Synthesis and properties of dihetaryl-substituted furanones : 222. Synthesis and photochromic properties of dithienylethenes with the pyridazinone bridge

Article abstract of DOI:10.1007/s11172-008-0294-2

The reactions of dithienyl-substituted furanones with hydrazines afford the corresponding pyridazinone-bridged dithienylethenes with photochromic properties. The structure of 4,5-bis-(2,5-dimethyl-3-thienyl)-2,6-dimethyl-2H- pyridazin-3-one was establishe

Full text of DOI:10.1007/s11172-008-0294-2

Russian Chemical Bulletin, International Edition, Vol. 57, No. 10, pp. 2168—2174, October, 2008
2168
Synthesis and properties of dihetarylꢀsubstituted furanones
2.* Synthesis and photochromic properties of dithienylethenes
with the pyridazinone bridge**
M. M. Krayushkin,a D. V. Pashchenko,a B. V. Lichitsky,a B. V. Nabatov,a
A. N. Komogortsev,a L. G. Vorontsova,a and Z. A. Starikovab
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: mkray@ioc.ac.ru
bA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 6549
The reactions of dithienylꢀsubstituted furanones with hydrazines afford the corresponding
pyridazinoneꢀbridged dithienylethenes with photochromic properties. The structure of 4,5ꢀbisꢀ
(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ2,6ꢀdimethylꢀ2Hꢀpyridazinꢀ3ꢀone was established by Xꢀray diffraction.
Key words: dithienylꢀsubstituted furanones, pyridazinꢀ3ꢀones, photochromic dihetarylꢀ
ethenes, Xꢀray diffraction study.
based on fiveꢀmembered bridges. Evidently, the size of the
bridging ring can have a substantial effect on the dihedral
and torsion angles between the heterocyclic moieties and,
as a consequence, on the photochromic properties of this
class of compounds. Hence, the development of methods
for the synthesis of dihetarylethenes with new sixꢀmemꢀ
bered bridges providing the high photochemical fatigue
resistance and the comparison of the properties of these
products with the properties of known photochromes are
important problems.
Earlier,1 we have developed a general approach to the
synthesis of photochromic furanones 4 based on the conꢀ
densation of heterocyclic αꢀhaloketones with hetarylacetic
acids in the presence of potassium carbonate followed by
the reaction of the resulting product with aromatic aldeꢀ
hydes. This method is suitable for the synthesis of comꢀ
pounds 4 containing various heteroaromatic substituents
in the furanone ring. At the same time, it is evident that
furanones 4 can be used as the convenient starting comꢀ
pounds for the preparation of a broad range of photochroꢀ
mic dithetarylethenes containing new bridging moieties.
Therefore, selective methods for transformations of the
lactone moiety with retention of the dihetarylethene
moiety of the molecules are of considerable interest. This
type of reactions involves the reaction of dihetarylethenes
4 with various binucleophiles. In the present study, we
performed the recyclization of furanones 4 under the
action of hydrazines giving rise to a new type of photoꢀ
chromic dithienylethenes with the pyridazinone bridge.
The chemistry of photochromic dithetarylethenes is
in active progress. These compounds hold considerable
promise and are used for the design of devices for recordꢀ
ing, storage, and reading of large amounts of information.
In the last decade, a broad range of dithienylethenes conꢀ
taining various substituted and fused thiophene moieties
were synthesized. At the same time, the high fatigue resisꢀ
tance of photochromic compounds necessary for the mulꢀ
tiple data recording, was achieved only for compounds
containing a limited number of bridging fragments.
Dihetarylethenes based on perfluorocyclopentene,2
maleic anhydride,3 and maleinimide4 were used as such
compounds. Earlier,5—7 we have synthesized dithetarylꢀ
ethenes with furopyrimidine (1), imidazolone (2), and
oxazolone (3) bridges and investigated their photochroꢀ
mic properties.
It should be noted that the overwhelming majority of
this type of products described earlier were constructed
* For Part 1, see Ref. 1.
** Dedicated to Academician B. A. Trofimov on the occasion of
his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2126—2132, October, 2008.
1066ꢀ5285/08/5710ꢀ2168 © 2008 Springer Science+Business Media, Inc.

Dithienylethenes with the pyridazinone bridge
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2169
Scheme 1
5
R
R´
5
R
R´
5
R
R´
5
R
R´
a
b
4ꢀOMe
4ꢀMe
H
H
c
d
H
Me
Me
e
f
2ꢀOMe
3,4ꢀ(OCH2O)
Me
Me
g
h
3ꢀCl
2ꢀCl
Me
Me
3ꢀOMe
The reaction of butyrolactones with hydrazines is
used for the synthesis of a broad range of compounds 5
containing various substituents in the benzyl moiety.
The structure of the bridging moiety in dithienylethenes
has a substantial effect on the photochromic properties.
One would expect that the presence of the benzyl substiꢀ
tuent at position 6 of the pyridazinone ring will lead to a
decrease in the quantum yield of the photochemical transꢀ
formation as a result of absorption of UV radiation by the
aromatic moiety, which is not conjugated with the dihetarylꢀ
ethene system. Hence, to improve the performance charꢀ
acteristics of photochromes with the pyridazinone bridge,
it seemed advantageous to synthesize dithienylꢀsubstituted
pyridazinone containing the methyl group at position 6. For
this purpose, we developed a convenient approach to the
synthesis of the starting 3,4ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
5ꢀhydroxyꢀ5ꢀmethylꢀ5Hꢀfuranꢀ2ꢀone (7) based on the
condensation of thienylacetic acid 8 with bromoketone 9.
The synthesis of thienylacetic acid 8 by the Willgerodt—
Kindler reaction followed by saponification of the resultꢀ
ing thiomorpholide has been described earlier.10 The startꢀ
ing bromoketone 9 was synthesized according to a known
method11 by the Friedel—Crafts acylation of 2,5ꢀdiꢀ
methylthiophene with propionyl chloride followed by broꢀ
mination of 2,5ꢀdimethylꢀ3ꢀpropanoylthiophene in
acetic acid. We showed that heating of thienylacetic acid
8 with bromoketone 9 in dimethylformamide in the presꢀ
ence of potassium carbonate affords labile intermediate
10 analogous to furanone 4. Intermediate 10 is easily
widely used for the synthesis of various pyridazines.8,9
However, the reactions of arylmethyl derivatives 4 with
hydrazines have not been previously studied. We found
for the first time that the reaction of compounds 4
with unsubstitued hydrazine affords dihetarylꢀsubstituted
pyridazinones 5a,b upon prolonged refluxing (24 h) in
ethanol (Scheme 1). The proposed scheme of transforꢀ
mations involves the nucleophilic opening the furan ring
under the action of hydrazine and the intramolecular
cyclization giving rise to the target product 5.
The reaction with methylhydrazine proceeds analoꢀ
gously. This reaction afforded photochromic pyridazinones
5c—h (see Scheme 1). However, it should be noted that in
this case, the recyclization proceeds much faster (3 h)
than that in the reaction with unsubstituted hydrazine.
Apparently, the difference in the reaction rate is attributed
to the fact that the reaction of lactones 4 with hydrazine
reversibly gives Nꢀaminoꢀsubstituted pyrrolones 6, thus
substantially decreasing the rate of formation of pyriꢀ
dazinones 5a,b. At the same time, the reaction with
methylhydrazine proceeds at the more nucleophilic alkyꢀ
lated nitrogen atom, thus making impossible the formation
of compounds 6 due to which the reaction rapidly affords the
target pyridazinones 5c—h (see Scheme 1). However, in spite
of the difference in the reaction rate, all reactions proceed
smoothly and give products 5 in high yields (80—94%).
Therefore, this method has a general character and can be

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Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
Krayushkin et al.
subjected to oxidation with atmospheric oxygen to give
the target furanone 7. The reaction of dithienylethene 7
with methylhydrazine produces photochromic pyridꢀ
azinone 11 in high yield (82%) (Scheme 2).
C(7)
C(8)
N(1)
N(2)
C(6)
O(1)
Scheme 2
C(3)
C(4)
C(5)
C(4´´)
C(5´´)
C(3´´)
C(2´´)
C(3´)
C(6´)
S(1´)
C(7´´)
C(4´)
C(6´´)
C(2´)
S(1´´)
C(5´)
C(7´)
Fig. 1. Molecular structure of compound 11.
ened, which is indicative of the exchange processes in
compounds 5 and 11. It should be noted that the proton
signals of other groups are not broadened. It seems probꢀ
able that the substituents at positions 3 and 6 of the bridging
heterocycle hinder free rotation of the thiophene rings,
resulting in rotamerism and a broadening of signals in the
NMR spectra.
The Xꢀray diffraction study confirmed the structure of
4,5ꢀbis(2,5ꢀdimethylthiophenꢀ3ꢀyl)ꢀ2,6ꢀdimethylꢀ2Hꢀ
pyridazinꢀ3ꢀone (11) (Fig. 1, Table 1). In molecule 11,
the thiophene rings are parallel to the pyridazinone bridge.
The thiophene ring in the ortho position with respect to
the carbonyl group is twisted by 55.21°. Another thiophene
ring is twisted to a somewhat larger angle (63.64°) due to
the presence of the sterically bulky methyl group in the
ortho position. The intramolecular distance between the
potential reaction centers (C(2″)—C(2´), 4.12 Å) is subꢀ
stantially larger than the sum of the van der Walls radii.
These data indicate that the conformation of the molꢀ
ecule in the crystalline state has no structural features
We studied the structures of the reaction products by
NMR spectroscopy. For most of known dithetarylethenes
containing a fiveꢀmembered ring as the bridge, the barrier
to rotation of the thiophene rings with respect to the
bridge is rather low, resulting in free rotation of the thienyl
rings. At the same time, the rotation of the thiophene
rings in some dithienylethenes with sixꢀmembered bridges
can be hindered due to the close proximity of the thioꢀ
phene moieties and the presence of substituents in the
pyridazine ring, which would be reflected in the 1H NMR
spectra. We suggested that the formation of rotamers is
possible for dithienylethenes containing the pyridazinone
bridge. Actually, in the 1H NMR spectra of pyridazinones
5 and 11 measured at room temperature, signals for the
protons of one of the thiophene rings at δ 5.80—6.50 and
signals for the methyl protons at δ 1.40—2.40 are broadꢀ
Table 1. Bond lengths (d) and bond angles (ω) in the pyridazinꢀ
3ꢀone ring of molecule 11
Bond
d/Å
Angle
ω/deg
N(1)—N(2)
N(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(5)—C(6)
C(4)—C(5)
1.356 (1.360)
1.389 (1.359)
1.472 (1.439)
1.370 (1.346)
1.451 (1.422)
1.308 (1.300)
C(6)—N(1)—N(2)
N(1)—N(2)—C(3)
N(2)—C(3)—C(4)
C(3)—C(4)—C(5)
C(4)—C(5)—C(6)
C(5)—C(6)—N(1)
117.8
126.5
114.7
119.2
119.0
122.6
Note. The average values calculated from the data found in the
CCDC are given in parentheses for comparison. The accuracy
of determination of the bond lengths and bond angles is 0.003 Å
and 0.2°, respectively.

Dithienylethenes with the pyridazinone bridge
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2171
characteristic of photoactive molecules (the antiparallel
conformation of the molecule; the distance between the
potential reaction centers shorter than 4.0 Å). Nevertheꢀ
less, compound 11 shows high photochemical activity in
solution, which is apparently attributed to the ease of
conformational changes in solution compared to the crysꢀ
talline state.
It should be noted that the pyridazinꢀ3ꢀone ring is
planar (within 0.02 Å), but it is substantially distorted
compared to the analogous rings in monoꢀ and dialkylꢀ
substituted derivatives. Thus, all bond lengths in the
ring between the substituents are larger than the average
values calculated based on 17 structures from the CCDC
(see Fig. 1, Table 1). Evidently, the steric interactions
between the ortho substituents cause an elongation of the
bonds and a deformation of the bond angles in the ring.
We performed spectroscopic studies of the photochroꢀ
mic and fluorescence properties of the newly synthesized
pyridazinones in an acetonitrile solution (at a concentraꢀ
tion of 1•10–4 mol L–1). The starting (open) forms of the
compounds, except for compound 5f, are characterized
by similar absorption bands, whose maxima are observed
in the 310—320 nm region (Table 2).
It was found that all these compounds are photochroꢀ
mic. After UV irradiation of the compounds in solution at
313 nm, the absorption spectra show a new rather intense
broad band in the visible spectral range with the correꢀ
sponding maxima in the 572—581 nm region and a halfꢀ
width of about 120 nm (see Table 1), which is indicative of
the formation of the closed (cyclic) forms of these comꢀ
pounds during irradiation in solution.2 The absorption
spectra typical of this group of compounds are exemplified
in Fig. 2 by the spectrum of compound 5h after irradiation
with filtered UV light during different periods of time.
As can be seen from Table 2, the positions of the
absorption maxima of the closed (cyclic) forms depend
only slightly on the nature of the benzyl substituent, but
the absorbance in the photostationary state changes subꢀ
stantially (by 25%). The following facts can be mentioned.
1. The replacement of the substituent in the para posiꢀ
tion of the benzyl moiety in the series 6ꢀ(4ꢀmethoxyꢀ
benzyl)pyridazinone 5a (OMe) — 6ꢀ(4ꢀmethylbenzyl)ꢀ
pyridazinone 5b (Me) — 6ꢀbenzylpyridazinone 5c (H) is
accompanied by a slight bathochromic shift of the abꢀ
sorption maxima of the cyclic forms and an increase in
the absorbance ABmax by 8 and 14%, respectively.
2. The change in the position of the OMe substituent
in the benzyl moiety in 6ꢀ(methoxybenzyl)pyridazinones
in the series 4ꢀOMe (5a, para position) — 3ꢀOMe (5d,
meta position) — 2ꢀOMe (5e, ortho position) leads to a
change in the absorbance ABmax by 19%.
3. Chloroꢀsubstituted pyridazinones show a substanꢀ
tially higher efficiency of photocoloration than the correꢀ
sponding methoxyꢀsubstituted derivatives. The absorbance
of compounds 5g,h is higher than that of 2ꢀmethoxyꢀ
benzylpyridazinone 5e by 7 and 12%, respectively.
4. Of all the compounds under consideration, the highest
efficiency of photocoloration is observed for compound
5h. The closed form of this compound is characterized
by the highest absorbance ABmax, other conditions being
the same.
Table 2. Photochromic and fluorescence properties of pyridꢀ
azinones 5a—h and 11
max
em
Comꢀ R´
R″
λ
λ
AB
λ
λ
exc A
A
B
pound
nm
nm
5a
5b
5c
5d
5e
5f
H
H
Me
Me
Me
4ꢀMeOBn
4ꢀMeBn
PhCH2
3ꢀMeOBn
2ꢀMeOBn
310 572 0.456 320 468
310 575 0.493 320 468
315 578 0.518 320 462
310 581 0.503 330 465
318 578 0.544 320 463
A (rel. units)
2.0
Me 3,4ꢀOCH2OBn 290 578 0.550 320 465
1.5
5g
5h
11
Me
Me
Me
3ꢀClBn
2ꢀClBn
Me
320 579 0.580 320 463
318 581 0.610 320 465
318 575 0.434 320 460
581, 0.583
1.0
Note. λA and λB are the maxima of the longꢀwavelength bands of
the starting (open) and colored (cyclic) forms, respectively; AB
max
0.5
is the absorbance of solutions in the photostationary state (for
the layer thickness of 1 cm) after irradiation with filtered light at
313 nm using a mercuryꢀvapor gasꢀdischarge lamp at the absorpꢀ
300
400
500
600
λ/nm
em
tion maximum of the cyclic form; λ
is the wavelength of the
fluorescence maximum of the startiAng (open) form. The duraꢀ
tion of irradiation of compounds 5a—h was 5 min; of compound
11, 8 min.
Fig. 2. Electronic absorption spectra A(λ) of a solution of comꢀ
pound 5h in acetonitrile before and after UV irradiation with
filtered light at 313 nm in a 1ꢀcm thick layer at 298 K.

2172
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
Krayushkin et al.
IF (rel. units)
of the substituents in the benzyl moiety. The fluorescence
spectra of solutions were measured both before and after
UV irradiation with excited light at λexc = 320—330 nm.
The UV irradiation of solutions for 5 min led to a decrease
in the fluorescence intensity by a factor of ~2.5—3.5, the
shape and positions of fluorescence bands remaining virꢀ
tually unchanged. The fluorescence spectra typical of this
group of compounds before and after UV irradiation of
solutions is exemplified by compound 5h in Fig. 3.
For solutions of compounds 5b,d, the absorption specꢀ
tra were measured also under cyclic successive irradiation
with filtered UV (313 nm for 4 min) and visible (577 nm
for 10 min) light. The absorbance of the solutions meaꢀ
sured at the absorption maximum of the closed form
decreased by 16 and 14%, respectively, after 10 cycles
of irradiation (Fig. 4).
0.20
0.15
1
0.10
0.05
UV
2
400
450
500
550
600 λ/nm
The measurements showed that all pyridazinones
synthesized in the present study are photochromic. These
compounds have good spectroscopic properties, are charꢀ
acterized by thermal stability of isomeric forms, and have
the photochemical fatigue resistance, but exhibit weak
fluorescence in the shortꢀwavelength visible region. The
changes in the absorption and luminescence spectra
depending on the presence of different substituents are
not principal, although the highest absorbances of the
closed forms of the compounds differ by more than 40%.
Fig. 3. Fluorescence spectra IF(λ) of a solution of compound 5h
in acetonitrile before (1) and after (2) UV irradiation with
filtered light at 313 nm for 5 min at an excitation wavelength of
320 nm in a 1ꢀcm thick layer at 298 K.
All compounds 5a—h exhibit a weak fluorescence with
emission maxima at 460—470 nm (see Table 1). The posiꢀ
tions of fluorescence maxima and the emission spectral
shape depend only slightly on the nature and the positions
D
A
2
0.45
1
0.35
1.5
0.25
2
0.15
0
1
2
3
4
5
6
7
8
9
10 N
1
575, 4.435
0.5
300
400
500
600
700 λ/nm
Fig. 4. Electronic absorption spectra A(λ) of a solution of compound 5c in acetonitrile after its cyclic successive irradiation with
filtered UV (313 nm) and visible (577 nm) light at 298 K in a 1ꢀcm thick layer. The dynamics of changes in the absorbance of the
solution measured at 575 nm after each cycle of successive irradiation with UV (1) and visible (2) light is presented in the inset; N is
the number of the cycle.

Dithienylethenes with the pyridazinone bridge
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2173
(250 mg, 1.73 mmol), and 1,8ꢀdiazabicyclo[5.4.0]undecꢀ7ꢀene
(DBU) (470 mg, 3.1 mmol) in EtOH (3 mL) was refluxed for 3 h
and then diluted with water (3 mL). The precipitate that formed
was filtered off and washed on a filter with 50% aqueous ethanol.
6ꢀBenzylꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ2ꢀmethylꢀ2Hꢀpyriꢀ
dazinꢀ3ꢀone (5c). The yield was 185 mg (88%), m.p. 135—137 °C.
1H NMR (DMSOꢀd6), δ: 1.30 (s, 3 H, Me); 1.80—2.25 (br.s,
6 H, 2 Me); 2.33 (s, 3 H, Me); 3.65—3.80 (m, 5 H, NMe + CH2);
5.90—6.45 (br.s, 1 H, HHet); 6.50 (s, 1 H, HHet); 6.75 (m, 2 H,
HAr); 7.15 (m, 3 H, HAr). Found (%): C, 68.83; H, 5.89; N,
6.92; S, 15.04. C24H24N2OS2. Calculated (%): C, 68.54; H, 5.75;
N, 6.66; S, 15.25.
Hence, in the present study, we developed convenient
approaches to the synthesis of the previously unknown
dithetarylethenes 5 and 11 with the pyridazinone bridge.
These methods for the synthesis are characterized by mild
conditions and good yields satisfactory for the preparative
synthesis of photochromic products. It was shown that
dithienylethenes 5 and 11 containing the bridging sixꢀ
membered pyridazinone moiety have photochromic propꢀ
erties. The structure of product 11 was established by
Xꢀray diffraction.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ6ꢀ(3ꢀmethoxybenzyl)ꢀ
2ꢀmethylꢀ2Hꢀpyridazinꢀ3ꢀone (5d). The yield was 194 mg (86%),
m.p. 157—159 °C. H NMR (DMSOꢀd6), δ: 1.40 (s, 3 H, Me);
Experimental
1
The 1H NMR spectra were recorded on Bruker AMꢀ300
(300 MHz) and Bruker WMꢀ250 (250 MHz) instruments in
DMSOꢀd6. The melting points were measured on a Boetius
hotꢀstage apparatus and are uncorrected. All reaction mixtures
were analyzed and the purity of the reaction products was
checked by TLC on Merck Silica gel 60 F254 plates using a 1 : 3
ethyl acetate—hexane mixture as the eluent.
The absorption and fluorescence spectra of solutions were
measured on a SFꢀ256 UVI doubleꢀbeam spectrophotometer
(LOMO) and a Flyuoratꢀ02 Panorama spectrofluorimeter
(Lyumeks). The UV irradiation of all solutions was carried out at
1.80—2.40 (m, 9 H, 3 Me); 3.65 (s, 2 H, CH2); 3.70 (s, 3 H,
NMe); 3.75 (s, 3 H, OMe); 5.90—6.05 (br.s, 1 H, HHet); 6.25 (s,
1 H, HHet); 6.37, 6.50, 6.70, and 7.05 (all m, 1 H each, HAr).
Found (%): C, 66.81; H, 5.97; N, 6.43; S, 14.02. C25H26N2O2S2.
Calculated (%): C, 66.64; H, 5.82; N, 6.22; S, 14.23.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ6ꢀ(2ꢀmethoxybenzyl)ꢀ
2ꢀmethylꢀ2Hꢀpyridazinꢀ3ꢀone (5e). The yield was 207 mg (92%),
m.p. 115—117 °C. 1H NMR (DMSOꢀd6), δ: 1.55 (br.s, 3 H, Me);
1.80—2.30 (m, 9 H, 3 Me); 3.55—3.87 (m, 2 H, CH2); 3.60 (s,
3 H, NMe); 3.70 (s, 3 H, OMe); 5.90—6.37 (br.s, 1 H, HHet);
6.40 (s, 1 H, HHet); 6.70—6.90 (m, 3 H, HAr); 7.10 (m, 1 H, HAr).
Found (%): C, 66.74; H, 5.91; N, 6.75; S, 14.10. C25H26N2O2S2.
Calculated (%): C, 66.64; H, 5.82; N, 6.22; S, 14.23.
6ꢀBenzo[1,3]dioxolꢀ5ꢀylmethylꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
2ꢀmethylꢀ2Hꢀpyridazinꢀ3ꢀone (5f). The yield was 218 mg (94%),
m.p. 175—177 °C. 1H NMR (DMSOꢀd6), δ: 1.45 (br.s, 3 H,
Me); 1.80—2.40 (m, 9 H, 3 Me); 3.65 (m, 2 H, CH2); 3.75 (s,
3 H, NMe); 5.85—6.00 (m, 3 H, HHet + OCH2O); 6.15 (m, 1 H,
HAr); 6.27 (s, 1 H, HHet); 6.50 (s, 1 H, HAr); 6.67 (m, 1 H, HAr).
Found (%): C, 64.85; H, 5.44; N, 6.12; S, 13.62. C25H24N2O3S2.
Calculated (%): C, 64.63; H, 5.21; N, 6.03; S, 13.80.
λ
irr = 313 nm with the use of an OIꢀ18A luminescent illuminator
(LOMO) equipped with a DRKꢀ120 mercury quartz lamp. The conꢀ
centration of all compounds in acetonitrile was 1•10–4 mol L–1
.
The measurements were performed in 10ꢀmm quartz cells;
the monochromator step was 1 nm; the slit width was 3 nm; the
averaging was performed over three—five points in each step).
The spectroscopic measurements were carried out in acetonitrile
(99% purity, Acros organics).
The starting compounds 1 were synthesized according to
known procedures.1
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ2Hꢀpyridazinꢀ3ꢀones 5a,b
(general procedure). A mixture of the corresponding arylmethylꢀ
furanone 4 (0.5 mmol) and hydrazine hydrate (100 mg, 2 mmol)
in EtOH (3 mL) was refluxed for 24 h and then diluted with
water (3 mL). The precipitate that formed was filtered off and
washed on a filter with 50% aqueous ethanol.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ6ꢀ(4ꢀmethoxybenzyl)ꢀ2Hꢀ
pyridazinꢀ3ꢀone (5a). The yield was 180 mg (87%), m.p. 206—
208 °C. 1H NMR (DMSOꢀd6), δ: 1.45 (s, 3 H, Me); 1.80—2.27
(m, 6 H, 2 Me); 2.30 (s, 3 H, Me); 3.60 (s, 2 H, CH2); 3.63 (s, 3 H,
Me); 5.90—6.45 (br.s, 1 H, HHet); 6.50 (s, 1 H, HHet); 6.60—6.80
(m, 4 H, HAr); 13.03 (s, 1 H, NH). Found (%): C, 66.24; H, 5.62;
N, 6.38; S, 14.57. C24H24N2O2S2. Calculated (%): C, 66.03;
H, 5.54; N, 6.42; S, 14.69.
6ꢀ(3ꢀChlorobenzyl)ꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
2ꢀmethylꢀ2Hꢀpyridazinꢀ3ꢀone (5g). The yield was 205 mg (90%),
m.p. 129—131 °C. H NMR (DMSOꢀd6), δ: 1.40 (s, 3 H, Me);
1
1.80—2.27 (m, 6 H, 2 Me); 2.35 (s, 3 H, Me); 3.65—3.85 (m,
5 H, NMe + CH2); 5.90—6.45 (br.s, 1 H, HHet); 6.50 (s, 1 H,
HHet); 6.70 and 6.77 (both m, 1 H each, HAr); 7.27 (m, 2 H,
HAr). Found (%): C, 63.43; H, 5.17; Cl, 7.82; N, 6.31; S, 14.22.
C24H23ClN2OS2. Calculated (%): C, 63.35; H, 5.09; Cl, 7.79;
N, 6.16; S, 14.09.
6ꢀ(2ꢀChlorobenzyl)ꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
2ꢀmethylꢀ2Hꢀpyridazinꢀ3ꢀone (5h). The yield was 189 mg (83%),
m.p. 107—109 °C. 1H NMR (DMSOꢀd6), δ: 1.60 (br.s, 3 H,
Me); 1.80—2.35 (m, 9 H, 3 Me); 3.65 (s, 3 H, NMe); 3.70—4.00
(m, 2 H, CH2); 5.90—6.00 (br.s, 1 H, HHet); 6.47 (s, 1 H, HHet);
7.05 (m, 1 H, HAr); 7.17 (m, 2 H, HAr); 7.30 (m, 1 H, HAr).
Found (%): C, 63.51; H, 5.22; Cl, 7.87; N, 6.29; S, 13.92.
C24H23ClN2OS2. Calculated (%): C, 63.35; H, 5.09; Cl, 7.79;
N, 6.16; S, 14.09.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ6ꢀ(4ꢀmethylbenzyl)ꢀ2Hꢀ
pyridazinꢀ3ꢀone (5b). The yield was 165 mg (80%), m.p. 227—
230 °C. 1H NMR (DMSOꢀd6), δ: 1.40 (br.s, 3 H, Me); 1.80—
2.40 (m, 12 H, 4 Me); 3.65 (s, 2 H, CH2); 5.85—6.45 (br.s, 1 H,
HHet); 6.50 (s, 1 H, HHet); 6.65 and 6.97 (both d, 2 H each, HAr
,
3,4ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ5ꢀhydroxyꢀ5ꢀmethylꢀ5Hꢀ
furanꢀ2ꢀone (7). A mixture of (2,5ꢀdimethylꢀ3ꢀthienyl)acetic
acid 8 10 (1.90 g, 0.011 mol), 2ꢀbromoꢀ1ꢀ(2,5ꢀdimethylꢀ3ꢀthiꢀ
enyl)propanꢀ1ꢀone 9 11 (2.47 g, 0.01 mol), and potassium carꢀ
bonate (4.14 g, 0.03 mol) in DMF (30 mL) was stirred at 80 °C
for 10 h. Then the reaction mixture was poured into water. The
precipitate that formed was filtered off and recrystallized from
J = 7 Hz); 13.05 (s, 1 H, NH). Found (%): C, 68.61; H, 5.83; N,
6.72; S, 15.62. C24H24N2OS2. Calculated (%): C, 68.54; H, 5.75;
N, 6.66; S, 15.25.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ2ꢀmethylꢀ2Hꢀpyridazinꢀ
3ꢀones 5c—h (general procedure). A mixture of the correspondꢀ
ing arylmethylfuranone 4 (0.5 mmol), methylhydrazine sulfate

2174
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
Krayushkin et al.
ethanol. The yield was 2.41 g (72%), m.p. 201—203 °C. 1H NMR
(DMSOꢀd6), δ: 1.43, 1.67, 1.85, 2.30, and 2.33 (all s, 3 H each,
Me); 6.60 and 6.95 (both s, 1 H each, HHet); 7.70 (s, 1 H, OH).
Found (%): C, 61.46; H, 5.51; S, 19.32. C17H18O3S2. Calcuꢀ
lated (%): C, 61.05; H, 5.42; S, 19.17.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ2,6ꢀdimethylꢀ2Hꢀpyridazinꢀ
3ꢀone (11). A mixture of furanone 7 (167 mg, 0.5 mmol),
methylhydrazine sulfate (250 mg, 1.73 mmol), and DBU
(470 mg, 3.1 mmol) in EtOH (3 mL) was refluxed for 8 h and
then diluted with water (3 mL). The precipitate that formed was
filtered off and washed on a filter with 50% aqueous ethanol.
The yield was 141 mg (82%), m.p. 125—127 °C. 1H NMR
(DMSOꢀd6), δ: 1.85 (br.s, 3 H, Me); 1.90—2.10 (br.s, 6 H, 2 Me);
2.20 (br.s, 3 H, Me); 2.30 (s, 3 H, Me); 3.65 (s, 3 H, NMe);
5.90—6.40 (br.s, 1 H, HHet); 6.53 (s, 1 H, HHet). Found (%):
C, 62.98; H, 5.93; N, 8.31; S, 18.45. C18H20N2OS2. Calculated
(%): C, 62.76; H, 5.85; N, 8.13; S, 18.61.
References
1. M. M. Krayushkin, D. V. Pashchenko, B. V. Lichitskii,
T. M. Valova, Yu. P. Strokach, V. A. Barachevskii, Zh. Org.
Khim., 2006, 42, 1827 [Russ. J. Org. Chem., 2006, 42, 1816
(Engl. Transl.)].
2. M. Irie, Chem. Rev., 2000, 100, 1685.
3. H. Miyasaka, T. Nobuto, M. Murakami, A. Itaya, N. Tamai,
M. Irie, J. Phys. Chem. A, 2002, 106, 8096.
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Soc. Jpn., 1998, 71, 1101.
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Lichitskii, A. A. Dudinov, B. M. Uzhinov, Izv. Akad. Nauk,
Ser. Khim., 2001, 2315 [Russ. Chem. Bull., Int. Ed., 2001, 50,
2424].
6. M. M. Krayushkin, S. N. Ivanov, A. Yu. Martynkin, B. V.
Lichitskii, A. A. Dudinov, L. G. Vorontsova, Z. A. Starikova,
B. M. Uzhinov, Izv. Akad. Nauk, Ser. Khim., 2002, 1588
[Russ. Chem. Bull., Int. Ed., 2002, 51, 1869].
7. M. M. Krayushkin, S. N. Ivanov, B. V. Lichitskii, A. A.
Dudinov, L. G. Vorontsova, Z. A. Starikova, A. Yu. Martynkin,
Zh. Org. Khim., 2004, 40, 88 [Russ. J. Org. Chem., 2004, 40
(Engl. Transl.)].
Xꢀray diffraction study. Crystals of compound 11 of comꢀ
position C18H20N2OS2 were grown by crystallization from a
mixture of ethanol and water. At 120 K, the crystals are triclinic,
a = 9.253(6) Å, b = 10.057(7) Å, c = 11.147(11) Å, α = 113.94(2)°,
β = 112.18(2)°, γ = 95.44(1)°, space group P–1, Z = 2, V =
3
= 839.4(11) Å , M = 344.48, dcalc = 1.363 g cm–3. The unit cell
parameters and the intensities of 3988 independent reflections
were measured on a Bruker SMART 1000 diffractometer using
the ϕ—ωꢀscanning technique in the angle range 2.25 ≥ θ ≤ 27.99°
(MoꢀKα radiation, graphite monochromator). The structure was
solved by direct methods, which revealed all nonhydrogen atꢀ
oms. The hydrogen atoms were located in difference electron
density maps. The structure was refined by the fullꢀmatrix leastꢀ
squares method with anisotropic displacement parameters for
nonhydrogen atoms; hydrogen atoms were refined isotropically.
The final R factors based on 3235 reflections with I > 2σ(I) were
R1 = 0.051, wR2 = 0.131; the R factors based on all independent
reflections were R1 = 0.061, wR2 = 0.138. The calculations were
carried out with the use of the SAINTPlus,12 SMART,13 and
SHELXTL program packages.14 The atomic coordinates, therꢀ
mal parameters, and geometric characteristics were deposited
with the Cambridge Structural Database (CCDC 675536).
8. S. Breukelman, D. Meakins, J. Chem. Soc., Perkin Trans. 1,
1627, 1985.
9. I. Estevez, E. Ravina, E. Sotelo, J. Heterocycl. Chem., 1998,
35, 1421.
10. J. Press, J. McNally, J. Heterocycl. Chem., 1988, 25, 1571.
11. N.ꢀH. BuuꢀHoi, Recl. Trav. Chim. PaysꢀBas, 1948, 67, 309.
12. Bruker. SAINTPlus. Data Reduction and Correction Program
v. 6.01, Bruker AXS, Madison, Wisconsin, USA, 1998.
13. Bruker. SMART. Bruker Molecular Analysis Research Tool,
v. 5.059, Bruker AXS, Madison, Wisconsin, USA, 1998.
14. G. M. Sheldrick, SHELXTL v. 5.10, Structure Determination
Software Suite, Bruker AXS, Madison, Wisconsin, USA, 1998.
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 07ꢀ03ꢀ00381ꢀa).
Received January 22, 2008;
in revised form June 25, 2008