Base-induced rearrangement of 4-amidino-3-R-furoxans into 1-substituted 3-(1-nitroalkyl)-5-R-1H-1,2,4-triazoles

Article abstract of DOI:10.1007/s11172-013-0170-6

A new base-induced rearrangement of furoxans, viz., a recyclization of 4-amidino-3-Rfuroxans into 1-substituted 3-(1-nitroalkyl)-5-R-1H-1,2,4-triazoles in the presence of alkali metal alkoxides and into 3-acyl-5-R-1H-1,2,4- triazoles in aqueous alkaline solutions, was found.

Full text of DOI:10.1007/s11172-013-0170-6

Russian Chemical Bulletin, International Edition, Vol. 62, No. 5, pp. 1238—1243, May, 2013
1238
Baseꢀinduced rearrangement of 4ꢀamidinoꢀ3ꢀRꢀfuroxans
into 1ꢀsubstituted 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀRꢀ1Hꢀ1,2,4ꢀtriazoles
S. I. Molotov,a A. S. Kulikov,a K. A. Lyssenko,b and N. N. Makhovaa
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: mnn@ioc.ac.ru
bA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (495) 135 5085. Eꢀmail: kostya@xrlab.ineos.ac.ru
A new baseꢀinduced rearrangement of furoxans, viz., a recyclization of 4ꢀamidinoꢀ3ꢀRꢀ
furoxans into 1ꢀsubstituted 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀRꢀ1Hꢀ1,2,4ꢀtriazoles in the presence of alkali
metal alkoxides and into 3ꢀacylꢀ5ꢀRꢀ1Hꢀ1,2,4ꢀtriazoles in aqueous alkaline solutions, was found.
Key words: azoleꢀazole rearrangements, base catalysis, 4ꢀamidinoꢀ3ꢀRꢀfuroxans, 1,2,4ꢀtriꢀ
azoles.
Scheme 1
Among plethora of known methods for the construcꢀ
tion of heterocyclic compounds, there is a group of methꢀ
ods, in which one heterocycle, as a rule, fairly available,
serves as a starting compound for the preparation of other
heterocycles. The rearrangements proceeding with retenꢀ
tion of molecular composition can be considered as one of
the versions of such reactions. For example, azoleꢀazole
rearrangements are studied well enough in azole series.
They in one step lead to other heterocycles with a wide
range of functional substituents, many of which can be
obtained by traditional methods only in multiꢀstep proꢀ
cesses.1—6 These rearrangements can be initiated thermalꢀ
ly, photochemically, or by treatment with bases. A necesꢀ
sary structural condition for the possibility to accomplish
an azoleꢀazole rearrangement is the presence of a threeꢀ
atom substituent in the molecule of azole, which in the
(Scheme 2) that along with a classic version of the rearꢀ
rangement (cleavage of the N—O bond with the formaꢀ
tion of other heterocycle and liberation of a 1ꢀnitroalkyl
fragment) (pathway A), furoxans are capable of giving the
rearrangement proceeding through the dinitrosoethylene
intermediate (pathway B), since the furoxan ring can unꢀ
dergo ring opening to form dinitrosoethylene19,20 (these
rearrangements are thermally initiated). Besides, furoxan
azo derivatives are capable of undergoing a cascade rearꢀ
rangement: two consecutive rearrangements proceeding
in situ result in the liberation of the nitro group concealed
in the furoxan ring, which form a bond with the carbon
atom of the newly forming heterocycle (see Scheme 2,
pathway C).
The purpose of the present work is to study the rearꢀ
rangement of 4ꢀamidinoꢀ3ꢀRꢀfuroxans 1. It could have
been expected that in this case the reaction would follow
a classic scheme with the formation of 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀ
Rꢀ1Hꢀ1,2,4ꢀtriazoles 2. To prepare the starting amidinoꢀ
furoxans 1, we have chosen two approaches, which are
commonly used for the synthesis of amidines: 1) an acidꢀ
catalyzed reaction of nitriles with amines21 and 2) a preꢀ
liminary synthesis of imino ethers by the reaction of amines
i
SN ꢀtype reaction plays the role of a nucleophile with reꢀ
spect to one of the nitrogen atoms of the ring with subseꢀ
quent cleavage of the neighboring N—O bond and formaꢀ
tion of a new azole. These requirements are met, in particꢀ
ular, by isoxazoles, 1,2,4ꢀ and 1,2,5ꢀoxadiazoles (furꢀ
azans). In a number of cases, these rearrangements can be
reversible (Scheme 1).
Until recently, such azoleꢀazole rearrangements of
furoxans were largely studied for benzofuroxans (Boulꢀ
ton—Katrizky rearrangement).7—9 Significant contribuꢀ
tion to the studies of azoleꢀazole rearrangements of unfused
furoxan derivatives was made by our research group.10—18
The rearrangements of these furoxan derivatives were found
to have a number of specific features, which are not
characteristic of other azoles. In particular, it appeared
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1238—1243, May, 2013.
1066ꢀ5285/13/6205ꢀ1238 © 2013 Springer Science+Business Media, Inc.

New baseꢀinduced rearrangement of furoxans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 5, May, 2013
1239
Scheme 2
Cat+ stands for cation.
with orthoformates or orthoacetates,22 followed by involveꢀ
ment of the imino ethers formed in the reaction with variꢀ
ous amines.23 4ꢀAminoꢀ3ꢀRꢀfuroxans 3a—c were taken as
the starting compounds in both cases. Based on the first
approach, we studied the reaction of 4ꢀaminofuroxans 3a—c
with trichloroacetonitrile under different conditions (a proꢀ
longed heating of the reaction mixture with the simultaꢀ
neous passing of gaseous HCl or heating in the presence of
sulfuric acid). Unfortunately, we failed to find suitable
conditions for the preparation of trichloromethylamidꢀ
ines 4 (Scheme 3).
in turn, were synthesized by reflux of aminofuroxans 3a—c
in the excess of triethyl orthoformate or triethyl orthoaceꢀ
tate (see Scheme 3).
Scheme 4
Scheme 3
Reagents and conditions: i. R3NH2, CHCl3, reflux, 3 h; ii. R3NH2,
H2O, 20 C, 12 h.
1
a
b
c
d
e
f
R1
Me
Ph
Ph
CO2Me
Ph
R2
H
H
H
H
R3
Yield of 1 (%)
4ꢀMeC6H4
4ꢀMeC6H4
4ꢀEtOC6H4
4ꢀMeC6H4
Me
75
97
82
54
64
47
H
Me
R1 = Me (3a, 4a), Ph (3b, 4b), COOMe (3c, 4c)
Ph
Me
Reagents and conditions: i. Cl3CCN, H+, 75—80 C; ii. R2C(OEt)3,
reflux, 24 h.
To obtain amidines 1, the reaction of imino ethers
5a—d was carried out with both aromatic and aliphatic
amines. It appeared that out of aromatic amines only
5
a
b
c
d
R1
Me
Ph
Ph
CO2Me
R2
H
H
Me
H
Yield of 5 (%)
90
96
65
72
anilines with electronꢀdonating substituents (R3
=
= 4ꢀMeC6H4, 4ꢀEtOC6H4) underwent the reaction, and
it was enough to reflux a mixture of reagents in chloroform
to obtain compound 1. Amidines 1a—d were prepared in
high yields. The weakly nucleophilic 4ꢀnitroaniline or
The target amidinofuroxans 1 were successfully obꢀ
tained starting from imino ethers 5a—d (Scheme 4), which,

1240
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 5, May, 2013
Molotov et al.
4ꢀaminobenzoic acid failed to be involved in the reaction
with imino ethers. Aliphatic amines (only methylamine
was used) gave this reaction in water at room temperature.
To prepare amidines of this type (1e,f), imino ethers 5b,c
synthesized from 4ꢀaminoꢀ3ꢀphenylfuroxan 3b were used
(see Scheme 4).
lower acidity of the amidine fragment in these compounds,
that interferes with the formation of the corresponding
anion, which is the species attacking the nitrogen atom
of furoxan.
In aqueous solution of NaOH, both types of amidines
underwent the rearrangement (studied for 1b,f as an exꢀ
ample), however, in both cases 3ꢀbenzoylꢀ1,2,4ꢀtriazoles
6a,b were obtained as the reaction products, rather than
the expected 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀRꢀ1Hꢀ1,2,4ꢀtriazoles 2b
and 2f, besides, a partial decomposition of the starting
amidines was observed (Scheme 6). It is obvious that the
expected rearrangement did occur, but the 1ꢀnitroalkyl
derivatives 2b and 2f formed underwent hydrolysis under
these conditions to the corresponding ketones following
the Nef reaction mechanism. Similar transformation was
described earlier for 4ꢀ(1ꢀnitroalkyl)ꢀ1,2,3ꢀtriazoles.12
A possibility of rearrangement of synthesized amidiꢀ
nofuroxans 1a—f into 1ꢀsubstituted 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀRꢀ
1Hꢀ1,2,4ꢀtriazoles 2 was studied for both the thermal and
the base induction. A possibility of thermally induced reꢀ
arrangement (in melt) was shown only for a single subꢀ
strate, amidinofuroxan 1b. This reaction resulted in obꢀ
taining a mixture of compounds, which gave the target
3ꢀ(1ꢀnitrobenzyl)ꢀ1,2,4ꢀtriazole 2b in 10% yield after isoꢀ
lation by preparative column chromatography. The baseꢀ
induced rearrangement was studied under various condiꢀ
tions (heating in the presence of tertiary or secondary
amines, treatment with MeOK in methanol or ButOK in
diverse solvents, reaction with aqueous solution of NaOH).
It appeared that no expected reaction took place in the
presence of organic bases. The use of MeOK in methanol
was more successful and allowed us to involve amidines
1a—d in the rearrangement even without heating to afford
the corresponding 3ꢀ(1ꢀnitroalkyl)ꢀ5ꢀRꢀ1Hꢀ1,2,4ꢀtriꢀ
azoles 2a—d in high yields (Scheme 5). Amidines 1e,f
containing a methylamine moiety underwent the reꢀ
arrangement only upon heating with ButOK in DMF at
100 C (see Scheme 5). The use of more drastic conditions
for amidines 1e,f is necessary apparently because of the
Scheme 6
Scheme 5
6
a
b
R1
Ph
Ph
R2
H
Me
R3
4ꢀMeC6H4
Me
Yield of 6 (%)
56
51
Yields, spectroscopic and physicochemical characterꢀ
istics of synthesized 1,2,4ꢀtriazole derivatives 2a—f and
6a,b are given in Tables 1 and 2, the starting imino ethers 5
and amidines 1 are described in the Experimental section;
the structure of compound 6a was additionally confirmed
by Xꢀray diffraction studies (Fig. 1).
C(5)
C(16)
Reagents and conditions: i. 1b, 145 C, 10 min; ii. for 2a—d: 1a—d,
MeOK, MeOH, 20 C, 6 h; iii. for 2e,f: 1e,f, ButOK, DMF.
N(4)
C(15)
C(17)
C(7)
C(8)
C(12)
C(6)
2
a
b
c
d
e
f
R1
Me
Ph
Ph
CO2Me
Ph
R2
H
H
H
H
R3
Yield of 2 (%)
C(18)
C(19)
C(13)
N(1)
C(11)
C(9)
4ꢀMeC6H4
4ꢀMeC6H4
4ꢀEtOC6H4
4ꢀMeC6H4
Me
86
92
95
68
70
58
C(3)
C(14)
N(2)
C(10)
O(1)
Fig. 1. General view of molecule 6a in the representation of
atoms by ellipsoids of thermal vibrations (p = 50%).
H
Me
Ph
Me

New baseꢀinduced rearrangement of furoxans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 5, May, 2013
1241
Table 1. Yields and some physicochemical characteristics of 1Hꢀ1,2,4ꢀtriazole derivatives 2a—f and 6a,b
Comꢀ
pound
Yield
(%)
M.p./C
Rf
Found
Calculated
Molecular formula
(%)
(CHCl3)
C
H
N
2a
2b
2c
2d
2e
2f
86
109—110
167—168
150—153
107—108
Oil
0.36
—
57.03
56.89
65.14
65.30
62.49
62.95
52.02
52.17
51.20
51.28
57.20
56.89
73.08
72.99
65.78
65.66
5.07
5.21
4.55
4.79
4.78
4.97
4.36
4.38
4.09
4.30
5.00
5.21
5.87
4.98
5.44
5.51
24.04
24.12
19.25
19.04
17.30
17.27
20.42
20.28
23.81
23.92
23.94
24.12
15.63
15.96
21.09
20.88
С11H12N4O2
С15H14N4O2
С16H16N4O3
С12H12N4O4
С10H10N4O2
С11H12N4O2
С16H13N3O
С11H11N3O
92
(10*)
95
—
68
70
58
56
51
—
0.45
0.48
0.52
0.63
Oil
6a
6b
127—128
73—74
* Thermally induced rearrangement.
known procedures.24—26 Xꢀray diffraction studies were carried
out on a Bruker SMART APEX II CCD diffractometer.
Xꢀray diffraction analysis of compound 6a showed that
the bond distances in the molecule statistically significant
did not differ from those in the known structures of
arylꢀsubstituted 1,2,4ꢀtriazoles. Despite a possible conꢀ
jugation between the cyclic fragments and the carbonꢀ
yl group, the rings in the molecule are somewhat turned
with respect to each other. Thus, the torsional angles
Synthesis of imino ethers 5a—d (general procedure). A soluꢀ
tion of 4ꢀaminoꢀ3ꢀmethylfuroxan (3a), (4ꢀaminoꢀ3ꢀphenylfuroxꢀ
an (3b) or methyl 4ꢀaminoꢀ3ꢀfuroxancarboxylate (3c)) (10 mmol) in
triethyl orthoformate (5 mL) (or 3b (10 mmol) in triethyl orthoꢀ
acetate (5 mL)) was refluxed for 24 h. The reaction mixture was conꢀ
centrated, a dry residue was dissolved in some CHCl3 and subꢀ
jected to flashꢀchromatography on a filter with silica gel (eluent
CHCl3 (30 mL)). A solution obtained was concentrated and the
product was recrystallized from light petroleum with b.p. 40—60 C.
4ꢀEthoxymethylideneaminoꢀ3ꢀmethylfuroxan (5a). The yield
was 90%, m.p. 47—48 C. Found (%): C, 42.26; H, 5.40;
N, 24.29. C6H9N3O3. Calculated (%): C, 42.10; H, 5.30; N, 24.55.
N(1)N(2)C(6)C(11),
N(2)C(3)C(13)O(1),
and
O(1)C(13)C(14)C(19) in the crystal are equal to 17.1,
20.6, and 21.4, respectively. The disturbed planarity of
the molecule observed can be due to both the steric repulꢀ
sion (for example, of hydrogen atoms at C(7) and C(5)
atoms) and the effects of the crystal packing. In fact, analꢀ
ysis of the intermolecular interactions showed that a whole
number of intermolecular interactions was present in the
crystal, including both the weak contacts CH...O and the
stacking interactions of the triazole and the tolyl rings.
1
MS, m/z: 171 [M]+. H NMR, : 1.39 (t, 3 H, CH3CH2); 2.12
(s, 3 H, CH3C(4) in furoxan ring); 4.45 (q, 2 H, CH3CH2); 8.34,
8.82 (both s, 1 H, EtOCH).
4ꢀEthoxymethylideneaminoꢀ3ꢀphenylfuroxan (5b). The yield
was 96%, m.p. 80—82 C. Found (%): C, 56.47; H, 4.81; N, 18.07.
C11H11N3O3. Calculated %: C, 56.65; H, 4.75; N, 18.02. Mass
1
spectrum m/z: 233 [M]+. H NMR, : 1.37 (t, 3 H, CH3CH2);
Experimental
4.45 (q, 2 H, CH3CH2); 7.62—8.07 (m, 5 H in Ph); 8.52, 9.03
(both s, 1 H, EtOCH).
NMR spectra were recorded on Bruker WMꢀ250 (1H,
250 MHz) and Bruker AMꢀ300 (13C, 75.5 MHz and 14N,
21.5 MHz) spectrometers in CDCl3, chemical shifts are given in
 scale. Chemical shifts in the 1H and 13C NMR spectra were
measured relative to Me4Si as an internal standard, in the
14N NMR spectra relative to MeNO2 as external standard. Mass
spectra were obtained on a Varian MAT CH 6 instrument (70 eV).
Thinꢀlayer chromatography was carried out on Silufol UVꢀ254
plates, a UV light was used for visualization. Preparative column
chromatography was performed on SiO2 (Merck, 70—230 mesh
ASTM). 4ꢀAminoꢀ3ꢀmethylꢀ (3a), 3ꢀphenylꢀ (3b), and 3ꢀmethꢀ
oxycarbonylfuroxans (3c) were synthesized according to the
4ꢀ1ꢀ(Ethoxyethylideneamino)ꢀ3ꢀphenylfuroxan (5c). The
yield was 65%, m.p. 65—67 C. Found (%): C, 58.12; H, 5.47;
N, 16.70. C12H13N3O3. Calculated (%): C, 58.29; H, 5.30;
N, 16.99. MS, m/z: 247 [M]+. 1H NMR, : 1.35 (t, 3 H,
CH3CH2); 2.22, 2.37 (both s, 3 H, CCH3); 4.45 (q, 2 H,
CH3CH2); 7.46—8.10 (m, 5 H in Ph).
Methyl 4ꢀ(ethoxymethylideneamino)furoxanꢀ3ꢀcarboxylate
(5d). The yield was 72%, m.p. 50—51 C. Found (%): C, 39.04;
H, 4.32; N, 19.71. C6H9N3O3. Calculated (%): C, 39.07; H, 4.22;
N, 19.53. MS, m/z: 215 [M]+. 1H NMR, : 1.29 (t, 3 H,
CH2CH3); 3.95 (s, 3 H, OCH3); 4.35 (q, 2 H, CH2CH3); 8.15,
8.67 (both s, 1 H, EtOCH).

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Russ.Chem.Bull., Int.Ed., Vol. 62, No. 5, May, 2013
Molotov et al.
Table 2. 1H, 13C, and 14N NMR spectroscopic and mass spectrometric data for 1Hꢀ1,2,4ꢀtriazole derivatives 2a—f and 6a,b
Comꢀ
pound
MS,
(m/z) [M]+
1H NMR, , J/Hz
13C NMR, 
[
14N NMR, ]
2a
232
294
1.75 (d, 3 Н, СН3СН); 2.37 (s, 3 H, CH3Ar);
6.17 (q, 1 Н, СНCH3); 7.32, 7.80 (both d, 4 H in Ar,
3J = 8.2); 8.58 (s, 1 Н, СН in triazole ring )
[5.87 (NO2)]
2b
2.47 (s, 3 H, CH3Ar); 6.17 (q, 1 Н, СНNO2);
7.25—7.82 (m, 9 Н in Ar); 8.61 (s, 1 Н, СН
in triazole ring)
21.06 (CH3), 87.61 (СNO2), 120.13, 128.63,
129.58, 130.28, 131.92, 134.27, 138.84,
141.84 (8 C in Ar), 156.02, 158.53 (C(4) and
С(5) in triazole ring) [3.67 (NO2)]
2c
324
1.29 (t, 3 H, CH2CH3); 4.15 (q, 2 Н, CH2CH3);
6.17 (q, 1 Н, СНNO2); 7.02—7.87 (m, 9 Н, Ar);
8.54 (s, 1 Н, СН in triazole ring)
14.91 (CH3), (8 C, Ar), 63.97 (CH2)
115.38, 121.90, 128.85, 129.59,
129.80, 130.08, 131.97, 141.87 (8 C),
158.44, 159.16 (C(4) and С(5) in triazole ring)
[3.52 (NO2)]
2d
2e
276
218
2.48 (s, 3 H, CH3Ar); 3.99 (s, 3 Н, ОСН3);
7.05, 7.87 (both d, 4 H in Ar, 3J = 8.0); 8.61
(s, 1 H, СН in triazole ring)
[6.07 (NO2)]
6.98 (s, 1 Н, СНNO2),
3.72 (s, 3 Н, СН3N); 6.87 (s, 1 Н, СНNO2);
7.35—7.82 (m, 5 Н, Ph); 8.34 (s, 1 H, СН
in triazole ring)
[3.36 (NO2)]
2f
232
263
2.32 (s, 3 Н, СН3C); 3.92 (s, 3 Н, СН3N);
6.82 (s, 1 Н, СНNO2); 7.32—7.76 (m, 5 Н, Ph)
[3.42 (NO2)]
—
6a
2.41 (s, 3 H, CH3Ar); 7.45, 7.87 (both d, 4 H in Ar,
3J = 8.4); 7.56—8.39 (m, 5 Н in PhСО);
9.22 (s, 1 H, СН in triazole ring)
6b
201
2.49 (s, 3 Н, СН3C); 3.89 (s, 3 Н, СН3N);
7.45—8.29 (m, 5 Н in Ph)
11.84 (СН3C), 35.78 (СН3N), 28.16, 130.57,
1131.51, 133.12 (4 C in Ph), 153.53, 158.47
(C(4) and С(5) in triazole ring), 185.06 (CO)
Synthesis of amidines 1a—f (general procedure). A. A solution
of imino ether 5a,b,d (10 mmol) and 4ꢀtoluidine (1.18 g, 11 mmol)
(or imino ether 5b (2.33 g, 10 mmol) and 4ꢀethoxyaniline (1.51 g,
11 mmol)) in CHCl3 (10 mL) was refluxed for 3 h. The reaction
mixture was concentrated, and the dry residue was recrystallized
from methanol.
B. A 20% aqueous MeNH2 (2 mL) was added to a solution of
imino ether 5b,c (10 mmol) in methanol (20 mL), and the mixꢀ
ture was stirred at room temperature for 12 h. The solvent was
evaporated, and the product was isolated by preparative column
chromatography on SiO2 (eluent CHCl3).
130—131 C. Found (%): C, 62.78; H, 4.68; N, 17.45. C16H16N4O2.
Calculated (%): C, 62.95; H, 4.97; N, 17.27. MS, m/z: 324 [M]+.
1H NMR, : 1.29 (t, 3 H, CH2CH3); 3.97 (q, 2 H, CH2CH3);
7.09—8.60 (m, 9 H, Ar); 8.64 (s, 1 H, NCH=N).
Methyl 4ꢀ[(4ꢀmethylphenylamino)methylideneamino]furoxanꢀ
3ꢀcarboxylate (1d) was obtained by method A. The yield was
54%, m.p. 107—108 C. Found (%): C, 52.05; H, 4.46; N, 20.53.
C12H12N4O4. Calculated (%): C, 52.17; H, 4.38; N, 20.28. MS,
m/z: 276 [M]+. 1H NMR, : 2.37 (s, 3 H, CH3—Ar); 3.95 (s, 3 H,
OCH3); 7.35, 7.72 (both d, 4 H in Ar, J = 7.9 Hz); 8.61 (s, 1 H,
NCH=N).
3ꢀMethylꢀ4ꢀ[(4ꢀmethylphenylamino)methylideneamino]furꢀ
oxan (1a) was obtained by method A. The yield was 75%, m.p.
98—99 C. Found (%): C, 56.67; H, 5.13; N, 24.30. C11H12N4O2.
Calculated (%): C, 56.89; H, 5.21; N, 24.12. MS, m/z: 232 [M]+.
1H NMR, : 2.12 (s, 3 H, CH3C(4) in furoxan ring); 2.32 (s, 3 H,
CH3—Ar); 7.25, 7.64 (both d, 4 H in Ar, J = 8.2 Hz); 8.32, 8.54
(both s, 1 H, NCH=N).
4ꢀ[(4ꢀMethylphenylamino)methylideneamino]ꢀ3ꢀphenylfurꢀ
oxan (1b) was obtained by method B. The yield was 97%, m.p.
140—141 C. Found (%): C, 65.01; H, 4.97; N, 19.22. C15H14N4O2.
Calculated (%): C, 65.30; H, 4.79; N, 19.04. MS, m/z: 294 [M]+.
1H NMR, : 2.36 (s, 3 H, CH3); 7.12—8.62 (m, 9 H, Ar); 8.70,
8.83 (both s, 1 H, NCH=N).
4ꢀ[(Methylamino)methylideneamino]ꢀ3ꢀphenylfuroxan (1e)
was obtained by method B. The yield was 64%, oil, Rf = 0.37.
Found (%): C, 51.11; H, 4.07; N, 23.60. C10H10N4O2. Calculatꢀ
ed (%): C, 51.28; H, 4.30; N, 23.92. MS, m/z: 218 [M]+. 1H NMR,
: 2.98 (d, 3 H, CH3N); 7.44—8.77 (m, 6 H, 5 H in Ph, 1 H in
NCH=N).
4ꢀ[1ꢀ(Methylamino)ethylideneamino]ꢀ3ꢀphenylfuroxan (1f)
was obtained by method B. The yield was 47%, oil, Rf = 0.37.
Found (%): C, 56.94; H, 5.00; N, 24.36. C11H12N4O2. Calculatꢀ
ed (%): C, 56.89; H, 5.21; N, 24.12. MS, m/z: 232 [M]+. 1H NMR,
: 2.32 (s, 3 H, CCH3); 3.00 (d, 3 H, CH3N); 7.52—8.87
(m, 5 H, Ph).
Synthesis of 3ꢀ(1ꢀnitroalkyl)ꢀ1ꢀR3ꢀ5ꢀR2ꢀ1Hꢀ1,2,4ꢀtriazoles
2a—f upon treatment of furoxans with bases (general procedure).
A. Potassium methoxide (0.77 g, 11 mmol) was added to a soluꢀ
4ꢀ[(4ꢀEthoxyphenylamino)methylideneamino]ꢀ3ꢀphenylfurꢀ
oxan (1c) was obtained by method A. The yield was 82%, m.p.

New baseꢀinduced rearrangement of furoxans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 5, May, 2013
1243
tion of amidinofuroxan 1a—d (10 mmol) in dry methanol
(20 mL), and the mixture was stirred at room temperature for 6 h,
then acidified with AcOH to рH 7. The solvent was evaporated
on a rotary evaporator, the residue was triturated with water and
filtered off.
B. Potassium tertꢀbutoxide (1.23 g, 11 mmol) was added to
a solution of amidine 1e,f (10 mmol) in anhydrous DMF (10 mL),
and the mixture was stirred at 100 C for 6 h, then acidified with
AcOH to рH 7. The solvent was evaporated on a rotary evaporaꢀ
tor, the residue was washed with water and dried in air. The
product was isolated by preparative column chromatography on
SiO2 (eluent CHCl3).
5. G. L´Abbé, J. Heterocycl. Chem., 1984, 21, 627.
6. G. L´Abbé, K. Buelens, J. Heterocycl. Chem., 1990, 27, 1993.
7. A. J. Boulton, P. B. Ghosh, Adv. Heterocycl. Chem., 1969,
10, 1.
8. A. J. Boulton, A. R. Katrizky, A. MajidꢀHanid, J. Chem.
Soc. C, 1973, 2005.
9. A. R. Katrizky, M. F. Gordeev, Heterocycles, 1993, 35, 483.
10. N. N. Makhova, T. I. Godovikova, Mendeleev Chem. J.
(Engl. Transl.), 1997, 41, No. 2, 81 [Ross. Khim. Zh., 1997,
41, No. 2, 54].
11. N. N. Makhova, A. N. Blinnikov, Mendeleev Commun., 1999,
9, 17.
12. E. L. Baryshnikova, N. N. Makhova, Mendeleev Commun.,
2000, 10, 190.
13. E. L. Baryshnikova, A. S. Kulikov, I. V. Ovchinnikov, V. S.
Solomentsev, N. N. Makhova, Mendeleev Commun., 2001,
11, 230.
Synthesis of 3ꢀ(1ꢀnitrobenzyl)ꢀ1ꢀ(4ꢀtolyl)ꢀ1Hꢀ1,2,4ꢀtriazole
(2b) by thermally induced rearrangement. A melt of furoxanylꢀ
amidine 1b (2.94 g, 10 mmol) was heated at 145 C for 10 min.
The product was isolated from the resinꢀlike mass by preparative
column chromatography on SiO2 (eluent CHCl3).
14. S. I. Molotov, A. S. Kulikov, Yu. A. Strelenko, N. N. Maꢀ
khova, K. A. Lyssenko, Russ. Chem. Bull. (Int. Ed.), 2003,
52, 1829 [Izv. Akad. Nauk, Ser. Khim., 2003, 1734].
15. S. I. Molotov, A. S. Kulikov, N. N. Makhova, K. A. Lyssenꢀ
ko, Mendeleev Commun., 2003, 13, 188.
16. I. V. Ovchinnikov, M. A. Epishina, S. I. Molotov, Yu. A.
Strelenko, K. A. Lyssenko, N. N. Makhova, Mendeleev Comꢀ
mun., 2003, 13, 272.
Synthesis of 3ꢀbenzoylꢀ1ꢀ(4ꢀtolyl)ꢀ1Hꢀ1,2,4ꢀtriazole (6a) and
3ꢀbenzoylꢀ1,5ꢀdimethylꢀ1Hꢀ1,2,4ꢀtriazole (6b) (general proceꢀ
dure). Sodium hydroxide (0.44 g, 11 mmol) was added to
a suspension of amidinofuroxan 1b,f (10 mmol) in water (10 mL),
and the mixture was stirred at room temperature for 4 h, then
acidified with AcOH to рH 7. The solvent was evaporated on
a rotary evaporator. Products 6a,b were isolated by preparative
column chromatography on SiO2 (eluent CHCl3).
17. A. B. Sheremetev, N. N. Makhova, W. Friedrichsen, Adv.
Heterocycl. Chem., 2001, 78, 66.
18. N. N. Makhova, I. V. Ovchinnikov, A. S. Kulikov, S. I.
Molotov, E. L. Baryshnikova, Pure Appl. Chem., 2004,
76, 1691.
19. L. I. Khmel´nitskii, T. I. Godovikova, S. S. Novikov, Khimiya
furoksanov. Stroenie i sintez [Chemistry of Furoxans. Structure
and Synthesis], Nauka, Moscow, 1996, p. 382 (in Russian).
20. Л. I. Khmel´nitskii, T. I. Godovikova, S. S. Novikov, Khimiya
furoksanov. Reaktsii i primenenie [Chemistry of Furoxans.
Reactions and Application], Nauka, Moscow, 1996, p. 430
(in Russian).
21. F. Shaefer, in The Chemistry of the Cyano Group, Intersci.
Publ., New York, 1970, p. 239.
22. V. G. Andrianov, E. N. Rozhkov, A. V. Eremeev, Chem.
Heterocycl. Compd. (Engl. Transl.), 1994, 30, 470 [Khim.
Geterotsikl. Soedin., 1994, 534].
Xꢀray diffraction studies. Crystals 6a (C16H13N3O, M = 263.29)
monoclinic, space group P21/c at 100 K: a = 11.2638(14),
3
b = 10.9245(13), c= 11.5430(14) Å, = 114.350(3), V= 1294.0(3) Å ,
Z = 4 (Z´ = 1), dcalc = 1.351 g cm–3, (MoK) = 0.88 cm–1
,
F(000) = 552. Intensities of 8279 reflections were measured on
a Bruker SMART APEX II CCD diffractometer [(MoK) =
= 0.71072 Å, ꢀscan mode, 2 < 54], and 2829 independent
reflections (Rint = 0.0401) were used in further refinement. The
structure was solved by direct method and refined by the fullꢀ
matrix least squares method on F2 in anisotropicꢀisotropic apꢀ
proximation. Positions of hydrogen atoms H(C) were calculated
geometrically. All hydrogen atoms were refined in isotropic apꢀ
proximation using the riding model. The final Qꢀfactor values
for: wR2 = 0.0873 and GOF = 1.051 for all independent reflecꢀ
tion (R1 = 0.0536 were calculated on F for 1732 observed reflecꢀ
tion with I > 2(I)). All calculation were carried out using the
SHELXTL PLUS 5.0. The structure was deposited with the Camꢀ
bridge Structural Database (CCDC 906682).
23. M. Ruccia, N. Vivova, G. Cusmano, G. Macaluso, J. Chem.
Soc., Perkin Trans. 1, 1977, 589.
24. A. Defilippi, G. Sorba, R. Calvino, A. Garrone, A. Gasco,
M. Orsetti, Arch. Pharm., 1988, 321, 77.
References
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26. A. S. Kulikov, I. V. Ovchinnikov, S. I. Molotov, N. N. Maꢀ
khova, Russ. Chem. Bull. (Int. Ed.), 2003, 52, 1822 [Izv. Akad.
Nauk, Ser. Khim., 2003, 1727].
1. H. C. van der Plas, Ring Transformation of Heterocycles, Vols
1, 2, Acad. Press., London—New York, 1973.
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Received December 10, 2012;
4. G. L´Abbé, Tetrahedron, 1982, 38, 3537.
in revised form February 28, 2013