Synthesis of 3-aminoselenoacrylamides and 3-amino-2-(selenazol-2-yl) acrylonitriles

Full text of DOI:10.1007/s10593-013-1227-z

Chemistry of Heterocyclic Compounds, Vol. 48, No. 12, March, 2013 (Russian Original Vol. 48, No. 12, December, 2012)
SYNTHESIS OF 3-AMINOSELENOACRYLAMIDES AND
3-AMINO-2-(SELENAZOL-2-YL)ACRYLONITRILES
K. A. Frolov1*, V. V. Dotsenko1, and S. G. Krivokolysko1
Keywords: 3-aminoselenoacrylamides, cyanoselenoacetamide, selenazoles, aminomethylenation, Hantzsch
reaction.
Thanks to their availability and high functionality, 3-aminothioacrylamides have emerged as efficient
reagents for the preparation of S,N-containing heterocycles (see review articles [1, 2]). At the same time, only
isolated examples are encountered in the literature regarding the synthesis and reactions of their selenium
analogs 3-aminoselenoacrylamides [3-7]. The latter are of interest as starting material for the preparation of
selenium-containing heterocycles, in particular selenophenes [8, 9].
We have discovered a convenient method for the synthesis of the novel 3-aminoselenoacrylamides 1a,b
based on a three-component condensation of primary aromatic amines, triethylorthoformate, and cyanoseleno-
acetamide (2). The unsaturated selenoamides 1a,b are formed as a mixture of E- and Z-isomers. According to
1H NMR data, the E/Z ratio for compound 1a is ~8:1 and for compound 1b ~7:1. The selenoamides 1a,b readily take
part in a Hantzsch reaction with -bromo ketones to form the functionally substituted selenazole derivatives 3a-c.
According to 1H NMR spectroscopy data, the latter exist principally as the Z-isomers. The ratio of E- to Z-isomers
was calculated from the integrated intensities of the NH–CH= fragment signals, while exploiting the fact that the
NH proton signals in the Z-isomers were markedly ( ~1.5-3.0 ppm) shifted to downfield relative to those in
the E-isomers, explained by the presence of an intramolecular hydrogen bond [10].
IR spectra were recorded on an IKS-29 spectrophotometer in nujol. 1H NMR spectra were recorded on a
Bruker Avance II 400 instrument (400 MHz) using DMSO-d6 with TMS as internal standard. Elemental
analysis was performed on a Carlo Erba 1106 instrument. Melting points were determined on a Kofler hot stage
apparatus and were not corrected. Purity of the obtained compounds was monitored by TLC on Silufol UV-254
plates with acetone–hexane (1:1) as eluent and visualized using iodine vapor and a UV detector. The
cyanoselenoacetamide (2) was obtained by a known method [11]. All of the syntheses were carried out under an
argon atmosphere.
3-Aminoselenoacrylamides 1a,b (General Method). A mixture of the primary amine (3.4 mmol),
HC(OEt)3 (0.85 ml, 5.1 mmol), and cyanoselenoacetamide (2) (0.50 g, 3.4 mmol) in EtOH (3 ml) was refluxed
for 1 min with vigorous stirring and left for 24 h at 20ºC. The precipitate that formed was filtered off and
washed with EtOH to give analytically pure compounds 1a,b.
_______
*To whom correspondence should be addressed, e-mail: ka.frolov@inbox.ru.
1"ChemEx" Laboratory, Vladimir Dal' East Ukrainian National University, 20-A/7 Molodyozhnyi Kv, Lugansk
91034, Ukraine.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 2008-2010, December, 2012.
Original article submitted September 24, 2012.
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0009-3122/13/4812-1886©2013 Springer Science+Business Media New York

CN
NC
NH2
Se
Se
NH
N
NH
R
HC(OEt)3
CN
Ar
(Z)-3a–c
R
(Z)-1a,b
BrCH2COAr
EtOH, 
+
+
+
NH2
DMF, 
NH2
Se
RNH2
Ar
Se
Se
N
2
NC
NC
R
HN
R
(E)-1a,b
N
(E)-3a–c
H
1 a R = Ph, b R = 4-MeC6H4; 3 a R = Ar = Ph, b R = Ph, Ar = 4-MeC6H4, с R = 4-MeC6H4, Ar = Ph
3-Anilino-2-cyanoprop-2-enselenoamide (1a). Yield 0.74 g (87%). Light-brown powder. Mp
214-216°C (decomp.). IR spectrum, , cm-1: 3487, 3290, 3192 (N–H), 2193 (C≡N). 1H NMR spectrum, , ppm
3
(J, Hz) (E/Z ~8:1); 7.16-7.21 (1Н, m, Н Ph); 7.39-7.42 (4Н, m, Н Ph); 8.59 (0.11Н, d, J = 13.7, CHNH (Z));
3
8.86 (0.89Н, d, J = 12.4, CHNH (Е)); 8.94 (0.11Н, s) and 9.80 (0.11Н, s, NH2 (Z)); 9.21 (0.89Н, s) and 9.77
3
3
(0.89Н, s, NH2 (E)); 10.70 (0.89Н, d, J = 12.4, NH (E)); 14.03 (0.11Н, d, J = 13.7, NH (Z)). Found, %:
С 47.88; Н 3.69; N 16.69. C10H9N3Se. Calculated, %: С 48.01; Н 3.63; N 16.80.
2-Cyano-3-[(4-methylphenyl)amino]prop-2-enselenoamide (1b). Yield 0.38 g (42%). Yellow-green
1
powder. Mp 248-250°C (decomp.). IR spectrum, , cm-1: 3420, 3290, 3225 (N–H), 2182 (C≡N). H NMR
spectrum, , ppm (J, Hz) (E/Z ~7:1): 2.28 (2.62Н, s, CH3 (E)); 2.33 (0.38Н, s, CH3 (Z)); 7.20-7.33 (4H, m,
H Ar); 8.54 (0.13Н, d, 3J = 12.6, CHNH (Z)); 8.83 (0.87Н, br. s, СНNH (E)); 8.89 (0.13Н, s) and 9.74 (0.13Н,
s, NH2 (Z)); 9.15 (0.87Н, s) and 9.71 (0.87Н, s, NH2 (E)); 10.67 (0.87Н, br. s, NH (E)); 14.01 (0.13Н, d,
3J = 12.6, NH (Z)). Found, %: С 49.83; Н 4.27; N 15.83. C11H11N3Se. Calculated, %: С 50.01; Н 4.20; N 15.91.
3-Amino-2-(selenazol-2-yl)acrylonitriles 3a-c (General Method). A mixture of the 3-aminoseleno-
acrylamide 1a,b (0.8 mmol) and the corresponding -bromo ketone (0.8 mmol) in DMF (4 ml) was heated with
stirring to reflux for 2 min, filtered through filter paper, and left for 24 h at 20ºC. The precipitate that formed
was filtered off, washed with EtOH and water, and dried with ether to give analytically pure compounds 3a-c.
3-Anilino-2-(4-phenylselenazol-2-yl)acrylonitrile (3a). Yield 0.17 g (61%). Yellow-orange, fine,
1
crystalline powder. Mp 212-214°C. IR spectrum, , cm-1: 3415, 3270 (N–H), 2198 (C≡N). H NMR spectrum,
, ppm (J, Hz): (E/Z ~1:12): 7.11-7.19 (1Н, m, H Ph); 7.31-7.47 (5Н, m, H Ph); 7.50-7.54 (2Н, m, H Ph);
3
7.96-8.00 (2Н, m, H Ph); 8.43 (0.08Н, d, J = 12.9, CHNH (E)); 8.49 (0.08Н, s, H-5 (E)); 8.50 (0.92Н, d,
3J = 12.9, CHNH (Z)); 8.54 (0.92Н, s, H-5 (Z)); 10.50 (0.08Н, d, 3J = 12.9, NH (E)); 11.99 (0.92Н, d, 3J = 12.9,
NH (Z)). Found, %: С 61.58; Н 3.81; N 11.94. C18H13N3Se. Calculated, %: С 61.72; Н 3.74; N 12.00.
3-Anilino-2-[4-(4-methylphenyl)selenazol-2-yl]acrylonitrile (3b). Yield 0.12 g (41%). Yellow, fine,
crystalline powder. Mp 222-224°C. IR spectrum, , cm-1: 3440 (N–H), 2195 (C≡N). 1H NMR spectrum, , ppm
(J, Hz): (E isomer content ~3 mol%): 2.36 (0.09Н, s, СH3 (E)); 2.40 (2.91Н, s, СH3 (Z)); 7.08-7.16 (1Н, m,
3
3
Н Ph); 7.15 (0.06Н, d, J = 8.3, H Ar (E)); 7.25 (1.94Н, d, J = 7.8, H Ar (Z)); 7.29-7.39 (4Н, m, H Ph);
3
7.75-7.80 (2Н, m, H Ar); 8.17 (1Н, br. s, H-5); 8.35 (1Н, br. d, J = 12.7, 2 CHNH); 10.42 (0.03Н, br. s, NH
(E)); 12.16 (0.97Н, d, J = 12.7, NH (Z)). Found, %: С 62.49; Н 4.22; N 11.55. C19H15N3Se. Calculated, %:
3
С 62.64; Н 4.15; N 11.53.
3-[(4-Methylphenyl)amino]-2-(4-phenylselenazol-2-yl)acrylonitrile (3c). Yield 0.21 g (73%).
1
Yellow, fine, crystalline powder. Mp 224-226°C. IR spectrum, , cm-1: 3419 (N–H), 2200 (C≡N). H NMR
spectrum, , ppm (J, Hz): (E isomer content ~5 mol%): 2.28 (0.15Н, s, CH3 (E)); 2.30 (2.85Н, s, CH3 (Z)); 7.19
(0.10Н, d, 3J = 8.6, H Ar (E)); 7.25 (1.90Н, d, 3J = 8.3, H Ar (Z)); 7.31-7.34 (2Н, m, H Ar); 7.38-7.44 (1Н, m, H
1887

Ph); 7.50-7.54 (2Н, m, H Ph); 7.95-7.99 (2Н, m, H Ph); 8.36 (0.05Н, br. s, CHNH (E)); 8.45 (0.05Н, s, H-5
3
(E)); 8.46 (0.95Н, d, J = 12.9, CHNH (Z)); 8.53 (0.95Н, s, H-5 (Z)); 10.47 (0.05Н, br. s, NH (E)); 11.97
3
(0.95Н, d, J = 12.9, NH (Z)). Found, %: С 62.53; Н 4.19; N 11.42. C19H15N3Se. Calculated, %: С 62.64;
Н 4.15; N 11.53.
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