Preparation and characterisation of several new N-disubstituted 2-aminoselenophene derivatives

Article abstract of DOI:10.1515/znb-2002-0407

N,N′-Persubstituted selenoacrylamides (4), easily available by reaction of 1-chlorovinamidinium salts (2) with sodium selenide, were transformed by means of acceptor-substituted halomethyl compounds (9-14) into new 2-aminoselenophene derivatives (15-20). Their UV/ vis data are presented, and the positive solvatochromism of 2-R₂N-5-acceptor-substituted selenophenes is reported.

Full text of DOI:10.1515/znb-2002-0407

Preparation and Characterisation of Several New N-Disubstituted
2-Aminoselenophene Derivatives*
Ines Zug and Horst Hartmann
Department of Chemistry, University of Applied Sciences, Merseburg, Geusaer Str.
D-06217 Merseburg, Germany
Reprint requests to Prof.Dr.H.Hartmann.Fax: +49(0)3461-462192.
E-mail: Horst.Hartmann@cui.fh-merseburg.de
Dedicated to Prof. Dr. Bärbel Schulze on the occasion of her 60th birthday
Z.Naturforsch. 57b, 420Ð426 (2002); received January 4, 2002
N-Disubstituted 2-Aminoselenophenes, 1-Chlorovinamidinium Salts, Solvatochromism
N,NЈ-Persubstituted selenoacrylamides (4), easily available by reaction of 1-chlorovinami-
dinium salts (2) with sodium selenide, were transformed by means of acceptor-substituted
halomethyl compounds (9Ð14) into new 2-aminoselenophene derivatives (15Ð20).Their UV/
vis data are presented, and the positive solvatochromism of 2-R2N-5-acceptor-substituted
selenophenes is reported.
Introduction
stituted 5-amino-2,2Ј-bithiophenes and 2-amino-5-
phenylthiophenes are of practical interest as
strongly solvatochromic compounds useful for
measuring the polarity of organic solvents [7, 8] or
for manufacturing of materials with high non-lin-
ear optical properties [9].
N,NЈ-Persubstituted 3-aminothioacrylamides of
the general structure 3 are well-known as versatile
synthons in organic chemistry [1].They are easily
available by several different routes [2], e.g., from
simple N-disubstituted acetamides 1 via corre-
sponding 1-chlorovinamidinium salts 2 [3], and are
highly reactive towards a lot of preferably electro-
philic reagents which are able to transform these
educts with their S-C-C-C moiety into a variety of
products.For instance, they can be transformed,
by reaction with halomethylcarbonyl compounds
as well as with nitro- or dicyanovinyl-substituted
(het)arylmethyl halides, via corresponding 1-mer-
capto-substituted vinamidinium salts of the gene-
ral structure 5, into 5-aceptor-substituted 2-amino-
thiophenes 7.Examples of the latter include 5-
acyl- or 5-alkoxycarbonyl-substituted 2-aminothio-
phenes [4], 5Ј-nitro- or 5Ј-dicyanovinyl-substituted
5-amino-2,2Ј-bithiophenes and 4Ј-nitro- or 4Ј-dicy-
anovinyl-substituted 5-phenyl-2-aminothiophenes
[5].Whereas the 5-acyl- and 5-alkoxycarbonyl-
substituted 2-aminothiophenes raise some interest
as starting materials for preparing deeply coloured
methine dyes [6], the nitro- and dicyanovinyl-sub-
Scheme 1.
Starting from the same 1-chloro-substituted vi-
namidinium salts 2, the N,NЈ-persubstituted 3-
aminoselenoacrylamides 4, as the selenium-ana-
logues of the thioacrylamides 3, have also been
prepared recently [3].Their use as starting materi-
als for preparing N-disubstituted 2-aminoseleno-
phenes is, however, rarely not documented as yet.
* Presented in part at the 5th Conference on Iminium
Salts (ImSaT-5), Stimpfach-Rechenberg (Germany),
September 11Ð13, 2001.
0932Ð0776/2002/0400Ð0420 $06.00 ” 2002 Verlag der Zeitschrift für Naturforschung, Tübingen · www.znaturforsch.com
D
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I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
421
Only their transformation into strongly solvatoch-
romic selenophenes of the general structure 8 by
their reaction with some acceptor-substituted ha-
lomethyl compounds was recently exemplified [7].
Now we report on further examples of the trans-
formation of the N,NЈ-persubstituted 3-aminosele-
noacrylamides 4 into 5-acceptor-substituted deriv-
atives of N-disubstituted 2-aminoselenophenes.
Results and Discussion
As reagents for this transformation the halo-
methyl compounds 9Ð14 have been used.As far
as they are not commercially available they have
been synthesised as described recently [6].
Scheme 3.
Similarly to their sulfur analogues [11], some of
the N-disubstituted 2-aminoselenophenes pre-
pared were used as starting materials for some fur-
ther 2-aminoselenophene derivatives.Thus, the al-
kyl 2-aminoselenophene-5-carboxylates 15 can
easily be transformed by saponification with aque-
Scheme 2.
The transformation of the N,NЈ-persubstituted ous bases into their corresponding 2-aminoseleno-
3-aminoselenoacrylamides 4 into 5-acceptor-sub- phene-5-carboxylic acids 21.These acids and their
stituted 2-aminoselenophenes can be performed, esters 15 are able, by analogy to corresponding 2-
analogously to the transformation of the N,NЈ-per- amino-5-thiophenecarboxylates [12], to react with
substituted 3-aminothioacrylamides 3 into the 5- arenediazonium salts.Whereas the alkyl 2-amino-
acyl-substituted 2-aminothiophenes 5, by allowing 5-selenophenecarboxylates 15 were transformed
to react these compounds with one equivalent of by this reaction, as exemplified with the 4-nitro-
the appropriate acylmethyl halide in a polar phenyldiazonium salt 25, into corresponding alkyl
solvent, such as acetonitrile, and subsequent addi- 2-amino-3-arylazo-5-selenophenecarboxylates 23,
tion of a base, such as triethylamine, to the reac- the 2-amino-5-selenophenecarboxylic acids 21
tion mixture at slightly elevated temperature.The
yield N-disubstituted 2-amino-5-arylazoseleno-
reactions proceed, analogously to the reaction of phenes 24.Obviously, in the course of the azo cou-
N,NЈ-persubstituted thioacrylamides 3 with halo- pling reaction a decarboxylation reaction of 21 oc-
methyl compounds [5, 10], via intermediate 1-sel- curs.Such a decarboxylation reaction can also be
eno-substituted vinamidinium salts of the general achieved, as checked by DSC measurements, by
structure 6 and give rise to the formation of the heating the carboxylic acids 21 at their melting
N,N-disubstituted 2-aminoselenophenes of the points.Efforts to obtain the 5-unsubstituted 2-
structure 15Ð20 (see Table 1).
aminoselenophenes 22 on a preparative scale by
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422
I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
Table 1.Characteristic physical data of the 2-aminoselenophenes prepared.
Compound R1R2N
Yield
[%]
M.p.
[∞C]
Formula calcd.
(m.w.) found
C
H
N
15a
15b
15c
15d
15e
15f
dimethylamino
70
Ð
135Ð136
Oil
C8H11NO2Se
(232.1)
41.39
41.21
46.12
Ð
43.80
43.82
48.53
48.52
60.68
60.52
55.96
56.12
54.87
Ð
4.78 6.03
5.00 5.93
5.67 5.38
diethylamino
morpholino
C10H15NO2Se
(260.2)
Ð
Ð
80
67
85
15
Ð
127Ð128
97
C10H13NO3Se
(274,2)
4.74 5.11
4.82 4.95
5.51 5.15
5.55 4.95
4.24 3.93
4.36 4.11
3.39 3.63
3.57 3.72
4.25 4.57
piperidino
C11H15NO2Se
(272.2)
diphenylamino
N-phenothiazino
N-indolenino
morpholino
68Ð69
135Ð137
Oil
C18H15NO2Se
(356.3)
C18H13NO2SSe
(386.3)
15 g
16c
16e
17c
17e
18a
18c
18e
19a
19c
19e
20c
20e
21b
21c
21d
21e
21 g
23a
23c
24b
24c
24d
24e
C14H13NO2Se
(306.2)
Ð
Ð
38
70
38
40
55
10
44
75
68
97
78
20
36
65
89
87
35
65
63
31
32
35
37
127Ð129
73Ð74
169Ð170
140Ð141
220Ð221
201Ð204
131Ð133
206Ð207
210Ð212
147
C10H13NO2Se
(258.2)
46.52
46.69
63.53
63.33
57.49
57.29
69.23
69.22
48.82
48.64
49.86
49.72
63.01
62.89
39.87
39.98
41.99
42.12
56.47
56.31
51.34
51.54
63.16
62.98
43.90
44.12
41.54
41.50
46.51
46.66
59.66
59.52
53.42
53.61
35.04
34.87
36.86
36.52
47.87
47.61
46.03
46.05
49.59
49.33
59.07
58.96
5.08 5.43
5.28 5.49
4.44 4.12
4.64 4.28
5.13 4.19
5.33 4.31
4.60 3.36
4.80 3.52
4.10 9.49
4.22 9.55
4.18 8.31
4.32 8.45
3.85 6.68
4.01 6.88
3.35 9.30
3.33 9.47
3.52 8.16
3.55 8.10
3.32 6.59
3.55 6.76
3.50 11.23
3.34 11.11
3.31 9.21
3.42 9.12
5.28 5.69
5.32 5.84
4.23 5.38
4.45 5.22
5.04 5.43
5.06 5.22
3.83 4.09
3.89 4.15
3.77 4.79
3.85 4.71
3.37 11.69
3.45 11.51
3.48 10.75
3.62 10.50
4.59 15.95
4.74 15.71
3.84 15.34
4.01 15.22
4.44 15.42
4.61 15.21
3.61 12.52
3.75 12.48
diphenylamino
morpholino
C18H15NOSe
(340.3)
C16H17NO2Se
(334.3)
diphenylamino
dimethylamino
morpholino
C24H19NOSe
(416.4)
C12H12N2O2Se
(295.2)
C14H14N2O3Se
(337.3)
diphenylamino
dimethylamino
morpholino
C22H16N2O3Se
(419.4)
C10H10N2O2SSe
(301.2)
C12H12N2O3SSe
(343.3)
diphenylamino
morpholino
C20H14N2O2SSe
(425.4)
208Ð209
181Ð183
93
C16H13N3OSSe
(374.3)
diphenylamino
diethylamino
morpholino
C24H15N3SSe
(456.4)
C9H13NO2Se
(246.2)
200
C9H11NO3Se
(260.2)
piperidino
137
C10H13NO2Se
(258.2)
diphenylamino
N-indolenino
dimethylamino
morpholino
142
C17H13NO2Se
(342.3)
128
C13H11NO2Se
(292.2)
223Ð225
216Ð218
117Ð120
267Ð269
180Ð185
168Ð170
C14H14N4O4Se.H2SO4
(479.3)
C16H16N4O5Se.H2SO4
(521.7)
diethylamino
morpholino
C14H16N4O2Se
(351.3)
C14H14N4O3Se
(365.3)
piperidino
C15H16N4O2Se
(442.2)
diphenylamino
C22H16N4O2Se
(447.4)
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I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
423
this route were not very successfully as yet, but
they are continued.
As seen from Table 3, in which the UV/vis
spectral data of some selected 2-aminoseleno-
phenes 18, 19, 20, and 24 as well as the correlation
parameter a and b of equation (1) and the regres-
sion coefficient r as measure for the quality of the
corresponding correlation are given, they exhibit
a pronounced positive solvatochromism indicated
by the negative sign of the coefficient b.The ex-
tent of solvatochromism, quantified by the b val-
ues, exceeds the one of analogously substituted 2-
aminothiophenes in most cases [7].The highest b
values measured in the series of 5-acceptor-substi-
tuted 2-aminoselenophenes is found with com-
pound 19a.Therefore, especially this 2-aminosele-
nophene derivative can be used as a much better
indicator for a rather precise measurement of the
polarity of solvents.It is worth mentioning that
the 2-amino-5-(4-nitrophenylazo)selenophenes 24
exhibit, besides of their relative long-wavelength
absorptions, only a low solvatochromic sensitivity.
Scheme 4.
Experimental Section
The structure of the N-disubstituted 2-aminosel-
enophenes 15Ð24 prepared were confirmed by el-
emental analysis, mass spectroscopy, and 1H NMR
measurements.Thus, all 2-aminoselenophenes 15Ð
24 with the exception of the 3-arylazo derivatives
Melting points were determined on a Boetius
heating-table microscope and are uncorrected.
The UV/VIS spectra were recorded in dichloro-
methane with
a
Perkin-Elmer spectrometer
Lambda 900, and the NMR spectra with a Varian
300 MHz spectrometer Gemini 300.The extinc-
tions in the UV/VIS spectra were measured in the
dimension m2 molÐ1 and for shortness recorded as
logarithmic values.The elemental analytical data
were obtained by means of a LECO analyzer
CHNS 932.
1
23 exhibit in their H NMR spectra characteristic
doublets at ~ 7.0 and 8.0 ppm confirming the pres-
ence of the heteroaromatic seleneophene subunits
(see Table 2).
In the UV/vis spectra of almost all N-disubsti-
tuted 2-aminoselenophenes prepared intense ab-
sorptions were recorded.The positions of the ap-
propriate absorption maxima strongly depend on
the substitution pattern at the selenophene moie-
ties as well as, in some cases, on the polarity of
solvents.Therefore, some of the prepared 5-accep-
tor-substituted 2-aminoselenophenes can be used,
as recently demonstrated briefly for the com-
pounds 18 and 19 [8] and further confirmed in Ta-
ble 3, as indicators for measurement of the polar-
ity of solvents.This solvatochromism can be
quantified by plotting the reciprocal wavelength
of the longest-wavelength absorption bands of the
corresponding 2-aminoselenophene derivative
versus the π* values introduced by Kamlet and
Taft [13] accordingly to Equation (1):
The preparation of the N,NЈ-persubstituted 1-
chlorovinamidinium salts 2 and N,NЈ-persubsti-
tuted 3-aminoselenoacrylamides 4 used as educts
for the synthesis of the 2-aminoseleophenes was
reported in ref.[3].The following educts hitherto
not described were prepared analogously:
3-(dimethylamino)selenoacryl-N-diethylamide (4b)
from N-[3-chloro-3-(diethylamino)-2-propenyli-
dene]dimethyliminium perchlorate (2b) and so-
dium selenide as an oil in a yield of 20%; 3-dime-
thylamino-1-selenoacrylpiperidide
(4d)
from
N-[3-chloro-3-(1-piperidino)-2-propenylidene]-di-
methyliminium perchlorate (2d) and sodium sele-
1
nide in a yield of 86% ; m.p. 93Ð95 ∞C; H NMR
(in CDCl3): δ = 1.59 (m, 6H, CH2), 2.89 (m, 6H,
NCH3), 3.93 (m, 4H, NCH ), 5.24 (d, 1H, CH),
2
8.27 (d, 1H, CH); N,N-dimethyl-N-[3-(10H-phe-
nothiazin-10-yl)-3-selenoxo-1-propenyl]amine (4f)
1/λmax = a + b · π*
(1) from N-[3-chloro-3-(phenothiazinyl)-2-propenyli-
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I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
Table 2.Selected spectral data of the 2-aminoselenophenes prepared.
Compound
λmax (log ε)
[nm] in MC
1H NMR, δ-values in ppm
in CDCl3 or [a] in D6-DMSO
15a
15c
Ð
Ð
3.00 (s, 6H, CH3), 3.70 (s, 3H, OCH3), 5.89 (d, 1H, CH), 7.68 (d, 1H, CH)
3.19 (t, 4H, NCH2), 3.78Ð3.83 (m, 7H, OCH2, OCH3), 6.06 (d, 1H, CH), 7.76 (d,
1H, CH)
15d
15e
15f
Ð
1.61 (m, 2H, CH2), 1.74 (m, 4H, NCH2), 3.23 (t, 4H, OCH2), 3.78 (s, 3H, OCH3),
6.10 (s. 1H, CH), 7.75 (s, 1H, CH)
Ð
3.70 (s, 3H, OCH3), 6.32 (d, 1H, CH), 7.24Ð7.31 (m, 6H, CH), 7.40 (t, 4H, CH),
7.70 (d, 1H, CH)
Ð
3.75 (s, 3H, OCH3), 6.70 (d, 1H, CH), 7.26 (m, 2H, CH), 7.37 (m, 2H, CH), 7.47
(m, 4H, CH), 7.78 (d, 1H, CH)
16c
16e
17c
17e
18a
18c
18e
19a
19c
19e
20c
20e
21b
21c
21d
21e
21 g
23a
23c
24b
24c
24d
24e
369 (4.32)
392 (4.40)
3.87 (4.38)
410 (4.42)
474 (4.30)
445 (4.30)
460 (4.25)
544 (4.26)
505 (4.19)
522 (4.33)
544 (4.08)
562 (4.53)
Ð
2.34 (s, 3H, CH3), 3.26 (t, 4H, NCH2), 3.73 (t, 4H, OCH2), 6.23 (d, 1H, CH), 7.79
(d, 1H, CH) [a]
2.36 (s, 3H, CH3), 6.30 (d, 1H, CH), 7.25Ð7.34 (m, 6H, CH), 7.43 (m, 4H, CH),
7.78 (d, 1H, CH) [a]
2.39 (s, 3H, CH3), 3.32 (t, 4H, NCH2), 3.75 (t, 4H, OCH2), 6.28 (d, 1H, CH), 7.30
(d, 2H, CH) [a]
2.39 (s, 3H, CH3), 6.30 (d, 1H, CH), 7.28Ð7.49 (m, 13H, CH), 7.59 (m, 2H, CH)
[a]
3.04 (s, 6H, CH3), 5.86 (d, 1H, CH), 7.38 (d, 1H, CH), 7.43 (d, 2H, CH), 8.10 (d,
2H, CH)
3.21(t, 4H, NCH2), 3.76 (t, 4H, OCH2), 6.28 (d, 1H, CH), 7.61 (d, 2H, CH), 7.66
(d, 1H, CH), 8.12 (d, 2H, CH) [a]
6.61 (d, 1H, CH), 7.16Ð7.26 (m, 6H, CH), 7.39 (m, 4H, CH), 7.68 (m, 3H, CH),
8.13 (m, 2H, CH) [a]
3.04 (s, 6H, CH3), 5.79 (d, 1H, CH), 6.66 (d, 1H, CH), 7.32 (d, 1H, CH), 7.76 (d,
1H, CH),
3.20 (m 4H, NCH2), 3.85 (m, 4H, OCH2), 6.06 (d, 1H, CH), 6.74 (d, 1H, CH), 7.30
(d, 1H, CH), 7.78 (d, 1H, CH)
6.49 (d, 1H, CH), 7.12 (d, 1H, CH), 7.20Ð7.29 (m, 6H, CH), 7.40 (m, 4H, CH), 7.54
(d, 1H, CH), 7.97 (d, 1H, CH)
3.23 (t, 4H, NCH2), 3.85 (t, 4H, OCH2), 6.10 (d, 1H, CH), 6.93 (d, 1H, CH), 7.40
(d, 1H, CH), 7.51 (d, 1H, CH), 7.63 (s, 1H, CH)
6.48 (d, 1H, CH), 7.21Ð7.31 (m, 7H, CH), 7.43 (m, 4H, CH), 7.53 (d, 1H, CH), 7.80
(d, 1H, CH), 8.42 (s, 1H, CH) [a]
1.16 (t, 6H, CH3), 3.34 (q, 4H, CH2), 5.84 (d, 1H, CH), 7.57 (d, 1H, CH), 11.70 (s,
1H, OH) [a]
Ð
3.16 (t, 4H, NCH2), 3.71 (t, 4H, OCH2), 6.18 (d, 1H, CH), 7.63 (d, 1H, CH), 12.19
(s, 1H, OH) [a]
Ð
1.60 (m, 6H, CH3), 3.21 (t, 4H, CH2), 6.07 (d, 1H, CH), 7.59 (d, 1H, CH), 11.79 (s,
1H, OH) [a]
Ð
6.33 (d, 1H, CH), 7.20Ð7.29 (m, 6H, CH), 7.40 (t, 4H, CH), 7.62 (d, 1H, CH), 12.49
(s, 1H, OH) [a]
Ð
3.23 (t, 2H, CH2), 4.06 (t, 2H, NCH2), 6.51 (d, 1H, CH), 6.91 (m, 1H, CH), 7.19
(m, 3H, CH), 7.75 (d, 1H, CH), 12.13 (s, 1H, OH) [a]
3.56 (s, 6H, CH3), 3.81 (s, 3H, OCH3), 7.73 (d, 2H, CH), 8.28 (d, 2H, CH), 8.32 (s,
1H, CH) [a]
495 (4.28)
490 (4.25)
570 (4.34)
552 (4.67)
575 (4.56)
566 (4.66)
3.79 (s, 3H, OCH3), 3.84 (t, 4H, NCH2), 3.98 (t, 4H, OCH2), 7.79 (d, 2H, CH), 8.28
(t, 3H, CH) [a]
1.27 (t, 6H, CH3), 3.61 (q, 4H, NCH2), 6.56 (d, 1H, CH), 7.54 (d, 2H, CH), 7.87 (d,
1H, CH), 8.16 (d, 2H, CH) [a]
3.60 (t, 4H, NCH2), 3,77 (t, 4H, NCH3), 6.68 (d, 1H, CH), 7.62 (d, 2H, CH), 7.93
(d, 1H, CH), 8.20 (d, 2H, CH) [a]
1.68 (m, 6H, CH2), 3.63 (m, 4H, CH2), 6.68 (d, 1H, CH), 7.55 (d, 2H, CH), 7,88 (d,
1H, CH), 8.17 (d, 2H, CH) [a]
6.73 (d, 1H, CH), 7.39Ð7.53 (m, 10H, CH), 7.69 (d, 2H, CH), 7.96 (d, 1H, CH),
8.25 (d, 2H, CH), [a]
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I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
425
Table 3.Solvatochromism of some 2-aminoselenophenes prepared; UV/Vis absorptions [nm], correlation parameters
a, b, and regression coefficients r according to eq.(1).
Compound Solventa
π*b Ð0.02 0.26 0.53 0.57 0.78
CH TE TO ET MC DMF DMSO
a
b
r
0.87
1.01
[10Ð5 mÐ1
]
[10Ð5 mÐ1
]
18a
18c
18e
19a
19c
19e
20c
24b
24c
24d
24e
437 446 459 468 474
418 425 434 438 445
416 426 436 439 445
478 497 517 538 544
460 471 488 501 505
478 490 497 509 522
513 524 530 541 544
535 544 552 565 570
515 524 538 555 552
533 545 556 572 575
541 550 552 556 566
483
454
455
562
525
527
553
581
574
588
567
492
464
461
574
538
534
562
588
585
600
574
22.965
24.059
24.077
20.918
21.876
21.017
19.517
18.805
19.567
18.859
18.617
Ð 2.53
Ð 2.26
Ð 2.25
Ð 3.47
Ð 3.06
Ð 2.23
Ð 1.61
Ð 1.71
Ð 2.28
Ð 2.05
Ð 1.04
Ð0.9898
Ð0.9806
Ð0.9901
Ð0.9868
Ð0.9798
Ð0.9770
Ð0.9797
Ð0.9656
Ð0.9591
Ð0,9717
Ð0.8007
a
CH: cyclohexane, TE: tetrachloromethane, TO: toluene, ET: ethanol, MC: dichloromethane, DMF: dimethyl-
b
formamide, DMSO: dimethylsulfoxide; values taken from ref.[13].
dene]dimethyliminium perchlorate (2f) and so- N-Disubstituted 5-acetyl-2-aminoselenophenes (16)
dium selenide in a yield of 75%; m.p. 156Ð159 ∞C;
General procedure
1H NMR (in [D6]-DMSO): δ = 2.12 (s, 6H, NCH3),
5.50 (d, 1H, CH), 7.27Ð7.41 (m, 2H, CH), 7.52Ð
By analogy to the previous procedure a mixture
of an N,NЈ-persubstituted selenoacrylamide 4
(0.02 mol) and 1-chloro-2-propanone (0.025 mol,
2.3 g) in acetonitrile (50 ml) was allowed to react
with triethylamine (10 ml).For the products ob-
tained see Table 1.
7.67 (m, 4H, CH), 7.73 (m, 2H, CH), 8.26 (d, 1H,
CH);
3-dimethylamino-1-(N-indoleninyl)seleno-
acrylamide (4 g) from N-[3-chloro-3-(N-indoleni-
nyl)-2-propenylidene]-dimethyliminium perchlo-
rate (2 g) and sodium selenide as an oil in a yield
1
of 65%; H NMR (in CDCl3): δ = 1.95 (s, 2H,
CH2), 3.00 (m, 6H, NCH3), 4.60 (t, 2H, NCH2),
5.95 (d, 1H, CH), 6.97 (t, 1H, CH), 7.10 (m, 2H,
CH), 7.16 (d, 1H, CH), 8.30 (d, 1H, CH).
The bromomethyl compounds 9Ð14, as far as
commercially not available, were prepared as de-
scribed in ref.[5].
N-Disubstituted 2-amino-5-(4-methylbenzoyl)-
selenophenes (17)
General procedure
By analogy to the previous procedure a mixture
of an N,NЈ-persubstituted selenoacrylamide 4
(0.02 mol) and 2-bromo-1-(4-tolyl)ethanone (0.02
mol, 4.0 g) in acetonitrile (50 ml) was allowed to
react with triethylamine (10 ml).See Table 1 for
products.
N-Disubstituted methyl 2-aminoselenophene-5-
carboxylates (15)
General procedure
A mixture of a N,NЈ-persubstituted selenoacry-
lamide 4 (0.02 mol) and methyl bromoacetate
(0.02 mol, 3.0 g) in methanol (50 ml) was refluxed
for 15 min.After cooling triethylamine (10 ml)
was added and the mixture was diluted with water.
Solid products were isolated by filtration, liquid
N-Disubstituted 2-amino-5-(4-nitrophenyl)-
selenophenes (18)
General procedure
By analogy to the previous procedure a mixture
products were extracted with dichloromethane. of an N,NЈ-persubstituted selenoacrylamide 4
After drying with CaCl2 the solvent was evapo- (0.02 mol) and 4-nitrobenzylbromide (0.02 mol,
rated and the residue left standing at r.t. until crys- 4.3 g) in acetonitrile (50 ml) was allowed to react
tallisation occurs.For the products so obtained
see Table 1.
with triethylamine (10 ml).See Table 1 for pro-
ducts.
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426
I.Zug ÐH.Hartmann · Several New N-Disubstituted-2-Aminoselenophene Derivatives
N-Disubstituted 2-amino-5-(5-nitro-2-thienyl)-
selenophenes (19)
(0.05 mol, 2,0 g) in ethanol (100 ml) was refluxed
for 1 h.After cooling the reaction mixture was
neutralized with acetic acid and diluted with water
(100 ml).The product crystallized was isolated by
filtration and washed with water.See Table 1 for
products.
General procedure
By analogy to the previous procedure a mixture
of an N,NЈ-persubstituted selenoacrylamide 4
(0.02 mol) and 2-bromomethyl-5-nitrothiophene
(0.02 mol, 4.2 g) in acetonitrile (50 ml) was al-
lowed to react with triethylamine (10 ml).See Ta-
ble 1 for products.
Methyl 2-(dialkylamino)3-(4-nitrophenylazo)-
selenophen-carboxylates (23) and N-disubstituted
2-amino-5-(4-nitrophenylazo)selenophenes (24)
General procedure
N-Disubstituted 2-amino-5-[5-(2-dicyanoethenyl)-
To a mixture of methyl 2-(dialkylamino)seleno-
phene-5-carboxylate 15 (0.01 mol) or 2-(dialkyl-
amino)selenophene-5-carboxylic acid 21 (0.01 ml)
in methanol (50 ml) an accordingly to ref.[14]
freshly prepared solution of 4-nitrophenyldiazon-
ium hydrosulphate (0.02 mol) was added under
stirring at 20 ∞C.After some standing the reaction
mixture was diluted with methanol (200 ml) and
the product formed isolated by filtration.
2-thienyl]selenophenes (20)
General procedure
By analogy to the previous procedure a mixture
of an N,NЈ-persubstituted selenoacrylamide 4
(0.02 mol) and 2-bromomethyl-5-(2-dicyanoethe-
nyl)thiophene [5] (0.02 mol, 5.1 g) in acetonitrile
(50 ml) was allowed to react with triethylamine
(10 ml).See Table 1 for products.
See Table 1 for products.
N-Disubstituted 2-aminoselenophene-5-
carboxylic acids (21)
Acknowledgements
The authors thank the Deutsche Forschungs-
gemeinschaft for generous financial support and
General procedure
A mixture of a methyl 2-aminoselenophene-5- Mrs.A.Schröder for recording the NMR and UV/
carboxylate 15 (0.02 mol) and sodium hydroxide vis spectral data.
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