Tautomerism and stereodynamics of indophenols, amidines, and their derivatives and analogs: XVI. Synthesis of tetrahydroquinoxalines having spiro-fused oxoindole and cyclohepta[c]furan fragments

Article abstract of DOI:10.1023/B:RUGC.0000039087.49416.5e

Alkylation of o-(N-sulfonylamino)phenylimino derivatives of indol-2-one and cyclohepta[c]furan with phenacyl bromides is accompanied by cyclization to previously unknown tetrahydroquinoxalines having spiro-fused oxoindole and cyclohepta[c]furan fragments. The structure of the latter includes a nitrogen-oxygen triangular system typical of most natural cytotoxic compounds.

Full text of DOI:10.1023/B:RUGC.0000039087.49416.5e

Russian Journal of General Chemistry, Vol. 74, No. 5, 2004, pp. 731 737. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 5, 2004,
pp. 797 803.
Original Russian Text Copyright
2004 by Kurbatov, Kuznetsov, Simakov, Voronina, Zhdanov, Olekhnovich.
Tautomerism and Stereodynamics of Indophenols, Amidines,
and Their Derivatives and Analogs:
XVI.1 Synthesis of Tetrahydroquinoxalines Having Spiro-Fused
Oxoindole and Cyclohepta[c]furan Fragments
S. V. Kurbatov, D. N. Kuznetsov, V. I. Simakov,
V. A. Voronina, Yu. A. Zhdanov, and L. P. Olekhnovich
Rostov State University, Rostov-on-Don, Russia
Received April 18, 2002
Abstract Alkylation of o-(N-sulfonylamino)phenylimino derivatives of indol-2-one and cyclohepta[c]furan
with phenacyl bromides is accompanied by cyclization to previously unknown tetrahydroquinoxalines having
spiro-fused oxoindole and cyclohepta[c]furan fragments. The structure of the latter includes a nitrogen oxygen
triangular system typical of most natural cytotoxic compounds.
In the preceding communications we described
cyclization of compounds II derived from
o-indophenols [2, 3] and o-indoanilines I [4] to spiro-
fused benzoxazines and quinoxalines III. Unlike
known methods [5] for building up analogous ring
systems, the proposed procedure involves closure of
C C rather than C O or C N bond in the final stage
(Scheme 1).
Scheme 1.
O
O
N
O
H
E
C
H
X
H
H
HlgCH2E
E
X
N^
X
H N
I
II
III
X = O, NSO2R; E = CH=CH2, Ar, COAr.
The general character of this rearrangement was
demonstrated with Schiff bases IV as examples; it
was shown that the six-membered heteroring in V can
be formed with participation of a carbon atom not
included in the quinonimine ring [1]. It was important
to elucidate whether such spiro systems could be ob-
tained when the six-membered quinonimine fragment
of o-indophenols or o-indoanilines I is replaced by a
five- or seven-membered fragment, e.g., oxoindole
(VI) or furotropone (VII) (Scheme 2).
The present communication reports on the syn-
thesis of tetrahydroquinoxalines having spiro-fused
oxoindole and furotropone fragments. The latter
constitute a part of the structure of many natural
compounds [6, 7] possessing various kinds of biolo-
gical activity [8], including antitumor; some spiro
derivatives of oxoindole were found to exhibit anti-
leucemic activity [9].
Spirocyclic compounds X were synthesized by
treatment with phenacyl bromides of thallium salts
VIII instead of parent 1,5-dimethyl-3-(o-R-sulfonyl-
aminophenylimino)indol-2-ones (Scheme 3). Reac-
1
For communication XV, see [1].
1070-3632/04/7405-0731 2004 MAIK Nauka/Interperiodica

732
KURBATOV et al.
Scheme 2.
O
H H
H
Ar1
Ar2
O
Ar1
H
SO2R
H N
N SO2R
O
N
N
H N
N
Ar2CCH2Br
N
~
~
O
IV
V
VI
VII
Scheme 3.
R2
R2
CH3
O=C
CH2
CH3
N
O
C
Ti
N
SO2R1
CH2
N SO2R1
Br
N
N
N
H3C
H3C
O
O
VIII
IX
5
R2
CH3
6
5
4
6
7
H
2
N1
H3C
C
3
2
2
3
O
N1
N
4
SO2R1
O
H
X
VIII, R1 = CH2Ph (a), 4-CH3C6H4 (b); IX, X, R1 = CH2Ph, R2 = 4-Br (a); R1 = 4-CH3C6H4, R2 = 4-Br (b); R1 = CH2Ph,
R2 = 3-NO2 (c); R1 = 4-CH3C6H4, R2 = 4-NO2 (d).
tions of the latter with phenacyl bromides on heating
in acetone in the presence of K2CO3 [1] resulted in
poor yields and strong contamination of the target
products. The transformation of intermediate phenacyl
derivatives IX into spiroquinoxalines X followed from
reactions with insufficient (less than equimolar)
amount of p-bromophenacyl bromide we isolated only
spiroquinoxaline XII substituted at N1 by the phen-
acyl group.
Also, the presence of a labile NH proton in mole-
cule XI hampered selective synthesis of the corres-
ponding thallium salt at the sulfonamide nitrogen
1
the appearance in the H NMR spectra of two one-
proton signals from the N1H and C3H protons instead
of one two-proton signal from the CH2 C=O group.
In addition, the spectrum of Xa contained an AB
quartet from the CH2SO2 group, indicating the pre-
sence of a chiral center.
1
atom. In the H NMR spectrum of XII we observed a
characteristic AB quartet with a low /J ratio due to
remoteness of the diastereotopic NCH2CO group from
the chiral center.
Scheme 4 illustrates the reaction of p-bromo-
phenacyl bromide with iminoisatin XI which has no
methyl group on the indole nitrogen atom. Even in
Unlike Schiff bases derived from isatin, which are
readily obtained by reaction with anilines [9], we
failed to synthesize in such a way furotroponimine
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TAUTOMERISM AND STEREODYNAMICS OF INDOPHENOLS, AMIDINES... : XVI.
733
Scheme 4.
Br
5* *
3
Br
6*
2*
CH3
O
O
CH3
N
6
7
5
C
O
4
CH2
H
Br
N1
5
H2C
H
N
3
2
6
2
Br
C
, acetone, K2CO3
N2 34N
3
N
1
O
H
SO2R
SO2R1
H
O
XI
XII
XI, XII, R = 4-CH3C6H4.
Scheme 5.
O
CH3
O
H3C
H
N SO2CH2Ph
O
H3C
CH3
H
C2H5O
H2N
H3C
N
N SO2CH2Ph
C2H5O
CH3
CH3
H3C
XIII
XV
O
+
CH3
H3C
NaHCO3
OC2H5
C2H5O
ClO4
O
H3C
C2H5O
CH3
H
H
N
N SO2CH2Ph
+
ClO4
CH3
H3C
XIV
XV even when the nucleophilicity of the amino group
was enhanced via introduction of two methyl groups
into the benzene ring (compound XIII; Scheme 5).
Schiff base XV was obtained by nucleophilic substitu-
tion of the ethoxy group in furotropylium cation [10]
and subsequent treatment of intermediate XIV with
sodium hydrogen carbonate. In this reaction, we also
used N-benzylsulfonyl-4,5-dimethylbenzene-1,2-di-
high solubility of the reactants (which was achieved
via introduction of methyl groups).
The reaction of furotroponimine XV with phenacyl
bromides under the conditions described in [1] af-
forded spiroquinoxalines XVIIa XVIIc (Scheme 6).
As in the alkylation of Schiff bases derived from
isatin, we failed to isolate even traces of open-chain
isomers XVI.
amine (XIII), for the transformation XIII
XIV
1
successfully occurred only in chloroform and required
Figure 1 shows the H NMR spectra of tropon-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 5 2004

734
KURBATOV et al.
Scheme 6.
H3C
O
3
R
1
C2H5O
O
C
CH3
O
8
O
O
H
7
H3C
6
CH3
4
C
5
6
CH2
5
2 34 N
CH2
2
Br
N1
N
N SO2CH2Ph
R
XV
C2H5O
, acetone, K2CO3
SO2CH2Ph
H
CH3
XVII
H3C
CH3
H3C
XVI
R = 4-Br (a), 3-NO2 (b), 4-NO2 (c).
imine XV and spiran XVIIa. The cyclic structure of
the latter is confirmed by the presence of singlets from
the CH ( 6.40 ppm) and NH protons ( 5.68 ppm)
and an AB quartet ( 4.55 ppm) from the CH2SO2
group.
Previous studies of the structure of about two
hundred natural cytotoxic compounds [11] revealed
that most of these contains a pharmacophoric triangle
with its sides of 3.1 0.2, 6.4 0.3, and 7.5 0.4
,
whose vertices are occupied by oxygen or nitrogen
(a)
C
CH2SO2
C C H N H
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0 , ppm
15.95 36.77 5.00
4.99 4.86 4.77 5.19 4.88
(b)
10.05 10.11
CH2SO2
7
6
5
4
, ppm
36.54
5.27
10.26
5.00
10.58 10.36
1
Fig. 1. H NMR spectra of compounds (a) XVIIa (Bruker DPX-250, 250 MHz) and (b) XV (Varian Unity-300, 300 MHz) in
acetone-d .
6
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TAUTOMERISM AND STEREODYNAMICS OF INDOPHENOLS, AMIDINES... : XVI.
735
OC2H5
CH3
6.93
O
H
N
H
7.75
CH3
N
H3C
O
SO2
CH2
H3C
Ph
Ph
3.16
Br
Ph
Fig. 2. Structure of compound XVIIa according to the MM2 and PM3 calculations.
atoms in any combination. The structure of compound
XVIIa according to the MM2 and PM3 calculations is
shown in Fig. 2. The carbonyl and ether oxygen atoms
and the sulfonamide nitrogen atoms give rise to a
3.25 s (3H, NCH3), 6.43 s (1H, NH), 6.71 d (1H, 6-H,
J = 7.9 Hz), 6.85 d (2H, 3 -H, 5 -H, J = 7.9 Hz),
7.04 7.27 m (5H, 4-H, 5-H, 4 -H, 6 -H, 7 -H), 7.54 d
(2H, 2 -H, 6 -H, J = 7.8 Hz), 7.70 d (1H, 3-H, J =
7.4 Hz).
triangle with its sides equal to 3.16, 6.93, and 7.75
.
Thus, the proposed procedure for building up
quinoxaline ring opens new prospects in the synthesis
of a large number of spiro structures which are dif-
ficult or impossible to obtain by other methods and
are potential pharmacologically active compounds.
N-[2-(1,5-Dimethyl-2-oxo-1,2-dihydroindol-3-
yideneamino)phenyl]phenylmethanesulfonamide
(VIb) was synthesized in a similar way. Yield 87%.
Red crystals, mp 125 C.
N-[2-(5-Methyl-2-oxo-1,2-dihydroindol-3-yli-
deneamino)phenyl]-p-toluenesulfonamide (XI) was
synthesized in a similar way. Yield 65%. Yellow
orange crystals, mp 160 C.
EXPERIMENTAL
1
The H NMR spectra were recorded on Bruker
DPX-250 (250 MHz) and Varian Unity-300
(300 MHz) spectrometers at 25 C. The elemental
compositions of the synthesized compounds were in
agreement with the calculated values.
N-[2-(1,5-Dimethyl-2-oxo-1,2-dihydroindol-3-
ylideneamino)phenyl]-p-toluenesulfonamide thal-
lium salt (VIIIa). A solution of 0.7 mmol of KOH in
1 ml of MeOH and a solution of 0.7 mmol of thallium
acetate in 5 ml of MeOH were added to a solution of
0.7 mmol of N-[2-(1,5-dimethyl-2-oxo-1,2-dihydro-
indol-3-ylideneamino)phenyl]-p-toluenesulfonamide
(VIa) in 5 ml of MeOH. The mixture was carefully
heated to the boiling point and cooled, and the pre-
cipitate was filtered off and washed with hexane.
Yield 70%. Violet black crystals, mp 240 C.
N-[2-(1,5-Dimethyl-2-oxo-1,2-dihydroindol-3-
ylideneamino)phenyl]-p-toluenesulfonamide (VIa).
A mixture of 1.9 mmol of N-(2-aminophenyl)-p-to-
luenesulfonamide [1], 1.9 mmol of 1,5-dimethyl-1H-
indole-2,3-dione [12], and 0.002 g of p-toluenesul-
fonic acid in 10 ml of toluene was heated for 2 h
under reflux. The mixture was evaporated, and the dry
residue was recrystallized from methanol. Yield 85%.
Orange crystals, mp 115 C. 1H NMR spectrum
(CDCl3), , ppm: 2.02 s (3H, CH3), 2.07 s (3H, CH3),
N-[2-(1,5-Dimethyl-2-oxo-1,2-dihydroindol-3-
ylideneamino)phenyl]phenylmethanesulfonamide
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 5 2004

736
KURBATOV et al.
thallium salt (VIIIb) was synthesized in a similar
way. Yield 78%. Violet black crystals, mp 255 C.
6 -H), 6.89 m (2H, 6-H, 7 -H), 7.00 d.d (1H, 7-H),
7.20 m (3H, 4 -H, 3 -H, 5 -H), 7.38 d (1H, 8-H),
7.53 d (2H, 2 -H, 6 -H), 7.99 d (2H, 2 -H, 6 -H),
8.24 d (2H, 3 -H, 5 -H).
N-[2-(5-Methyl-2-oxo-1,2-dihydroindol-3-ylide-
neamino)phenyl]-p-toluenesulfonamide thallium
salt (VIIIc) was synthesized in a similar way. Yield
70%. Violet black crystals, mp 230 C.
3-p-Bromobenzoyl-1 -p-bromophenacyl-5 -
methyl-2 -oxo-4-p-tolylsulfonyl-1,2,2 ,3,3 ,4-hexa-
hydroquinoxaline-2-spiro-3 -indole (XII). Freshly
calcined potassium carbonate, 2 g, and p-bromo-
phenacyl bromide, 0.27 g, were added to a solution
of 0.2 g of N-[2-(5-methyl-2-oxo-1,2-dihydroindol-3-
ylideneamino)phenyl]-p-toluenesulfonamide in 10 ml
of acetone. The mixture was heated for 30 min under
reflux and filtered, the filtrate was evaporated, and the
dry residue was recrystallized from isopentyl alcohol.
Yield 0.28 g (70%). Gray yellow crystals, mp 250 C.
1H NMR spectrum (DMSO-d6), , ppm: 2.11 s (3H,
CH3), 2.34 s (3H, CH3), 5.28 br.s (2H, CH2), 6.06 s
(1H, CH), 6.63 6.78 m (3H, 7-H, 8-H, NH), 6.89
7.00 m (2H, 5-H, 6-H), 7.10 m (2H, 6 -H, 7 -H),
7.31 m (3H, 4 -H, 2*-H, 6*-H), 7.54 d (2H, 3*-H,
5*-H, J = 8.2 Hz), 7.63 d (2H, 2 -H, 6 -H, J =
8.3 Hz), 7.75 7.84 m (4H, 3 -H, 5 -H, 3 -H, 5 -H),
8.03 d (2H, 2 -H, 6 -H, J = 8.2 Hz).
Quinoxalines Xa Xd (general procedure). A
mixture of 0.3 mmol of thallium salt VIIIa VIIIc and
0.3 mmol of the corresponding phenacyl bromide in
5 ml of acetonitrile was refluxed for 15 min. The
mixture was filtered, the filtrate was evaporated, and
the dry residue was recrystallized from isobutyl
alcohol.
4-Benzylsulfonyl-3-p-bromobenzoyl-1 ,5 -di-
methyl-2 -oxo-1,2,2 ,3,3 ,4-hexahydroquinoxaline-2-
spiro-3 -indole (Xa). Yield 50%. Orange pink crys-
1
tals, mp 180 C. H NMR spectrum (acetone-d6), ,
ppm: 2.21 s (3H, CH3), 3.01 s (3H, NCH3), 4.60 d
(1H, CH, J = 14.1 Hz), 4.70 d (1H, CH, J = 14.1 Hz),
5.68 s (1H, CH), 6.84 d (1H, 8-H, J = 7.9 Hz), 6.88
6.94 m (2H, 7-H, 4 -H), 6.99 s (1H, NH), 7.05 d.d
(1H, 6-H), 7.12 7.23 m (5H, 2 -H 6 -H), 7.30 d
(2H, 6 -H, 7 -H, J = 6.6 Hz), 7.49 d (2H, 2 -H, 6 -H,
J = 8.8 Hz), 7.57 d (2H, 3 -H, 5 -H, J = 8.7 Hz),
7.75 d (1H, 5 -H, J = 8.2 Hz).
N-(2-Amino-4,5-dimethylphenyl)phenylmetha-
nesulfonamide (XIII). Phenylmethanesulfonyl chlo-
ride, 2.5 g, was added to a solution of 1.79 g of 4,5-
dimethyl-1,2-phenylenediamine and 1.9 ml of pyri-
dine in 20 ml of THF. The mixture was stirred for 2 h
at room temperature, 100 ml of water was added, the
mixture was heated to the boiling point and cooled,
and the precipitate was filtered off and recrystallized
from methanol. Yield 1.64 g (50%). Beige fine crys-
tals, mp 158 160 C.
1 ,5 -Dimethyl-3-p-nitrobenzoyl-2 -oxo-4-p-tolyl-
sulfonyl-1,2,2 ,3,3 4-hexahydroquinoxaline-2-spiro-
3 -indole (Xb). Yield 65%. Light yellow crystals, mp
1
230 C. H NMR spectrum (CDCl3), , ppm: 2.26 s
(3H, CH3), 2.34 s (3H, CH3), 3.06 s (3H, NCH3),
4.48 s (1H, NH), 6.02 s (1H, CH), 6.77 6.87 m (3H,
6-H, 7-H, 8-H), 7.00 m (2H, 6 -H, 7 -H), 7.15 m (3H,
4 -H, 3 -H, 5 -H), 7.33 d (1H, 5-H, J = 8.1 Hz), 7.53
m (4H, 2 -H, 6 -H, 2 -H, 6 -H), 7.69 d (2H, 3 -H,
5 -H, J = 8.4 Hz).
4-(2-Benzylsulfonylamino-4,5-dimethylphenyl-
imino)-8-ethoxy-1,3-dimethyl-4H-cyclohepta[c]-
furan (XV). A solution of 0.33 g of 1,3-dimethyl-4,8-
cyclohepta[c]furylium perchlorate [10] and 0.27 g of
N-(2-amino-4,5-dimethylphenyl)phenylmethanesul-
fonamide in 10 ml of dry chloroform was heated for
1.5 h under reflux. The mixture was cooled and poured
into 100 ml of a 5% solution of NaHCO3, and (after
stirring) the organic phase was separated. The solvent
was removed, and the residue was recrystallized from
methanol to obtain orange crystals of 4-(2-benzylsul-
fonylamino-4,5-dimethylphenylimino)-8-ethoxy-1,3-
4-Benzylsulfonyl-1 ,5 -dimethyl-3-m-nitroben-
zoyl-2 -oxo-1,2,2 ,3,3 ,4-hexahydroquinoxaline-2-
spiro-3 -indole (Xc). Yield 55%. Yellow crystals, mp
170 C. 1H NMR spectrum (acetone-d6), , ppm:
2.21 s (3H, CH3), 2.98 s (3H, NCH3), 4.47 s (2H,
CH2), 5.70 s (1H, CH), 5.78 s (1H, NH), 6.81 d (1H,
8-H, J = 7.9 Hz), 6.92 m (3H, 6-H, 7-H, 4 -H), 7.04
7.19 m (5H, 2 -H 6 -H), 7.30 d (2H, 6 -H, 7 -H, J =
7.4 Hz), 7.67 d.d (1H, 5 -H), 7.80 d (1H, 5-H, J =
8.0 Hz), 7.93 d (1H, 6 -H, J = 7.7 Hz), 8.27 s (1H,
2 -H), 8.34 d (1H, 4 -H, J = 6.1 Hz).
dimethyl-4H-cyclohepta[c]furan. Yield 0.28 g (60%),
1
mp 170 173 C. H NMR spectrum (acetone-d6),
,
1 ,5 -Dimethyl-3 -p-nitrobenzoyl-2 -oxo-4-p-tolyl-
sulfonyl-1,2,2 ,3,3 ,4-hexahydroquinoxaline-2-spiro-
3 indole (Xd). Yield 50%. Dark orange crystals, mp
ppm: 1.45 d.d (3H, CH3), 2.25 t (6H, 2CH3), 2.40 s
(3H, CH3), 2.59 s (3H, CH3), 4.05 q (2H, OCH2, J =
6.7 Hz), 4.45 s (2H, CH2), 5.48 d (1H, 6 -H), 6.09 d
1
135 C. H NMR spectrum (CDCl3), , ppm: 2.21 s
(1H, 4 -H), 6.35 d.d (1H, 5 -H, J4 ,5 = 12.6 Hz, J5 ,6 =
(3H, CH3), 2.35 s (3H, CH3), 3.05 s (3H, NCH3),
4.38 s (1H, NH), 6.01 s (1H, CH), 6.79 m (2H, 5-H,
9.3 Hz), 6.70 s (1H, 6-H), 7.45 7.10 m (7H, 3-H, Ph,
NH).
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TAUTOMERISM AND STEREODYNAMICS OF INDOPHENOLS, AMIDINES... : XVI.
737
Quinoxalines XVIIa XVIIc (general procedure).
Freshly calcined potassium carbonate, 2 g, and the
corresponding phenacyl bromide, 0.41 mmol, were
added to a solution of 0.41 mmol of compound XV in
10 ml of acetone. The mixture was heated for 15 min
under reflux, cooled, and filtered, the filtrate was
evaporated, and the residue was recrystallized from
isopentyl alcohol.
ACKNOWLEDGMENTS
This study was financially supported by the Rus-
sian Foundation for Basic Research (project nos. 01-
03-32549 and 99-03-33496).
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1. Kurbatov, S.V., Kuznetsov, D.N., Simakov, V.I.,
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1 ,3 ,6,7-tetramethyl-1,2,3,4-tetrahydro-4 H-quino-
xaline-2-spiro-4 -cyclohepta[c]furan (XVIIa). Yield
65%. Yellow gray crystals, mp 175 C. 1H NMR spec-
trum (acetone-d6), , ppm: 1.54 d.d (3H, CH3), 2.08 s
(3H, CH3), 2.21 s (3H, CH3), 2.23 s (3H, CH3), 2.25 s
(3H, CH3), 4.11 q (2H, OCH2), 4.50 d (1H, CH, J =
13.8 Hz), 4.60 d (1H, CH, J = 13.8 Hz), 5.30 d (1H,
7 -H, J = 11.3 Hz), 5.46 d (1H, 5 -H, J = 7.2 Hz),
5.69 s (1H, NH), 6.04 d.d (1H, 6 -H, J = 7.2 Hz),
6.40 s (1H, CH), 6.80 s (1H, 8-H), 7.30 7.43 m (7H,
2 -H 6 -H, 2 -H, 6 -H), 7.54 7.59 m (3H, 5-H, 3 -H,
5 -H).
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1
60%. Dark orange crystals, mp 150 C. H NMR spec-
trum (CDCl3), , ppm: 1.46 m (3H, CH3), 1.92 s (3H,
CH3), 2.18 s (3H, CH3), 2.20 s (3H, CH3), 2.23 s (3H,
CH3), 4.01 m (2H, OCH2), 4.10 s (1H, NH), 4.45 m
(2H, CH2), 5.30 m (2H, 7 -H, 5 -H), 5.97 d.d (1H,
6 -H), 6.29 s (1H, CH), 6.61 s (1H, 8-H), 7.73 7.45 m
(8H, 5-H, 2 -H 6 -H, 2 -H, 6 -H), 8.04 d (2H, 3 -H,
5 -H).
6. Semenov, A.A., Prirodnye protivoopukholevye soe-
dineniya (Natural Antitumor Compounds), Novosi-
birsk: Nauka, 1979.
7. Yunusov, M.S., Azotistye geterotsikly i alkaloidy
(Nitrogenous Heterocycles and Alkaloids), Moscow:
Iridium, 2001, vol. 1, p. 203.
8. da Silva, J.F.M., Garden, S.J., and da C. Pinto, A.,
The Chemistry of Isatins: a Review from 1975, 2000,
Suppl. 1.
4-Benzylsulfonyl-8 -ethoxy-1 ,3 ,6,7-tetramethyl-
3-m-nitrobenzoyl-1,2,3,4-tetrahydro-4 H-quinoxa-
line-2-spiro-4 -cyclohepta[c]furan (XVIIc). Yield
9. Rajopadhye, M. and Popp, F.D., J. Heterocycl. Chem.,
1
60%. Dark yellow crystals, mp 160 C. H NMR spec-
1987, vol. 24, p. 1637.
trum (CDCl3), , ppm: 1.35 m (3H, CH3), 1.90 s (3H,
CH3), 2.18 s (3H, CH3), 2.20 s (3H, CH3), 2.24 s (3H,
CH3), 3.96 m (2H, OCH2), 4.09 s (1H, NH), 4.41 d
(1H, CH, J = 13.9 Hz), 4.50 d (1H, CH, J = 13.9 Hz),
5.23 d (1H, 7 -H, J = 11.3 Hz), 5.29 d (1H, 5 -H, J =
7.4 Hz), 5.99 d.d (1H, 6 -H, J = 7.2 Hz), 6.23 s (1H,
CH), 6.61 s (1H, 8-H), 6.95 7.39 m (7H, 2 -H 6 -H,
5-H, 5 -H), 7.54 d (1H, 6 -H, J = 7.6 Hz), 8.06 s (1H,
2 -H), 8.20 d (1H, 4 -H, J = 7.7 Hz).
10. Olekhnovich, E.P., Boroshko, S.L., Borodkin, G.S.,
Korobka, I.V., Minkin, V.I., and Olekhnovich, L.P.,
Zh. Org. Khim., 1997, vol. 33, no. 2, p. 267.
11. Semenov, A.A. and Frolova, N.M., Khim.-Farm. Zh.,
1976, no. 4, p. 6.
12. Zhungietu, G.I. and Rekhter, M.A., Izatin i ego proiz-
vodnye (Isatin and Its Derivatives), Kishinev: Shti-
intsa, 1977.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 5 2004