Synthesis and spectral studies of photochromism of 1,3-benzoxazinone spiropyrans

Article abstract of DOI:10.1007/s11172-009-0337-3

Photochromism of the spiropyran derivatives of the 1,3-benzoxazinone series was studied. A relationship between the structure of substituents and photochromic properties of the compounds was revealed.

Full text of DOI:10.1007/s11172-009-0337-3

Russian Chemical Bulletin, International Edition, Vol. 58, No. 12, pp. 2418—2422, December, 2009
2418
Full Articles
Synthesis and spectral studies of photochromism
of 1,3ꢀbenzoxazinone spiropyrans
L. D. Popov,a I. N. Shcherbakov,a A. O. Bulanov,a O. I. Kobeleva,b T. M. Valova,b and V. A. Barachevskyb
aSouthern Federal University,
105 ul. B. Sadovaya, 344104 RostovꢀonꢀDon, Russian Federation.
Eꢀmail: shcherbakov@rsu.ru
bPhotochemistry Center, Russian Academy of Sciences,
7a ul. Novatorov, 119421 Moscow, Russian Federation.
Eꢀmail: barva@photonics.ru
Photochromism of the spiropyran derivatives of the 1,3ꢀbenzoxazinone series was studied.
A relationship between the structure of substituents and photochromic properties of the
compounds was revealed.
Key words: photochromism, 1,3ꢀbenzoxazinone spiropyrans, absorption spectra, photoꢀ
induced absorbance.
Interest in extension of the area of using photochroꢀ
tions between two forms, in particular, between the initial
closed colorless spiropyran form А and the photoinduced
colored merocyanine form B (Scheme 1).
mic spiro compounds, in particular, for the development
of reversive photocontrolled chemosensors, has recently
increased.1—3 In this work we present the results of the
spectral kinetic study of photochromism of the recently
synthesized new 1,3ꢀbenzoxazinone spiropyrans.
Under the action of the UV light absorbed by the
closed form А, a spiro compound molecule is transformed
into the merocyanine (open) form B due to the photoꢀ
dissociation of the Сspiro—О bond followed by thermal
cis—transꢀisomerization. The form B can spontaneously
undergo recyclization to the form А. This process can
be accelerated by the light absorbed by the form B or by
heating of the solution. The processes of reversible photoꢀ
and thermal transformations can multiply be repeated.
Fatigue resistance of photochromic transformations is
Results and Discussion
The objects of the study were solutions of 1,3ꢀbenzꢀ
oxazinone spiropyrans 1—9.
It is known4 that spiro compounds of general formula
А (Q = CH, N) experience reversible phototransformaꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2340—2344, December, 2009.
1066ꢀ5285/09/5812ꢀ2418 © 2009 Springer Science+Business Media, Inc.

Photochromism of 1,3ꢀbenzoxazinone spiropyrans
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009 2419
Z = O (7), S (8)
Scheme 1
Due to the slow process of thermal relaxation, the photoꢀ
induced change in the absorbance (ΔDph) at the waveꢀ
length of the absorption band maximum of the photoinꢀ
duced merocyanine form reaches the value ΔDph = 0.64
Table 1. Results of the spectral kinetic study of
phototransformations of solutions of compounds 1—9
in DMSO and MeCN
ΔDph
max
max
Comꢀ
pound
Solvent
λ
λ
B
А
nm
1
2
DMSO
MeCN
DMSO
MeCN
260, 294
258, 295
282, 362
281, 351
400
400
453
445
505
450, 587
455
490
478
490
<0.02
0.03
0.64
0.76
0.47
0.09
0.15
0.07
0.02
0.18
0.08
0.05
0.02
limited by irreversible photoꢀ and thermodegradation proꢀ
cesses of the forms А and B, which usually accompany
these transformations.
The results of studies of photochromism of benzꢀ
oxazinone spiropyrans are presented in Table 1 and
in Figs 1—4.
3
4
5
6
DMSO 270, 317, 375
DMSO
DMSO
DMSO
MeCN
DMSO
MeCN
DMSO
DMSO
286, 347
280, 350
315
305
Compound 2 in DMSO in the initial spiropyran form
is characterized by absorption bands at 283, 362, and
453 nm (see Fig. 1, curve 1). After the solution was
UVꢀirradiated, the intensity of the absorption band at
283 nm decreases and the absorption at 400—500 nm
increases (see Fig. 1, curve 2). After switching off the
UVꢀradiation source, the initial absorption spectrum
is recovered (see Fig. 1, curves 3—7) due to the sponꢀ
taneous transformation of the form B into the form А,
7
282, 325
285, 315
282, 338
285, 354
475
480
483
8
9
max
max
Note. λ
and λ
are the wavelengths of absorpꢀ
А
B
tion band maxima of the spiropyran and photoinduced
merocyanine forms, respectively; ΔDph is the maxiꢀ
mum photoinduced change in the absorbance of
the solution at the absorption band maximum of the
photoinduced merocyanine form.
which is characterized by the rate constant k = 0.06 s–1
.

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Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009
Popov et al.
A
A
1.25
1.00
0.75
0.50
0.25
1.0
0.8
0.6
0.4
0.2
1
2
7
2
350
400
450
λ/nm
1
Fig. 3. Absorption spectra of a solution of compound 5 in DMSO
before (1) and after (2) UV irradiation with the wavelength
313 nm.
300
400
500
λ/nm
Fig. 1. Absorption spectra of a solution of compound 2 in DMSO
before (1) and after (2—7) UV irradiation with the wavelength
313 nm.
A
1.6
1.4
A
1.2
1
0.6
1.0
0.8
0.6
0.4
0.2
0.4
2
0.2
300
350
400
450
500
λ/nm
Fig. 4. Absorption spectra of a solution of compound 8 in DMSO
before (1) and after (2) UV irradiation with the wavelength 313 nm.
300
350
400
450
λ/nm
Fig. 2. Absorption spectra of a solution of compound 1 in MeCN
before UV irradiation.
Unlike the above considered photochromic spiroꢀ
pyrans, other compounds studied are characterized by
the high rate of thermal decoloration. Therefore, they
are characterized by substantially lower values of photoꢀ
induced changes in the absorbance, which do not exceed
ΔDph = 0.18 (see Table 1).
Unlike the spectra of compounds 2 and 3, the absorpꢀ
tion spectrum of the spiropyran form of compound 1
exhibits no longꢀwavelength absorption band (see Fig. 2).
This is due, most likely, that compound 1 contains no
imine moiety absorbing at 360—380 nm. Probably, this is
a reason for the sharp hypsochromic shift of the absorpꢀ
tion band maximum of the photoinduced open form to
400 nm and for the acceleration of spontaneous decolorꢀ
ation (see Table 1).
(see Table 1). When the polar solvent (DMSO, ε = 48.9)
is replaced by a less polar one (MeCN, ε = 36.1), the
absorption bands at 362 and 453 nm undergo the hypsoꢀ
chromic shift by 8—11 nm (see Table 1), which, as in the
case of spirooxazines,5 indicates the quinoid character of
the merocyanine form of compound 2. The photoinduced
change in the absorbance increases to ΔDph = 0.76 (see
Table 1). It should be mentioned that the absorption band
at 362 nm experiences insignificant photoinduced changes.
The introduction of the acceptor substituent NO2
(compound 3) into the imine moiety results in the bathoꢀ
chromic shift of the longꢀwavelength absorption bands of
the spiropyran and merocyanine forms by 13 and 53 nm,
respectively (see Table 1). The photoinduced change in
the absorbance remains rather high (ΔDph = 0.47).
Unlike all the compounds studied, two absorption
bands of the photoinduced form were observed for
spiropyran 4: at 450 and 587 nm (see Table 1).

Photochromism of 1,3ꢀbenzoxazinone spiropyrans
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009 2421
hydrazide (7) and thiocarbohydrazide (8), were synthesized
according to a known procedure.6 Compounds 1—6 and 9 were
synthesized as described below.
The photochromic transformations of isomeric comꢀ
pounds 5 and 6 differ substantially when they are comꢀ
pared with each other and also for comparison with other
compounds (see Table 1). The photoinduced change in
the absorption spectra of compound 5, unlike the spectra
of compounds 2 and 3, appears a sharp decrease in the
intensity of the longꢀwavelength absorption band of
the cyclic form at 350 nm (see Fig. 3). The least efficient
photochromic transformations were observed for comꢀ
pound 9 (see Table 1). It should be mentioned that, as in
the case of compound 2, the replacement of more polar
DMSO by less polar MeCN results in the hypsochromic
shift, whereas the bathochromic shift of the absorption
bands of both the spiropyran and merocyanine forms is
observed for compound 7 (see Table 1).
8´ꢀMethoxyꢀ3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzꢀ
oxazineꢀ2,2´ꢀchromene] (1) was synthesized by a procedure
published earlier.7 The yield was 74%, m.p. 152—153 °C.
Found (%): C, 69.50; H, 4.30; N, 5.07. C18H15NO4. Calculꢀ
ated (%): С, 69.99; H, 4.85; N, 4.52. IR, ν/cm–1: 1680 (C=O),
1656 (C=C, chromene), 1612 (С=С, arom.), 1374 (С—N),
988, 935, 766 (Cspiro—O). 1H NMR, δ: 7.91 (dd, 1 H, H(5),
J = 7.7 Hz, J = 1.6 Hz); 7.49 (ddd, 1 H, H(7), J = 8.0 Hz,
J = 7.5 Hz, J = 1.6 Hz); 7.17 (dd, 1 H, H(6), J = 7.7 Hz,
J = 7.5 Hz); 7.07 (d, 1 H, H(4´), J = 9.7 Hz); 6.82—6.98 (m,
4 H, H(8), H(5´), H(6´), H(7´)); 6.17 (d, 1 H, H(3´),
J = 9.70 Hz); 3.60 (s, 3 H, OMe); 3.07 (s, 3 H, NMe).
7´ꢀHydroxyꢀ8´ꢀ(2ꢀhydroxyphenyliminomethyl)ꢀ3ꢀmethylꢀ
4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene] (2).
A solution of 2ꢀaminophenol (0.1 g, 0.001 mol) in ethanol
(5 mL) was added to a solution of 7´ꢀhydroxyꢀ8´ꢀformylꢀ3ꢀmethylꢀ
4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene]7
(0.32 g, 0.001 mol) in ethanol (10 mL). The mixture was refluxed
for 2.5 h. The orange precipitate formed was filtered off, washed
with hot methanol, and recrystallized from an ethanol—MeCN
mixture. The yield was 0.12 g (25%), m.p. 225 °С. Found (%):
C, 69.90; Н, 3.70; N, 6.30. C24H18N2O5. Calculated (%): С,
69.58; H, 4.34; N, 6.75. IR, ν/cm–1: 3500 (OH´, anyl), 2800—3100
(OH, chromene), 1664 (C=O), 1647 (C=C, chromene), 1609,
1602 (С=С, arom.), 1590 (С=N), 1320 (С—N). 1H NMR, δ:
14.47 (s, 1 H, OH); 9.86 (s, 1 H, OH″); 8.40 (s, 1 H, CH=N);
7.98 (dd, 1 H, H(5), J = 7.7 Hz, J = 1.3 Hz); 7.57 (ddd, 1 H,
H(7), J = 8.1 Hz, J = 7.7 Hz, J = 1.3 Hz); 7.47 (d, 1 H, H(5´),
J = 8.6 Hz); 7.31 (dd, 1 H, H(6), J = 7.7 Hz, J = 7.7 Hz); 7.18
(d, 1 H, H(4´), J = 9.7 Hz); 7.09 (dd, 1 H, H(3″), J = 7.9 Hz,
J = 7.7 Hz); 7.02 (d, 1 H, H(8), J = 8.1 Hz); 6.90 (d, 1 H, H(1″),
J = 8.0 Hz); 6.77 (dd, 1 H, H(2″), J = 8.0 Hz, J = 7.7 Hz); 6.65
(d, 1 H, H(6´), J = 8.5 Hz); 6.52 (d, 1 H, H(4″), J = 7.9 Hz);
6.30 (d, 1 H, H(3´), J = 9.7 Hz); 3.13 (s, 3 H, NMe).
7´ꢀHydroxyꢀ8´ꢀ(2ꢀhydroxyꢀ5ꢀnitrophenyliminomethyl)ꢀ
3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene]
(3) was synthesized similarly to compound 2. The red precipitate
formed from the reaction mixture was filtered off, washed with
hot methanol, and recrystallized from dioxane. The yield was
45%, m.p. >290 °C. Found (%): C, 79.70; H, 5.30; N, 12.10.
С24H17N3O7. Calculated (%): С, 80.24; H, 4.73; N, 11.69.
IR, ν/cm–1: 3400 (OH´, anyl), 2900—3100 (OH, chromene),
1670 (C=O), 1642 (C=C, chromene), 1615, 1603 (С=С, arom.),
1585 (С=N), 1320 (С—N). 1H NMR, δ: 13.63 (s, 1 H, OH);
10.53 (s, 1 H, OH″); 8.49 (s, 1 H, CH=N); 7.96 (d, 1 H, H(5),
J = 7.5 Hz); 7.69 (d, 1 H, H(1″), J = 2.5 Hz); 7.60 (dd, 1 H,
H(3″), J = 8.2 Hz, J = 2.5 Hz); 7.54 (dd, 1 H, H(7), J = 7.8 Hz,
J = 8.0 Hz); 7.42 (d, 1 H, H(5´), J = 8.5 Hz); 7.28 (dd, 1 H,
H(6), J = 7.8 Hz, J = 7.5 Hz); 7.09 (d, 1 H, H(4´), J = 9.8 Hz);
6.92 (d, 1 H, H(8), J = 8.0 Hz); 6.69 (dd, 1 H, H(4″), J = 7.6 Hz,
J = 2.5 Hz); 6.69 (d, 1 H, H(6´), J = 8.5 Hz); 6.14 (d, 1 H, H(3´),
J = 9.8 Hz); 3.14 (s, 3 H, NMe).
Similar photoinduced spectral changes were observed
for bis(spiropyrans) 7—9. The photoinduced spectral
changes for compound 8 are shown in Fig. 4.
The replacement of the С=О group (compound 7) by
the С=S group (compound 8) induces the bathochromic
shift of the longꢀwavelength absorption band of the initial
spiropyran form and the hypsochromic shift of the
absorption band of the photoinduced merocyanine form.
In addition, compound 8 is characterized by the high rate
of dark decoloration compared to that of spiropyran 7,
which decreases the photoinduced change in the absorbꢀ
ance at the equilibrium state (see Table 1).
Thus, the study of spiropyrans of the 1,3ꢀbenzꢀ
oxazinone series 1—9 showed that all of them manifest
the photochromic transformations. The data of the study of
solvatochromism show that the photoinduced merocyanine
form of these compounds has the quinoid structure.
Due to the high rate of dark decoloration of the phoꢀ
toinduced form, at 20 °С the photoinduced change in the
absorbance in the visible region is low for the most part of
compounds. The exception is spiropyrans bearing imine
moieties as substituents, which, most likely, impede
cis—transꢀisomerization and, hence, decrease the rate
of spontaneous relaxation of the photoinduced meroꢀ
cyanine form to the initial spiro form.
Experimental
The IR spectra of the compounds studied were recorded in a
Nujol suspension on a Varian Scimitar spectrometer in the region
from 400 to 4000 cm–1. The 1H NMR spectra were measured in
a DMSOꢀd6 solution at 20 °C on a Bruker AMꢀ300 instrument
using Me4Si as the internal standard. Spectral studies were carried
out using a USB2000 opticalꢀfiber spectrometer (Ocean Optics).
A CARY UV 50 spectrophotometer (Varian) was used to
study the kinetics of photochromic transformations of the
compounds. The solvents used were DMSO and MeCN (Aldrich).
7´ꢀHydroxyꢀ3ꢀmethylꢀ4ꢀoxoꢀ8´ꢀ(1,2,4ꢀtriazolꢀ4ꢀyliminoꢀ
methyl)ꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene] (4).
A solution of 4ꢀaminoꢀ1,2,4ꢀtriazole (0.168 g, 0.002 mol)
in ethanol (7 mL) was poured to a solution of 7´ꢀhydroxyꢀ
8´ꢀformylꢀ3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ
2,2´ꢀchromene] (0.652 g, 0.002 mol) in ethanol (10 mL), and
the mixture was refluxed for 1 h. A yellowish precipitate formed
The working concentration of solutions was 2•10–4 mol L–1
A 0.2ꢀcm quartz cell was used for measurements. Irradiation
was carried out by the filtered light from a DRShꢀ250 lamp.
Bis(hydrazones), 7´ꢀhydroxyꢀ8´ꢀformylꢀ3ꢀmethylꢀ4ꢀoxoꢀ
3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene] with carboꢀ
.

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Russ.Chem.Bull., Int.Ed., Vol. 58, No. 12, December, 2009
Popov et al.
was filtered off, washed with hot methanol, and recrystallized
from an ethanol—dioxane mixture. The yield was 0.46 g (75%),
m.p. >260 °C. Found (%): C, 61.30; H, 3.30; N, 17.59.
C20H15N5O4. Calculated (%): С, 61.72; H, 3.85; N, 17.19.
IR, ν/cm–1: 2900—3200 (OH, chromene), 1665 (C=O), 1648
(C=C, chromene), 1610 (С=С, arom.), 1590 (С=N), 1320
(С—N). 1H NMR, δ: 10.58 (s, 1 H, OH); 8.62 (s, 1 H, CH=N);
8.46 (s, 2 H, H of triazole); 7.98 (dd, 1 H, H(5), J = 7.3 Hz,
J = 1.3 Hz); 7.49 (ddd, 1 H, H(7), J = 8.1 Hz, J = 7.6 Hz,
J = 1.3 Hz); 7.37 (d, 1 H, H(5´), J = 8.5 Hz); 7.22 (dd, 1 H,
H(6), J = 7.3 Hz, J = 7.6 Hz); 7.06 (d, 1 H, H(4´), J = 9.7 Hz);
6.86 (d, 1 H, H(8), J = 8.1 Hz); 6.65 (d, 1 H, H(6´), J = 8.5 Hz);
6.09 (d, 1 H, H(3´), J = 9.7 Hz); 3.12 (s, 3 H, NMe).
Schiff base of 4ꢀaminoacetoacetanilide and 7´ꢀhydroxyꢀ
8´ꢀformylꢀ3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ
2,2´ꢀchromene] (5) was synthesized similarly to compound 2.
The orange precipitate formed from the reaction mixture
was separated by filtration, washed with hot methanol, and
recrystallized from an ethanol—dioxane mixture. The yield
was 56%, m.p. >260 °C. Found (%): C, 68.60; H, 5.10; N, 9.70.
С26H21N3O5. Calculated (%): С, 68.59; H, 4.61; N, 9.23.
IR, ν/cm–1: 3340 (NH), 2750—3100 (OH, chromene), 1665
(C=O), 1648 (C=C, chromene), 1600 (С=С, arom.), 1580
(С=N), 1321 (С—N). 1H NMR, δ: 13.71 (s, 1 H, OH); 9.84 (s,
1 H, NH); 8.30 (s, 1 H, CH=N); 7.99 (dd, 1 H, H(5), J = 7.4 Hz,
J = 1.3 Hz); 7.51 (d, 2 H, H(3″), J = 8.0 Hz); 7.50 (ddd, 1 H,
H(7), J = 8.0 Hz, J = 7.5 Hz, J = 1.3 Hz); 7.35 (d, 1 H, H(5´),
J = 8.3 Hz); 7.23 (dd, 1 H, H(6), J = 7.5 Hz, J = 7.4 Hz); 7.07
(d, 1 H, H(4´), J = 9.7 Hz); 6.92 (d, 1 H, H(8), J = 8.0 Hz); 6.74
(d, 2 H, H(2″), J = 8.0 Hz); 6.59 (d, 1 H, H(6´), J = 8.3 Hz);
6.12 (d, 1 H, H(3´), J = 9.7 Hz); 3.13 (s, 3 H, NMe); 2.03 (s,
3 H, C(O)Me).
azone)8 (0.116 g, 0.001 mol) in ethanol (10 mL) was added to a
solution of 7´ꢀhydroxyꢀ8´ꢀformylꢀ3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydroꢀ
spiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene] (0.652 g, 0.002 mol) in
ethanol (10 mL). The mixture was refluxed for 3 h. A dark
yellow precipitate formed was separated, washed with boiling
methanol, and refluxed for 5 h in anhydrous methanol (20 mL) for
further purification. The yield was 0.48 g (62%), m.p. >250 °C.
Found (%): C, 62.70; H, 3.80; N, 15.60. С38H28N8O8. Calꢀ
culated (%): С, 62.98; H, 3.89; N, 15.46. IR, ν/cm–1: 3504,
3401 (NH), 2600—3100 (OH, chromene), 1679 (C=O), 1649
(C=C, chromene), 1616 (С=С, arom.), 1595 (С=N), 1320
1
(С—N), 944, 767 (Cspiro—O). H NMR, δ: 11.74 (s, 2 H, OH);
8.25 (s, 2 H, CH=N); 7.94 (dd, 2 H, H(5), J = 7.78 Hz, J = 1.6 Hz);
7.51 (ddd, 2 H, H(7), J = 8.1 Hz, J = 7.5 Hz, J = 1.6 Hz); 7.29
(d, 2 H, H(5´), J = 8.5 Hz); 7.20 (dd, 2 H, H(6), J = 7.7 Hz,
J = 7.5 Hz); 7.05 (d, 2 H, H(4´), J = 9.7 Hz); 6.89 (d, 2 H, H(8),
J = 8.2 Hz); 6.61 (d, 2 H, H(6´), J = 8.5 Hz); 6.50 (br.s, 4 H,
NH2); 6.04 (d, 2 H, H(3´), J = 9.7 Hz); 3.10 (s, 6 H, NMe).
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos 05ꢀ03ꢀ32406
and 08ꢀ03ꢀ01123) and the Division of Chemistry and
Materials Science of the Russian Academy of Sciences
(Program No. 1).
References
1. V. A. Barachevsky, Khim. Vys. Energ., 2003, 37, 8 [High Energy
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Schiff base of 4ꢀmethoxybenzhydrazide and 7´ꢀhydroxyꢀ
8´ꢀformylꢀ3ꢀmethylꢀ4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ
2,2´ꢀchromene] (6) was synthesized similarly to compound 2.
A yellowish precipitate was filtered off, washed with hot
methanol, and recrystallized from an ethanol—dioxane mixture.
The yield was 70%, m.p. 244—245 °С. Found (%): C, 66.50;
H, 4.90; N, 8.40. С26H21N3O6. Calculated (%): С, 66.24; H,
4.49; N, 8.91. IR, ν/cm–1: 3277 (NH), 2800—3100 (OH),
chromene), 1672 (C=O), 1654 (C=O), 1645 (C=C, chromene),
1600 (С=С, arom.), 1580 (С=N), 1311 (С—N), 964, 950, 768
(Cspiro—O). 1H NMR, δ: 12.49 (s, 1 H, OH); 11.94 (s, 1 H,
NH); 8.38 (s, 1 H, CH=N); 7.97 (dd, 1 H, H(5), J = 7.7 Hz,
J = 1.6 Hz); 7.82 (d, 2 H, H(2″), J = 8.7 Hz); 7.52 (ddd, 1 H,
H(7), J = 8.2 Hz, J = 7.7 Hz, J = 1.6 Hz); 7.26 (d, 1 H, H(5´),
J = 8.5 Hz); 7.21 (dd, 1 H, H(6), J = 7.7 Hz, J = 7.7 Hz); 7.05
(d, 1 H, H(4´), J = 9.7 Hz); 6.94 (d, 2 H, H(3″), J = 8.7 Hz);
6.91 (d, 1 H, H(8), J = 8.2 Hz); 6.61 (d, 1 H, H(6´), J = 8.5 Hz);
6.04 (d, 1 H, H(3´), J = 9.7 Hz); 3.84 (s, 3 H, OMe); 3.13 (s,
3 H, NMe).
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H. BouasꢀLaurent, Elsevier, Amsterdam, 1990.
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Fotokhromizm i ego primenenie [Photochromism and Its Appliꢀ
cation], Khimiya, Moscow, 1977, 279 pp. (in Russian).
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1015 [Russ. Chem. Rev. (Engl. Transl.), 2002, 71, 893].
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Bis(hydrazone) based on 7´ꢀhydroxyꢀ8´ꢀformylꢀ3ꢀmethylꢀ
4ꢀoxoꢀ3,4ꢀdihydrospiro[1,3ꢀbenzoxazineꢀ2,2´ꢀchromene]
and oxalic acid bis(amidrazone) (9). A hot solution of bis(amidrꢀ
Received September 10, 2007;
in revised form February 26, 2008