
C
Reaction time, h
Yield, %
Formula
C
H
C
H
XIX
XX
XXI
XXII
XXIII
XXIV
XXV
XXVI
5 6
2.5 3
2.5 3
11
2 2.5
2 2.5
20 20.5
2 2.5
82
84
85
15
77
75
9
109.5 110.5
79.5 80.5
96.5 97.5
(0.75)
61.68
63.43
64.98
5.21
5.93
6.44
C9H9N3O
C10H11N3O
C11H13N3O
61.70
63.48
65.01
5.18
5.86
6.45
(0.73)
(0.75)
(0.76)
(0.69)
66.28
66.30
6.99
6.98
C12H15N3O
C12H15N3O
66.34
66.34
6.96
6.96
64
67.43
7.47
C13H17N3O
67.51
7.41
a
For oily products; eluent acetone.
sure (water-jet pump). The oily residue was dissolved
in 2 ml of dry benzene, and 1 ml of dry petroleum
ether was added. The precipitate was filtered through
a glass filter, and the filtrate was evaporated. The
reaction time and yields, melting points, TLC data,
and elemental analyses of the products are given in
Table 2.
REFERENCES
1. Pan’kov, S.V., Belyakova, N.A., Vishnyakov, V.V.,
and Purygin, P.P., Zh. Org. Khim., 2000, vol. 36,
no. 3, pp. 460 461.
2. Zil’berman, E.N., Reaktsii nitrilov (Reactions of
Nitriles), Moscow: Khimiya, 1972, pp. 27, 97.
Alkyl benzimidazole-1-carboximidates XIX
XXVI (general procedure). Preliminarily sublimed
1-cyanobenzimidazole, 0.100 g, was dissolved in
10 ml of the corresponding anhydrous alcohol, and the
solution was heated for several hours on a water bath
at 62 65 C. Excess alcohol was removed under
reduced pressure (water-jet pump), the precipitate was
dissolved in 2 ml of dry benzene, and 2 ml of dry
petroleum ether was added. The precipitate was fil-
tered off through a glass filter, and the filtrate was
evaporated. The reaction time and yields, melting
points, TLC data, and elemental analyses of products
XIX XXVI are given in Table 3.
3. Hedayatullah, M., Brancourt, M., and Penivelle, L.,
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 8 2002