Dimerization of 3-(2-aryl-2-oxoethylidene)oxindoles

Article abstract of DOI:10.1007/s11172-008-0098-4

6-Aroyl-7-arylindolo[3,4-jk]phenanthridin-5(4H)-ones (2a-i) were synthesized by heating 3-(2-aryl-2-oxoethylidene)-2,3-dihydroindol-2-ones (1a-i) in DMF. Compounds 2a-i are formed via the dimerization of two molecules of unsaturated ketones 1a-i proceedin

Full text of DOI:10.1007/s11172-008-0098-4

Russian Chemical Bulletin, International Edition, Vol. 57, No. 3, pp. 622—631, March, 2008
622
Dimerization of 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindoles
B. V. Paponov,a O. V. Shishkin,b S. V. Shishkina,b R. I. Zubatyuk,b A. L. Kalyuzhny,a and V. I. Musatovb

aV. N. Karazin Kharkov National University,
4 pl. Svobody, 61077 Kharkov, Ukraine.
Eꢀmail: boris.v.paponov@univer.kharkov.ua
bState Scientific Institution "Institute for Single Crystals," National Academy of Sciences of Ukraine,
60 prosp. Lenina, 61001 Kharkov, Ukraine
6ꢀAroylꢀ7ꢀarylindolo[3,4ꢀjk]phenanthridinꢀ5(4H)ꢀones (2a—i) were synthesized by heating
3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)ꢀ2,3ꢀdihydroindolꢀ2ꢀones (1a—i) in DMF. Compounds 2a—i
are formed via the dimerization of two molecules of unsaturated ketones 1a—i proceeding as
the [2+4] cycloaddition through the formation of intermediate spiro adducts. The further Pfitzinger
rearrangement, decarboxylation, and heteroaromatization afford compounds 2a—i. The structures of
the reaction products were established by spectroscopic methods and Xꢀray diffraction.
Key words: oxindoles, dimerization, [2+4] cycloaddition, spiro adducts, indolophenanthridines.
Scheme 1
3ꢀ(2ꢀArylꢀ2ꢀoxoethylidene)oxindoles (3ꢀ(2ꢀarylꢀ2ꢀ
oxoethylidene)ꢀ2,3ꢀdihydroindolꢀ2ꢀones) are polyfuncꢀ
tional α,βꢀunsaturated ketones having a wide range of
reaction possibilities. The reactions with nucleophilic
reagents,1—3 the synthesis of 2ꢀarylquinolineꢀ4ꢀcarboxyꢀ
lic acids by the Pfitzinger reaction,4–6 and the [2+2],7
[2+3],8 and [2+4] cycloaddition reactions9,10 are of most
importance.
In the present study, we investigated the dimerization
of 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindoles 1a—i under heatꢀ
ing in a polar solvent (DMF).
Heating of 3ꢀ(2ꢀmethylꢀ2ꢀoxoethylidene)oxindoles in
toluene affords two dimers.11—13 3,4ꢀDiacetylꢀ1,2a,3,4ꢀ
tetrahydrospiro[benz[cd]indoleꢀ5,3´ꢀindoline]ꢀ2(2H),2´ꢀ
dione was obtained as the major reaction product;
5ꢀacetylꢀ2ꢀ(2,3ꢀdihydroꢀ2ꢀoxoꢀ1Hꢀindolꢀ3ꢀyl)spiroꢀ
[cyclopentaneꢀ1,3´ꢀ(3H)indole]ꢀ2´,3(1´H)ꢀdione, as
the minor product. The latter compound was identified
by Xꢀray diffraction.13 Heating of 3ꢀ(2ꢀarylꢀ2ꢀoxoꢀ
ethylidene)oxindoles 1a—i in toluene or xylene did not
yield any reaction products, and only the starting comꢀ
pounds were isolated from the solution. By contrast,
heating of oxindoles 1 in DMF for 1 h gave compounds
2a—i in moderate yields. These compounds were identiꢀ
fied by IR and 1H NMR spectroscopy, mass spectrometry,
and Xꢀray diffraction (for compound 2d) as 6ꢀaroylꢀ7ꢀarylꢀ
indolo[3,4ꢀjk]phenanthridinꢀ5(4H)ꢀones (Scheme 1).
The IR spectra (Table 1) of compounds 2a—i show the
following characteristic bands: a lowꢀintensity broad band
at 3150 cm–1 belonging to N—H stretching vibrations,
two intense bands at 1690 and 1665 cm–1 assigned to
C=O stretching vibrations of the aroyl and oxindole carꢀ
bonyl groups, respectively, and a mediumꢀintensity band
R = H (a—f), Br (g), Me (h, i); Ar = Ph (a, h), 4ꢀClC6H4 (b),
4ꢀBrC6H4 (c, g, i), 4ꢀIC6H4 (d), 4ꢀMeOC6H4 (e), 2ꢀnaphthyl (f)
at 1635 cm–1 corresponding to a superposition of C=C
and C=N stretching vibrations.
1
The H NMR spectra of compounds 2a—f (Table 2)
show a broad singlet for one proton, N(4)H, at δ 11, three
doublets for the aromatic protons H(12), H(1), and H(9),
with an integrated intensity of 1 H each, at δ 9.2, 8.8, and
8.2, respectively, and signals for H(12), H(1), and H(9)
at δ 9.2, 8.8, and 8.2, respectively. The multiplet with an
integrated intensity of 3 H at δ 7.8—8.0 corresponds to
signals for H(2), H(10), and H(11). The signals for the
aromatic protons H(3) of the aroyl substituent at position
6 and a part of the aromatic protons of the aryl substituent
at position 7 of 6ꢀaroylꢀ7ꢀarylindolo[3,4ꢀjk]phenanꢀ
thridinꢀ5(4H)ꢀone are observed at δ 6.7—7.5 as a multiꢀ
plet with an integrated intensity of 7 H—9 H. Compound
2f, which contains the naphthyl substituents and, correꢀ
spondingly, bears a larger number of aromatic protons,
is an exception. The signals at δ 6.1—7.2 can appear
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 609—618, March, 2008.
1066ꢀ5285/08/5703ꢀ622 © 2008 Springer Science+Business Media, Inc.

Dimerization of 3ꢀ(2ꢀoxoarylethylidene)ꢀ2ꢀoxindoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
623
Table 1. IR spectra of compounds 2—4
proton at δ 11. This fact and the chemical shift of this
signal characteristic of NH of oxindole systems provide
evidence that compounds 2a—f contain only one oxinꢀ
dole fragment. The integrated intensity of the broad sinꢀ
glets at δ 6.1—7.2 remains virtually unchanged upon
the addition of deuteromethanol and, consequently, these
singlets cannot be assigned to mobile protons giving
this type of signals. At the same time, an increase in
the temperature led to changes in the character of these
signals. At 30 °C, the signals appear as broadened singꢀ
lets; at 60 °C, the signals coalesce; at 90 °C, the signals
appear as a slightly broadened singlet with an integrated
intensity of 2 H at δ 7. This dependence is characteristic
of systems with the hindered rotation of aryl substituents
about a single bond.14 The unexpectedly large chemical
shifts of the doublets for the protons H(12) and H(1)
(9.2 and 8.8 ppm, respectively) and the retention of
the characteristic aromatic spinꢀspin coupling constant
(8.2 Hz) suggest that the protons can be influenced by
diamagnetic ring currents of more than one benzene ring.
It should be noted that the introduction of 5ꢀsubstituted
3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)ꢀ1,3ꢀdihydroindolꢀ2ꢀones
1g—i into the reaction leads to changes in the spectral
Comꢀ
pound
IR, ν/cm–1
NH
C=O
C=C
2a
2b
2c
2d
2e
2f
2g
2h
2i
4a
4b
4c
4d
4e
3152
3163
3158
3159
3172
3162
3167
3169
3161
—
1692, 1665
1697, 1663
1693, 1661
1698, 1657
1688, 1665
1693, 1667
1699, 1665
1692, 1668
1690, 1662
1632
1637
1635
1641
1639
1637
1632
1637
1639
1600
1598
1602
1599
1599
1765, 1717, 1673
1760, 1721, 1667
1762, 1728, 1660
1769, 1722, 1660
1769, 1722, 1660
—
—
—
—
either as a broad singlet with an integrated intensity of 2 H
or as two broad singlets with an integrated intensity of 1 H
each. The addition of deuteromethanol to the sample
under study led to the disappearance of the signal for one
1
pattern of this portion of the H NMR spectra of comꢀ
Table 2. 1H NMR spectra of compounds 2a—i (δ, J/Hz)
Comꢀ
pound
Aromatic protons
NH
(s, 1 H)
Other protons
—
2a
2b
2c
2d
2e
2f
9.21 (d, 1 H, H(12), J = 7.9); 8.74 (d, 1 Н, H(1), J = 8.5);
8.31 (d, 1 H, H(9), J = 7.9); 7.83—8.05 (m, 3 H, H(2), H(10), H(11));
7.08—7.57 (m, 9 H, Н(3), Ar); 6.81, 6.51 (both br.s, 1 H each, Ar)
9.27 (d, 1 H, H(12), J = 7.9); 8.72 (d, 1 Н, H(1), J = 8.5);
8.22 (d, 1 H, H(9), J = 7.9); 7.83—8.05 (m, 3 H, H(2), H(10), H(11));
7.27—7.55 (m, 7 H, Н(3), Ar); 6.86, 6.54 (both br.s, 1 H each, Ar)
9.24 (d, 1 H, H(12), J = 7.9); 8.73 (d, 1 Н, H(1), J = 8.5);
8.20 (d, 1 H, H(9), J = 7.9); 7.81—8.01 (m, 3 H, H(2), H(10), H(11));
7.22—7.56 (m, 7 H, Н(3), Ar); 7.20, 6.91 (both br.s, 1 H each, Ar)
9.25 (d, 1 H, H(12), J = 7.9); 8.74 (d, 1 Н, H(1), J = 8.5);
8.20 (d, 1 H, H(9), J = 7.9); 7.80—8.01 (m, 3 H, H(2), H(10), H(11));
7.26—7.59 (m, 7 H, Н(3), Ar); 7.19, 6.88 (both br.s, 1 H each, Ar)
9.23 (d, 1 H, H(12), J = 7.9); 8.70 (d, 1 Н, H(1), J = 8.5);
8.17 (d, 1 H, H(9), J = 7.9); 7.81—7.99 (m, 3 H, H(2), H(10), H(11));
6.74—7.43 (m, 7 H, Н(3), Ar); 7.51, 6.13 (both br.s, 1 H each, Ar)
9.30 (d, 1 H, H(12), J = 7.9); 8.79 (d, 1 Н, H(1), J = 8.5);
8.21 (d, 1 H, H(9), J = 7.9); 7.24—8.18 (m, 17 H, Н(3), Ar);
7.03, 6.59 (both br.s, 1 H each, Ar)
8.11 (d, 1 H, H(9), J = 8.6); 8.02 (s, 1 H, H(12)); 7.80—7.86
(m, 2 H, H(2), H(10)); 7.21—7.59 (m, 7 H, Н(3), Ar);
7.11, 6.78 (both br.s, 1 H each, Ar)
8.06 (d, 1 H, H(9), J = 8.5); 7.96 (s, 1 H, H(12));
7.67—7.76 (m, 2 H, H(2), H(10)); 7.23—7.56 (m, 9 H, Н(3), Ar);
6.99, 6.74 (both br.s, 1 H each, Ar)
8.12 (d, 1 H, H(9), J = 8.5); 8.00 (s, 1 H, H(12)); 7.69—7.77
(m, 2 H, H(2), H(10)); 7.22—7.50 (m, 7 H, Н(3), Ar);
7.12, 6.79 (both br.s, 1 H each, Ar)
11.06
11.08
10.86
—
—
10.92
10.85
—
3.80, 3.63
(both s, 3 H each, OMe)
10.92
10.97
10.81
10.83
—
—
2g
2h
2i
2.62, 2.58
(both s, 3 H each, Me)
2.62, 2.57
(both s, 3 H each, Me)

624
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
Paponov et al.
pounds 2g—i. Thus, the doublet at δ 8.8 corresponding to
H(1) disappears, the integrated intensity of the multiplet
at δ 8.0—7.8 decreases to two protons due to the disꢀ
appearance of the signal for H(11), and the doublet for
H(12) at δ 9.2 appears at higher field as a singlet with
a chemical shift of 8 ppm, which can indicate that
the system becomes nonplanar due to the steric mutual
influence of the substituents at positions 1 and 11 of
6ꢀaroylꢀ7ꢀarylindolo[3,4ꢀjk]phenanthridinꢀ5(4H)ꢀone.
The mass spectra of compounds 2a—i (Table 3) have
molecular ion peaks of 6ꢀaroylꢀ7ꢀarylindolo[3,4ꢀjk]ꢀ
phenanthridinꢀ5ꢀ(4H)ꢀones corresponding to the molecꢀ
ular weights of these compounds.
stituents with respect to the tetracyclic fragꢀ
ment
(the
C(10)—C(11)—C(19)—O(2)
and
N(2)—C(12)—C(26)—C(27) torsion angles are
–70.8(8)° and —71.5(7)°, respectively). This is accomꢀ
panied by an increase in the C(10)—C(11)—C(19) and
C(10)—C(12)—C(26)
bond
angles
(123.3(5)°
and 121.2(4)°, respectively) compared to the
C(2)—C(11)—C(19) and N(2)—C(12)—C(26) bond
angles (118.7(5)° and 114.8(5)°, respectively) and an
elongation of the C(11)—C(19) and C(12)—C(26) bonds
to 1.516(8) and 1.512(8) Å, respectively (the average
bond length is 1.478 Å).15 In addition, the followꢀ
ing bonds are elongated: C(17)—C(18), 1.435(7) Å;
C(9)—C(13), 1.454(7) Å; C(9)—C(10), 1.420(7) Å;
C(8)—C(9), 1.443(8) Å; C(7)—C(8), 1.440(8) Å;
C(5)—C(6), 1.428(8) Å; C(10)—C(11), 1.454(7) Å; and
C(10)—C(12), 1.452(8) Å. The C(16)—C(17),
C(2)—C(11), and C(6)—C(7) bonds are shortened
(1.339(9), 1.320(8), and 1.342(8) Å, respectively) comꢀ
pared to the standard length of the aromatic carꢀ
bon—carbon bonds (1.384 Å). However, these bondꢀ
length deformations and, consequently, the deviation
from aromaticity are typical of polycyclic systems.16
In the crystal structure, the molecules are packed in
stacks along the twofold screw axis due to stacking interꢀ
actions between the polycyclic fragments of the reference
molecule and the symmetryꢀrelated molecule (0.5 – x,
–0.5 + y, –0.5 – z). The mean planes of the rings are
strictly parallel. The distance between the rings is
3.451(2) Å. The stacks are linked to each other by the
intermolecular N(1)—H(1N)...O(1)´ hydrogen bonds
(–x, 1 – y, –z) (H...O, 2.04 Å; N—H...O, 158°) and the
strongly shortened I(2)...I(1)´ contacts (0.5 – x, 0.5 + y,
0.5 – z) with a length of 3.69 Å (4.30 Å). Apparently,
the formation of the latter contacts leads to the deviation
of the I(2) atom from the mean plane of the parent benꢀ
The structures of compounds 2 were conclusively esꢀ
tablished by Xꢀray diffraction study of 6ꢀ(4ꢀiodobenꢀ
zoyl)ꢀ7ꢀ(4ꢀiodophenyl)indolo[3,4ꢀjk]phenanthridinꢀ
5(4H)ꢀone (2d) (Fig. 1, Table 4).
The polycyclic fragment in molecule 2d is nonplanar.
Due to the rather strong repulsion between the substituꢀ
ents at the C(12) and C(11) atoms (the shortened intramoꢀ
lecular C(19)...C(26) contact is 2.83 Å; the sum of the
van der Waals radii is 3.42 Å)15 and the repulsions beꢀ
tween the atoms of the aromatic rings C(1)—C(4)...C(8)
and C(13)...C(18) (the shortened intramolecular conꢀ
tacts are H(14)...C(7), 2.52 Å (2.87 Å); H(7)...C(14),
2.63 Å (2.87 Å); H(7)...H(14), 1.91 Å (2.34 Å)),
the pyridine and benzene rings C(2)—C(1)—C(8)...C(11)
are substantially nonplanar. The endocyclic torsion anꢀ
gles are as large as 14.5°.
The angle between the planes of the terminal benzene
rings is 20.6°. The steric factors (the shortened intramoꢀ
lecular contacts are C(19)...C(27), 3.22 Å; C(19)...C(31),
3.31 Å; C(20)...C(26), 3.30 Å; C(20)...C(31), 3.23 Å;
C(25)...C(31), 3.15 Å; the sum of the van der
Waals radii is 3.42 Å) are responsible also for a subꢀ
stantial twist of the iodophenyl and iodobenzoyl subꢀ
Table 3. Massꢀspectrometric data for compounds 2a—i (EI, 70 eV)
Comꢀ
pound
m/z (Irel (%))*
2a
2b
2c
450 [M]+ (8), 373 [M – C6H5]+ (5), 345 [M – C6H4CO]+ (57), 105 [C6H4CO]+ (100)
518 [M]+ (11), 407 [M – 4ꢀCl—C6H4]+ (4), 379 [M – 4ꢀCl—C6H4CO]+ (62), 139 [C6H4CO]+ (100)
608 [M]+ (10), 452 [M – 4ꢀBr—C6H4]+ (39), 424 [M – 4ꢀBr—C6H4CO]+ (5), 344 [M – 4ꢀBr—C6H4CO — Br]+ (100),
184 [4ꢀBr—C6H4CO]+ (80)
2d
702 [M]+ (7), 499 [M – 4ꢀI—C6H4]+ (52), 471 [M – 4ꢀI—C6H4CO]+ (9), 344 [M – 4ꢀI—C6H4CO — I]+ (13),
231 [4ꢀI—C6H4CO]+ (100)
2e
2f
2g
510 [M]+ (12), 403 [M – 4ꢀСН3О—C6H4]+ (4), 375 [M – 4ꢀСН3О—C6H4CO]+ (62), 135 [4ꢀСН3О—C6H4CO]+ (100)
550 [M]+ (4), 423 [M – naphthyl]+]+ (6), 395 M – naphthoyl]+ (32), 155 [naphthoyl]+ (100)
766 [M]+ (4), 607 [M – 4ꢀBr—C6H4]+ (21), 582 [M – 4ꢀBr—C6H4CO]+ (30), 502 [M – 4ꢀBr—C6H4CO — Br]+ (100),
184 [4ꢀBr—C6H4CO]+ (92)
2h
2i
478 [M]+ (7), 401 [M – C6H4]+ (8), 373 [M – C6H4CO]+ (42), 105 [C6H4CO]+ (100)
636 [M]+ (4), 480 [M – 4ꢀBr—C6H4]+ (11), 452 [M – 4ꢀBr—C6H4CO]+ (23), 373 [M – 4ꢀBr—C6H4CO — Br]+ (100),
184 [4ꢀBr—C6H4CO]+ (67)
* In addition, the plasmaꢀdesorption mass spectra (PDMS) were measured for compounds 2e and 2f, m/z: 511 [M + H]+ (2e), 551 [M + H]+ (2f).

Dimerization of 3ꢀ(2ꢀoxoarylethylidene)ꢀ2ꢀoxindoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
625
C(17)
C(28)
C(27)
C(16)
C(18)
N(2)
I(2)
C(29)
C(15)
C(26)
C(12)
C(10)
C(30)
O(2)
C(31)
C(20)
C(14)
C(13)
C(9)
C(21)
C(22)
C(23)
C(19)
C(11)
C(8)
I(1)
C(2)
C(3)
C(1)
C(25)
C(24)
C(7)
O(1)
C(5)
C(4)
C(6)
N(1)
Fig. 1. Molecular structure of compound 2d.
zene ring by 0.16 Å. The iodophenyl fragments linked by
the I...I contact are in a Tꢀshaped orientation relative to
each other, due to which no substantial deviations from
planarity are observed for the iodobenzoyl substituent
(the rms deviation of the atoms from the plane is 0.017 Å).
Evidently, the molecules of compounds 2 consist of
the 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindole and 2ꢀarylquinꢀ
oline fragments. Therefore, two pathways giving rise to
the indolophenanthridine molecule can be suggested. One
pathway involves the Pfitzinger rearrangement of one
molecule of 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindole 1 into
2ꢀarylquinolineꢀ4ꢀcarboxylic acid followed by the reacꢀ
tion with the second 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindole
molecule. Another pathway involves the Diels—Alder
reaction of two molecules of 3ꢀ(2ꢀarylꢀ2ꢀoxoethylꢀ
idene)oxindole 1, one double bond of the diene compoꢀ
nent being involved in the aromatic system of the molecule.
Upon heating of 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindole
1a with 2ꢀarylquinolineꢀ4ꢀcarboxylic acids (or 2ꢀarylꢀ
quinolines) in DMF, indolophenanthridine containing
the benzoyl substituent corresponding to 3ꢀ(2ꢀarylꢀ2ꢀ
oxoethylidene)oxindole 1a at position 6 and the aryl subꢀ
stituent corresponding to 2ꢀarylquinolineꢀ4ꢀcarboxylic
acid (or 2ꢀarylquinoline) at position 7 was not detected.
Table 4. Selected bond lengths and bond angles in molecule
Bond
d/Å
Bond
d/Å
Angle
ω/deg
Angle
ω/deg
I(1)—C(23)
O(1)—C(3)
N(1)—C(3)
N(2)—C(12)
C(1)—C(8)
C(1)—C(2)
C(2)—C(3)
C(5)—C(6)
C(7)—C(8)
C(9)—C(10)
C(10)—C(12) 1.452(8)
C(11)—C(19) 1.516(8)
C(13)—C(18) 1.386(8)
C(14)—C(15) 1.378(8)
C(16)—C(17) 1.339(9)
C(19)—C(20) 1.465(9)
2.118(7)
1.216(7)
1.349(8)
1.319(7)
1.391(7)
1.404(8)
1.517(7)
1.428(8)
1.440(8)
1.420(7)
I(2)—C(29)
O(2)—C(19)
N(2)—C(4)
N(2)—C(18)
C(1)—C(4)
C(2)—C(11)
C(4)—C(5)
C(6)—C(7)
C(8)—C(9)
C(9)—C(13)
C(10)—C(11)
C(12)—C(26)
C(13)—C(14)
C(15)—C(16)
C(17)—C(18)
2.097(7)
1.216(8)
1.399(7)
1.367(7)
1.393(7)
1.320(8)
1.358(9)
1.342(8)
1.443(8)
1.454(7)
1.454(7)
1.512(8)
1.405(8)
1.36(1)
C(3)—N(1)—C(4)
C(8)—C(1)—C(4)
C(4)—C(1)—C(2)
C(11)—C(2)—C(3)
O(1)—C(3)—N(1)
N(1)—C(3)—C(2)
C(5)—C(4)—N(1)
C(4)—C(5)—C(6)
C(6)—C(7)—C(8)
C(1)—C(8)—C(9)
C(10)—C(11)—C(19) 123.3(5)
N(2)—C(12)—C(26) 114.8(5)
N(2)—C(18)—C(17) 115.3(5)
O(2)—C(19)—C(20) 124.2(6)
C(12)—N(2)—C(18) 116.8(5)
112.7(4)
125.4(5)
110.5(5)
133.3(5)
127.5(5)
105.3(5)
133.2(5)
115.6(5)
120.6(5)
115.4(5)
C(11)—C(2)—C(1)
C(1)—C(2)—C(3)
O(1)—C(3)—C(2)
C(5)—C(4)—C(1)
C(1)—C(4)—N(1)
C(7)—C(6)—C(5)
C(1)—C(8)—C(7)
C(7)—C(8)—C(9)
C(2)—C(11)—C(19)
121.9(5)
104.8(5)
127.2(5)
120.3(5)
106.4(5)
124.6(6)
113.3(5)
130.9(5)
118.7(5)
N(2)—C(12)—C(10) 123.6(5)
N(2)—C(18)—C(13) 125.3(4)
O(2)—C(19)—C(11)
116.9(6)
1.435(7)
C(20)—C(25) 1.372(9)
C(8)—C(1)—C(2)
124.1(5)

626
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
Paponov et al.
Compound 2a was the only indolophenanthridine isoꢀ
lated from the reaction mixture. The yield of compound
2a based on 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindole 1a difꢀ
fers only slightly from that obtained according to the
standard procedure without the use of 2ꢀarylquinolineꢀ4ꢀ
carboxylic acid (or 2ꢀarylquinoline). Based on this fact,
the first pathway giving rise to the indolophenanthridine
system can be excluded (Scheme 2).
in KBr pellets show characteristic intense bands at 1765,
1700, and 1675 cm–1 corresponding to stretching vibraꢀ
tions of the aroyl, acetyl, and oxindole carbonyl groups
and a mediumꢀintensity band at 1600 cm–1 correspondꢀ
ing to a superposition of stretching vibrations of the aroꢀ
matic C=C bonds.
1
The H NMR spectra of compounds 4a—e (Table 5)
show two singlets for the methyl protons of the acetyl
fragments of the spiroacenaphthylenone molecule at
δ 2.22—2.45. The signals of the AMX system for
the protons of the cyclohexene fragment appear as a douꢀ
blet with an integrated intensity of 1 H at δ 4.33—4.45
(the signal for the proton at the bridgehead C(2a) atom)
and a multiplet with an integrated intensity of 2 H at
δ 4.77—5.05 (the signals for the protons at positions 3
and 4 of the benzindole fragment). The signals for
the protons of the aromatic moieties of compounds 4a—e
are observed at δ 6.85—7.41. The doublet for one aromatꢀ
ic proton is substantially shifted upfield (δ 6.33—6.44)
and corresponds to the signal for the ortho proton of
the aroyl substituent at position 4 of the benzindole sysꢀ
tem. The upfield shift of the signal is associated with
the fact that this proton is located above the plane of
the benzene ring of the 3ꢀspirooxindole fragment of
molecule 4.
Scheme 2
The structures of compounds 4a—e were conclusively
established by the Xꢀray diffraction study of 1,1´ꢀdiaceꢀ
tylꢀ3,4ꢀdibenzoylꢀ1,2,2a,3,4,5ꢀhexahydrospiro[benzꢀ
[cd]indolꢀ5,3´ꢀindoline]ꢀ2,2´(1H)dione 4a (Fig. 2, Taꢀ
bles 6 and 7).
O(4)
C(36)
C(35)
C(25)
C(30)
C(31)
C(26)
N(2)
C(34)
C(24)
C(29)
C(32)
C(27)
C(22)
O(3)
The dimerization of compounds 1 in acetic anhydride
unambiguously demonstrated that this reaction proceeds
as the [2+4]ꢀcycloaddition, one 3ꢀ(2ꢀarylꢀ2ꢀoxoethꢀ
ylidene)ꢀ2,3ꢀdihydroindolꢀ2ꢀone molecule (1) acting as
the diene and another molecule serving as a dienophile.
This reaction involves the following successive oneꢀpot
processes: the introduction of the acyl protecting group
into the NH centers of the oxindole bicyclic systems of
starting 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindoles 1, which
allows the exclusion of the Pfitzinger rearrangement, and
the dimerization of the resulting Nꢀacetylꢀ3ꢀ(2ꢀarylꢀ2ꢀ
oxoethylidene)oxindoles 3 (Scheme 3).
C(4)
C(28)
C(23)
C(33)
C(21)
C(3)
C(21)
C(6)
C(7)
C(5)
C(1)
O(5)
C(10)
C(2)
C(8)
O(6)
C(9)
C(14)
C(11)
O(2) N(1)
C(12)
C(13)
C(15)
C(16)
C(20)
C(19)
The reaction affords 1,1´ꢀdiacetylꢀ3,4ꢀdiaroylꢀ
1,2,2a,3,4,5ꢀhexahydrospiro[benz[cd]indolꢀ5,3´ꢀindoꢀ
line]ꢀ2,2´(1´H)ꢀdiones 4a—e, which were identified by
O(1)
C(17)
C(18)
Fig. 2. Molecular structure of compound 4a.
1
IR and H NMR spectroscopy and the Xꢀray diffraction
study of compound 4a. The IR spectra of 4a—e recorded

Dimerization of 3ꢀ(2ꢀoxoarylethylidene)ꢀ2ꢀoxindoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
627
Scheme 3
3, 4: Ar = Ph (a), 4ꢀClC6H4 (b), 4ꢀBrC6H4 (c), 4ꢀMeOC6H4 (d), 2ꢀthienyl (e)
The tetrahydro ring involved in the tricyclic fragment
adopts a sofa conformation (the puckering parameters17
are S = 0.82, θ = 41.2°, ψ = 0.9°). The deviation of the
C(8) atom from the mean plane passing through the other
atoms of the ring is 0.77 Å. The bicyclic fragment spiroꢀ
fused to the tetrahydro ring is planar within 0.02 Å and is
located virtually perpendicular to the plane of the tricyꢀ
clic fragment (the C(10)—C(5)—C(6)—C(28) torsion
angle is 116.3(2)°). This gives rise to the shortened inꢀ
tramolecular H(4)...C(34) contact (2.78 Å; the sum of
the van der Waals radii is 2.87 Å). The acyl substituent at
the N(2) atom is noncoplanar with the plane of the biꢀ
cyclic fragment (the C(28)—N(2)—C(35)—C(36) torꢀ
sion angle is 7.9(3)°), which is apparently attributed to
the presence of the shortened intramolecular contacts:
H(30)...O(4), 2.23 Å (2.46 Å); H(30)...C(35), 2.84 Å
(2.87 Å); H(36b)...O(3), 2.40 Å (2.46 Å); H(36b)...C(28),
2.82 Å (2.87 Å).
The benzoyl substituent at the C(7) atom is in an
equatorial orientation with respect to the mean plane of
the tetrahydro ring (the C(5)—C(6)—C(7)—C(21)
torsion angle is —157.0(1)°), resulting in the formation
of the shortened intramolecular H(7)...H(9) contact
with a length of 2.30 Å (2.34 Å). This substituent is
oriented in such a way that the benzene ring adopts an sc
conformation with respect to the C(6)—C(7) bond (the
C(6)—C(7)—C(21)—C(22) torsion angle is —70.3(2)°).
Strong repulsions between the atoms of the tetrahydro
ring and the atoms of the aromatic ring C(22)...C(27)
(shortened intramolecular contacts: H(7)...C(23),
2.67 Å (2.87 Å); H(7)...H(23), 2.19 Å (2.34 Å);
H(23)...C(7), 2.84 Å (2.87 Å)) are responsible for
the twist of the benzene ring with respect to the C(7)—C(21)
bond (the C(7)—C(21)—C(22)—C(27) torsion angle is
134.7(2)°). The bicyclic fragment and the aromatic ring
of the benzoyl substituent at the C(7) atom are virtually
parallel to each other; the distance between these moiꢀ
eties is 3.3—3.6 Å, which suggests the presence of inꢀ
tramolecular stacking interactions. Two rather bulky subꢀ
stituents at the adjacent carbon atoms in the tetrahydro
ring cause also a substantial elongation of the C(6)—C(7)
bond to 1.577(2) Å compared to its average value (1.540 Å).
The benzoyl substituent at the C(8) atom is in an
equatorial orientation (the C(14)—C(8)—C(19)—C(10)
torsion angle is 179.2(1)°). The benzene ring is virꢀ
tually perpendicular to the plane of the tetrahydro
ring and is twisted with respect to the C(8)—C(14)
bond
(the
C(9)—C(8)—C(14)—C(15)
and
C(8)—C(14)—C(15)—C(16) torsion angles are —89.7(2)°
and 157.1(2)°, respectively) due, apparently, to repulꢀ
sions between the atoms of the tetrahydro ring and
the aromatic ring (shortened intramolecular contacts:
H(8)...C(20), 2.61 Å (2.87 Å); H(8)...H(20), 2.02 Å
(2.34 Å); H(20)...C(8), 2.67 Å (2.87 Å)).

628
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
Paponov et al.
Table 5. 1H NMR spectra of compounds 4a—e (δ, J/Hz)
СН3
СН3
2.46
Comꢀ
pound
AMX system
Aromatic protons
Other
protons
(s, 3 H, MeCO)
4a
4b
4c
2.25
2.23
2.23
4.44 (d, 1 Н, Н(5а),
J = 10.5); 4.97—5.07
(m, 2 Н, Н(6), Н(7))
6.37 (d, 1 Н, H(2) of 6ꢀaroyl, J = 8.5);
7.10 (d, 2 Н, Ar, J = 7.8); 7.16—7.21
(m, 2 Н, Ar); 7.27—7.37, 7.51—7.55
(both m, 4 H each, Ar); 7.66 (t, 1 Н, Ar,
J = 7.8); 7.82, 7.87 (both d, 1 H each,
Ar, J = 7.8); 8.24 (d, 2 Н, Ar, J = 8.5)
6.43 (d, 1 Н, H(2) of 6ꢀaroyl, J = 8.5);
7.21 (d, 2 Н, Ar, J = 8.2); 7.27—7.35
(m, 2 Н, Ar); 7.41—7.47 (m, 4 Н, Ar);
7.54—7.59 (m, 2 Н, Ar); 7.70 (t, 1 Н,
Ar, J = 8.5); 7.87, 7.92 (both d, 1 H each,
Ar, J = 7.8); 8.25 (d, 2 Н, Ar, J = 8.5)
6.39 (d, 1 Н, H(2) of 6ꢀaroyl, J = 8.5);
7.18 (d, 2 Н, Ar, J = 8.2); 7.24—7.31
(m, 2 Н, Ar); 7.37—7.43 (m, 4 Н, Ar);
7.58—7.62 (m, 2 Н, Ar); 7.67 (t, 1 Н,
Ar, J = 8.3); 7.84, 7.89 (d, 1 Н, Ar,
J = 7.8); 8.25 (d, 2 Н, Ar, J = 8.5)
6.35 (d, 1 Н, H(2) of 6ꢀaroyl, J = 8.0);
6.88 (d, 2 Н, Ar, J = 8.2); 7.01 (d, 2 Н,
Ar, J = 8.4); 7.11—7.29 (m, 6 Н, Ar);
7.80—7.86 (m, 3 Н, Ar); 8.17 (d, 2 Н,
Ar, J = 8.7)
—
—
—
2.44
2.47
4.42 (d, 1 Н, Н(5а),
J = 10.6); 4.99—5.10
(m, 2 Н, Н(6), Н(7))
4.43 (d, 1 Н, Н(5а),
J = 10.5); 4.98—5.11
(m, 2 Н, Н(6), Н(7))
4d
4e
2.30
2.40
2.45
2.47
4.32 (d, 1 Н, Н(5а),
J = 10.2); 4.83—4.96
(m, 2 Н, Н(6), Н(7))
3.75, 3.85
(both s,
3 H each,
OMe)
4.41 (d, 1 Н, Н(5а),
J = 10.2); 4.76—4.83
(m, 2 Н, Н(6), Н(7))
6.42 (d, 1 Н, H(2) of 6ꢀthienoyl, J = 7.6);
7.16—7.30 (m, 6 Н, Ar); 7.65 (d, 1 Н,
Ar, J = 6.2); 7.85—7.93 (m, 4 Н, Ar);
8.02, 8.37 (d, 1 Н, Ar, J = 6.2)
—
The fiveꢀmembered heterocycle involved in the triꢀ
cyclic fragment adopts an envelope conformation. The deꢀ
viation of the C(11) atom from the mean plane passing
through the other atoms of the ring is 0.18 Å. The acyl subꢀ
stituent at the N(1) atom is slightly twisted with respect to
the N(1)—C(1) bond (the C(1)—N(1)—C(12)—O(2)
torsion angle is —10.1(2)°), which is, apparently, attribꢀ
uted to the presence of the attractive H(2)...O(2) interacꢀ
tion with a length of 2.33 Å (2.46 Å).
The Xꢀray diffraction data and the absence of doublꢀ
ing of the sameꢀtype signals in the 1H NMR spectra
of compounds 4a—e provide evidence that the dimeriꢀ
zation of Nꢀacetylꢀ3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindoles
affords the only diastereomer, which is an important
argument that this reaction proceeds as the [2+4]
cycloaddition.
Table 6. Selected bond lengths in molecule 4a
The removal of the acetyl groups from compound 4a
gave rise to Nꢀunsubstituted spiro[benzindoleꢀ5,3´ꢀ
indoline]dione 5. Heating of the latter in DMF affordꢀ
ed 6ꢀbenzoylꢀ7ꢀphenylindolo[3,4ꢀjk]phenanthridinꢀ5ꢀ
(4H)ꢀone (2a). This compound is identical to the product
synthesized under the same conditions from 3ꢀ(2ꢀoxoꢀ2ꢀ
phenylethylidene)oxindole 1a.
Therefore, the dimerization of 3ꢀ(2ꢀarylꢀ2ꢀoxoꢀ
ethylidene)oxindoles 1a—i, like that of Nꢀacetylꢀ3ꢀ(2ꢀ
arylꢀ2ꢀoxoethylidene)oxindoles 3a—e, proceeds as
the Diels—Alder reaction with the involvement of dienes
(see Scheme 3). The aromaticity of the benzene ring in
the tricyclic fragment of the intermediate molecule is
recovered as a result of the 1,3ꢀhydrogen shift giving rise
to spirobenzindoleindolines 5a—e. Compounds 5a—e
Bond
d/Å
Bond
d/Å
N(1)—C(12)
N(1)—C(1)
N(2)—C(35)
O(1)—C(11)
O(3)—C(28)
O(5)—C(21)
C(1)—C(2)
C(5)—C(6)
C(6)—C(28)
C(7)—C(21)
C(8)—C(14)
C(9)—C(10)
C(12)—C(13)
N(1)—C(11)
1.396(2)
1.430(2)
1.409(2)
1.194(2)
1.196(2)
1.204(2)
1.361(2)
1.517(2)
1.523(2)
1.507(2)
1.515(2)
1.474(2)
1.485(3)
1.417(2)
N(2)—C(28)
N(2)—C(29)
O(2)—C(12)
O(4)—C(35)
O(6)—C(14)
C(1)—C(10)
C(5)—C(10)
C(6)—C(34)
C(6)—C(7)
C(7)—C(8)
C(8)—C(9)
C(9)—C(11)
C(14)—C(15)
1.396(2)
1.421(2)
1.204(2)
1.193(2)
1.205(2)
1.387(2)
1.366(2)
1.500(2)
1.577(2)
1.525(2)
1.526(2)
1.508(2)
1.474(2)

Dimerization of 3ꢀ(2ꢀoxoarylethylidene)ꢀ2ꢀoxindoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
629
Table 7. Bond angles in molecule 4a
Angle
ω/deg
Angle
ω/deg
Angle
ω/deg
C(12)—N(1)—C(11)
C(11)—N(1)—C(1)
C(28)—N(2)—C(29)
C(2)—C(1)—C(10)
C(10)—C(1)—N(1)
C(4)—C(3)—C(2)
C(10)—C(5)—C(4)
C(4)—C(5)—C(6)
C(34)—C(6)—C(28)
C(34)—C(6)—C(7)
C(28)—C(6)—C(7)
C(21)—C(7)—C(6)
C(14)—C(8)—C(7)
C(7)—C(8)—C(9)
C(10)—C(9)—C(8)
C(5)—C(10)—C(1)
C(1)—C(10)—C(9)
O(1)—C(11)—C(9)
126.2(1)
109.1(1)
109.7(1)
120.8(2)
108.1(1)
122.2(2)
117.0(2)
123.0(2)
101.7(1)
114.2(1)
108.4(1)
108.7(1)
111.1(1)
105.3(1)
108.5(1)
122.0(2)
111.1(1)
127.5(2)
O(2)—C(12)—N(1)
N(1)—C(12)—C(13)
O(6)—C(14)—C(8)
O(5)—C(21)—C(22)
C(22)—C(21)—C(7)
O(3)—C(28)—C(6)
C(30)—C(29)—N(2)
O(4)—C(35)—N(2)
N(2)—C(35)—C(36)
C(12)—N(1)—C(1)
C(28)—N(2)—C(35)
C(35)—N(2)—C(29)
C(2)—C(1)—N(1)
C(1)—C(2)—C(3)
C(5)—C(6)—C(28)
C(5)—C(6)—C(7)
C(21)—C(7)—C(8)
C(8)—C(7)—C(6)
119.1(2)
117.6(2)
119.8(2)
121.2(2)
117.8(2)
124.6(2)
129.7(2)
118.8(2)
118.7(2)
124.5(1)
125.5(2)
124.5(2)
131.0(2)
117.1(2)
108.4(1)
111.5(1)
112.0(1)
114.2(1)
C(14)—C(8)—C(9)
C(10)—C(9)—C(11)
C(11)—C(9)—C(8)
C(5)—C(10)—C(9)
O(1)—C(11)—N(1)
N(1)—C(11)—C(9)
O(2)—C(12)—C(13)
O(6)—C(14)—C(15)
C(15)—C(14)—C(8)
C(15)—C(20)—C(19)
O(5)—C(21)—C(7)
O(3)—C(28)—N(2)
N(2)—C(28)—C(6)
C(34)—C(29)—N(2)
C(29)—C(34)—C(6)
O(4)—C(35)—C(36)
111.8(1)
102.7(1)
122.1(1)
126.0(2)
124.8(2)
107.6(1)
123.2(2)
121.4(2)
118.7(2)
120.7(2)
121.0(2)
126.7(2)
108.7(2)
109.1(2)
110.7(2)
122.5(2)
undergo the Pfitzinger rearrangement (Scheme 3). The
subsequent decarboxylation and heteroaromatization
under severe reaction conditions afford indolophenanꢀ
thridine systems 2a—i.
Table 8. Yields and physicochemical characteristics of compounds 2a—i and 4a—e
Comꢀ
динеꢀ
Yield
(%)
M.p.
/°C
Found
Calculated
Molecular
formula
(%)
C
H
N
2a
2b
2c
2d
2e
2f
62
60
65
60
59
63
63
57
66
66
43
47
71
71
374—376
375—377
377—378
371—373
363—365
370—372
377—379
369—371
372—374
247—249
251—253
253—255
239—241
235—237
82.31
82.65
71.73
71.69
61.19
61.21
52.97
53.02
77.66
77.63
85.12
85.07
48.56
48.60
82.80
82.83
62.24
62.29
73.95
74.22
66.35
66.37
58.34
58.40
70.98
71.02
64.58
64.63
3.99
4.03
3.08
3.11
2.61
2.65
2.32
2.30
4.32
4.34
4.08
4.03
1.87
1.84
5.81
4.63
3.14
3.17
4.41
4.50
3.66
3.71
3.26
3.27
4.66
4.71
3.69
3.73
6.24
6.22
5.36
5.39
4.56
4.61
3.95
3.99
5.45
5.49
5.07
5.09
3.70
3.66
5.70
5.85
4.36
4.40
4.86
4.81
4.27
4.30
3.73
3.78
4.34
4.36
4.43
4.41
C31H18N2O2
C31H16Cl2N2O2
C31H16Br2N2O2
C31H16I2N2O2
C33H22N2O4
C39H22N2O2
2g
2h
2i
C31H14Br4N2O2
C33H22N2O2
C33H20Br2N2O2
C36H26N2O6
4a
4b
4c
4d
4e
C36H24Cl2N2O6
C36H24Br2N2O6
C38H30N2O8
C32H22N2O6S2

630
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
Paponov et al.
B. A solution of 3ꢀ(2ꢀoxoꢀ2ꢀphenylethylidene)oxindole (2a)
(0.5 g, 2 mmol) in acetic anhydride (4 mL) was heated for 4 h. Then
a 70% ethanolic solution (10 mL) was added, the reaction mixture
was heated for 10 min, and compound 4a was filtered off. The yield
was 0.33 g (66%), m.p. 247—249 °C (from AcOEt). Found (%):
C, 73.95; H, 4.86; N, 4.41. C36H26N2O6. Calculated (%): C, 74.22;
H, 4.50; N, 4.81. IR (KBr), ν/cm–1: 1765 (C=O); 1717 (C=O);
1673 (C=O); 1600 (C=C). 1H NMR (DMSOꢀd6), δ: 2.25 (s, 3 H,
CH3 (Ac)); 2.46 (s, 3 H, CH3 (Ac)); 4.44 (d, 1 H, H(5a),
J = 10.5 Hz); 4.97—5.07 (m, 2 H, H(6), H(7)); 6.37 (d, 1 H, H(2)
6ꢀaroyl, J = 8.5 Hz); 7.10 (d, 2 H, Ar, J = 7.8 Hz); 7.16—7.21
(m, 2 H, Ar); 7.27—7.37 (m, 4 H, Ar); 7.51—7.55 (m, 4 H, Ar);
7.66 (t, 1 H, Ar, J = 7.8 Hz); 7.82 (d, 1 H, Ar, J = 7.8 Hz); 7.87
(d, 1 H, Ar, J = 7.8 Hz); 8.24 (d, 2 H, Ar, J = 8.5 Hz).
Compounds 4b—e were synthesized according to the method B.
The physicochemical and spectroscopic data for these compounds
are summarized in Tables 1 and 5.
3,4ꢀDibenzoylꢀ1,2,2a,3,4,5ꢀhexahydrospiro[benz[cd]indoleꢀ
5,3´ꢀindoline]ꢀ2,2´(1´H)ꢀdione (5) was synthesized from diacetyl
derivative 4a by the reaction with Et3O+BF4– in CH2Cl2 according
to a procedure described earlier.20
Triethyloxonium tetrafluoroborate (0.8 g, 4 mmol) was added
to a solution of compound 4a (0.5 g, 0.8 mmol) in CH2Cl2 (30 mL).
The reaction mixture was stirred for 2 h. The precipitate was filtered
off and treated with an excess of an aqueous sodium bicarbonate
solution. The residue was recrystallized from ethyl acetate (50 mL), and
compound 5 was obtained in a yield of 0.2 g (55%), m.p. 327—329 °C
(from DMF). Found (%): C, 77.02; H, 4.41; N, 5.57. C32H22N2O4.
Calculated (%): C, 77.10; H, 4.45; N, 5.62. IR (KBr), ν/cm–1: 1742
(C=O); 1693 (C=O); 1666 (C=O); 1604 (C=C). 1H NMR
(DMSOꢀd6), δ: 3.79 (d, 1 H, H(5a), J = 10.6 Hz); 4.42—4.54 (t, 1 H,
H(6), J = 10.6 Hz); 4.71 (d, 1 H, H(7), J = 10.6 Hz); 5.99 (d, 1 H,
H(2), 6ꢀaroyl, J = 7.4 Hz); 6.60—6.69 (m, 2 H, Ar); 6.81—7.26
(m, 6 H, Ar); 7.63 (d, 1 H, Ar, J= 7.8 Hz); 7.86 (d, 1 H, Ar, J= 8.0 Hz);
7.97 (d, 1 H, Ar, J = 8.0 Hz); 8.32 (d, 1 H, Ar, J = 7.8 Hz); 10.43
(s, 1 H, NH); 10.68 (s, 1 H, NH). PDMS: m/z = 499 [M + H]+.
Xꢀray diffraction study. Xꢀray diffraction data for crystals of
compound 2d were collected on an automated fourꢀcircle Siemens
P3/PC diffractometer (MoꢀKα radiation, graphite monochromator,
θ/2θꢀscanning technique, 2θmax = 50°). The semiempirical ψꢀscan
absorption correction was applied (Tmin = 0.622, Tmax = 0.762).
The structure was solved by direct methods using the SHELXTL
program package21 and refined by the fullꢀmatrix leastꢀsquares
method based on F2 with anisotropic displacement parameters
for nonhydrogen atoms. The hydrogen atoms were located in differꢀ
ence electron density maps and refined using a riding model with
Uiso = 1.2Uequiv of the parent nonhydrogen atoms. The atomic
coordinates and complete tables of the bond lengths and bond
angles were deposited with the Cambridge Structural Database
(CCDC 249069).
Experimental
The IR spectra were measured on a Specord 75IR spectrophoꢀ
tometer in KBr pellets. The instrument was calibrated against
polystyrene standards (ν 1602 and 3003 cm–1). The error of meaꢀ
surements was 2 cm–1. The 1H NMR spectra were recorded on
a Varian VXRꢀ200 Mercury spectrometer operating at 200 MHz in
DMSOꢀd6 with SiMe4 as the internal standard; the δ scale was used
in all cases.
The mass spectra were obtained on a Finnigan MAT 4615P
instrument using a direct inlet system. The temperature of the
ionization chamber was 180 °C, the ionization voltage was 70 eV,
and the emission current was 100 µA. The mass spectra of comꢀ
pounds 2e,f and 5 were measured on an MSBKh timeꢀofꢀflight mass
spectrometer (PO Elektron, Sumy, Ukraine). The ionization was
performed by bombardment with 252Cf fission fragments. The enerꢀ
gy of ionizing particles was 90—110 MeV. The tube length was
45 cm, the accelerating voltage was 20 kV, and the accumulation
time was 15—20 min.
The reaction products were purified by crystallization from the
corresponding solvents. The progress of the reactions was moniꢀ
tored and the purity of the compounds was checked by TLC on
Silufol UVꢀ254 plates using ethyl acetate, chloroform, toluene, or
their mixtures as the eluents. The melting points were determined on
a Kofler hotꢀstage apparatus.
The starting 3ꢀ(2ꢀarylꢀ2ꢀoxoethylidene)oxindoles 1a—i
(see Refs 18 and 19) and Nꢀacetyl derivative 3a (see Ref. 19) were
synthesized according to procedures described earlier. NꢀAcetyl
derivatives 3b—e were synthesized analogously and were used withꢀ
out isolation from the reaction mixtures.
6ꢀBenzoylꢀ7ꢀphenylindolo[3,4ꢀjk]phenanthridinꢀ5(4H)ꢀone
(2a). A. A solution of 3ꢀ(2ꢀoxoꢀ2ꢀphenylethylidene)oxindole (1a)
(0.5 g, 2 mmol) in DMF (0.5 mL) was heated to 150 °C for 1 h,
resulting in precipitation. Benzene (20 mL) was added to the reacꢀ
tion mixture, and compound 2a was filtered off. The yield was 0.28 g
(62%), m.p. 374—376 °C (from DMF). Found (%): C, 82.31;
H, 3.89; N, 6.34. C31H18N2O2. Calculated (%): C, 82.66; H, 4.03;
N, 6.22. IR (KBr), ν/cm–1: 3152 (NH); 1692 (C=O); 1665 (C=O);
1632(C=C). 1H NMR (DMSOꢀd6), δ: 9.21 (d, 1 H, H(12),
J = 7.9 Hz); 8.74 (d, 1 H, H(1), J = 8.5 Hz); 8.31 (d, 1 H, H(9),
J = 7.9 Hz); 7.83—8.05 (m, 3 H, H(2), H(10), H(11)); 7.08—7.57
(m, 9 H, H(3), Ar); 6.81 (br.s, 1 H, Ar); 6.51 (br.s, 1 H, Ar); 11.06
(s, 1 H). MS (EI, 70 eV), m/z (Irel (%)): 450 [M]+ (8), 373
[M – C6H5]+ (5), 345 [M – Bz]+ (57), 105 [Bz]+ (100).
Compounds 2b—i were synthesized according to an analogous
procedure. The yields, physicochemical characteristics, and
spectroscopic data for these compounds are summarized in Taꢀ
bles 1—3 and 8.
B. A solution of compound 5 (0.5 g, 1 mmol) in DMF (2 mL)
was heated to 150 °C for 1 h. Then the reaction mixture was cooled,
and compound 2a was filtered off. The yield was 0.4 g (89%).
The physicochemical and spectroscopic data for this compound are
identical to those for compound 2a, which was synthesized by
heating 3ꢀ(2ꢀoxoꢀ2ꢀphenylethylidene)oxindole (1a) in DMF.
1,1ꢀDiacetylꢀ3,4ꢀdibenzoylꢀ1,2,2a,3,4,5ꢀhexahydrospiroꢀ
[benz[cd]indolꢀ5,3´ꢀindoline]ꢀ2,2´(1H)ꢀdione (4a). A. A solution
of Nꢀacetylꢀ3ꢀ(2ꢀoxoꢀ2ꢀphenylethylidene)oxindole (3a) (0.5 g,
1.7 mmol) in DMF (1 mL) was heated to 150 °C for 1 h. Then a 70%
ethanolic solution (10 mL) was added, the reaction mixture was
heated for 10 min, and compound 4a was filtered off. The yield was
0.3 g (60%), m.p. 247 °C (from AcOEt).
Xꢀray diffraction data for crystals of compound 4a were collectꢀ
ed on a Xcaliburꢀ3 diffractometer (MoꢀKα radiation, CCD detecꢀ
tor, graphite monochromator, ωꢀscanning technique, 2θmax = 50°).
The structure was solved by direct methods with the use of the
SHELXTL program package21 and refined by the fullꢀmatrix leastꢀ
squares method based on F2 with anisotropic displacement paramꢀ
eters for nonhydrogen atoms. The hydrogen atoms were located in
difference electron density maps and refined isotropically.
The atomic coordinates and complete tables of the bond lengths and
bond angles were deposited with the Cambridge Structural Dataꢀ
base (CCDC 665531).

Dimerization of 3ꢀ(2ꢀoxoarylethylidene)ꢀ2ꢀoxindoles
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 3, March, 2008
631
Table 9. Crystallographic characteristics and the Xꢀray data collecꢀ
tion and refinement statistics for compounds 2d and 4a
4. D. Du Puis, H. G. Lindwall, J. Am. Chem. Soc., 1934, 56, 471.
5. P. H. Zrike, H. G. Lindwall, J. Am. Chem. Soc., 1935, 57, 207.
6. R. S. Belen´kaya, E. I. Boreko, M. N. Zemtsova, M. I. Kalinina,
M. M. Timofeeva, P. L. Trakhtenberg, V. M. Chelnov, A. E.
Lipkin, V. I. Votyakov, Khim.ꢀfarm. Zh., 1981, 15, No. 3, 29
[Pharm. Chem. J., 1981, 15, No. 3, 171 (Engl.Transl.)].
7. A. C. Coda, G. Desimoni, P. P. Righetti, G. Tacconi, E. Dradi,
Gazz. Chim. Ital., 1983, 113, 191.
8. A. B. Serov, V. G. Kartsev, Yu. A. Aleksandrov, Abstrs Intern.
Conf. "Chemistry of Nitrogen Containing Heterocycles" (Septemꢀ
ber 30—October 3, 2003), Kharkov, Ukraine, 2003, p. 258.
9. C. G. Richards, D. E. Thurston, Tetrahedron, 1983, 39, 1817.
10. G. Tacconi, A. C. Piccolini, P. P. Righetti, E. Selva, G. Desiꢀ
moni, J. Chem. Soc., Perkin Trans. 1, 1976, 1248.
11. P. Bamfield, A. W. Jonson, A. F. Katner, J. Chem. Soc. (C),
1966, 1028.
12. A. Kubo, T. Nakai, T. Nozoye, A. Itai, Y. IItaka, Heterocycles,
1978, 9, 1051.
13. A. Itai, Y IItaka, A. Kubo, Acta Crystallogr., Sect. B, 1978,
34, 3775.
14. H. Günter, NMRꢀSpectroscopie, Georg Thieme Verlag, Stutꢀ
tgart, 1973.
15. Yu. V. Zefirov, Kristallografiya, 1997, 42, 936 [Crystallogr.
Repts., 1997, 42 (Engl. Transl.)].
Parameter
2d
4а
Molecular formula
Molecular weight
Unit cell parameters
a/Å
C
31H16N2O2I2
702.26
C36H26N2O6
582.59
19.50(1)
6.902(3)
19.51(1)
105.30(5)
10.532(3)
12.654(3)
21.237(2)
100.79(1)
b/Å
c/Å
β/deg
Crystal system
Space group
Z
Monoclinic
P21/n
4
2533(3)
1352
P21/c
4
2780(1)
1216
V/Å2
F(000)
dcalc/g cm–3
µ(MoꢀKα)/mm–1
Number of measured/
independent reflections
Rint
1.842
2.516
4949/4418
1.392
0.096
11518/4773
0.060
334
0.028
501
Number of refinement parameters
parameters
wR2
R1 (I > 2σ(I))
S
0.170
0.070
1.00
0.077
0.034
0.822
16. H. B. Burgi, J. D. Dunitz, Structure Correlation, 2, VCH,
Weinheim, 1994, p. 741.
17. N. S. Zefirov, V. A. Palyulin, E. E. Dashevskaya, J. Phys. Org.
Chem., 1990, 3, 147.
18. H. G. Lindwall, J. S. Maclennan, J. Am. Chem. Soc., 1932,
54, 4739.
19. G. Tacconi, P. Iadarola, F. Marinone, P. P. Righetti, G. Desiꢀ
moni, Tetrahedron, 1975, 31, 1179.
Principal crystallographic characteristics and the Xꢀray data
collection and refinement statistics for compounds 2d and 4a are
given in Table 9.
20. S. Hanessian, Tetrahedron Lett., 1967, 1549.
21. G. M. Sheldrick, SHELXTL PLUS. PC Version. A System
of Computer Programs for the Determination of Crystal Structure
from Xꢀray Diffraction Data, Rev. 5.1, 1998.
References
1. A. S. ElꢀAhl Abdel, H. Afeefy, M. A. Metwally, J. Chem. Res.
Miniprint, 1994, 1, 201.
2. K. S. Joshi, R Jain, Heterocycles, 1990, 31, 473.
3. A. Dandia, M. Upreti, B. Rani, U. C. Pant, I. J. Gupta,
J. Fluorine Chem., 1998, 91, 171.
Received December 13, 2006;
in revised form January 14, 2008