4-Aminofurazan-3-carboxylic acid iminoester in reactions with N,O-nucleophiles

Article abstract of DOI:10.1023/A:1020307708515

Reactions of 4-aminofurazan-3-carboxylic acid iminoester with o-aminophenol and ethylenediamine give rise respectively to 4-(1,3-benzoxazol-2-yl)- and 1-(4,5-dihydro-1H-imidazol-2-yl)-1,2,5-oxadiazol-3-amines, with aminoethanol arises 2-[(Z)-1-amino-1-(4-

Full text of DOI:10.1023/A:1020307708515

Russian Journal of Organic Chemistry, Vol. 38, No. 6, 2002, pp. 872 874. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 6, 2002,
pp. 915 917.
Original Russian Text Copyright
,
2002 by Sergievskii, Krasnoshek, Mel nikova, Tselinskii.
4
-Aminofurazan-3-carboxylic Acid Iminoester in Reactions
with N,O-Nucleophiles
,
A. V. Sergievskii, O. A. Krasnoshek, S. F. Mel nikova, and I. V. Tselinskii
St. Petersburg State Technological Institute, St. Petersburg, 198013 Russia
Received December 26, 2001
Abstract Reactions of 4-aminofurazan-3-carboxylic acid iminoester with o-aminophenol and ethylenediamine
give rise respectively to 4-(1,3-benzoxazol-2-yl)- and 1-(4,5-dihydro-1H-imidazol-2-yl)-1,2,5-oxadiazol-3-
amines, with aminoethanol arises 2-[(Z)-1-amino-1-(4-amino-1,2,5-oxadiazol-3-yl)methylideneamino]-1-
ethanol. Treating of 3-amino-4-(1H-benzo[d]imidazol-2-yl)-1,2,5-oxadiazole with triethyl orthoformate in
acetic anhydride yielded benzo[4,5]imidazo[1,2-c][1,2,5]oxadiazolo[3,4-e]pyrimidine, and alkylation with
haloalkanes furnished 3-amino-4-(1-R-benzo[d]imidazol-2-yl)-1,2,5-oxadiazoles.
We showed formerly that application of 4-amino-
furazan-3-carboxylic acid iminoester (I) to the syn-
thesis of 4-(5-R-1,2,4-triazol-3-yl)furazan with
various substituents in 5 position of the triazole ring
was promising.
did not form 4-(1,3-benzoxazol-2-yl)-1,2,5-oxadiazol-
3-amine (III), although the basicity of o-aminophenol
+
(pKBH 4.72) is somewhat higher than that of
+
o-phenylenediamine (pKBH 4.52) [4].
However the raising of reaction temperature to
120 C (use of 1-butanol for the solvent) and longer
reaction time resulted in preparation of compound III
in over 75% yield.
In extension of study of probable synthetic routes
to polycyclic structures containing 1,2,5-oxadiazole
(
furazan) moiety we carried out reactions between
iminoester I with a series of bifunctional N,N and
N,O-nucleophiles, among them o-pheylenediamine,
o-aminophenol, ethylenediamine, and 2-aminoethanol,
for similar condensation is widely used for building
up heterocyclic systems.
Similarly to o-phenylenediamine reacted ethylene-
diamine providing 3-amino-4-(4,5-dihydro-1H-imid-
azol-2-yl)-1,2,5-oxadiazole (IV) whereas the reaction
of compound I with aminoethanol instead of expected
3
-amino-4-(4,5-dihydro-1,3-oxazol-2-yl)-1,2,5-oxadi-
We showed before that heating iminoester I with
o-phenylenediamine in boiling ethanol (80 C) readily
yielded 3-amino-4-(1H-benzo[d]imidazol-2-yl)-1,2,5-
oxadiazole (II) [2]. However in reaction of imino-
ether I with o-aminophenol under similar conditions
azole (V) furnished an amidine, 2-[(Z)-1-amino-1-(4-
amino-1,2,5-oxadiazol-3-yl)methylideneamino]-1-
ethanol (VI). The lack of oxazole ring closure is
apparently due to considerably lower nucleophilicity
of hydroxy group compared with amino group, and
1
070-4280/01/3806-872$27.00 2002 MAIK Nauka/Interperiodica

Task yields, melting points, spectral data of spectral and elemental analyses of compounds synthesized
1
13
Compd. Yield,
IR spectrum,
H NMR spectra,
, ppm
C
NMR
spectrum,
ppm
Found, %
H
Calculated, %
1
no.
%
mp, C
, cm
Formula
C H N
,
C
N
C
H
N
III
IV
VI
78
170 171 3400, 3304 (NH ), 2361 7.91 d (1H, Ph), 155.71, 152.59, 54.88 3.61 28.64
53.47 2.99 27.71
39.22 4.61 45.73
35.09 6.30 40.92
2
9
6
402
(
(
1
1
(
CH), 1638(C N),
1617 7.85 d (1H, Ph),) 150.02, 140.29,
O N O), 1559, 1508, 7.55 t (1H, Ph), 136.84, 127.46,
491, 1474(C=N), 1448, 7.51 t (1H, Ph), 125.80, 120.76,
246, 1113, 1091, 1007 6.62 s (2H, NH2) 111.66
0 N)
92
83
114
3388 (NH ), 3315 (NH), 6.15 in (2H, NH ; 156.55, 156.07, 39.43 5.02 46.05
894 (CH ), 1640 (C N), 1H, NH), 3.70 in 138.90, 55.92,
(2H, CH ), 3.0 in 44.67
2
487, 1461 (C=N), 1334, (2H,
288, 1184, 1136, 1013
C H N
5 7
2
2
50
2
1
1
1
2
608 (O N O), 1551,
CH2)
(
O N), 978
117 118 3566 (OH), 3401, 3350 6.65 s (2H, NH ), 156.55, 148.68, 35.12 6.15 41.73
C H N
2
5
9
502
(
NH), 3000, 2954, 2898, 6.46 s (2H, NH ), 141.94, 62.50,
2
2
1
1
850 (CH ), 1667 (C N), 4.59 s (1H, OH), 51.18
2
624 (O N O), 1540,
3.65 d (2H, CH ),
2
527, 1507, 1478, 1459 3.25 m (2H, CH2)
(
C=N), 1404, 1310,1189,
063 (O N), 1012, 908
272 273 1650 (C N), 1587, 1563, 9.85 s (1H, CH),
1
VII
60
85
57.31 2.57 32.76
57.03 5.64 30.25
C H N
50
56.88 2.39 33.16
57.63 4.84 30.55
1
0
5
1
1
553, 1433 (C=N), 1345, 8.41 d(1H, Ph),
309, 1260, 1172, 1018 8.02 d (1H, Ph),
(
O N), 951
7.64 M (2H, Ph)
7.76 m (2H, Ph),
VIIIa
147
168
3401, 3299 (NH ),
C H N
2
11 11 50
2
985 (CH ), 1633 (C N), 7.37 m (2H, Ph),
2
1592 (O N O), 1471
6.92 c (2H, NH ),
2
(
C=N), 1444, 1329, 1200, 4.71 q (2H, CH2)
073 (O N), 996 1.42 t (3H, CH3)
3409, 3312 (NH ), 2985 7.79 m (2H, Ph),
1
VIIIb
93
55.01 5.12 24.85
C H N
54.35 4.56 24.38
2
13 13 503
(
(
CH ), 1743 (C=O), 1637 7.39 m (2H, Ph),
2
C N), 1462(C=N), 1378, 6.88 s (2H, NH ),
2
1
280, 1229, 1177, 1022 5.53 s (2H, CH ),
2
(O N) 986
4.19 q (2H, CH ),
2
1
.23 t (3H, CH3)

874
SERGIEVSKII et al.
also higher conformational lability of the hydroxy-
ethylene chain in contrast to conformationally rigid
system of o-aminophenol.
separated precipitate was filtered off and dried at
60 C Yield 0.55 g.
3
-amino-4-(4,5-dihydro-1H-imidazol-2-yl)-1,2,5-
Benzimidazole II contrary to the presence in posi-
tion 2 of an electron-withdrawing 1,2,5-oxadiazole
ring cleanly reacted with triethyl orthoformate in
acetic anhydride yielding benzo[4,5]imidazo[1,2-c]-
oxadiazole (IV) and 2-[(Z)-1-amino-1-(4-amino-
1,2,5-oxadiazol-3-yl)methylideneamino]-1-ethanol
(VI). A mixture of 3.5 mmol of iminoester I and
3.5 mmol od ethylenediamine or 2-aminoethanol in
10 ml of 2-propanol was boiled for 3 h. On cooling
the solution was evaporated in air, and the residue
[
1,2,5]oxadiazolo[3,4-e]pyrimidine. It also underwent
alkylation with haloalkanes in alkaline medium
affording N-alkyl derivatives (VIII).
was crystallized from
a
mixture chloroform
+
2
-propanol, 2: 1. Found, M : 153 (IV), 171 (V).
Calculated, M: 153 (IV), 171 (V).
Benzo[4,5]imidazo[1,2-c][1,2,5]oxadiazolo[3,4-e]-
pyrimidine (VII). A mixture of 0.5 g (2.48 mmol)
of benzimidazole II, 3 ml of triethyl orthoformate,
and 1 ml of acetic anhydride was boiled for 12 h. On
cooling the separated precipitate was filtered off and
dried at 60 C. Yield 0.31 g.
3
-Amino-4-(1-ethyl-1H-benzo[d]imidazol-2-yl)-
1
1
,2,5-oxadiazole (VIIIa) and methyl-2-[2-(4-amino-
,2,5-oxadiazol-3-yl)-1H-benzo[d]imidazol-1-yl]
acetate (VIIIb).A mixture of 0.5 g (2.48 mmol) of
compound II, 4 mmol of alkyl halide, 1 g of
anhydrous K CO in 5 ml of DMF was stirred for 3 h
at 20 C, then poured into 30 ml of water, the
separated precipitate was filtered off, washed with
water (3 10 ml), and dried in air.
R = Me (a), CH COOEt (b).
2
2
3
EXPERIMENTAL
1H and 13C NMR spectra were registered on
spectrometer Bruker DPX-300, solvent and internal
reference DMSO-d . IR spectra were measured on
6
REFERENCES
Perkin Elmer Spectrum BX 1000 instrument from
thin film on KBr sublayer, mass spectra were
recorded on Varian CH-6 device.
,
1. Tselinskii, I.V., Mel nikova, S.F., Pipogov, S.V., and
Sepgievskii, A.V., Zh. Org. Khim., 1999, vol. 35,
no. 2, pp. 315 319.
Melting points, elemental analyses, and spectral
characteristics of compounds synthesized are
presented in the table.
,
2
. Sepgievskii, A.V., Pipogov, S.V., Mel nikova, S.F.,
and Tselinskii, I.V., Zh. Org. Khim., 2001, vol. 37,
no. 5, pp. 755 758.
4
-(1,3-Benzoxazol-2-yl)-1,2,5-oxadiazol-3-amine
III). A mixture of 0.5 g (3.5 mmol) of iminoester I
and 0.38 g (3.5 mmol) of o-aminophenol in 10 ml of
-butanol was boiled for 3 days. On cooling the
3. Spravochnik khimika, Moscow: Khimiya, 1964, vol. 3,
pp. 98 104.
4. Kelapev, V.I. and Koshelev, V.N., Usp. Khim., 1995,
vol. 64, no. 4, pp. 339 371.
(
1
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 6 2002