Photochromic dihetarylethenes 17. Synthesis and photochromic properties of dithienylethenes containing new heterocyclic bridging fragments

Article abstract of DOI:10.1023/A:1021367909022

Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)ethenes containing the imidazol-2-one, 1,3-dioxol-2-one, or 1,3-oxazol-2-one fragments as ethene bridges. These compounds were demonstrated to exhibit the photochromic p

Full text of DOI:10.1023/A:1021367909022

Russian Chemical Bulletin, International Edition, Vol. 51, No. 9, pp. 1731—1736, September, 2002
1731
Photochromic dihetarylethenes
17.* Synthesis and photochromic properties of dithienylethenes
containing new heterocyclic bridging fragments
a
a
a
a
a
M. M. Krayushkin,a S. N. Ivanov, A. Yu. Martynkin, B. V. Lichitsky, A. A. Dudinov, L. G. Vorontsova,
ꢀ
Z. A. Starikova,b and B. M. Uzhinovc
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 5328. Eꢀmail: mkray@mail.ioc.ac.ru
bA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 5085
cDepartment of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119899 Moscow, Russian Federation.
Fax: +7 (095) 932 8846. Eꢀmail: uzhinov@light.chem.msu.su
Procedures were developed for the synthesis of substituted bis(2,5ꢀdimethylꢀ3ꢀthiꢀ
enyl)ethenes containing the imidazolꢀ2ꢀone, 1,3ꢀdioxolꢀ2ꢀone, or 1,3ꢀoxazolꢀ2ꢀone fragꢀ
ments as ethene bridges. These compounds were demonstrated to exhibit the photochromic
properties. The cyclic forms of some imidazolone and oxazolone photochromes possess high
thermal stability. The structure of photochromic 4,5ꢀbis(4ꢀacetylꢀ2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
3ꢀmethylꢀ2,3ꢀdihydroꢀ1,3ꢀoxazolꢀ2ꢀone was established by Xꢀray diffraction analysis. The
molecule adopts an antiꢀparallel conformation similar to that of perfluorocyclopenteneꢀ
bridged dithienylethenes.
Key words: 1,2ꢀdithienylethenes, 4,5ꢀdithienylimidazolꢀ2ꢀones, 4,5ꢀdithienylꢀ1,3ꢀdioxolꢀ
2ꢀones, 4,5ꢀdithienylꢀ1,3ꢀoxazolꢀ2ꢀones, αꢀhydroxy ketones, thenoins, photochromes, therꢀ
mal stability, fatigue resistance, Xꢀray diffraction analysis.
Scheme 1
Previously, with the aim of searching for new availꢀ
able compounds possessing photochromic activity, we
have synthesized dithienylethenes containing cycloꢀ
butenedione2, azine3, azole,4 pyrrole, furan, or furoꢀ
pyrimidine5 bridges. In the present study, we synthesized
bis(2,5ꢀdimethylꢀ3ꢀthienyl)ethenes in which the thienyl
rings are bound to imidazolꢀ2ꢀone, 1,3ꢀdioxolꢀ2ꢀone, or
1,3ꢀoxazolꢀ2ꢀone and examined their photochromic
properties.
Results and Discussion
We used thenoin 1, which is a convenient starting
compound for the preparation of compounds of this type.3
By analogy with benzoin,6 we prepared 4,5ꢀbis(2,5ꢀdiꢀ
methylꢀ3ꢀthienyl)imidazolꢀ2ꢀone (2) by the reaction of
compound 1 with urea in acetic acid. Treatment of comꢀ
pound 2 with acetyl and benzoyl chlorides afforded the
diacetyl (3) and dibenzoyl (4) derivatives, respectively,
in good yields (Scheme 1).
R =
; R´ = Me (3), Ph (4)
The reaction of thenoin 1 with an excess of carbonylꢀ
* For Part 16, see Ref. 1.
diimidazole in refluxing benzene afforded dithienylꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1588—1593, September, 2002.
1066ꢀ5285/02/5109ꢀ1731 $27.00 © 2002 Plenum Publishing Corporation

1732
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
Krayushkin et al.
Scheme 3
ethene 5 containing the bridging 1,3ꢀdioxolꢀ2ꢀone
(carbonate) fragment in virtually quantitative yield
(Scheme 2).
Scheme 2
X = O (8a), NMe (8b)
All the compounds synthesized in the present study
exhibit the photochromic properties (Scheme 4). The
spectroscopic properties of selected products are given
in Table 1.
Scheme 4
Compounds 2—4 are of no interest as photochromes.
When exposed in the dark, the cyclic form B of comꢀ
pound 2 gave a byꢀproduct rather than the open form.
This byꢀproduct is characterized by a longꢀwavelength
absorption band with a maximum at 363 nm. Upon UV
R =
; R´ = Me (a), CH2Ph (b), 4ꢀMeC6H4CH2 (c),
4ꢀClC6H4CH2 (d), 3,4ꢀCl2C6H3CH2 (e), PhC(O)CH2 (f)
Like cyclic carbonate of benzoin,7 product 5 reacted
with primary alkylꢀ or arylalkylamines to form 3ꢀsubstiꢀ
tuted 4ꢀhydroxyꢀ1,3ꢀoxazolidinꢀ2ꢀones 6. The latter comꢀ
pounds were readily dehydrated under the action of
trifluoroacetic acid at room temperature to give the
corresponding 3ꢀsubstituted 1,3ꢀoxazolꢀ2ꢀones 7 (see
Scheme 2). Intermediates 6a—f were characterized. Acꢀ
cording to the NMR data, these intermediates were obꢀ
tained as one of two possible diastereomers. The carbonꢀ
ateꢀring opening gave rise to the first asymmetric center
and then the second center was generated in the step of
formation of the oxazolone ring. The configuration of
the latter is, apparently, determined by the configuration
of the first asymmetric center present in the acyclic inꢀ
termediate.
It is known8 that the fatigue resistance of photochroꢀ
mic dithienylethenes is enhanced upon the introduction
of alkyl groups at position 4 of the thiophene ring. In the
present study, we synthesized 4,4´ꢀdiacetyl derivatives
8a,b by acylation of compounds 5 and 7a with an excess
of acetyl chloride in dichloromethane in the presence of
aluminum chloride (Scheme 3).
Table 1. Spectroscopic characteristics of compounds 2—5,
7a—f, and 8a,b
Comꢀ
pound
λ
a/nm
kb•105/s–1
max
Open
Cyclic
form (A)
form (B)
2
3
4
5
7a
7b
7c
7d
7e
7f
8a
8b
294
244
243
280
287
286
285
286
284
283
220
245
464
462
450
442
450
453
452
449
457
447
447
445
—
—
—
0.035
0.002
0.002
0.93
2.1
9.1
0.011
0.003
0.0003
a The maxima of the longꢀwavelength absorption bands.
b The rate constant of the dark ringꢀopening reaction.

Dithienylethenes with new heterocyclic fragments
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
1733
irradiation, the diacetyl (3) and dibenzoyl (4) derivatives
of imidazolꢀ2ꢀone yielded the cyclic forms in small
amounts. Previously,4 we have already observed that
dithienylethenes lose their photochromic properties as
the number of electronꢀwithdrawing groups in the bridgꢀ
ing fragment is increased.
Since the oxazolꢀ2ꢀone ring was first treated as a
bridge in photochromes, it was of interest to compare
the conformation of compound 8b established by Xꢀray
diffraction analysis (Fig. 1) with the data for the open
forms of dithienylethenes studied previously. Recall that
the latter compounds are characterized by substantial
rotation of the thienyl fragments with respect to the plane
of the linking ring, i.e., there is no conjugation between
the πꢀelectrons of the aromatic heterocycles and the
double bond of the bridge. The conformation of molꢀ
ecule 8b is similar to that of photochromic perfluoroꢀ
cyclopenteneꢀbridged dithienylethenes.9 The thiophene
rings (T and T´) are in the antiꢀparallel orientation, i.e.,
the methyl substituents at the C(2) and C(2´) active
centers are located on the opposite sides with respect to
the plane of the oxazolone ring (OR). The thiophene
rings are substantially rotated with respect to the plane
of the bridge, i.e., there is no conjugation between the
heterocycles. However, the angles of rotation of the
thienyl fragments in molecule 8b, unlike those in diꢀ
thienylperfluorocyclopentenes, differ from each other.
Thus, the dihedral angle OR—T is 46.19°, whereas the
OR—T´ angle is increased to 58.72° due, apparently, to
steric hindrances between the methyl and acetyl groups.
The thienyl fragments are rotated with respect to each
other by 68.35°. The angles of rotation of the acetyl
groups with respect to the thienyl fragments are virtually
equal (33.50°). There are no shortened intraꢀ and interꢀ
molecular contacts in the structure. In the oxazolꢀ2ꢀone
ring, the C(4″)—C(5″) bond length (1.336(2) Å) is equal
to the standard Csp=Csp double bond length typical of
oxazolones,10,11 which indicates that there is no electron
density delocalization in this heterocycle.
Carbonate 5 possesses the photochromic properties.
As can be seen from Table 1, the cyclic form of 5 is
rather stable (the rate constant of the ring opening k =
3.55•10–7 s–1). It should be emphasized that the introꢀ
duction of the acetyl groups at positions 4 and 4´ of the
thienyl rings leads to a decrease in this constant by alꢀ
most an order of magnitude for 1,3ꢀdioxolꢀ2ꢀone 8a and
by two orders of magnitude for 3ꢀmethylꢀ1,3ꢀoxazolꢀ
2ꢀone 8b. Hence, it means that exposition of compounds
8a and 8b in the dark at room temperature for 100 h
leads to a decrease in the amount of their cyclic forms B
by less than 1 and by 0.1%, respectively. It can be asꢀ
sumed that the acetyl groups in these compounds are
favorable for stabilization of the cyclic forms B of
dithienylethenes. It should also be noted that the introꢀ
duction of the acetyl substituents leads to an increase in
the fatigues resistance of photochromes. Thus, after eight
openingꢀclosing photocycles, the optical density of
oxazolꢀ2ꢀone 7a was only 23% of the initial optical denꢀ
sity at the maximum of the cyclic form, whereas the
corresponding value for substituted product 8b was 82%.
Oxazolinone photochromes 7a, 7b, and 7f also proved
to be thermally stable (k = 1.95•10–8, 1.95•10–8, and
1.13•10–7 s–1, respectively). However, it remains unꢀ
clear why the constants k for their close analogs containꢀ
ing the alkyl substituents (7c) or halogen atoms (7d,e) in
the phenyl ring are much higher (1•10–5—1•10–4 s–1).
O(2)
C(2″)
C(10)
O(1)
O(3)
C(9)
C(8)
N
C(5″)
C(4″)
O(3´)
C(3)
C(4)
C(3´)
C(8´)
C(4´)
C(5´)
C(9´)
C(6´)
C(5)
C(2´)
C(7)
C(2)
C(6)
S´
C(7´)
S
Fig. 1. Molecular structure of compound 8b.

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Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
Krayushkin et al.
1,3ꢀDiacetylꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ1H,3Hꢀimidꢀ
azolꢀ2ꢀone (3). A solution of compound 2 (0.304 g, 1 mmol) in
Ac2O (5 mL, 0.053 mol) was refluxed for 4 h. The reaction
mixture was cooled, water (5 mL) was added, and the precipiꢀ
tate that formed was filtered off. After recrystallization from
EtOH, product 3 was obtained in a yield of 0.280 g (72%), m.p.
179—180 °C. Found (%): C, 58.59; H, 5.05; N, 7.59; S, 16.23.
C19H20N2O3S2. Calculated (%): C, 58.74; H, 5.19; N, 7.21;
S, 16.51. 1H NMR (DMSOꢀd6), δ: 1.88, 2.28, and 2.56 (all s,
6 H, 2 Me); 6.41 (s, 2 H, 2 CH).
1,3ꢀDibenzoylꢀ4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ1H,3Hꢀimidꢀ
azolꢀ2ꢀone (4). A mixture of compound 2 (0.100 g, 0.33 mmol)
and PhCOCl (0.141 g, 1 mmol) in Py (2 mL) was heated at
100 °C for 2 h. The reaction mixture was cooled, water (10 mL)
was added, and the product was extracted with ether (3×10 mL).
The extract was successively washed with water, a 10% HCl
solution, and water, and dried with MgSO4. The solvent was
concentrated in vacuo and the residue was recrystallized from
AcOH. Product 4 was obtained in a yield of 0.100 g (59%),
m.p. 183—184 °C. Found (%): C, 68.18; H, 4.64; N, 5.11;
S, 12.82. C29H24N2O3S2. Calculated (%): C, 67.95; H, 4.72;
N, 5.46; S, 12.51. 1H NMR (DMSOꢀd6), δ: 2.04 and 2.26
(both s, 6 H each, 2 Me); 6.51 (s, 2 H, 2 CH); 7.58 (m, 6 H,
6 CHAr); 7.94 (m, 4 H, 4 CHAr).
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ1,3ꢀdioxolꢀ2ꢀone (5). A
mixture of thenoin 1 (0.560 g, 2 mmol) and 1,1´ꢀcarbonylꢀ
diimidazole (0.486 g, 3 mmol) in benzene (8 mL) was refluxed
for 5—6 h. The reaction mixture was cooled and washed with
water, a 10% HCl solution, and water. The solvent was conꢀ
centrated in vacuo and the residue was recrystallized from
EtOH. Product 5 was obtained in a yield of 0.550 g (90%),
m.p. 106—107 °C. Found (%): C, 58.92; H, 4.56; S, 21.21.
C15H14O3S2. Calculated (%): C, 58.80; H, 4.61; S, 20.93.
1H NMR (CDCl3), δ: 2.21 and 2.41 (both s, 6 H each, 2 Me);
6.58 (s, 2 H, 2 CH).
Synthesis of 3ꢀsubstituted 4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
4ꢀhydroxyꢀ1,3ꢀoxazolidinꢀ2ꢀones 6 (general procedure). The corꢀ
responding primary amine* (1.5 mmol) was added to a solution
of carbonate 5 (0.306 g, 1 mmol) in EtOH (3 mL). The reacꢀ
tion mixture was stirred at ∼25 °C for 1—1.5 h. The precipiꢀ
tate that formed was filtered off and the product was reꢀ
crystallized from EtOH. The physicochemical characterisꢀ
tics of 4ꢀhydroxyꢀ1,3ꢀoxazolidinꢀ2ꢀones 6a—f are given in
Table 2.
On the whole, a comparison of the properties of
1,3ꢀazoleꢀbridged dithienylethenes studied previously
with photochromes bearing carbonylꢀcontaining heteroꢀ
cycles provides evidence that a weakening of the aromaꢀ
ticity in the cyclic bridge is favorable for the enhanceꢀ
ment of stability of the cyclic form and, as a conseꢀ
quence, for an increase in its thermal stability.
To summarize, we developed methods for the synꢀ
thesis of substituted bis(2,5ꢀdimethylꢀ3ꢀthienyl)ethenes
in which the imidazolꢀ2ꢀone, 1,3ꢀdioxolꢀ2ꢀone, or
1,3ꢀoxazolꢀ2ꢀone systems serve as the ethene fragment.
It was demonstrated that these compounds exhibit phoꢀ
tochromic properties, the latter two compounds being
virtually thermally stable.
Experimental
The 1H and 13C NMR spectra were recorded on Bruker
AMꢀ300 (300.13 MHz) and Bruker WMꢀ250 (250.13 MHz)
instruments in DMSOꢀd6 and CDCl3, respectively. The meltꢀ
ing points were determined on a Boetius stage and were not
corrected. The mass spectrum was measured on a Kratos MSꢀ30
instrument with direct inlet of the sample into the ion source;
the energy of ionizing electrons was 70 eV. The course of the
reactions and the purities of the products were monitored by
TLC on Merck Silica gel 60 F254 plates using an AcOEt—hexane
mixture as the eluent.
The photochromic characteristics of compounds 2—5, 7,
and 8 were studied in a solution in MeCN (special purity grade).
The cyclic forms B of the photochromes were prepared by
irradiation of the samples with a DRShꢀ500 mercury lamp
using light filters to separate lines of the Hg spectrum (313,
546, and 578 nm) and were then identified based on λmax in the
UV spectrum. The intensity of radiation of the Hg lamp was
determined using a F4 photoelement calibrated against a
ferrioxalate actinometer12 for λ = 313 nm and against an actiꢀ
nometer based on the Reinecke salt13 for λ = 546 and 578 nm.
The absorption spectra were recorded on a Shimadzu UVꢀ3100
spectrophotometer.
The reaction rate of the dark ringꢀopening reaction k was
determined according to the equation
Synthesis of 3ꢀsubstituted 4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ
oxazolꢀ2ꢀones 7 (general procedure). A solution of the correꢀ
sponding 4ꢀhydroxyꢀ1,3ꢀoxazolidinꢀ2ꢀone 6 (0.5 mmol) in
CF3COOH (5 mL, 0.065 mol) was kept at ∼25 °C for 3—3.5 h.
The solvent was concentrated in vacuo and the residue was
crystallized from EtOH. The physicochemical characteristics
of 1,3ꢀoxazolꢀ2ꢀones 7a—f are given in Table 3.
Acylation of bis(2,5ꢀdimethylꢀ3ꢀthienyl)ethenes (general proꢀ
cedure). Aluminum chloride (2.5 g, 0.019 mol) was added with
stirring to a solution of the corresponding dithienylethene
(1 mmol) and AcCl (1.7 g, 0.022 mol) in CH2Cl2 (15 mL). The
resulting mixture was stirred at ∼25 °C for 6 h and careꢀ
fully poured onto ice. The product was extracted with ether
Dt = D0exp(–kt),
where D0 is the initial optical density at the maximum of the
longꢀwavelength band in the absorption spectrum of the cyclic
form and Dt is the optical density at this maximum at the
moment t.
4,5ꢀBis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ1H,3Hꢀimidazolꢀ2ꢀone (2).
A solution of thenoin 1 3 (0.840 g, 3 mmol) and urea (0.360 g,
6 mmol) in AcOH (4 mL) was refluxed for 2 h. The reaction
mixture was cooled. The precipitate that formed was filtered
off and washed with a small amount of EtOH. Product 2 was
obtained in a yield of 0.668 g (73%), m.p. 280—281 °C.
Found (%): C, 58.95; H, 5.19; N, 9.48; S, 21.35. C15H16N2OS2.
Calculated (%): C, 59.18; H, 5.30; N, 9.20; S, 21.06.
1H (DMSOꢀd6), δ: 1.98 and 2.32 (both s, 6 H each, 2 Me); 6.53
(s, 2 H, 2 CH); 10.16 (s, 2 H, 2 NH).
* In the case of MeNH2, a 2.0 M methanolic solution (Aldrich)
was used.

Dithienylethenes with new heterocyclic fragments
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
1735
Table 2. Physicochemical characteristics of 3ꢀsubstituted 4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ4ꢀhydroxyꢀ1,3ꢀoxazolidinꢀ2ꢀones 6a—f
Comꢀ M.p.
pound /°С
Yield
(%)
Found
Calculated
Molecular
formula
1H NMR spectrum
(DMSOꢀd6, δ, J/Hz)
(%)
С
Н
N
S
6a
6b
227—228
248—249
86
82
56.81 5.75 3.93 19.26
56.95 5.68 4.15 19.00
C16H19NO3S2
C22H23NO3S2
1.82, 2.13, 2.32, 2.39, 2.68 (all s, 3 H each, Me);
5.27 (s, 1 Н, СН); 6.53 (s, 1 Н, OН);
6.61, 6.82 (both s, 1 H each, СН)
1.80, 1.97, 2.18, 2.36 (all s, 3 H each, Me);
4.07 (d, 1 Н, НСН, J = 15.4); 4.41 (d, 1 Н, НСН,
J = 15.4); 5.45, 6.45 (both s, 1 H each, СН);
6.62 (s, 1 Н, OН); 6.82 (s, 1 Н, СН);
64.00 5.54 3.64 15.37
63.90 5.61 3.39 15.51
7.25 (m, 5 Н, СНAr
)
6c
253—254
92
91
94
64.45 5.78 3.46 14.76
64.61 5.89 3.28 15.00
C23H25NO3S2
1.79, 1.97, 2.19, 2.27, 2.36 (all s, 3 H each, Me);
4.03 (d, 1 Н, НСН, J = 15.2); 4.36 (d, 1 Н, НСН,
J = 15.2); 5.43, 6.45 (both s, 1 H each, СН);
6.58 (s, 1 Н, OН); 6.82 (s, 1 Н, СН);
7.07 (m, 4 Н, СНAr
)
6d* 258—259
6e** 226—227
59.06 4.87 3.46 14.48 C22H22ClNO3S2 1.81, 2.03, 2.20, 2.37 (all s, 3 H each, Me);
58.98 4.95 3.13 14.31
4.12 (d, 1 Н, НСН, J = 15.4); 4.38 (d, 1 Н, НСН,
J = 15.4); 5.47, 6.45 (both s, 1 H each, СН);
6.60 (s, 1 Н, OН); 6.82 (s, 1 Н, СН);
7.18, 7.32 (both d, 2 H each, СНAr, J = 8.3)
54.68 4.46 3.18 13.43 C22H21Cl2NO3S2 1.82, 2.07, 2.21, 2.36 (all s, 3 H each, Me);
54.77 4.39 2.90 13.29
4.14 (d, 1 Н, НСН, J = 15.4); 4.38 (d, 1 Н, НСН,
J = 15.4); 5.53, 6.49 (both s, 1 H each, СН);
6.62 (s, 1 Н, OН); 6.81 (s, 1 Н, СН);
7.19 (d, 1 Н, СНAr, J = 8.2); 7.33 (s, 1 Н, СНAr);
7.53 (d, 1 Н, СНAr, J = 8.3)
6f
209—210
63
62.63 5.33 3.49 14.27
62.56 5.25 3.17 14.52
C23H23NO4S2
1.88, 2.12, 2.27, 2.39 (all s, 3 H each, Me);
4.61 (s, 2 Н, СН2); 5.45 (s, 1 Н, СН);
6.57 (s, 1 Н, СН); 6.68 (s, 1 Н, OН);
6.85 (s, 1 Н, СН); 7.62 (m, 3 Н, СНAr);
7.95 (d, 2 Н, СНAr, J = 8.3)
* Found (%): Cl, 8.05. Calculated (%): Cl, 7.91.
** Found (%): Cl, 14.83. Calculated (%): Cl, 14.70.
Table 3. Physicochemical characteristics of 3ꢀsubstituted 4,5ꢀbis(2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ1,3ꢀoxazolꢀ2ꢀones 7a—f
Comꢀ M.p.
pound /°С
Yield
(%)
Found
Calculated
Molecular
formula
1H NMR spectrum
(DMSOꢀd6, δ, J/Hz)
(%)
С
Н
N
S
7a
7b
137
71
42
59.98 5.42 4.65 19.84
60.16 5.36 4.38 20.07
66.67 5.27 3.78 15.98
66.81 5.35 3.54 16.21
C16H17NO2S2
C22H21NO2S2
2.02, 2.11, 2.32, 2.43, 3.01 (all s, 3 H each, Me);
6.42, 6.83 (both s, 1 H each, СН)
1.79, 2.17, 2.29, 2.40 (all s, 3 H each, Me);
4.62 (br.s, 2 Н, СН2); 6.36, 6.65 (both s,
1 H each, СН); 6.97 (d, 2 Н, СНAr, J = 7.3);
123—124
7.27 (m, 3 Н, СНAr
)
7c
154
96
90
67.29 5.73 3.65 15.47
67.45 5.66 3.42 15.66
C23H23NO2S2
1.78, 2.15, 2.24, 2.25, 2.38 (all s, 3 H each, Me);
4.56 (br.s, 2 Н, СН2); 6.35, 6.65 (both s,
1 H each, СН); 6.85 (d, 2 Н, СНAr, J = 7.2);
7.08 (d, 2 Н, СНAr, J = 7.2)
7d* 120—121
61.63 4.75 2.93 15.13 C22H20ClNO2S2 1.81, 2.16, 2.27, 2.38 (all s, 3 H each, Me);
61.45 4.69 3.26 14.91
4.61 (br.s, 2 Н, СН2); 6.36, 6.63 (both s,
1 H each, СН); 6.99 (d, 2 Н, СНAr, J = 7.9);
7.34 (d, 2 Н, СНAr, J = 7.9)
(to be continued)

1736
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
Krayushkin et al.
Table 3 (continued)
Comꢀ M.p.
pound /°С
Yield
(%)
Found
Calculated
Molecular
formula
1H NMR spectrum
(DMSOꢀd6, δ, J/Hz)
(%)
С
Н
N
S
7e** 146—147
77
57.12 4.03 2.75 14.07 C22H19Cl2NO2S2 1.84, 2.16, 2.26, 2.38 (all s, 3 H each, Me);
56.90 4.12 3.02 13.81
4.63 (br.s, 2 Н, СН2); 6.36, 6.63 (both s,
1 H each, СН); 7.02 (d, 1 Н, СНAr, J = 7.8);
7.15 (s, 1 Н, СНAr); 7.55 (d, 1 Н, СНAr, J = 7.8)
2.00, 2.16, 2.27, 2.29 (all s, 3 H each, Me);
5.01 (s, 2 Н, СН2); 6.41, 6.63 (both s,
1 H each, СН); 7.60 (m, 3 Н, СНAr);
7.94 (d, 2 Н, СНAr, J = 7.6)
7f
184—185
96
65.46 4.92 2.98 15.42
65.22 5.00 3.31 15.14
C23H21NO3S2
* Found (%): Cl, 8.38. Calculated (%): Cl, 8.25.
** Found (%): Cl, 15.44. Calculated (%): Cl, 15.27.
(3×15 mL). The extract was successively washed with water, a
NaHCO3 solution, and again with water and then dried with
MgSO4. The solvent was concentrated in vacuo and the residue
was crystallized from EtOH.
4,5ꢀBis(4ꢀacetylꢀ2,5ꢀdimethylꢀ3ꢀthienyl)dioxolꢀ2ꢀone (8a)
was prepared in a yield of 0.350 g (90%), m.p. 152—153 °C.
Found (%): C, 58.26; H, 4.74; S, 16.78. C19H18O5S2. Calcuꢀ
lated (%): C, 58.44; H, 4.65; S, 16.42. 1H NMR, (CDCl3), δ:
2.08, 2.43, and 2.55 (all s, 6 H each, 2 Me). MS (EI),
m/z (Irel (%)): 390 [M+] (55).
References
1. M. M. Krayushkin, V. Z. Shirinyan, L. I. Belen´kii, A. A.
Shimkin, A. Yu. Martynkin, and B. M. Uzhinov, Zh. Org.
Khim., 2002, 38, 1391 [Russ. J. Org. Chem., 2002, 38, No. 8
(Engl. Transl.)].
2. V. Z. Shirinyan, M. M. Krayushkin, L. I. Belen´kii, L. G.
Vorontsova, Z. A. Starikova, A. Yu. Martynkin, V. L. Ivanov,
and B. M. Uzhinov, Khim. Geterotsikl. Soedin., 2001, 81
[Chem. Heterocycl. Compd., 2001 (Engl. Transl.)].
3. S. N. Ivanov, B. V. Lichitskii, A. A. Dudinov, A. Yu.
Martynkin, M. M. Krayushkin, and B. M. Uzhinov, Khim.
Geterotsikl. Soedin., 2001, 89 [Chem. Heterocycl. Compd.,
2001 (Engl. Transl.)].
4. M. M. Krayushkin, S. N. Ivanov, A. Yu. Martynkin, B. V.
Lichitskii, A. A. Dudinov, and B. M. Uzhinov, Izv. Akad.
Nauk, Ser. Khim., 2001, 113 [Russ. Chem. Bull., Int. Ed.,
2001, 50, 116].
5. M. M. Krayushkin, S. N. Ivanov, A. Yu. Martynkin, B. V.
Lichitskii, A. A. Dudinov, and B. M. Uzhinov, Izv. Akad.
Nauk, Ser. Khim., 2001, 2315 [Russ. Chem. Bull., Int. Ed.,
2001, 50, 2424].
6. H. Biltz, Liebigs Ann. Chem., 1905, 339, 243.
7. J. C. Sheehan and F. S. Guziec, J. Am. Chem. Soc., 1972,
94, 6561.
8. M. Irie, Chem. Rev., 2000, 100, 168.
9. M. M. Krayushkin, L. G. Vorontsova, and B. M. Uzhinov,
Intern. J. Photoenergy, 2001, 3, 25.
10. N. N. Tsou, R. G. Ball, P. J. Roy, and Y. Leblanc, Acta
Crystallogr., Sect. C (Cryst. Struct. Comm.), 1998, 54, 1493.
11. T. Ishizuka, S. Ishibuchi, and T. Kunieda, Tetrahedron
Lett., 1989, 30, 3449.
12. C. B. Hatchard and C. A. Parker, Proc. Roy. Soc., 1956,
A235, 518.
13. E. W. Wagner and A. W. Adamson, J. Am. Chem. Soc.,
1966, 88, 394.
14. G. M. Sheldrick, SHELXTL, v. 5.10, Structure Determination
Software Suite, Bruker AXS, Madison, Wisconsin, USA, 1998.
4,5ꢀBis(4ꢀacetylꢀ2,5ꢀdimethylꢀ3ꢀthienyl)ꢀ3ꢀmethyloxazolꢀ
2(3H )ꢀone (8b) was prepared in a yield of 0.227 g (56%), m.p.
142—143 °C. Found (%): C, 59.66; H, 5.17; N, 3.72; S, 15.64.
C
20H21NO4S2. Calculated (%): C, 59.53; H, 5.25; N, 3.47;
1
S, 15.89. H NMR (DMSOꢀd6), δ: 1.93, 2.09, 2.31, 2.43, 2.49,
2.62, and 2.87 (all s, 3 H each, Me).
Xꢀray diffraction study of compound 8b. Colorless single
crystals of composition C20H21NO4S2 were grown from a soluꢀ
tion in EtOH. The crystals are triclinic, a = 9.506(2), b =
9.785(2), c = 11.582(2) Å, α = 99.83(3), β = 92.99(3), γ =
–
112.28(3)°, space group P1, Z = 2, V = 974.1(3) Å3, dcalc
=
1.376 g cm–3, M = 403.50. The unit cell parameters and intenꢀ
sities of 4226 independent reflections were measured on an
automated fourꢀcircle Enraf—Nonius CADꢀ4 diffractometer
at ∼20 °C (graphite monochromator, MoꢀKα radiation, q—5/3q
scanning technique). The intensities of reflections were meaꢀ
sured in the angle range 1.80° ≤ θ ≤ 26.97°. The calculations
were carried out using 3025 reflections with I > 2σ(I). The
structure was solved by direct methods and the positions of all
nonhydrogen atoms were revealed. The structure was refined
by the fullꢀmatrix leastꢀsquares method based on F2 with anisoꢀ
tropic thermal parameters for the nonhydrogen atoms. The
positions of the hydrogen atoms were revealed from difference
electron density syntheses and then refined isotropically by the
leastꢀsquares method. The final reliability factors were as folꢀ
lows: R1 = 0.037 (wR2 = 0.105) and R1 = 0.066 (wR2 = 0.124)
for all reflections. Calculations were carried out with the use of
the SHELXTL PLUS 5.10 program package.14 The atomic
coordinates, thermal parameters, and geometric parameters of
the molecule were deposited with the Cambridge Structural
Database.
Received November 6, 2001;
in revised form April 1, 2002