Synthesis and photochromic properties of spiropyrans containing a fused benzopyranone fragment

Article abstract of DOI:10.1134/S1070428009070173

New spiro compounds of the indole, phthalazine, isobenzofuran, and benzopyran series, containing a fused benzopyranone fragment in the chromene moiety, were synthesized. Indole derivatives were found to exhibit photochromic properties under stationary con

Full text of DOI:10.1134/S1070428009070173

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 7, pp. 1091–1097. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © O.G. Nikolaeva, E.B. Gaeva, E.N. Shepelenko, A.V. Tsukanov, A.V. Metelitsa, B.S. Luk’yanov, A.D. Dubonosov, V.A. Bren’,
V.I. Minkin, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 7, pp. 1102–1106.
Synthesis and Photochromic Properties of Spiropyrans
Containing a Fused Benzopyranone Fragment
O. G. Nikolaevaa, E. B. Gaevaa, E. N. Shepelenkob, A. V. Tsukanovb, A. V. Metelitsaa,
B. S. Luk’yanova, A. D. Dubonosovb, V. A. Bren’a, b, and V. I. Minkina, b
a Research Institute of Physical and Organic Chemistry, Southern Federal University,
pr. Stachki 194/2, Rostov-on-Don, 344090 Russia
e-mail: aled@ipoc.rsu.ru
b Southern Research Center, Russian Academy of Sciences, Rostov-on-Don, Russia
Received August 13, 2008
Abstract—New spiro compounds of the indole, phthalazine, isobenzofuran, and benzopyran series, containing
a fused benzopyranone fragment in the chromene moiety, were synthesized. Indole derivatives were found to
exhibit photochromic properties under stationary conditions at 293 K. The thermal stability of merocyanine
isomers sharply decreases upon introduction of electron-withdrawing nitro group into the indole fragment and
fusion of a benzene ring to the chromene fragment.
DOI: 10.1134/S1070428009070173
Photochromic compounds on the basis of spiro-
pyrans and spirooxazines are promising as materials
for optical data storage devices and photoswitches and
are widely used in technics due to their photo-, thermo-,
and solvatochromic properties [1–3]. Photodynamic
parameters of spiropyrans depend on the structure of
both chromene and hetarene fragments of their mole-
cules [4]. The mechanism of photochromic transforma-
tions of spiropyrans involves reversible dissociation of
the Cspiro–O bond in the cyclic isomer, followed by
Z–E isomerization to colored merocyanine structure.
The latter may be converted into the initial spiro iso-
mer on heating or irradiation with visible light. Some
spiropyrans of the indole series containing a benzo-
pyranone fragment were reported previously [5, 6]. In
the present work we synthesized new spiro compounds
of the indole, phthalazine, isobenzofuran, and benzo-
pyran series and examined their spectral and photo-
chromic properties with a view to estimate the effects
of benzene ring fusion in the pyranone fragment and
structure of the hetarene fragment on the behavior of
the spirocyclic isomers.
hydrolysis with dilute hydrochloric acid to obtain
3-hydroxy-6-oxo-6H-benzo[c]chromene-4-carbalde-
hyde (II). Spiro compounds III–V were synthesized
by condensation of 3-hydroxy-6-oxo-6H-benzo[c]-
chromene-4-carbaldehyde (II) with the corresponding
3H-indolium or 1-methyl-2,4-diphenylphthalazinium
perchlorates in the presence of triethylamine. Com-
pounds VI and VII were obtained by heating aldehyde
II with an equimolar amount of 1,3,3-trimethylisoben-
zofuranium or 2,3-dimethylchromenylium perchlorate,
respectively, in boiling acetic acid and subsequent
treatment of the oxonium salt thus formed with anhy-
drous ammonia in benzene (Scheme 1).
The IR spectra of III–VII contained absorption
bands at 1600–1630 cm–1, typical of stretching vibra-
tions of C=C bond in the pyran ring, and carbonyl
absorption bands in the region 1720–1740 cm–1.
1
Compounds III–VII displayed in the H NMR spectra
two singlets at δ 1.15–1.75 ppm from nonequivalent
geminal methyl groups, which indicated their cyclic
structure. The doublet signal from 3′-H in the pyran
ring was characterized by a coupling constant J of 9.7–
10.7 Hz, which corresponds to cis configuration of the
vinyl fragment.
Condensation of 3-hydroxy-6H-benzo[c]chromen-
6-one with ethyl N-(4-methylphenyl)formimidate gen-
erated in situ from p-toluidine and ethyl orthoformate
gave 3-hydroxy-4-(4-methylphenyliminomethyl)-6H-
benzo[c]chromen-6-one (I) which was subjected to
In the electronic absorption spectra of spiropyrans
III–VII in toluene the long-wave absorption maxima
were located at λ 333–339 nm, i.e., in the region
1091

NIKOLAEVA et al.
1092
Scheme 1.
Me
O
O
N
O
N
O
CHOEt
+
HO
HO
Me
I
Me
Me
R1
Me
Me
O
O
Me
O
R1
N
R2
ClO4
O
O
O
HCl
N
HO
R2
II
IIIa–IIIf, IVa–IVc
Me
Ph
Ph
N
O
N
ClO4
O
Ph
N
N
O
Ph
V
Me
Me
O
O
O
ClO4
Me
II
Me
Me
O
O
VI
Me
ClO4
Me
Me
O
O
O
O
O
VII
III, R1 = H, R2 = Me (a), Et (b), C8H17 (c), i-Pr (d), PhCH2 (e), HO(CH2)2 (f); IV, R2 = Me, R1 = Me (a), Cl (b), O2N (c).
typical of cyclic isomers A [1, 2, 7] (Scheme 2, Fig. 1).
The position of the long-wave absorption maximum
depends only slightly on the nature of the heterocyclic
fragment (compounds III–VII) and on the substituents
(R1, R2) in the indole fragment (IIIb–IIIf, IVa–IVc).
As shown previously, the reason is that structural
components of molecules III–VII are not coplanar to
each other, and the electron transition responsible for
the long-wave absorption band is localized on the
chromene fragment [8]. The lack of appreciable elec-
tronic interaction between the molecular fragments
allows us to consider the electronic absorption spectra
of III–VII to be linear combination of the spectra of
the corresponding components. Structural modeling
studies showed that the longwave maximum belongs
to photochemically active chromene fragment and that
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 7 2009

SYNTHESIS AND PHOTOCHROMIC PROPERTIES OF SPIROPYRANS
1093
Scheme 2.
O
Me
O
Me
Me
O
Me
R1
O
hν1
hν2, Δ
N
R1
N
O
R2
R2
O
A
B
the shortwave absorption maximum originates from
the other heterocyclic fragment [8].
where the substituents in the indole and naphtho-
oxazine fragments affected the degree of quinoidiza-
tion or dipolar character of the merocyanine form.
Electron-donor substituents in the indole fragment and
electron-withdrawing substituents in the naphthooxa-
zine fragment of these compounds favored delocaliza-
tion of the positive charge on the nitrogen atom, and of
the negative charge, on the oxygen atom, thus stabiliz-
ing the dipolar structure. In contrast, electron-with-
drawing substituents in the indole fragment and elec-
tron-donating groups in the naphthooxazine fragment
favor localization of the positive charge on the nitro-
gen atom and of the negative charge on the oxygen; as
a result, the dipolar structure becomes thermodynam-
ically unfavorable, while quinoid merocyanine struc-
ture is stabilized [10]. Likewise, the presence of a nitro
group in the indole fragment of molecule IVa reduces
the degree of charge separation between the nitrogen
and oxygen atoms in merocyanine structure B (its
polarity decreases) and weakens stabilizing effect of
the solvent.
Acyclic merocyanine isomers B absorb at consider-
ably longer wavelengths as compared to their cyclic
isomers A [1, 2, 7]. The absence of absorption bands
with λmax > 400 nm in the spectra of spiro compounds
III–VII in toluene suggests that the ring–chain equilib-
rium A
B in toluene at 293 K is completely dis-
placed toward spiro isomer A.
Irradiation of solutions of III and IV at a wave-
length corresponding to absorption maximum of the
cyclic form is accompanied by appearance in the elec-
tronic absorption spectra of two structured bands in
the visible region with their maxima at λ1 405–429 and
λ2 572–663 nm (the solution turns colored) due to elec-
tronic transitions S0→S2 and S0→S1, respectively, in
merocyanine isomers B (see table, Fig. 1) [2, 7]. As
follows from the data in table, the position of vibra-
tional maxima on the long-wave absorption band of
structure B depends on the nature of the R1 and R2
substituents. In going from R2 = Alk to R2 = PhCH2
(IIIe) these maxima shift to longer wavelengths,
whereas blue shift is observed for compound IIIf with
R2 = HOCH2CH2. Compound IVb (R1 = Cl) absorbs at
longer wavelength than does its 5′-methyl-substituted
analog IVa. No fluorescence was observed at 293 K
for both cyclic isomer A and merocyanine structure B.
The lifetime of the colored form also shortens upon
replacement of methyl group on the nitrogen atom by
benzyl (IIIe), as well as upon substitution of hydrogen
D
1.2
After termination of UV irradiation, thermal relaxa-
tion processes B→A were observed for compounds
III and IV, and the solutions turned colorless. The
kinetics of thermal recyclization are well described by
exponential function (Fig. 2). The lifetime of merocya-
nine form B of III and IV in toluene at 293 K ranges
from 1.2 to 27.6 s. As shown previously, introduction
of a nitro group into the chromene fragment of indole-
based spiro compounds considerably increases the life-
time of their merocyanine isomers [9]. In contrast, the
presence of a nitro group in position 5′ of the indole
fragment (compound IVc) sharply shortens the lifetime
of the colored form as compared to 5′-methyl analog
IVa. A similar pattern was observed for spiro com-
pounds derived from indole and naphthooxazines,
0.8
5
0.4
4
3
2
1
500
0.0
300
400
600
700
λ, nm
Fig. 1. Electronic absorption spectra of spiro compound IIIb
in toluene (1) before irradiation and after irradiation with UV
light (λ 365 nm; c = 8.55× 10–5 M) for (2) 6, (3) 10, (4) 15,
and (5) 45 s.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 7 2009

NIKOLAEVA et al.
1094
Me
O
Spectral parameters of isomers A and B of compounds III
and IV and lifetimes of merocyanine isomers B; solvent
toluene, temperature 293 K
Me
O
Me
O
N
Cyclic isomer A
Merocyanine isomer B
Me
O
Me
Comp.
no.
λmax
,
εmax, mol× λ1max,
Xa
λ2max, nm
τ, s
nm
l–1 cm–1
10600
10200
10300
12700
09700
10100
11400
18800
nm
405
405
405
406
405
405
408
Me
Me
IIIb
IIIc
IIId
IIIe
IIIf
IVa
IVb
IVc
338
339
339
338
335
339
335
353
592, 630
593, 630
592, 628
595, 635
609
16.0
16.1
17.7
03.8
15.4
27.6
06.3
O2N
O
N
O
Me
Me
Xb
592, 630
595, 637
tively. Comparison of the lifetimes in couples IVa/Xa
and IVc/Xb showed that fusion of a benzene ring to
the chromene fragment destabilizes the corresponding
merocyanine isomers. The ratio τB/τB for 5′-methyl
derivatives IVa and Xa is 1 :4, whereas the corre-
sponding difference for 5′-nitro analogs IVc and Xb is
considerably smaller. Presumably, destabilizing effect
of the 5′-nitro group predominates. This unobvious
conclusion is supported by the data for other series of
spiro compounds, in particular for 5′-(4,5-diphenyl-
1,3-oxazol-2-yl)-substituted spiro[indole-benzo(or
naphtho)pyrans] [12, 13].
429 572, 615, 663 01.2
in position 5′ of the indole fragment by chlorine (IVc).
The lifetime of acyclic structure B is more sensitive to
substitution at the 5′-position. Introduction of a methyl
group into that position increases the lifetime by more
than 40% relative to 5′-unsubstituted analog.
In order to estimate the effect of benzene ring
fusion to the chromene fragment of spiropyrans on the
thermal stability of their merocyanine isomers, we
synthesized compounds Xa and Xb according to the
procedure described previously [11].
Introduction of a nitro group into the chromene
fragment reduces the stability of spiro compounds
toward photodecomposition as a result of promotion of
triplet deactivation channel of electronic excitation
energy [14]. Analogous effect is observed for com-
pound IVc having a nitro group in the indole fragment.
Figure 3 illustrates variations in optical density at the
absorption maximum of colored forms of compounds
IVa and IVc under comparable irradiation conditions.
It is seen that the photocoloration plot for compound
IVa only approaches the maximal optical density in
70 s, while the optical density at the long-wave absorp-
tion maximum of isomer B of compound IVc attains
its maximum value in 2 s and then decreases by
a factor of 4, indicating low stability of the photo-
induced structure.
The kinetics of dark relaxation processes following
photoisomerization of compounds Xa and Xb were
studied under the same conditions as for compounds
III and IV. The lifetimes of the merocyanine forms of
Xa and Xb were estimated at 112.0 and 1.4 s, respec-
D
(a)
ln[(Di – D∞)/(D0 – D∞)]
(b)
0
0.25
0.20
0.15
0.10
0.05
0.00
–1
–2
–3
–4
Spiropyrans V–VII showed no photochromism at
293 K. Presumably, the reason is high rate of recy-
clization B→A, which hampers detection of isomer B
under stationary irradiation conditions.
0
20
Time, s
40
60
0
20
40
60
80
100 120 140
EXPERIMENTAL
Time, s
The electronic absorption spectra were measured on
a Specord M40 spectrophotometer. The IR spectra
were recorded from samples dispersed in mineral oil
Fig. 2. Kinetic curves for thermal relaxation of compound
IIIb in toluene (c = 8.55×10–5 M) in the coordinates (a) D–τ
and (b) ln[(Di – D∞)/(D0 – D∞)]–τ
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 7 2009

SYNTHESIS AND PHOTOCHROMIC PROPERTIES OF SPIROPYRANS
1095
1
D
on a Specord 75IR instrument. The H NMR spectra
1
were obtained on a Varian Unity-300 spectrometer at
300 MHz using CDCl3 as solvent and reference
(CHCl3, δ 7.25 ppm). Solutions of compounds III–VII
were irradiated with a DRSh-250 mercury lamp using
a set of light filters.
0.16
0.12
0.08
0.04
0.00
3-Hydroxy-4-(4-methylphenyliminomethyl)-6H-
benzo[c]chromen-6-one (I). A mixture of 10 g
(47 mmol) of 3-hydroxy-6H-benzo[c]chromen-6-one
[15], 10 g (93 mmol) of p-toluidine, and 14 ml of tri-
ethyl orthoformate was heated for 12 h at 170°C. The
bright orange precipitate was filtered off, washed with
ethanol, and recrystallized from DMF. Yield 36%,
2
0
10
20
30
40
50
60
70
1
mp 185–186°C. H NMR spectrum, δ, ppm: 2.41 s
Time, s
(3H, CH3), 6.98–8.40 m (10H, Harom), 9.41 s (1H,
=CH), 15.17 s (1H, OH). Found, %: C 76.40; H 4.65;
N 4.20. C21H15NO3. Calculated, %: C 76.58; H 4.59;
N 4.25.
Fig. 3. Variation of optical density at the long-wave absorp-
tion maxima during irradiation of solutions of spiro com-
pounds (1) IVa (c = 7.33 × 10–5 M) and (2) IVc (c =
4.37×10–5 M) in toluene with UV light (λ 365 nm).
3-Hydroxy-6-oxo-6H-benzo[c]chromene-4-carb-
aldehyde (II). Compound I, 5 g (15 mmol), was dis-
solved in 100 ml of dioxane, 100 ml of 15% hydro-
chloric acid was added on heating, and the mixture was
heated for 10 min at the boiling point, cooled, and
diluted with water (500 ml). The precipitate was fil-
tered off, dried, and recrystallized from acetone. Yield
78%, mp 232–233°C. IR spectrum, ν, cm–1: 1740,
H 5.30; N 3.53. C26H21NO3. Calculated, %: C 78.97;
H 5.35; N 3.54.
1′-Ethyl-3′,3′-dimethyl-1′,3′-dihydro-6H-spiro-
[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-one
(IIIb). Yield 38%, mp 146–147°C. IR spectrum, ν,
1
cm–1: 1730, 1620, 1610. H NMR spectrum, δ, ppm:
1.15–1.32 m (9H, CH3), 3.21–3.41 m (2H, CH2),
5.82 d (1H, 3-H, J = 10.5 Hz), 6.56–8.38 m (11H,
Harom, 4-H). Found, %: C 79.11; H 5.65; N 3.57.
C27H23NO3. Calculated, %: C 79.20; H 5.66; N 3.42.
1
1640, 1600. H NMR spectrum, δ, ppm: 6.96–8.40 m
(6H, Harom), 10.68 s (1H, CHO), 12.16 s (1H, OH).
Found, %: C 70.13; H 3.40. C14H8O4. Calculated, %:
C 70.00; H 3.36.
3′,3′-Dimethyl-1′-octyl-1′,3′-dihydro-6H-spiro-
[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-one
(IIIc). Yield 51%, mp 105–106°C. IR spectrum, ν,
Spiro compounds IIIa–IIIf and IVa–IVc (general
procedure). Triethylamine, 0.1 ml (0.7 mmol), was
added on heating to a solution of 1.1 mmol of com-
pound II and 1 mmol of the corresponding 2,3,3-tri-
methyl-3H-indolium perchlorate in propan-2-ol. The
mixture was heated for 2–3 h under reflux, cooled,
poured into water, and extracted with several portions
of chloroform. The extracts were combined, dried over
calcium chloride, and evaporated to a volume of 10–
15 ml. The residue was subjected to chromatography
on aluminum oxide using chloroform as eluent, and the
product was additionally purified by recrystallization
from propan-2-ol.
1
cm–1: 1720, 1600. H NMR spectrum, δ, ppm: 1.15–
1.37 m (21H, CH3, CH2), 3.14–3.26 m (2H, CH2),
5.83 d (1H, 3-H, J = 10.6 Hz), 6.55–8.38 m (11H,
Harom, 4-H). Found, %: C 80.15; H 7.22; N 2.80.
C33H35NO3. Calculated, %: C 80.29; H 7.15; N 2.84.
1′-Isopropyl-3′,3′-dimethyl-1′,3′-dihydro-6H-
spiro[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-
one (IIId). Yield 6%, mp 255–256°C. IR spectrum, ν,
1
cm–1: 1720, 1620, 1600. H NMR spectrum, δ, ppm:
1.15–1.42 m (12H, CH3), 3.83 m (1H, CH), 5.80 d
(1H, 3-H, J = 10.4 Hz), 6.71–8.39 m (11H, Harom, 4-H).
Found, %: C 79.51; H 6.06; N 3.28. C28H25NO3. Cal-
culated, %: C 79.41; H 5.95; N 3.31.
1′,3′,3′-Trimethyl-1′,3′-dihydro-6H-spiro[benzo-
[c]pyrano[2,3-h]chromene-2,2′-indol]-6-one (IIIa).
Yield 38%. IR spectrum, ν, cm–1: 1730, 1610. 1H NMR
spectrum, δ, ppm: 1.16 s and 1.28 s (3H each, CH3),
2.62 s (3H, NCH3), 5.83 d (1H, 3-H, J = 10.3 Hz),
6.57–8.42 m (11H, Harom, 4-H). Found, %: C 79.06;
1′-Benzyl-3′,3′-dimethyl-1′,3′-dihydro-6H-spiro-
[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-one
(IIIe). Yield 64%, mp 172–173°C. IR spectrum, ν,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 7 2009

NIKOLAEVA et al.
1096
1
cm–1: 1740, 1630, 1600. H NMR spectrum, δ, ppm:
1.32 s and 1.37 s (3H each, CH3), 4.21 d (1H, CH2, J =
16.5 Hz), 4.59 d (1H, CH2, J = 16.5 Hz), 5.88 d (1H,
3-H, J = 10.7 Hz), 6.32–8.38 m (16H, Harom, 4-H).
Found, %: C 81.42; H 5.30; N 3.08. C32H25NO3. Cal-
culated, %: C 81.51; H 5.34; N 2.97.
3,3-Dimethyl-3H,6′H-spiro[2-benzofuran-1,2′-
benzo[c]pyrano[2,3-h]chromen]-6′-one (VI). A mix-
ture of 1 mmol of 1,3,3-trimethyl-2-benzofuranium
perchlorate and 1 mmol of compound II in 10 ml of
acetic acid was heated for 15–20 min under reflux. The
mixture was cooled, the precipitate was filtered off and
dissolved in 50 ml of benzene, and dry ammonia was
passed through the solution. The mixture was evapo-
rated, and the residue was recrystallized from propan-
2-ol. Yield 33%, mp 192–193°C. IR spectrum, ν, cm–1:
1′-(2-Hydroxyethyl)-3′,3′-dimethyl-1′,3′-dihydro-
6H-spiro[benzo[c]pyrano[2,3-h]chromene-2,2′-in-
dol]-6-one (IIIf). Yield 16%, mp 85–86°C. IR spec-
trum, ν, cm–1: 1720, 1610. 1H NMR spectrum, δ, ppm:
1.21 s and 1.33 s (3H each, CH3), 1.83 t (1H, OH),
3.37–3.83 m (4H, CH2), 5.84 d (1H, 3-H, J = 10.5 Hz),
6.67–8.39 m (11H, Harom, 4-H). Found, %: C 76.25;
H 5.31; N 3.35. C27H23NO4. Calculated, %: C 76.22;
H 5.45; N 3.29.
1
1720, 1610. H NMR spectrum, δ, ppm: 1.57 s and
1.70 s (3H each, CH3), 5.98 d (1H, 3′-H, J = 10.4 Hz),
6.91–8.40 m (11H, Harom, 4′-H). Found, %: C 78.61;
H 4.69. C25H18O4. Calculated, %: C 78.52; H 4.74.
3′-Methyl-6H-spiro[benzo[c]pyrano[2,3-h]chro-
mene-2,2′-chromen]-6-one (VII) was synthesized in
a similar way from 2,3-dimethylchromenylium per-
chlorate. Yield 10%. IR spectrum, ν, cm–1: 1730, 1610.
1H NMR spectrum, δ, ppm: 2.00 s (3H, CH3), 5.98 d
(1H, 3-H, J = 9.7 Hz), 6.91–8.40 m (12H, Harom, 4-H).
Found, %: C 79.05; H 4.20. C25H16O4. Calculated, %:
C 78.94; H 4.24.
1′,3′,3′,5′-Tetramethyl-1′,3′-dihydro-6H-spiro-
[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-one
(IVa). Yield 37%, mp 205–206°C. IR spectrum, ν,
cm–1: 1730, 1610. H NMR spectrum, δ, ppm: 1.20 s
1
and 1.32 s (3H each, CH3), 2.34 s (3H, 5′-CH3), 2.73 s
(3H, NCH3), 5.83 d (1H, 3-H, J = 10.5 Hz), 6.45–
8.38 m (10H, Harom, 4-H). Found, %: C 79.05; H 5.64;
N 3.51. C27H23NO3. Calculated, %: C 79.20; H 5.66;
N 3.42.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
nos. 06-03-32561, 06-03-32988, 08-03-90029-Bel),
by the President of the Russian Federation (Program
for Support of Leading Scientific Schools, project
no. NSh-363.2008.3), and by the Foundation for Sup-
port of Russian Sciences.
5′-Chloro-1′,3′,3′-trimethyl-1′,3′-dihydro-6H-
spiro[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-
one (IVb). Yield 42%, mp 160–161°C. IR spectrum, ν,
1
cm–1: 1720, 1610, 1600. H NMR spectrum, δ, ppm:
1.20 s and 1.30 s (3H each, CH3), 2.74 s (3H, NCH3),
5.79 d (1H, 3-H, J = 10.4 Hz), 6.44–8.39 m (10H,
Harom, 4-H). Found, %: C 72.68; H 4.75; N 3.17.
C26H20ClNO3. Calculated, %: C 72.64; H 4.69; N 3.26.
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1′,3′,3′-Trimethyl-5′-nitro-1′,3′-dihydro-6H-
spiro[benzo[c]pyrano[2,3-h]chromene-2,2′-indol]-6-
one (IVc). Yield 6%, mp 255–256°C. IR spectrum, ν,
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chromic Compounds, Crano, J.C. and Guglielmetti, R.J.,
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1
cm–1: 1730, 1610. H NMR spectrum, δ, ppm: 1.22 s
and 1.35 s (3H each, CH3), 2.88 s (3H, NCH3), 5.82 d
(1H, 3-H, J = 10.5 Hz), 6.54–8.40 m (10H, Harom, 4-H).
Found, %: C 70.91; H 4.45; N 6.40. C26H20N2O5. Cal-
culated, %: C 70.90; H 4.58; N 6.36.
4. Sheng, Y., Leszczynski, J., Garcia, A., Rosario, R., and
Gust, D., J. Phys. Chem. B, 2004, vol. 108, p. 16233.
5. Metelitsa, A.V., Knyazhansky, M.I., Ivanitsky, V.V., Niko-
laeva, O.G., Palchkov, V.A., Panina, A.P., Shelepin, N.E.,
and Minkin, V.I., Mol. Cryst. Liq. Cryst., 1994, vol. 246,
p. 37.
6. Ivanitskii, V.V., Nikolaeva, O.G., Metelitsa, A.V., Vol-
bushko, N.V., Luk’yanov, B.S., Palchkov, V.A., and She-
lepin, N.E., Khim. Geterotsikl. Soedin., 1992, p. 601.
2′,4′-Diphenyl-2′H,6H-spiro[benzo[c]pyrano-
[2,3-h]chromene-2,1′-phthalazin]-6-one (V) was syn-
thesized as described above for compounds III and IV
from 1-methyl-2,4-diphenylphthalazinium perchlorate.
Yield 8%, mp 220–221°C. IR spectrum, ν, cm–1: 1720,
1600. 1H NMR spectrum, δ, ppm: 6.00 d (1H, 3-H, J =
10.2 Hz), 6.69–8.37 m (21H, Harom, 4-H). Found, %:
C 81.03; H 4.35; N 5.32. C35H22N2O3. Calculated, %:
C 81.07; H 4.28; N 5.40.
7. Guglielmetti, R., Photochromism: Molecules and
Systems, Dürr, H. and Bouas-Laurent, H., Amsterdam:
Elsevier, 1990, p. 314.
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12. Chernyshev, A.V., Voloshin, N.A., Raskita, I.M., Meteli-
tsa, A.V., and Minkin, V.I., J. Photochem. Photobiol. A,
2006, vol. 184, p. 289.
13. Voloshin, N.A., Gaeva, E.B., Chernyshev, A.V., Mete-
litsa, A.V., and Minkin, V.I., Izv. Ross. Akad. Nauk, Ser.
Khim., 2009, p. 156.
8. Tyer, N.W., Jr. and Becker, R.S., J. Am. Chem. Soc.,
1970, vol. 92, p. 1289.
9. Berman, E., Fox, R.E., and Thomson, F.D., J. Am.
Chem. Soc., 1959, vol. 81, p. 5605.
10. Metelitsa, A.V., Lokshin, V., Micheau, J.C., Samat, A.,
Guglielmetti, R., and Minkin, V., Phys. Chem. Chem.
Phys., 2002, vol. 4, p. 4340.
14. Gaude, D., Le Baccon, M., Guglielmetti, R., and
Gautron, R., Bull. Soc. Chim. Fr., 1979, p. 489.
11. Hinnen, A.A., FR Patent no. 1555666, 1968; Ref. Zh.,
Khim., 1970, no. 7N755.
15. Adams, R., Pease, D.C., Clark, J.H., and Baker, B.R.,
J. Am. Chem. Soc., 1940, vol. 62, p. 2197.
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