The Synthesis and Cytotoxic Activity of D-Ribofuranosides and 2-Deoxy-D-Ribofuranosides of Substituted Bis(indolyl)furan, Bis(indolyl)pyrrole, and Indolo[2,3-a]carbazole Derivatives

Article abstract of DOI:10.1023/A:1023212532748

1-(2,3,5-Tri-O-acetyl)-β-D-ribofuranosyl indole, the key compound in the synthesis of glycosides with the bis(indole) aglycone, was obtained for the first time by the indoline-indole method. There were synthesized 3-(1-methylindol-3-yl)-4-(1-glycosylindol

Full text of DOI:10.1023/A:1023212532748

Russian Journal of Bioorganic Chemistry, Vol. 29, No. 2, 2003, pp. 160–167. Translated from Bioorganicheskaya Khimiya, Vol. 29, No. 2, 2003, pp. 181–189.
Original Russian Text Copyright © 2003 by Garaeva, Bakhmedova, Yartseva, Melnik, Adanin.
The Synthesis and Cytotoxic Activity of D-Ribofuranosides and
2-Deoxy-D-Ribofuranosides of Substituted Bis(indolyl)furan,
Bis(indolyl)pyrrole, and Indolo[2,3-a]carbazole Derivatives
1
L. D. Garaeva*, A. A. Bakhmedova,* I. V. Yartseva,* S. Ya. Melnik,* and V. M. Adanin**
*Blokhin Cancer Research Center, Russian Academy of Medical Sciences, Kashirskoe sh. 24, Moscow, 115478 Russia
**Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences,
pr. Nauki 5, Pushchino, Moscow oblast, 142290 Russia
Received December 19, 2001; in final form, March 6, 2002
Abstract—1-(2,3,5-Tri-O-acetyl)-β-D-ribofuranosyl indole, the key compound in the synthesis of glycosides
with the bis(indole) aglycone, was obtained for the first time by the indoline–indole method. There were syn-
thesized 3-(1-methylindol-3-yl)-4-(1-glycosylindol-3-yl)furan(or pyrrole)-2,5-diones containing the residue of
β-D-ribofuranose or 2-deoxy-β-D-ribofuranose and analogous glycosides of indolo[2,3-a]furano(or pyr-
rolo)[3,4-Ò]carbazol-5,7-diones, which are structurally relative to the antitumor antibiotic rebeccamycin. Their
cytotoxicities toward a number of human tumor cell lines were studied in vitro, and the carbazole N-glycosides
were shown to be more active than the bis(indole) glycosides. At the same time, the ribofuranosides were found
to be less active than the corresponding ribopyranosides synthesized previously.
Key words: bis(indolyl)furan, bis(indolyl)pyrrole, 2-deoxy-D-ribofuranosides, indolocarbazole, N-glycosides,
D-ribofuranosides
1
INTRODUCTION
three possible glycosylation sites in the indolocarba-
zole molecule. Therefore, as previously, we chose the
indoline–indole method for the synthesis of the starting
indolyl N-glycoside; this provides the necessary config-
uration of glycoside bond and does not require the pre-
liminary protection of the aglycone [12].
We had previously reported the synthesis of N-gly-
copyranosides of bis(indole) derivatives and substituted
indolo[2,3-a]carbazoles, analogues of the natural anti-
2
tumor antibiotic rebeccamycin [1–3]. The study of
biological properties of the synthesized glycosides
showed that the nature of glycoside residue markedly
affects their cytotoxic and antitumor activities in vitro
[4] and also their activity toward protein kinase C [5].
The compounds that contained the β-D-ribopyranosyl
or α-L-arabinopyranosyl residues turned out to be most
cytotoxic. This fact prompted us to study also the
dependence of the biological properties of the glyco-
sides on the size of their carbohydrate rings. To this
end, we have synthesized D-ribofuranosides and 2-
deoxy-D-ribofuranosides of substituted bis(indoles)
and indolocarbazoles.
First, we were to synthesize the ribose derivative in
the fixed furanose form for the subsequent glycosyla-
tion. The interaction of D-ribose with TBDMS chloride
led in 83% yield to 5-é-TBDMS-D-ribofuranose (I),
which was initially targeted for the glycosylation. How-
ever, the treatment of (I) with indoline and subsequent
acetylation resulted in a complex mixture of products,
from which we failed to isolate é-protected β-D-ribo-
furanosyl indoline. Therefore, (I) was acetylated by a
standard procedure. The glycosylation of indoline with
the resulting 1,2,3-tri-é-acetyl-5-é-TBDMS-D-ribo-
furanose (II) and subsequent dehydration with manga-
Microbiological methods or chemical glycosylation nese dioxide in benzene resulted in the protected N-gly-
by the Mitsunobu reaction or the method of mercuric, coside (III). However, the low total yield of this com-
silver, and other salts are usually used for introducing a pound (<1% from D-ribose) hindered its use as the
glycoside residue into the indolocarbazole molecule starting compound in the chosen synthetic scheme.
[6–11]. However, these methods are rather laborious,
because they require the selective introduction of pro-
tective groups and their subsequent removal owing to
RESULTS AND DISCUSSION
We attempted to obtain 2',3',5'-tri-é-acetyl deriva-
1
Please send correspondence to phone, +7 (095) 111-8279 or e-
tive (IV), even though it had previously been consid-
mail, chemsyn@mail.ru.
ered unavailable [12, p. 19]. 1-(2,3,5-Tri-é-acetyl)-β-
D-ribofuranosyl indoline was obtained in 53% yield
after a prolonged (~27 h) reflux of 1,2,3,5-tetra-é-
2
Abbreviations: DDQ, dichlorodicyanobenzoquinone; HR MS,
high resolution mass spectrometry; TBDMS, tert-butyldimethyl-
silyl; and Tol, p-toluyl (p-CH C H CO).
3
6 4
1068-1620/03/2902-0160$25.00 © 2003 MAIK “Nauka /Interperiodica”

THE SYNTHESIS AND CYTOTOXIC ACTIVITY
161
N
R'O
R'O
O
O
OR
~
RO
OR
RO
OR
(III) R = Ac, R' = TBDMS
(IV) R = R' = Ac
(IV)
(I) R = H, R' = TBDMS
(II) R = Ac, R' = TBDMS
1. (COCl)2
CH2COOH
2.
N
CH3
(V)
X
X
O
O
O
O
7
5
8
4
1
9
3
2
12
N
13
N
10
N
N
11
RO
RO
O
O
CH3
CH3
RO
OR
RO
OR
(VI) R = Ac, X = O
(VII) R = H, X = O
(VIII) R = H, X = NH
(IX) R = Ac, X = O
(X) R = H, X = O
(XI) R = H, X = NH
Scheme 1.
acetyl-β-D-ribofuranose and indoline in ethanol. The riboside (ï). To transform its furan ring into the pyrrole
subsequent dehydration of this compound with DDQ in one, per-é-acetylated derivative of (IX) was treated
toluene led to the target indole derivative (IV) in 76% with ammonia, which, as in the case of bis(indoles), led
yield (Scheme 1).
to (XI) isolated in 73% yield.
é-Protected 1-(2-deoxy-β-D-ribofuranosyl)indole
(XII), which was synthesized from indole and 2-deoxy-
2,5-di-é-p-toluyl-α-D-ribofuranosyl chloride by the
reported procedure [13] in 54% yield, was used as the
starting compound in the synthesis of 2-deoxyribofura-
noside derivatives of indolocarbazoles. The treatment
of (XII) with oxalyl chloride in anhydrous dichlo-
romethane at 0°ë for 2.5 h and the subsequent reaction
with (1-methylindol-3-yl)acetic acid (V) was accompa-
nied by anomerization; it gave a hardly separable mix-
ture of 3-(1-methylindol-3-yl)-4-[1-(2-deoxy-3,5-di-
é-p-toluyl-D-ribofuranosyl)indol-3-yl]furan-2,5-dione
(XIII) and its α-anomer in a ratio of 1 : 1 (according to
As previously reported for other N-glycosides, the
synthesized per-é-acetylated ribofuranoside (IV) was
converted into the derivative of bis(indolyl)furan-2,5-
dione (VI) in 44% yield by the treatment with oxalyl
chloride in dichloromethane and subsequent interaction
of the resulting intermediate with (1-methylindol-3-
yl)acetic acid (V) [1]. The removal of acetyl groups
from (VI) by sodium methylate in methanol gave (VII)
in 68% yield. Heating of the mixture of furan derivative
(VI) with ammonia solution in DMF at 140°ë resulted
in transformation of the furan to pyrrole cycle and the
deprotection of carbohydrate residue to give (VIII) in
75% yield. Like other similar compounds, (VI) was
photochemically oxidized by the atmospheric oxygen 1H NMR) (cf. [12], p. 90). Silver carbonate was added
in benzene in the presence of catalytic amount of iodine to the reaction mixture to bind hydrogen chloride that is
to transform its bis(indole) into the carbazole structure generated in the reaction and catalyzes the anomeriza-
[3]. Acetyl derivative (IX) was obtained in 52% yield. tion. Furthermore, the time of treatment with oxalyl
The deacetylation of (IX) with heated potassium car- chloride was decreased to 40 min. This allowed the iso-
bonate in anhydrous methanol resulted in 82% yield of lation of (XIII) in 53% yield. The minor admixture of
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 29 No. 2 2003

162
GARAEVA et al.
O
O
O
1. (COCl)2
Ag2CO3
N
N
N
RO
RO
O
O
CH3
CH2COOH
2.
N
CH3
RO
(XII) R = Tol
(V)
RO
O
Et3N
(XIII) R = Tol
(XIV) R = H
O
O
O2, hν
N
N
I2, C6H6
RO
O
CH3
RO
(XV) R = Tol
Scheme 2.
the corresponding α-anomer generated in the reaction glycoside bond in the synthesized ribofuranosides.
mixture was easily separated by preparative TLC. We However, it had been previously shown by the method
deacetylated (XIII) by 0.1 N sodium methylate in of circular dichroism that, irrespective of the aglycone
methanol for 20 min at room temperature and obtained nature, the indoline–indole method results in the N-
bis(indole) glycoside (XIV) in 91% yield. The photo- riboside with the β-configuration of the glycoside bond
chemical oxidation of (XIII) in benzene in the presence as the main (or even the only) reaction product [12].
of a catalytic amount of iodine at air bubbling and irra-
1
The H NMR spectra of acylated deoxyribosides
diation with a Hg lamp for 3 h led to (XV) in 42% yield
(XIII) and (XV) manifest the signals of anomeric pro-
tons as the doublets of doublets with the J1'2' coupling
(Scheme 2). All the attempts to transform the furandi-
one to the pyrroldione ring in (XV) or to deacetylate it
constants equal to 6.5 and 8.5 and 5.9 and 9.4 Hz,
respectively. This is characteristic of the presence of
bulky substituents at C3' and C5' of the deoxyribose
residue. At the same time, the signal of anomeric proton
in (XIV) with the free hydroxyl groups in the carbohy-
drate residue is a pseudotriplet with the coupling con-
stant of 6.6 Hz, which is characteristic of β-anomers of
pyrimidine and purine nucleosides. The resonances
from the protons at C2' in the spectra of each of com-
pounds (XIII), (XIV), and (XV) practically coincide
and form multiplets at 2.68–2.80, 2.48–2.34, and 2.94–
3.06 ppm, respectively. This is also characteristic of the
β-anomers of deoxyribofuranosides [14].
resulted in the complete degradation of the carbohy-
drate residue (1H NMR data).
The carbohydrate residue in the resulting (III), (IV),
and (VI)–(XI) is in the furanose form and has the β-
configuration of the glycoside bond. The size of the car-
bohydrate ring is confirmed by 1H NMR spectroscopy
(Table 1). A downfield shift of the signal of the ano-
meric proton (∆δ ~ 0.3 ppm) and a simultaneous upfield
shift of the protons at C3' (∆δ ~ 0.1–0.4 ppm) were
observed in the spectra of (IV) and (VI)–(XI) in com-
parison with the corresponding ribopyranosyl deriva-
tives (cf. [1, 3]). A significant upfield shift of the proton
signal at C4' (∆δ ~ 0.9 ppm) due to the absence of acetyl
group at C4' was observed for acetyl derivatives (IV)
and (VII). In the case of ribofuranosyl derivatives (IV)
and (VI)–(XI), the spin–spin coupling constant of the
anomeric proton is in the range 5.0–6.9 Hz, whereas
The mass spectra of the synthesized compounds
(Table 2) exhibit peaks of molecular [M]+ and aglycone
ions, which confirm their structure. Degradation of the
molecules of é-acyl derivatives (IV), (VI), (IX), and
(XIII) occurs with the formation of the carbohydrate
their values are 8.5–10.0 Hz for their β-ribopyranose
1
analogues [1, 3]. The H NMR data do not allow the residue ion. In all, the mass spectra of D-ribofurano-
unambiguous conclusion about the stereochemistry of sides and 2-deoxy-D-ribofuranosides of substituted
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 29 No. 2 2003

1
Table 1. H NMR spectra of the synthesized compounds*
Chemical shifts, δ, ppm (J, Hz)
Compound,
Aglycone
solvent
carbohydrate residue
H1′
H2′
3.75m, 3.69m
H3′
H4′
4.16m
H5′
other protons
(I)
–
5.10dd
(≈1.0, 5.7)
3.79m [2H]
4.89d (5.7) [1'-OH];
4.08d(5.0); 3.94d(5.2)
[2'-OH, 3'-OH]; 0.91s
[3CH3]; 0.09c [2CH3]
0.91s [3CH3]; 0.07s,
0.06s [2 CH3; 2.10s,
2.08s, 2.06s [3Ac]
0.97s [3CH3];
(CD3)2CO
(II)
6.15d (1.9) 5.36dd
5.40dd
4.20 ddd
3.76dd;
CDCl3
(1.9, 5.0)
(5.0, 5.3)
(5.3, 4.0, 4.0) 3.74dd (≈11)
(III)
CDCl3
7.60d (7.9)*; 7.54d (8.2);
7.42d [H2, (3.4)]; 7.21t;
7.12t; 6.56d [H3]
7.61d; 7.49d; 7.28d [H3, (3.3)];
7.23dt; 7.15dt; 6.60d [H2]
7.84s; 7.80s; 7.49d; 7.31d;
7.2–7.1m [3H]; 6.90t;
6.18d (5.3) 5.58dd
(5.3, 5.7)
5.51dd
(5.7, 2.6)
4.22ddd
(2.6, 2.3, 2.3) [2 H] (≈11)
3.91dd
0.15s [2CH3];
2.15s, 1.98s [2Ac]
2.16s [2Ac];
2.03s [Ac]
2.15s; 2.07s;
2.05s [3Ac]
(IV)
6.18d (6.3) 5.59dd
(6.3, 6.3)
6.18d (6.4) 5.46dd
(6.4, 6.4)
5.46dd
4.41–4.33m
[3H]
CDCl3
(VI)
(6.3, 3.7)
5.31dd
4.37ddd
(3.8, 3.8, 3.0) (3.8.12.7),
4.11dd(3.0)
4.08ddd
(5.1, 3.8, 3.8) 3.69dd (3.8)
4.06ddd
(5.1, 3.9, 3.9) (3.9.12.6),
3.69dd(3.9)
4.20dd
CDCl3
(6.4, 3.8)
6.81d; 6.79d; 3.87s [CH3]
8.14s; 7.90s; 7.43d; 7.34d; 7.11t [2 H];
(VII)
6.05d (5.1) 4.37dd
(5.1, 5.1)
6.01d (5.0) 4.36dd
(5.0, 4.8)
4.2dd
3.77dd(3.8,12.6)
(CD3)2CO 6.88d; 6.79t [2H]; 6.75d; 3.93s [CH3]
(5.1, 5.1)
4.19dd
(VIII)
9.68¯c [NH]; 7.99s; 7.77s; 7.56d;
3.78dd
(CD3)2CO 7.36d; 7.05t [2H]; 7.01d; 6.88d; 6.71t;
6.77t; 3.90s [CH3]
(4.8, 5.1)
(IX)
CDCl3
(X)
9.09d; 9.04d; 7.92d; 7.70d; 7.62d;
7.56t; 7.50t; 7.45t; 4.28 s [CH3]
6.43d (6.6) 5.44dd
(6.6, 6.6)
6.42d (6.9) 4.55m
5.40dd
(6.6, 6.6)
4.36m
4.44ddd
(6.6,≈3; 3)
4.25m
4.61m [2 H]
2.32s; 2.07s;
1.55s [3Ac]
9.08d; 9.06d; 8.36d; 7.84d; 7.40t; 7.61t;
4.15–4.00m
[2H]
(CD3)2CO 7.51t [2 H]; 4.38s [CH3]
(XI)
9.91s [NH]; 9.21d; 9.17d; 8.22d; 7.71d;
6.36d (6.7) 4.45dd
(6.7, 6.7)
4.30dd
(6.7, ≈3.5)
4.20ddd
4.09dd
(CD3)2CO 7.63d; 7.50t; 7.40t; 7.38t; 4.30s [CH3]
(≈3.5, 2.8, 3.2) (2.8.12.0)
4.01dd (3.2)
(XII)
7.59dd; 7.50d; 7.27d [H3, (3.5)];
7.00–7.18m [2H]; 6.52d [H2, (3.5)]
6.46dd
2.85ddd
5.70ddd
4.54m
4.51m
4.65m [2H]
7.97d*; 7.93d; 7.25d;
7.22d [2H each, 2Tol];
2.44s; 2.41s [2CH3]
7.96d*; 7.85d; 7.29d,
7.21d [2H each, 2 Tol];
2.45s; 2.41s [2CH3]
CDCl3
(5.6, 9.0)
(9.0, 6.8,14.3),
2.63ddd (5.6, 2.4)
2.68–2.80m
[2H]
(6.8, 2.4, 2.4)
(XIII)
CDCl3
7.73s; 7.62d; 7.50d, 7.28d [2H];
7.13m [2H]; 6.93t; 6.85m;
6.75m; 3.81 [CH3]
6.46dd
(6.5, 8.5)
5.59ddd
(5.7, 2.6, 2.6)
4.34m [2H]
(XIV)
CD3OD
(XV)
7.93s; 7.84s; 7.53d; 7.39d; 7.11m [2H];
7.02d; 6.84–6.66m [3H]; 3.86s [CH3]
9.02m [2H]; 7.94d; 7.62d; 7.70–7.35m
[4H]; 4.30s [CH3]
6.43pt
(6.6)
6.85dd
(5.7, 9.2)
2.34–2.48m
[2H]
2.94–3.06m
[2H]
4.34m
5.75m
3.95m
3.65–3.45m
[2H]
5.02dd
4.59ddd
(≈4, 2.7, 3.5) (2.7, 12.3)
8.10d*, 7.90d, 7.34d,
7.21d [2H each, 2 Tol];
2,51s, 2.40s [2CH3]
CDCl3
4.83dd (3.5)
1
* All the aromatic protons exhibit usual values of coupling constants (J) in the H NMR spectra.

164
GARAEVA et al.
m/z (I, %)
Table 2. Mass spectra of the synthesized compounds
Com-
pound
[M]+
aglycone fragments
117 (89.71), 118 (17.5), 89 (63.75)
carbohydrate fragments
447 (45.12)
(III)
331 (23.91), 330 (64.39), 288 (75.10),
271 (26.28), 270 (100.00), 229 (63.84)
(IV)
(VI)
375 (33.43)
600 (59.05)
117 (34.51)
259 (49.52), 157 (15.69), 139 (100)
259 (32.15), 139 (100), 97 (47.61)
342 (36.12), 343 (8.28), 270 (15.48)
(VII) 474 (43.28)
342 (100), 343 (24.88), 270 (52.60),
269 (23.84), 255 (13.06)
(VIII) 473 (38.80)
341 (100), 342 (24.00), 324 (10.11), 297 (8.52),
270 (11.89), 269 (17.87), 255 (7.69)
(IX)
598 (8.62)
339 (6.73), 340 (6.39), 268 (11.89), 267 (11.92)
259 (60.94), 199 (1.91), 157 (15.94),
139 (100), 97 (39.66), 43 (71.74)
(X)
472
471
340 (100.00), 341 (23.04), 268 (83.24), 267 (16.59)
(XI)
339 (100), 340 (23.56), 324 (21.60) 268 (22.26), 267
(11.85)
(XIII) 694 (41.1)
(XIV) 458 (32.08)
(XV) 692 (2.95)
343 (14.01), 342 (60.70), 297 (3.48), 270 (18.02), 255 353 (2.98), 119 (58.79), 81 (100)
(2.84)
343 (24.24), 342 (100), 341 (3.77), 297 (5.38), 270
(52.47), 255 (9.60), 227 (6.63)
341 (23.02), 340 (100), 268 (83.30), 253 (16.19)
119 (15.91), 81 (6.51)
Table 3. Antiproliferative activity of β-D-ribofuranosides and 2-deoxy-β-D-ribofuranosides (VII), (VIII), (XI), and (XIV)
(the concentration inhibiting the tumor growth by 50%, GI50, M, is given)
Cell line
(VII)
(VIII)
(XI)
(XIV)
Leukemia
SR
–
2.47 × 10–6
1.67 × 10–5
3.54 × 10–6
3.49 × 10–7
1.71 × 10–7
2.22 × 10–7
>1.00 × 10–4
3.76 × 10–5
–
CCRF-CEM
ä-562
4.90 × 10–5
>1.00 × 10–4
Breast Cancer
MDA-MB-435
MDA-N
>1.00 × 10–4
6.51 × 10–5
3.09 × 10–6
2.51 × 10–6
7.20 × 10–7
7.29 × 10–7
>1.00 × 10–4
4.44 × 10–5
Ovarian Cancer
OVCAR-3
5.10 × 10–5
2.99 × 10–5
–
5.23 × 10–7
2.45 × 10–7
6.61 × 10–5
1.78 × 10–5
IGROV1
1.45 × 10–5
Non–small Cell Lung Cancer
NCI-H522
3.90 × 10–5
6.04 × 10–6
4.26 × 10–7
5.03 × 10–5
bis(indole) and indolocarbazoles are close to those of what less cytotoxic than the corresponding ribopyrano-
sides synthesized previously [1–5].
the analogous D-ribopyranosides synthesized previ-
ously [1, 3].
The study of the cytotoxic activity of N-glycosides
synthesized was performed in the National Institute of
Cancer (United States) using the panel of 60 lines of
human tumor cells of various geneses. The data listed
in Table 3 attest that the derivatives of indolocarbazoles
are the most active as in the case of other compounds of
EXPERIMENTAL
The 1H NMR spectra of the synthesized compounds
were recorded on a Bruker WH-360 (Germany) spec-
trometer using tetramethylsilane as an internal stan-
dard. The method of double resonance was used for
assigning the signals in the spectra and for refinement
this series. At the same time, ribofuranosides are some- of the spin–spin coupling constants.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 29 No. 2 2003

THE SYNTHESIS AND CYTOTOXIC ACTIVITY
165
Mass spectra, including the high resolution mass anol (2.5 ml) was refluxed for 5.5 h and evaporated. The
spectra, were registered on a Finnigan MAT 8430 (Ger- residue was chromatographed on plates in a 40 : 1 ben-
many) mass spectrometer with the SS-300 system of zene–acetone system. The zone with Rf 0.22 was eluted
data processing (the accelerating voltage was 3 kV, the
energy of ionizing ions was 70 eV, the temperature of
ion source was 250°ë; the system of the direct inlet of
substance in the ionization area functioning at 170–
250°ë was used.
UV spectra were taken on a Specord UV–VIS (Ger-
many) spectrophotometer in ethanol at an optical length
of 1 cm; the values of λmax, nm (ε, M–1 cm–1), are given.
to give 0.07 g (21%) of 1-(5-é-TBDMS-2,3-di-é-
acetyl-β-D-ribofuranosyl)indoline. The resulting com-
pound (0.31 g, 0.69 mmol) and MnO2 (1.55 g) in ben-
zene (50 ml) were refluxed under vigorous stirring in an
apparatus supplied with a Dean–Stark trap for 7 h [16].
The reaction mixture was cooled and filtered, the sol-
vent was removed in a vacuum, and the residue was iso-
lated by a preparative TLC in a 40 : 1 benzene–acetone
system. The zone with Rf 0.69 was eluted to give 0.095 g
(31%) of (III) as a colorless oil; UV: 265 (7800), 277
(6000), and 288 (3800); IR: 1755 (CO); HR MS, m/z:
[M]+ found 447.2121, calculated for C23H33NO6Si
447.2077.
1-(2,3,5-Tri-O-acetyl-b-D-ribofuranosyl)indole
(IV). A solution of 1,2,3,5-tetra-é-acetyl-β-D-ribo-
furanose (3.1 g, 9.78 mmol) and indoline (1.40 g,
19.56 mmol) in absolute ethanol (35 ml) was refluxed
for 26.5 h under a TLC-monitoring in a 20 : 1 benzene–
acetone and evaporated in a vacuum. The residue was
chromatographed on plates using the same developing
system (double development) to yield 2.04 g (55%) of
1-(2,3,5-tri-é-acetyl-β-D-ribofuranosyl)indoline. A
solution of DDQ (0.30 g, 1.31 mmol) in anhydrous tol-
uene (3 ml) was added dropwise at room temperature to
a solution of the resulting compound (0.45 g,
1.19 mmol) in anhydrous toluene (12 ml). After 18 h,
the reaction mixture was evaporated in a vacuum, and
the residue was purified by preparative TLC in a 30 : 1
chloroform–acetone to give 0.34 g (76%) of (IV); UV:
262 (6000), 277 (4300), and 287 (3000); IR: 1755
(CO); HR MS, m/z: [M]+ found 375.1398, calculated
for C19H21NO7 375.1318.
3-(1-Methylindol-3-yl)-4-[1-(2,3,5-tri-O-acetyl-
b-D-ribofuranosyl)indol-3-yl]furan-2,5-dione (VI).
Oxalyl chloride (0.233 ml, 2.50 mmol) in anhydrous
dichloromethane (2 ml) was added dropwise to a solu-
tion of (IV) (0.625 g, 1.67 mmol) in anhydrous dichlo-
romethane (13 ml) cooled to 0°ë, and the mixture was
kept overnight at room temperature. The solution was
evaporated to dryness. The resulting foam-like residue
was dried in a vacuum over ê2é5, dissolved in anhy-
drous dichloroethane (12 ml), and a solution of (1-me-
thylindol-3-yl)acetic acid (V) (0.417 g, 2.20 mmol) and
triethylamine (0.51 g, 3.89 mmol) in dichloroethane
(4 ml) was added dropwise. The reaction mixture was
refluxed for 8 h, cooled, and evaporated to dryness. The
residue was separated by preparative TLC in 30 : 1
chloroform–acetone (double development) to give
0.425 g (44%) of (VI) as amorphous red powder; UV:
284 (10 200), 370 (5900), and 460 (10 800); IR: 1816
and 1755 (CO). HR MS, m/z: [M]+ found 600.1796, cal-
culated for C32H28N2O10 600.1743.
IR spectra were recorded on a Perkin-Elmer 283
(United States) instrument in KBr pellets; the values of
characteristic oscillations (cm–1) are given.
Analytical TLC was performed on Silufol UV254
precoated plates. Preparative TLC was carried out on
Silica gel 60PF254 + 366 (Germany) and Silica gel LSL254
5–40 µm (Chemapol, Czechia) precoated glass plates
with a layer thickness of 2.5 mm. The spots were visu-
alized on the plates by UV irradiation with a MinUVIS
(Desaga, Germany) lamp at wavelength of 254 or
366 nm. Column chromatography was performed on
Sephadex LH-20 (Sigma, United States) at the elution
with acetone.
1,2,3,5-Tetra-é-acetyl-β-D-ribofuranose (Sigma,
United States) was used for the synthesis of 1-(2,3,5-
tri-O-acetyl-β-D-ribofuranosyl)indole (IV).
Photochemical oxidation was performed using a Hg
lamp with a rated input of 250 W.
Antiproliferative activity of the synthesized com-
pounds was studied in the National Institute of Cancer
(United States) on a series of human cell lines accord-
ing to the method [15].
5-O-TBDMS-D-ribofuranose (I). A mixture of D-
ribose (1.58 g, 10.5 mmol) and TBDMS chloride
(1.90 g, 12.6 mmol) in anhydrous pyridine (15 ml) was
stirred for 18 h at room temperature. Then a saturated
NaHCO3 solution was added, and the product was
extracted with chloroform (3 × 10 ml). The combined
extracts were filtered and evaporated in a vacuum to
give 2.33 g (83%) of (I) as almost colorless oil.
5-O-TBDMS-1,2,3-tri-O-acetyl-D-ribofuranose
(II). Acetic anhydride (1.53 ml) was added to a stirred
solution of 5-O-TBDMS-D-ribofuranose (I) (0.76 g,
2.88 mmol) in anhydrous pyridine (7 ml) cooled to 0°ë.
After 1 h, the cooling was removed, the reaction mix-
ture was kept at room temperature for 18 h, and then
poured in ice. The resulting suspension was filtered,
and the resulting residue was purified by preparative
TLC in 20 : 1 benzene–acetone system. The substance
was detected by sulfuric acid. The zone with Rf 0.63
was eluted to give 0.18 g (16%) of (II) as colorless
glassy substance.
b
1-(5-O-TBDMS-2,3-di-O-acetyl- -D-ribofurano-
syl)indole (III). A solution of 5-é-TBDMS-1,2,3-tri-
3-(1-Methtylindol-3-yl)-4-(1-b-D-ribofurano-
é-acetyl-D-ribofuranose (II) (0.26 g, 0.67 mmol) and sylindol-3-yl)furan-2,5-dione (VII).A 1 M solution of
a freshly distilled indoline (0. 15 g, 2.03 mmol) in eth- sodium methylate in methanol (0.315 ml) was added to
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 29 No. 2 2003

166
GARAEVA et al.
a suspension of (VI) (0.150 g, 0.25 mmol), and the mix- 0.15 mmol) in DMF (2 ml), and the mixture was kept in
ture was stirred for 30 min at room temperature. Then an autoclave at 140°ë for 4 h. After cooling, the reac-
the solution was neutralized with KU-2 (ç+) cation
exchange resin to pH 7 using a universal indicator. The
resin was removed and washed with methanol, the sol-
vent was removed in a vacuum, and the residue was
purified by preparative TLC in 1 : 1 benzene–acetone
and then on a Sephadex LH-20 column to give 0.081 g
(68%) of (VII); UV: 227 (26 000), 285 (9400), 370
tion mixture was evaporated to dryness, and water was
added to the residue. The resulting precipitate was sep-
arated, dried in air, and chromatographed on a Sepha-
dex LH-20 column to give 0.052 g (73%) of carbazole
(XI) as an yellow powder; UV: 238 (29 200), 255
(14100), 280 (15 400), 288 (19 800), 306 (27 300), 316
(44300), and 400 (3300); IR: 3400, 1755, and 1710;
(5000), and 460 (8600); IR: 1816 and 1750 (CO). HR HR MS, m/z: [M]+ found 471.1429, calculated for
MS, m/z: [M]+ found 474.1502, calculated for
C26H22N2O7 474.1427.
C19H21N3O6 471.1430.
1-(2-Deoxy-3,5-di-O-p-toluyl-b-D-ribofurano-
syl)indole (XII) [13]. A mixture of indole (0.35 g,
2.99 mmol) and sodium hydride (0.15 g of 80% sus-
pension in oil, 5 mmol) in anhydrous acetonitrile
(30 ml) was stirred under nitrogen at room temperature
for 30 min. Then 2-deoxy-3,5-di-é-p-toluyl-α-D-ribo-
furanosyl chloride (1.41 g, 3.63 mmol) [17] was added
in portions, and the reaction mixture was kept at the
same temperature for 24 h. The precipitate was sepa-
rated, acetonitrile was removed in a vacuum, and the
residue was purified by preparative TLC in 20 : 1 ben-
zene–ethyl acetate. Yield of (XII) 0.75 g (54%).
3-(1-Methylindol-3-yl)-4-(1-b-D-ribofuranosylin-
dol-3-yl)-1H-pyrrol-2,5-dione (VIII). Concentrate
ammonia (2 ml) was added to a solution of (VI) (0.100
g, 0.17 mmol) in DMF (2 ml), and the mixture was kept
in an autoclave at 140°ë for 4 h. The reaction mixture
was cooled and evaporated to dryness. The residue was
dissolved in acetone (2 ml) and chromatographed on a
Sephadex LH-20 column to give 0.059 g (75%) of gly-
coside (VIII) as a red powder; UV: 227 (27000), 282
(8800), 370 (4000), and 453 (6000); IR: 3400, 1710
(NH), and 1754 (CO); HR MS, m/z: [M]+ found
473.1585, calculated for C26H23N3O6 473.1586.
3-(1-Methylindol-3-yl)-4-[1-(2-deoxy-3,4-di-O-p-
toluyl-b-D-ribofuranosyl)indol-3-yl]furan-2,5-dione
(XIII). A solution of oxalyl chloride (0.12 g, 0.91 mmol)
in anhydrous dichloromethane (2 ml) was added to a
cooled to 0°C and stirred solution of (XII) (0.1 g,
0.21 mmol) in anhydrous dichloromethane(2 ml) contain-
ing a suspension of silver carbonate (0.15 g, 0.36 mmol).
The reaction mixture was stirred for 40 min at 0°ë and
filtered from the precipitate of silver salts. The filtrate
was evaporated to dryness, and (1-methylindol-3-
yl)acetic acid (V) (0.05 g, 0.26 mmol) and triethy-
lamine (0.1 ml, 0.72 mmol) were added to the residue
dissolved in dichloroethane (3 ml) at 0°ë. The reaction
mixture was refluxed for 4 h, evaporated in a vacuum,
and the residue was separated by preparative TLC in
4 : 1 CCl4–acetone (double development) to isolate
0.08 g (53%) of (XIII); UV: 237 (40000), 277 (11000),
370 (5300), and 462 (8300); IR: 1820 and 1750; HR
MS, m/z: [M]+ found 694.2250, calculated for
C42H34N2O8 694.2315.
13-Methyl-12-(2,3,5-tri-O-acetyl-b-D-ribofura-
nosyl)indolo[2,3-a]furano[3,4-c]carbazol-5,7-dione
(IX). A mixture of (VI) (0.225 g, 0.37 mmol), toluene
(200 ml), and iodine (a catalytic amount) was placed in
a quartz flask, irradiated with the Hg lamp for 3 h when
bubbling air, and evaporated to dryness. Methanol (50
ml) was added to the residue, and the mixture was
cooled to 5°ë. The precipitate was separated, washed
with cooled methanol, and dried in a vacuum over ê2é5
to give 0.117 g (52%) of (IX) as an yellow powder; UV:
237 (19200), 255 (9000), 289 (18600), 305 (28000),
313 (38300), and 400 (4100); IR: 1822 and 1752; HR
MS, m/z: [M]+ found 598.1635, calculated for
C32H26N2O10 598.1587.
13-Methyl-12-(b-D-ribofuranosyl)indolo[2,3-
a]furano[3,4-c]carbazol-5,7-dione (X). Absolute
methanol (3 ml) and dried by heating potash (0.80 g)
were added to (IX) (0.085 g, 0.14 mmol), and the mix-
ture was stirred for 20 min at room temperature (TLC
monitoring in 1 : 1 benzene–acetone). Then the precip-
itate was removed, and the solution was neutralized
with KU-2 (ç+) cation exchange resin to pH 7. The
resin was removed and washed with methanol, and the
filtrate was evaporated in a vacuum. The residue was
chromatographed on a Sephadex LH-20 column to give
0.045 g (82%) of (X) as an yellow powder; UV: 238
(24600), 256 (11100), 277sh (10 400), 291sh (16500),
307sh (31200), 316 (46700), and 406 (4200); IR: 1816
and 1745; HR MS, m/z: [M]+ found 472.1282, calcu-
lated for C26H20N2O7 472.1270.
3-(1-Methylindol-3-yl)-4-[1-(2-deoxy-b-D-ribo-
furanosyl)indol-3-yl]furan-2,5-dione (XIV). A 0.1 N
solution of sodium methylate in methanol (1 ml) was
added to a solution of (XIII) (0.05 g, 0.7 mmol) in
methanol (2 ml). The reaction mixture was stirred for
20 min at room temperature and then neutralized with
Dowex 50 (ç+) cation exchange resin to pH 7 using an
universal indicator. The resin was filtered off, and the
filtrate was evaporated in a vacuum. Product (XIV) was
isolated by preparative TLC in 20 : 1 ethyl acetate–
methanol; yield 0.03 g (91%); UV: 227 (16700), 278
(10800), 375 (5500), 530 (2800), and 610 (4800); IR:
1820 and 1750; HR MS, m/z: [M]+ found 458.1503, cal-
culated for C26H22N2O6 458.1477.
13-Methyl-12-(b-D-ribofuranosyl)indolo[2,3-
a]pyrrolo[3,4-c]carbazol-5,7-dione (XI). Concentrate
ammonia (2 ml) was added to a solution of (VII) (0.090 g,
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 29 No. 2 2003

THE SYNTHESIS AND CYTOTOXIC ACTIVITY
167
NCI–EORTC Symp. on New Drugs in Cancer Therapy,
13-Methyl-12-(2-deoxy-3,5-di-O-p-toluyl-b-D-
ribofuranosyl)indolo[2,3-a]furano[3,4-c]carbazol-
5,7-dione (XV). A solution of (XIII) (0.19 g,
0.37 mmol) and a catalytic amount of iodine in benzene
(190 ml) was placed in a quartz tube and irradiated with
the Hg lamp for 3 h at air bubbling (TLC monitoring in
10 : 1 CCl4–acetone). The benzene solution was
washed with a saturated sodium thiosulfate (2 × 50 ml)
and water (2 × 50 ml) and evaporated in a vacuum, and
the residue was purified by preparative TLC in the same
developing system (double development) to give 0.08 g
(42%) of (XV); UV: 238 (31 000), 315 ((32 500), and
400 (4170); IR: 1830 and 1760; HR MS, m/z: [M]+
found 692.2092, calculated for C42H32N2O8 692.2158.
Amsterdam, Netherlands, 1998, p. 113
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