Synthesis and structure of indoline spiropyrans of the coumarin series

Article abstract of DOI:10.1007/s11172-006-0131-4

New indoline spiropyrans of the coumarin series were synthesized by the condensation of indoline and hydroxyformylcoumarin derivatives. Spiropyrans, viz., derivatives of 8-formyl-7-hydroxy-4-methylcoumarin and 5-formyl-6-hydroxy-4-methylcoumarin, under irradiation are transformed into open forms, which are recyclized in the dark. The compounds formed by the condensation of the indoline derivatives with 3-formyl-4-hydroxycoumarin have an open structure of the merocyanine dyes and are transformed into spiro forms neither in the dark nor under irradiation with the visible light.

Full text of DOI:10.1007/s11172-006-0131-4

Russian Chemical Bulletin, International Edition, Vol. 54, No. 10, pp. 2417—2424, October, 2005
2417
Synthesis and structure of indoline spiropyrans of the coumarin series
V. F. Traven,aꢀ V. S. Miroshnikov,a T. A. Chibisova,a V. A. Barachevsky,b O. V. Venidiktova,b and Yu. P. Strokachb
aD. I. Mendeleev Chemical Technological University,
9 Miusskaya pl., 125047 Moscow, Russian Federation.
Eꢀmail: traven@muctr.edu.ru
bPhotochemistry Center, Russian Academy of Sciences,
7a ul. Novatorov, 119421 Moscow, Russian Federation.
New indoline spiropyrans of the coumarin series were synthesized by the condensation of
indoline and hydroxyformylcoumarin derivatives. Spiropyrans, viz., derivatives of 8ꢀformylꢀ7ꢀ
hydroxyꢀ4ꢀmethylcoumarin and 5ꢀformylꢀ6ꢀhydroxyꢀ4ꢀmethylcoumarin, under irradiation are
transformed into open forms, which are recyclized in the dark. The compounds formed by the
condensation of the indoline derivatives with 3ꢀformylꢀ4ꢀhydroxycoumarin have an open
structure of the merocyanine dyes and are transformed into spiro forms neither in the dark nor
under irradiation with the visible light.
Key words: spiropyrans, indole and coumarin derivatives, photochromic properties,
merocyanine derivatives.
Scheme 1
Indoline spiropyrans and their heteroanalogs are
known as intensely studied photochromic compounds.1—9
Interest in them is caused by prospects of their use in
different areas of molecular electronics: optical systems of
information recording and storage, dynamic chemoꢀ and
biosensors, in systems of solar energy accumulation, transꢀ
portation systems, catalysis, etc.
The photochromic properties of indoline spiropyrans
are based on the photoinduced reaction of pyran ring
opening followed by the thermal cis—trans isomerization
of the open form with the formation of colored meroꢀ
cyanine and the subsequent thermal or photochemical
recyclization of the open form to the starting colorless
spiro compound. The mutual transformations of the
spiro (А) and open (В) forms are shown in Scheme 1 for
substituted spiro[2Hꢀ1ꢀbenzopyranꢀ2,2´ꢀindoline].
The important parameters of the photochromic propꢀ
erties are the absorption wavelength of the open form,
the lifetime of this form, and the quantum yield of
the photoreaction. A change in the structure of the spiro
derivative exerts a substantial effect on these paramꢀ
eters. The role of one of the structural factors is shown
in Scheme 2: the nature of the substituent in the benzoꢀ
pyran moiety of spiro[2Hꢀ1ꢀbenzopyranꢀ2,2´ꢀindoline].
The introduction of a strong electronꢀacceptor (nitro
group) into the benzopyran fragment leads to the resoꢀ
nance delocalization of a negative charge, which is
formed upon pyran ring opening and, thus, to an increase
in the lifetime of the open form of spiropyran. Strucꢀ
ture В2, which contains a hydrogen bond, and quinoid
structure В3 introduce, most likely, the maximum contriꢀ
bution to the stabilization of the open form of meroꢀ
cyanine.
Numerous published data are available on the influꢀ
ence of both substituents in the fused benzene rings and
different heteroatoms in the indoline and benzopyran
moieties on the photochromic properties. In particular,
spiro compounds containing benzoxazine or naphthꢀ
oxazine fragments instead of the benzopyran fragment
were synthesized and studied.1,5,6
The syntheses of some representatives of indoline
spiropyrans of the coumarin series have previously been
reported.10—13 However, details of the syntheses and methꢀ
ods for identification of the corresponding compounds
are not presented in the literature. We planned to prepare
a series of spiropyrans 1—3 for the systematic study of the
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2342—2349, October, 2005.
1066ꢀ5285/05/5410ꢀ2417 © 2005 Springer Science+Business Media, Inc.

2418
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
Traven et al.
Scheme 2
influence of the coumarin component on the photochroꢀ
mic properties of indoline spiropyrans of this type.
8ꢀFormylꢀ7ꢀhydroxyꢀ4ꢀmethylcoumarin, 5ꢀformylꢀ6ꢀ
hydroxyꢀ4ꢀmethylcoumarin, and 3ꢀformylꢀ4ꢀhydroxyꢀ
coumarin were used as coumarin components in the synꢀ
thesis of spiropyrans 1а—е and 2а—c and expected spirans
3а—d, respectively.
sation of Fischer´s base (or its heterocyclic analog) with
formylhydroxycoumarin. Despite structural differences of
the coumarin derivatives used, spiropyrans 1 and 2
are formed via the general scheme of nucleophilic adꢀ
dition of heterocyclic enamine to the formyl group
of formylhydroxycoumarin. This reaction occurs durꢀ
ing reflux of equimolar amounts of substituted indolꢀ
enine and coumarin derivative in ethanol (Scheme 3)
(the spirocyclization mechanism is discussed in detail
below).
Indolenines, which are necessary for the synthesis of
spiropyrans 1—3, were prepared from aniline and its pꢀsubꢀ
stituted derivatives15—18 similarly to the method shown in
Scheme 4.
The formylhydroxycoumarins were synthesized by
the formylation of 7ꢀhydroxyꢀ4ꢀmethylꢀ, 6ꢀhydroxyꢀ4ꢀ
methylꢀ, and 4ꢀhydroxycoumarins, respectively.19—21
As a rule, the Wizinger—Wennig condensation is carꢀ
ried out in ethanol, methanol, dimethylformamide, or
methyl ethyl ketone. We used anhydrous ethanol, because
both methylene bases and formylhydroxycoumarins are
highly soluble and indoline spiropyrans that formed are
easily precipitated in this alcohol.
The structures of compounds 1, 2, and 4 were studied
by 1H NMR and electronic absorption spectroscopy, takꢀ
ing into account that they can exist in both the cyclic
(spiro) and open forms. The data of their 1H NMR specꢀ
tra, which are characteristic of the spiro and open forms,
are given in Table 1.
R = H(a), Me (b), Br (c), NO2 (d), MeO (e)
The highꢀfield region of the 1H NMR spectra of
spiropyrans 1 and 2 exhibits two signals from the magnetiꢀ
cally nonequivalent (due to the nonsymmetric spiro atom)
geminal Me groups, which indicates the cyclic structure
of these compounds. The methyl groups in position 3´ of
Results and Discussion
Spiropyrans 1, 2, and 3 were synthesized by the
Wizinger—Wennig method14, which includes the condenꢀ

Indoline spiropyrans of coumarin series
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
2419
Scheme 3
Scheme 4
R = H, Me, Br, NO2, MeO
the indoline moiety of spiropyrans 1 and 2 give two threeꢀ
proton singlets at 1.18—1.35 ppm. Differences in chemiꢀ
cal shifts ∆δ of these singlet signals depend on the position
and nature of the substituent, being 0.05—0.08 ppm. This
signal of the Nꢀmethyl substituent of spiropyrans 1 and 2
is observed at 2.68—2.87 ppm.
The lowꢀfield region of the spectrum of spiropyrans 1
contains three groups of signals. One group of four or
three protons is assigned to the benzene ring of the indoline
fragment (containing no substituent or containing one
substituent, respectively). There are two groups of two
interacting nuclei, one of which corresponds to the
methine protons of the C(3)H=C(4)H double bond, and
the second group is attributed to the H(9) and H(10)
aromatic protons of the benzene ring in the coumarin
fragment.
The signals of the H(4´), H(5´), H(6´), and H(7´)
protons of the indoline fragment in spiropyran 1а have

2420
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
Traven et al.
Table 1. Parameters of the 1H NMR spectra of compounds 1, 2,
and 4, which are specific for the spiro and open forms
1
An analysis of the H NMR spectra of compounds,
which were synthesized from 3ꢀformylꢀ4ꢀhydroxyꢀ
coumarin and 5ꢀsubstituted 1,3,3ꢀtrimethylꢀ2ꢀmethyleneꢀ
indolines, showed that these compounds exist in the open
form 4a—d rather than in the spiro form 3.
Comꢀ
pound
δ (J/Hz)
NMe, s
CMe2, s
Н(3), Н(4)*,
H(2), H(1)**; d
1а
1b
1c
1d
1e
2а
2b
2c
4а
1.20, 1.30
1.20, 1.28
1.18, 1.27
1.23, 1.35
1.18, 1.28
1.18, 1.32
1.20, 1.30
1.18, 1.25
1.78
2.75
2.72
2.71
2.87
2.68
2.70
2.70
2.68
3.62
5.81, 7.48 (J = 10.7)
5.81, 7.48 (J = 10.4)
5.78, 7.48 (J = 10.4)
5.80, 7.54 (J = 10.4)
5.79, 7.46 (J = 10.7)
5.85, 7.60 (J = 10.7)
5.85, 7.59 (J = 10.7)
5.78, 7.48 (J = 10.4)
7.64, 9.03 (J = 14.7);
8.24, 8.82 (J = 14.7)
7.64, 9.03 (J = 14.7);
8.22, 8.80 (J = 14.7)
7.60, 9.01 (J = 14.7);
8.16, 8.80 (J = 14.7)
7.65, 9.03 (J = 14.3);
8.05, 8.85 (J = 14.3)
R = H(a), Me (b), Br (c), NO2 (d)
It turned out that the methyl groups in position 3″ of
the indoline fragment of compounds 4 give one sixꢀproꢀ
ton singlet at 1.75—1.82 ppm. The character of the signal
of these protons indicate unambiguously in favor of the
open form in which these compounds exist in solution.
The lowꢀfield part of the spectrum of compounds 4 exhibꢀ
its two groups of mutually related signals. One group of
four or three protons is assigned to the benzene ring of the
indoline fragment (containing no substituents or containꢀ
ing one substituent). One of the two other groups of interꢀ
acting protons corresponds to the H(1) and H(2) methine
protons (see Table 1), and the second group corresponds
to the H(5´), H(6´), H(7´), and H(8´) protons attributed
to the coumarin moiety.
4b
4c
4d
1.75
1.78
1.82
3.62
3.58
3.63
* H(3) and H(4) for compounds 1a—e and 2a—c.
** H(2) and H(1) for compounds 4a—d.
splittings characteristic of the ABCD system and are obꢀ
served as a multiplet at 6.54—7.20 ppm.
The H(4´), H(6´), and H(7´) protons of the benzene
ring in the indoline moiety of 5´ꢀsubstituted spiropyrans 1
are observed as a singlet and two doublets. For instance,
in the spectrum of compound 1b, the signals of these
protons are detected at 6.88, 6.98, and 6.43 ppm, respecꢀ
tively. The signals of the H(3) and H(4) protons of the
double bond in the pyran ring of 1 are detected as two
doublets at 5.78—5.81 and 7.46—7.54 ppm, respectively.
In the spectrum of spiropyrans 1, the signals of the H(9)
and H(10) protons of the benzene ring in the coumarin
fragment are observed as two doublets at 7.33—7.38 and
6.53—6.68 ppm, respectively.
1
It was unexpected that the analysis of the H NMR
spectra of compounds 4 revealed four doublets of the
H(2) and H(1) protons (that correspond to the H(3) and
H(4) methine protons of the expected structure 3) with a
relative intensity of signals of 1.3 : 1. A possibility that
merocyanines 5 exist in the transꢀ and cisꢀforms can be
1
The H NMR spectra of spiropyrans 2 are similar to
those of spiropyrans 1. The signals of the H(4´), H(5´),
H(6´), and H(7´) protons of the indoline fragment in
spiropyran 2а have splittings characteristic of the ABCD
system and are observed as a multiplet at 6.52—7.08 ppm.
The H(4´) and H(6´) protons in the indoline moiety
of 5´ꢀsubstituted spiropyrans 2 are observed as a multiplet
at 6.92—7.22 ppm, and the H(7´) proton appears as a
doublet at 6.38—6.43 ppm.
transꢀ5
∆Hf = –8.79 kcal mol–1
The signals of the H(3) and H(4) protons of the double
bond in the pyran ring are detected as two doublets at
5.78—5.85 and 7.48—7.60 ppm, respectively. The signals
of the H(9) and H(10) protons of the benzene ring of the
coumarin moiety in the spectra of spiropyrans 2 are obꢀ
served as two doublets at 7.22—7.36 and 6.67—6.92 ppm,
respectively.
cisꢀ5
∆Hf = –1.45 kcal mol–1

Indoline spiropyrans of coumarin series
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
2421
assumed as a reason for this fact. However, as shown by
quantum chemical calculations by the standard AM1 proꢀ
cedure, the energy of formation of the cisꢀisomer is much
higher than that of the transꢀisomer and, therefore, a
considerable predomination of the transꢀisomer could
be expected in the step of formation of the central
double bond.
In addition, the transꢀ and cisꢀisomers of the meroꢀ
cyanine form should differ noticeably by spinꢀspin couꢀ
pling constants of the transꢀ and cisꢀprotons. However,
no difference is observed in the spectra of compounds 4
synthesized: both groups of doublets have the same conꢀ
stants, for instance, J = 14.7 Hz for 4a,b.
By analogy to other merocyanines,22 compounds 4
can exist in both bipolar B and quinoid C forms.
but to two C(2´´ )—C(2) and C(1)—C(3´) double bonds
(Scheme 5).
All of the four configurations should have similar spinꢀ
spin coupling constants of the H(1)—H(2) protons (in
each of the structures shown, they are in the transꢀposiꢀ
tion toward each other) and differ insignificantly by the
calculated values of the standard energies of formation.
The Z2´´ꢀ2ꢀ4a and Z1ꢀ3´ꢀ4a configurations are the most
stable and similar in ∆Hf values.
It should be mentioned that in a series of experiꢀ
ments in different solvents (CDCl3, DMSOꢀd6, and
CDCl3—DMSOꢀd6 (1 : 1) mixture) at different temperaꢀ
tures (293, 303, 313, and 323 K) the character of the
1H NMR spectra of compounds 4 undergo no substantial
changes, and the relative intensity of signals of doublets
depends only insignificantly on the substituent in posiꢀ
tion 5´´ of the indoline fragment.
The data on the electronic absorption spectra agree
with the data of the 1H NMR spectra and indicate unamꢀ
biguously that compounds 1 and 2 exist in solution in the
cyclic spiran form before irradiation, whereas compounds
4 exist in the open (merocyanine) form. The absorption
spectra of compounds 1a, 2a, and 4a are shown in Fig. 1
(curves a—c, respectively). In the complete agreement
with the cyclic structure of compounds 1a and 2a, their
solutions absorb predominantly in the nearꢀUV region.
By contrast, compound 4a has an absorption maximum
in the visible region of the electronic spectrum, which is
characteristic of absorption of merocyanine dyes. All comꢀ
pounds 1, 2, and 4 possess pronounced fluorescence propꢀ
erties. Their fluorescence spectra are compared to the
electronic absorption spectra in Fig. 1.
According to the positive charge on the cyclic nitroꢀ
gen atom, bipolar form B should differ by a considerable
downfield shift of signals of the protons of the indolenine
fragment. However, this shift is not observed in the
1H NMR spectra. For example, in the spectrum of 1а,
signals of the benzene protons of the indolenine fragꢀ
ment are observed at 6.54—7.20 ppm, while they are at
6.92—7.29 ppm in the spectrum of compound 4a. The
downfield shift of signals of the protons of the Nꢀmethyl
groups is not so high: in the spectra of compounds 4,
the shift is observed at 3.58—3.63 ppm instead of
2.68—2.87 ppm, e.g., in the spectra of spiropyrans 1.
It seems rather probable that the quinoid structure of
the synthesized merocyanines exists as two isomers relaꢀ
tive to the C(1)—C(2) central ordinary bond.
However, the spinꢀspin coupling constants of the H(2)
and H(1) protons should differ considerably for these isoꢀ
mers. In addition, they have substantially different values
of the standard energies of formation calculated by the
AM1 method.
In our opinion, the most adequate explanation of the
existence of two doublets attributed to the H(1) and H(2)
methine protons in the spectra of compounds 4 is a possiꢀ
bility of the merocyanine form to exist in different conꢀ
figurations relative not to the C(1)—C(2) central bond
Let us consider the spirocyclization mechanism (see
Scheme 3) to understand reasons for the formation of
different reaction products of the Wizinger—Wennig conꢀ
densation using 7ꢀ and 6ꢀhydroxyformylcoumarins.

2422
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
Traven et al.
Scheme 5
A
Ifl (rel. units)
0.8
0.6
0.4
0.2
a
8
6
4
2
1
2
(1)
300
400
500
600
λ/nm
A
Ifl (rel. units)
b
6
0.6
0.4
0.2
1
2
4
2
(2)
325
425
525
λ/nm
Note. In the case of equilibrium (1), the E/Zꢀisomers relative to
A
Ifl (rel. units)
the C(2″)—C(2) bond are formed, ∆H° = –9.68 (Z2´´ ꢀ2ꢀ4a),
f
–8.79 kcal mol–1 (E2´´ ꢀ2ꢀ4a); in the case of equilibrium (2), the
50
40
30
20
c
E/Zꢀisomers relative to the C(1)—C(3) bond are formed, ∆H° =
f
0.6
–9.66 (Z1ꢀ3´ꢀ4a), ∆Hf = –9.54 kcal mol–1 (E1ꢀ3´ꢀ4a).
1
2
The first and second steps of Scheme 3, namely, nuꢀ
cleophilic addition of enamine to the formyl group of
coumarin and dehydration of the adduct that formed to
merocyanine B, proceed, most likely, with the same easiꢀ
ness for each coumarin aldehyde.
0.4
0.2
10
Success of the final step of spirocyclization, viz., intraꢀ
molecular nucleophilic addition of the hydroxy group of
the coumarin fragment to the immonium ion (structure B),
depends, most likely, on the degree of negative charge
delocalization on the oxygen atom of the hydroxy group.
In the 7ꢀ and 6ꢀhydroxycoumarin derivatives, this hydrꢀ
oxy group is sufficiently nucleophilic for an efficient atꢀ
tack of the αꢀC atom of the immonium fragment leading
to the formation of spiro compound A.
500
600
λ/nm
Fig. 1. Absorption (1) and fluorescence (2) spectra (C =
0.5•10–4 mol L–1) of compound 1a in toluene (a), compound
2a in toluene (b), and compound 4a in benzene (c).
oxy group is substantially lower (a high contribution of
resonance structure C) and insufficient for the compleꢀ
tion of spirocyclization. According to this, the process
In the derivatives of 4ꢀhydroxycoumarin (which is a
much stronger OH acid), the negative charge of the hydrꢀ

Indoline spiropyrans of coumarin series
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
2423
C, 62.97; H, 4.56; N, 3.30. C23H20NO3Br. Calculated (%):
C, 63.01; H, 4.57; N, 3.20.
ceases at the step of formation of the corresponding
merocyanine C.
8,1´,3´,3´ꢀTetramethylꢀ5´ꢀnitrospiro[indolineꢀ2,2´ꢀ
[2H,6H ]pyrano[6,5ꢀf ][1]ꢀbenzopyranꢀ6ꢀone] (1d). The yield
was 61%, m.p. 191—192 °C. 1H NMR (CDCl3), δ: 2.87 (s, 3 H,
NMe); 1.23, 1.35 (both s, 6 H, C(3´)Me2); 6.89 (s, 1 H, H(4´));
Experimental
1
H NMR spectra were recorded in CDCl3, DMSOꢀd6, and
8.20 (d, 1 H, H(6´), J6´,7´ = 8.5 Hz); 6.70 (d, 1 H, H(7´), J7´,6´
=
a CDCl3—DMSOꢀd6 (1 : 1) mixture on a Bruker WPꢀ200ꢀSY
spectrometer with a working frequency of 200 MHz at different
temperatures of 293, 303, 313, and 323 K. IR spectra were
measured on a Specord Mꢀ80 spectrophotometer in KBr pellets.
Electron absorption spectra were obtained on a Specord Mꢀ400
spectrophotometer in ethanol in a 1ꢀcm cell. Mass spectra were
recorded on a GCQ mass spectrometer at an energy of ionizing
electrons of 70 eV and a temperature of the source of 200 °C.
Synthesis of indoline spiropyrans 1а—e and 2а—c (general
8.5 Hz); 5.80 (d, 1 H, H(3), J3,4 = 10.4 Hz); 7.54 (d, 1 H, H(4),
J4,3 = 10.4 Hz); 6.15 (s, 1 H, H(7)); 2.38 (s, 3 H, C(8)Me);
7.38 (d, 1 H, H(9) J9,10 = 8.9 Hz); 6.53 (d, 1 H, H(10),
J10,9 = 8.9 Hz). IR, ν/cm–1: 1735 (αꢀpyron), 1647 (C=C), 949
(C—O). Absorption spectrum, λmax/nm (logε): 350 (4.34). Mass
spectrum, m/z (Irel (%)): 404 (26). Found (%): C, 67.35;
H, 4.96; N, 6.78. C23H20N2O5. Calculated (%): C, 68.32;
H, 4.95; N, 6.93.
8,1´,3´,3´ꢀTetramethylꢀ5´ꢀmethoxyspiro[indolineꢀ2,2´ꢀ
[2H,6H ]pyrano[6,5ꢀf ][1]benzopyranꢀ6ꢀone] (1е). The yield was
92%, m.p. 198—199 °C. 1H NMR (CDCl3), δ: 2.68 (s, 3 H,
NMe); 1.18, 1.28 (both s, 6 H, C(3´)Me2); 3.80 (s, 1 H,
5´ꢀOMe); 6.45 (d, 1 H, H(7´), J7´,6´ = 9.1 Hz); 5.79 (d, 1 H,
H(3), J3,4 = 10.7 Hz); 7.46 (d, 1 H, H(4), J4,3 = 10.7 Hz); 6.12
procedure).
A mixture of 8ꢀformylꢀ7ꢀhydroxyꢀ4ꢀmethylꢀ
coumarin19 (or 5ꢀformylꢀ6ꢀhydroxyꢀ4ꢀmethylcoumarin20
)
(0.56 g, 0.0027 mol) and anhydrous ethanol (10 mL) was heated
until the coumarin derivative dissolved completely. 1,3,3ꢀTriꢀ
methylꢀ2ꢀmethyleneindoline15 (0.44 g, 0.0027 mol) was added
to the resulting solution, and the mixture was refluxed for 5.5 h,
cooled, and left for 18 h at 20 °C. Then water was added to the
reaction mixture until a precipitate was formed. The precipitate
was filtered off, dried, and recrystallized from dilute ethanol.
8,1´,3´,3´ꢀTetramethylspiro[indolineꢀ2,2´ꢀ[2H,6H ]pyraꢀ
no[6,5ꢀf ][1]ꢀbenzopyranꢀ6ꢀone] (1а). The yield was 85%, m.p.
123—124 °C. 1H NMR (CDCl3), δ: 2.75 (s, 3 H, NMe); 1.20,
1.30 (both s, 6 H, C(3´)Me2); 6.54—7.20 (m, 4 H, H(4´), H(5´),
H(6´), H(7´)); 5.81 (d, 1 H, H(3), J3,4 = 10.7 Hz); 7.48 (d, 1 H,
H(4), J4,3 = 10.7 Hz); 6.12 (s, 1 H, H(7)); 2.35 (s, 3 H, C(8)Me);
(s, 1 H, H(7)); 2.35 (s, 3 H, C(8)Me); 7.33 (d, 1 H, H(9), J9,10
=
8.5 Hz); 6.65—6.78 (m, H(4´), H(6´), H(10)). IR, ν/cm–1: 1730
(αꢀpyron), 1646 (C=C), 952 (CO). Absorption spectrum,
λ
max/nm (logε): 558 (3.22). Mass spectrum, m/z (Irel (%)): 389
(20). Found (%): C, 73.99; H, 5.90; N, 3.82. C24H23NO4. Calꢀ
culated (%): C, 74.04; H, 5.91; N, 3.60.
5,1´,3´,3´ꢀTetramethylspiro[indolineꢀ2,2´ꢀ[2H,7H ]pyraꢀ
no[5,6ꢀf ][1]benzopyranꢀ7ꢀone] (2a). The yield was 88%, m.p.
224—225 °C. 1H NMR (CDCl3), δ: 2.70 (s, 3 H, NMe); 1.20,
1.32 (both s, 6 H, C(3´)Me2); 6.52—7.08 (m, 4 H, H(4´); H(5´),
H(6´), H(7´)); 5.85 (d, 1 H, H(3), J3,4 = 10.7 Hz); 7.60 (d, 1 H,
H(4), J4,3 = 10.7 Hz); 2.65 (s, 3 H, C(5)Me); 6.28 (s, 1 H,
H(6)); 7.02—7.18 (m, 2 H, H(9), H(10)). IR, ν/cm–1: 1728
(αꢀpyron), 1646 (C=C), 975 (CO). Absorption spectrum,
7.34 (d, 1 H, H(9), J9,10 = 8.9 Hz); 6.68 (d, 1 H, H(10), J10,9
=
8.9 Hz). IR, ν/cm–1: 1735 (αꢀpyron), 1646 (C=C), 951 (C—O).
Absorption spectrum, λmax/nm (logε): 555 (2.65). Mass specꢀ
trum, m/z (Irel (%)): 359 (10). Found (%): C, 76.17; H, 5.98;
N, 3.88. C23H21NO3. Calculated (%): C, 76.88; H, 5.85; N, 3.90.
8,1´,3´,3´,5´´ꢀPentamethylspiro[indolineꢀ2,2´ꢀ[2H,6H ]pyꢀ
rano[6,5ꢀf ][1]ꢀbenzopyranꢀ6ꢀone] (1b). The yield was 55%, m.p.
112—113 °C. 1H NMR (CDCl3), δ: 2.72 (s, 3 H, NMe); 1.20,
1.28 (both s, 6 H, C(3´)Me2); 6.88 (s, 1 H, H(4´)); 2.33 (s, 1 H,
C(5´)Me); 6.98 (d, 1 H, H(6´), J6´,7´ = 7.9 Hz); 6.43 (d, 1 H,
H(7´), J7´,6´ = 7.9 Hz); 5.81 (d, 1 H, H(3), J3,4 = 10.4 Hz); 7.48
(d, 1 H, H(4), J4,3 = 10.4 Hz); 6.15 (s, 1 H, H(7)); 2.39 (s, 3 H,
C(8)Me); 7.34 (d, 1 H, H(9), J9,10 = 8.9 Hz); 6.68 (d, 1 H,
H(10), J10,9 = 8.9 Hz). IR, ν/cm–1: 1733 (αꢀpyron), 1646 (C=C),
951 (CO). Absorption spectrum, λmax/nm (logε): 560 (3.07).
Mass spectrum, m/z (Irel (%)): 373 (14). Found (%): C, 76.39;
H, 6.32; N, 3.92. C24H23NO3. Calculated (%): C, 77.21;
H, 6.17; N, 3.75.
λ
max/nm (logε): 552 (3.04). Mass spectrum, m/z (Irel (%)): 359
(10). Found (%): C, 76.87; H, 5.90; N, 3.87. C23H21NO3. Calꢀ
culated (%): C, 76.88; H, 5.85; N, 3.90.
5, 1´, 3´, 3´, 5´ꢀPentamethylspiro[indolineꢀ2, 2 ´ꢀ
[2H,7H ]pyrano[5,6ꢀf ][1]benzopyranꢀ7ꢀone] (2b). The yield was
93%, m.p. 213—214 °C. 1H NMR (CDCl3), δ: 2.70 (s, 3 H,
NMe); 1.20, 1.30 (both s, 6 H, C(3´)Me2); 2.33 (s, 1 H,
C(5´)Me); 5.85 (d, 1 H, H(3), J3,4 = 10.7 Hz); 7.59 (d, 1 H,
H(4), J4,3 = 10.7 Hz); 6.28 (s, 1 H, H(6)); 2.48 (s, 3 H, C(5)Me);
6.43 (d, 1 H, H(7´), J7´,6´ = 7.6 Hz); 6.92—7.22 (m, 4 H, H(4´),
H(6´), H(9), H(10)). IR, ν/cm–1: 1725 (αꢀpyron), 1616 (C=C),
974 (CO). Absorption spectrum, λmax/nm (logε): 560 (3.53).
Mass spectrum, m/z (Irel (%)): 373 (14). Found (%): C, 77.16;
H, 6.01; N, 3.85. C24H23NO3. Calculated (%): C, 77.21;
H, 6.17; N, 3.75.
5´ꢀBromoꢀ5,1´,3´,3´ꢀtetramethylspiro[indolineꢀ2,2´ꢀ
[2H,7H ]pyrano[5,6ꢀf ][1]benzopyranꢀ7ꢀone] (2c). The yield was
65%, m.p. 197—198 °C. 1H NMR (CDCl3), δ: 2.68 (s, 3 H,
NMe); 1.18, 1.25 (s, 6 H, C(3´)Me2); 7.12—7.17 (m, 2 H,
H(4´), H(6´)); 6.38 (d, 1 H, H(7´), J7´,6´ = 8.5 Hz); 5.78 (d, 1 H,
H(3), J3,4 = 10.4 Hz); 7.48 (d, 1 H, H(4), J4,3 = 10.4 Hz); 6.12
5´ꢀBromoꢀ8,1´,3´,3´ꢀtetramethylspiro[indolineꢀ2,2´ꢀ
[2H,6H ]pyrano[6,5ꢀf ][1]ꢀbenzopyranꢀ6ꢀone] (1c). The yield
was 78%, m.p. 196—197 °C. 1H NMR (CDCl3), δ: 2.71 (s, 3 H,
NMe); 1.18, 1.27 (both s, 6 H, C(3´)Me2); 7.16 (d, 1 H, H(4´),
J4´,6´ = 1.8 Hz); 7.29 (d, 1 H, H(6´), J6´,7´ = 8.2 Hz); 6.41 (d,
1 H, H(7´), J7´,6´ = 8.2 Hz); 5.78 (d, 1 H, H(3), J3,4 = 10.4 Hz);
7.48 (d, 1 H, H(4), J4,3 = 10.4 Hz); 6.13 (s, 1 H, H(7)); 2.38 (s,
3 H, C(8)Me); 7.35 (d, 1 H, H(9), J9,10 = 8.8 Hz); 6.67 (d, 1 H,
H(10), J10,9 = 8.8 Hz). IR, ν/cm–1: 1733 (αꢀpyron), 1647 (C=C),
952 (C—O). Absorption spectrum, λmax/nm (logε): 557 (2.63).
Mass spectrum, m/z (Irel (%)): 437/439 (44/24). Found (%):
(s, 1 H, H(6)); 2.35 (s, 3 H, C(5)Me); 7.36 (d, 1 H, H(9), J9,10
=
8.8 Hz); 6.67 (d, 1 H, H(10), J10,9 = 8.8 Hz). IR, ν/cm–1: 1727
(αꢀpyron), 1647 (C=C), 953 (CO). Absorption spectrum,
λ
max/nm (logε): 557 (3.12). Mass spectrum, m/z (Irel (%)):

2424
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 10, October, 2005
Traven et al.
437/439 (24/15). Found (%): C, 62.96; H, 4.61; N, 3.28.
C23H20NO3Br. Calculated (%): C, 63.01; H, 4.57; N, 3.20.
Synthesis of compounds 4а—c (general procedure). A mixꢀ
ture of 3ꢀformylꢀ4ꢀhydroxycoumarin21 (0.56 g, 0.0029 mol) and
anhydrous ethanol (10 mL) was heated until the coumarin disꢀ
solved completely. 1,3,3ꢀTrimethylꢀ2ꢀmethyleneindoline15 or its
5ꢀsubstituted derivative (0.51 g, 0.0029 mol) was added to the
solution that formed, and the mixture was heated with boiling
for 5.5 h. Then the reaction mixture was cooled and left for 18 h
at 20 °C. Then a precipitate that formed was filtered off, recrysꢀ
tallized from dilute ethanol, and dried in air.
2ꢀ(2,4ꢀDioxochromanylidene)ꢀ1ꢀ(1,3,3ꢀtrimethylindolinylꢀ
idene)ethane (4а). The yield was 67%, m.p. 281—282 °C.
1H NMR (CDCl3), δ: 3.62 (s, 3 H, NMe); 1.78 (s, 6 H,
C(3´)Me2); 6.92 (d, 1 H, H(7´´), J7´,6´ = 8.5 Hz); 7.64, 8.24
(both d, 1 H each, H(2), Eꢀisomer, Zꢀisomer, Jtrans = 14.7 Hz);
IR, ν/cm–1: 1701 (αꢀpyron), 1636 (C=C), 938 (C—O). Absorpꢀ
tion spectrum, λmax/nm (logε): 500 (4.97). Mass spectrum,
m/z (Irel (%)): 390 (10). Found (%): C, 67.42; H, 4.96; N, 7.23.
C22H18N2O5. Calculated (%): C, 67.69; H, 4.62; N, 7.18.
References
1. R. C. Bertelson, in Photochromism, Ed. G. H. Brown, Wileyꢀ
Interscience, New York, 1971, 45.
2. V. A. Krongauz and E. I. Goldburt, Nature, 1978, 271, 43.
3. V. A. Barachevsky, G. I. Lashkov, and V. A. Tsekhomskii,
Fotokhromizm i ego primenenie [Photochromism and Its Appliꢀ
cation], Khimiya, Moscow, 1977, 279 pp. (in Russian).
4. A. K. Chibisov and H. Gorner, Chem. Phys., 1998, 237, 425.
5. R. C. Bertelson, in Organic Photochromic and Thermochromic
Compounds, Eds J. C. Crano and R. Guglielmetti, Plenum
Press, New York, 1999, 11.
6. S. Maeda, in Organic Photochromic and Thermochromic Comꢀ
pounds, Eds J. C. Crano and R. Guglielmetti, Plenum Press,
New York, 1999, 85.
7. V. A. Barachevsky, J. Fluorescence, 2000, 10, 185.
8. S. A. Antipin, A. N. Petrukhin, F. E. Gostev, V. S. Marevtsev,
A. A. Titov, V. A. Barachevsky, Yu. P. Strokach, and O. M.
Sarkisov, Chem. Phys. Lett., 2000, 331, 378.
9. V. A. Lokshin, A. Sama, and A. V. Metelitsa, Usp. Khim.,
2002, 71, 1015 [Russ. Chem. Rev., 2002, 71 (Engl. Transl.)].
10. Fr. Pat. 1555666; RZhKhim [Russian Chemical Abstracts],
1973, 7N755 (in Russian).
11. Jpn Pat. 89203388, Chem. Abstr., 1990, 112, 45742.
12. A. V. Metelitsa, M. I. Knyazhansky, V. V. Ivanitsky, O. G.
Nikolaeva, V. A. Palchkov, A. P. Panina, N. E. Shelepin,
and V. I. Minkin, Mol. Cryst. Liq. Cryst., 1994, 246, 37.
13. V. F. Traven, L. D. Kozakova, O. Yu. Fedorovsky, and
B. M. Uzhinov, XX Intern. Conf. Photochem, Book of Abꢀ
stracts, 2001, 238.
14. R. Wizinger and H. Wennig, Helv. Chim. Acta, 1940, 23, 247.
15. Laboratornyi praktikum po sintezu promezhutochnykh
produktov i krasitelei [Practical Laboratory Works on Syntheꢀ
sis of Intermediates and Dyes], Ed. A. V. El´tsov, Khimiya,
Leningrad,1985, 352 pp. (in Russian).
8.82, 9.03 (both d, 1 H each, H(1), Eꢀisomer, Zꢀisomer, Jtrans
=
14.7 Hz); 8.10 (m, 1 H, H(6´)); 7.20—7.29 (m, 3 H, H(4´´),
H(5´´), H(6´´)); 7.36—7.43 (m, 2 H, H(8´), H(5´)); 7.48—7.57
(m, 1 H, H(7´)). IR, ν/cm–1: 1735 (αꢀpyron), 1646 (C=C), 950
(C—O). Absorption spectrum, λmax/nm (logε): 490 (4.90). Mass
spectrum, m/z (Irel (%)): 345 (10). Found (%): C, 76.04; H, 5.72;
N, 4.01. C22H19NO3. Calculated (%): C, 76.52; H, 5.51; N, 4.06.
2ꢀ(2,4ꢀDioxochromanylidene)ꢀ1ꢀ(1,3,3,5ꢀtetramethylinꢀ
dolinylidene)ethane (4b). The yield was 51%, m.p. 188—189 °C.
1H NMR (CDCl3), δ: 3.62 (s, 3 H, NMe); 1.75 (s, 6 H,
C(3´´)Me2); 2.92 (s, 3 H, C(5´´)Me); 6.98 (d, 1 H, H(7´´),
J
7´´,6´´ = 8.5 Hz); 7.64, 8.22 (both d, 1 H each, H(2), Eꢀisomer,
Zꢀisomer, Jtrans = 14.7 Hz); 8.80, 9.03 (both d, 1 H each, H(1),
Eꢀisomer, Zꢀisomer, Jtrans = 14.7 Hz); 8.10 (m, 1 H, H(6´));
7.15—7.25 (m, 4 H, H(4´´), H(6´´), H(8´), H(5´)); 7.46—7.56
(m, 1 H, H(7´)). IR, ν/cm–1: 1701 (αꢀpyron), 1619 (C=C), 943
(C—O). Absorption spectrum, λmax/nm (logε): 494 (4.79). Mass
spectrum, m/z (Irel (%)): 359 (15). Found (%): C, 76.78; H, 5.95;
N, 3.93. C23H21NO3. Calculated (%):C, 76.88; H, 5.85; N, 3.90.
2ꢀ(2,4ꢀDioxochromanylidene)ꢀ1ꢀ(5ꢀbromoꢀ1,3,3ꢀtrimethylꢀ
indolinylidene)ethane (4c). The yield was 87%, m.p. 308—309 °C.
1H NMR (CDCl3), δ: 3.58 (s, 3 H, NMe); 1.78 (s, 6 H,
C(3´´)Me); 6.91 (d, 1 H, H(7´´), J7´´,6´´ = 8.9 Hz); 7.60, 8.16
(both d, 1 H each, H(2), Eꢀisomer, Zꢀisomer, Jtrans = 14.7 Hz);
8.80, 9.01 (both d, 1 H each, H(1), Eꢀisomer, Zꢀisomer, Jtrans
=
16. O. Mumm, H. Hinz, and J. Diederichsen, Ber. Deutsch.
Chem. Ges., 1939, 72, 2107.
17. D. J. Gale, and F. K. Wilshirt, J. Soc. Dyes Colour.,
1974, 90, 97.
18. E. Pottier, M. Sergent, R. Phan Tan Luu, and
R. Guglielmetti, Bull. Soc. Chim. Fr., 1992, 101, 719.
19. R. Bender, D. Kanne, J. D. Frarier, and H. Rapport, J. Org.
Chem., 1983, 48, 2709.
20. R. M. Naik and V. M. Thakor, J. Org. Chem., 1957, 22, 1626.
21. H. Samoua and H. Fahmy, J. Agric. Food Chem., 1984,
32, 756.
14.7 Hz); 8.10 (m, 1 H, H(6´)); 7.50—7.58 (m, 2 H, H(4´´),
H(6´´)); 7.19—7.23 (m, 2 H, H(8´), H(5´)); 7.48—7.57 (m, 1 H,
H(7´)). IR, ν/cm–1: 1699 (αꢀpyron), 1617 (C=C), 984 (CO).
Absorption spectrum, λmax/nm (logε): 493 (4.96). Mass specꢀ
trum, m/z (Irel (%)): 423/425 (17/10). Found (%): C, 62.17;
H, 4.11; N, 3.30. C22H18NO3Br. Calculated (%): C, 62.26;
H, 4.25; N, 3.30.
2ꢀ(2,4ꢀDioxochromanylidene)ꢀ1ꢀ(1,3,3ꢀtrimethylꢀ5ꢀnitroꢀ
indolinylidene)ethane (4d). The yield was 94%, m.p. 273—275 °C.
1H NMR (CDCl3), δ: 3.63 (s, 3 H, NMe); 1.82 (s, 6 H,
C(3´´)Me); 8.24 (s, 1 H, H(4´´)); 8.32 (d, 1 H, H(6´´), J6´´,7´´
=
22. S. M. Aldoshin, Usp. Khim., 1990, 59, 1144 [Russ. Chem.
Rev., 1990, 59 (Engl. Transl.)].
8.5 Hz); 7.09 (d, 1 H, H(7´´), J7´´,6´´ = 8.5 Hz); 7.65, 8.05
(both d, 1 H each, H(2), Eꢀisomer, Zꢀisomer, Jtrans = 14.3 Hz);
8.85, 9.03 (both d, 1 H each, H(1), Eꢀisomer, Zꢀisomer, Jtrans
=
14.3 Hz); 7.52—7.59 (m, 1 H, H(8´)); 7.20—7.29 (m, 2 H, H(7´),
H(6´)); 7.58 (dd, 1 H, H(5´), J5´,6´ = 7.92 Hz, J5´,7´ = 1.5 Hz).
Received December 29, 2004;
in revised form June 29, 2005