Synthesis and in vitro antitumor activity of some amino-deoxy 7-hexofuranosylpyrrolo[2,3-d] pyrimidines

Article abstract of DOI:10.1016/S0008-6215(98)00098-6

7-(6-amino-6-deoxy-β-D-glucofuranosyl)-5-cyanopyrrolo[2,3-d]pyrimidine (22) and 7-(3-aminomethyl-3-deoxy-β-D-allofuranosyl)-5-cyanpyrrolo[2,3-d]pyrimidine (28) were synthesized by sequentially coupling silylated 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine with the corresponding protected sugars 9 and 17, followed by deblocking and catalytic hydrogenation. Conversion of the 5-nitrile in 22 and 28 into a carboxamide gave the corresponding sangivamycin derivatives 23 and 29. Whereas 5'-aminomethyl nucleosides 22 and 23 inhibited the growth of four different human tumor cell lines at μM concentrations, the 3'-aminomethyl analogs 28 and 29 were much less active against these cells.

Full text of DOI:10.1016/S0008-6215(98)00098-6

308
Carbohydrate Research 308 (1998) 319±328
Synthesis and in vitro antitumor activity of
some amino-deoxy 7-hexofuranosylpyrrolo[2,3-d]
pyrimidines
Bao-Guo Huang, Miroslav Bobek*
Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and
Carlton Streets, Bu€alo, NY 14263, USA
Received 20 January 1998; accepted 30 March 1998
Abstract
7-(6-amino-6-deoxy-ꢀ-d-glucofuranosyl)-5-cyanopyrrolo[2,3-d]pyrimidine (22) and 7-(3-amino-
methyl-3-deoxy-ꢀ-d-allofuranosyl)-5-cyanopyrrolo[2,3-d]pyrimidine (28) were synthesized by
sequentially coupling silylated 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine with the cor-
responding protected sugars 9 and 17, followed by deblocking and catalytic hydrogenation.
Conversion of the 5-nitrile in 22 and 28 into a carboxamide gave the corresponding sangiva-
mycin derivatives 23 and 29. Whereas 50-aminomethyl nucleosides 22 and 23 inhibited the
growth of four di€erent human tumor cell lines at ꢁM concentrations, the 30-aminomethyl
analogs 28 and 29 were much less active against these cells. # 1998 Elsevier Science Ltd. All
rights reserved
Keywords: 30-Branched-30-deoxy nucleosides; Aminomethyl nucleosides; Pyrrolo[2,3-d]pyrimidines; Synthesis;
Antitumor activity
1. Introduction
kinase C (PKC) and/or protein kinase A (PKA).
Because, among these agents, 50-amino-50-deoxy-
sangivamycin (2a) inhibited PKC more potently
than 1a, and because of the suggested presence of
an amine-binding site at the ATP-binding domain
of PKC [3], it was of interest to examine the e€ect
on biological activity of the aminomethyl func-
tionality attached to other positions of 1a and/or
1b. In this report, we describe the synthesis of 30-
and 50-aminomethyl analogs of 1a and 1b. Taking
into consideration that xylofuranosyl sangivamy-
cin (2b) was a better inhibitor [4] of PKC than (1a),
we incorporated this structural feature into the
design of the 50-aminomethyl analogs.
Inhibition of signal-transducing protein kinases
has recently emerged as a promising approach to
anticancer design. As part of our e€ort to develop
ATP-competitive inhibitors of such kinases, we
prepared a series of analoges of sangivamycin (1a)
and toyocamycin (1b) that were resistant to phos-
phorylation and found that substituting certain
groups for the 50-hydroxyl in these nucleosides
gave rise to more potent inhibitors [1,2] of protein
* Corresponding author.
0008-6215/98/$19.00 # 1998 Elsevier Science Ltd. All rights reserved
PII S0008-6215(98)00098-6

320
B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
azido-2,3,5-tri-O-benzoyl-6-deoxy-ꢂ,ꢀ-d-glucofur-
anose (9) (Scheme 1) and 1-O-acetyl-3-azido-
methyl-2,5,6-tri-O-benzoyl-3-deoxy-ꢀ-d-allofur-
anose (17) (Scheme 2).
Thus, benzoylation of 3-O-benzoyl-1,2-O-iso-
propylidene-6-O-p-toluenesulfonyl-ꢂ-d-glucofur-
anose (3) [7] (Scheme 1) furnished the dibenzoyl
derivative 4 [8], which gave the 6-azido-6-deoxy
derivative 6 [9] on treatment with lithium azide in
DMF. Alternatively, 6 was prepared by treating 3
with lithium azide in DMF at room temperature to
give 5 [7], followed by benzoylation. Compound 6
had previously been prepared by benzoylation of
6-azido-6-deoxy-1,2-O-isopropylidene-ꢂ-d-gluco-
furanose and puri®ed by silica gel chromatography
in benzene±EtOH and crystallization from EtOH
[9]. In our hands, silica gel chromatography of 6 in
petroleum ether±EtOAc gave a suciently pure
product to be used in the subsequent methanolysis
step. In the present study, we found it more con-
venient to use 1% iodine in methanol [10] in place
of methanolic HCl followed by neutralization with
solid lead carbonate [9] to convert 6 into an
anomeric mixture of methyl glucofuranosides 7 [9],
which a€orded the sugar acetates 9 by benzoyla-
tion (to give 8), followed by acetolysis.
2. Results and discussion
For the synthesis of the target 7-glycosylated
pyrrolo[2,3-d]pyrimidine nucleosides, we chose the
coupling [5] of the silylated 4-amino-6-bromo-5-
cyanopyrrolo[2,3-d]pyrimidine with the appro-
priate blocked sugar in the presence of trimethyl-
silyl tri¯uoromethanesulfonate (Me3SiOTf) [6],
which involved the preparation of 1-O-acetyl-6-
The 3-azidomethyl-3-deoxy derivative 17 was
prepared in several steps starting from 3-C-hydroxy-
Scheme 1.

B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
321
Scheme 2.
methyl-3-deoxy-1,2:5,6-di-O-isopropylidene-ꢂ-d-
allofuranose (10) [11] (Scheme 2). Treatment of 10
with methanesulfonyl chloride in pyridine gave
3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methane-
sulfonyloxymethyl-ꢂ-d-allofuranose (11) that was
converted to 3-azidomethyl-3-deoxy-1,2:5,6-di-O-
isopropylidene-ꢂ-d-allofuranose (12) by displace-
ment of the methanesulfonyloxy group with
lithium azide in DMF. Selective deblocking [12] of
the 5,6-O-isopropylidene group in 12 gave 13,
which was benzoylated with benzoyl chloride in
pyridine to furnish a 5,6-di-O-benzoyl derivative
14. Methanolysis of 14, followed by benzoylation
of the intermediate anomeric mixture of methyl
allosides 15, gave methyl 3-C-azidomethyl-2,5,6-
tri-O-benzoyl-3-deoxy-ꢂ,ꢀ-d-allofuranoside (16),
and acetolysis of 16 with acetic anhydride and sul-
furic acid a€orded an azidomethyl sugar 17. The
structure of 17, which was isolated as a single ꢀ-
Me3SiOTf yielded an inseparable mixture (77%
yield) of N-7 and N-1 nucleosides 18 and 19,
respectively. Treatment of this mixture with
Me3SiOTf in 1,2-dichloroethane at re¯ux tempera-
ture resulted in an isomerization of 19 to give 18 as
a single product in 52% yield. Compound 18 and
the mixture of 18 and 19 were deblocked with
methanolic ammonia to a€ord 20 and a mixture of
nucleosides 20 and 21, which was separated by
silica gel chromatography. Debromination of 20 by
catalytic hydrogenation over 10% Pd/C was
accompanied by the reduction of the azido group
to give an amino nucleoside 22. Treatment of 22
with hydrogen peroxide in concentrated ammo-
nium hydroxide produced a 50-aminomethyl analog
of sangivamycin 23.
Similarly, coupling of 3-azidomethyl-3-deoxy
sugar 17 with the silylated pyrrolo[2,3-d]pyrimidine
(Scheme 4) a€orded an inseparable mixture of 24
and its N-1 isomer 25 in 68% yield. Treatment of
this mixture with Me3SiOTf in 1,2-dichloroethane
at re¯ux temperature gave 24 as the sole product,
which was deprotected by treatment with methan-
olic ammonia to provide 26. Similar deprotection
of the mixture of 24 and 25 gave a mixture of 26
1
anomer, was con®rmed by its H NMR spectrum
where the signal for the anomeric proton appeared
as a singlet at ꢃ 6.25.
Coupling of 9 with silylated 4-amino-6-bromo-5-
cyanopyrrolo[2,3-d]pyrimidine [13,14] (Scheme 3)
in 1,2-dichloroethane and in the presence of

322
B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
Scheme 3.
and 27 that was separated by chromatography.
Catalytic hydrogenation converted 26 to a bran-
ched-chain aminomethyl analog of toyocamycin
28, which when treated with hydrogen peroxide in
concentrated ammonium hydroxide, gave the cor-
responding sangivamycin analog 29.
Assignment of the site of ribosylation in 20 and
26 as N-7, and in 21 and 27 as N-1, was made on
the basis of their ultraviolet spectra [14,15]. The
anomeric con®guration of the newly prepared
nucleosides was assigned as ꢀ-based on the basis of
1H NMR studies. In the 50-aminomethyl series of
nucleosides, a singlet corresponding to the anome-
ric proton was observed in the 1H NMR spectra of
21, 22 and 23. For the 30-aminomethyl nucleoside
29, a doublet appeared at ꢃ 6.02 with a coupling
20-OBz group in the glycosylation reaction [17]
under Lewis acid conditions and with the results of
our previous studies [5,15]. The IR spectra con-
®rmed the presence of the azido and/or nitrile
groups in the sugar precursors and in the target
nucleosides by the sharp absorbance observed in
1
the 2100±2150 and 2250±2280 cm
respectively.
regions,
The newly synthesized compounds were eval-
uated for their in vitro anticancer activity by
growth-inhibition studies using four human tumor-
cell lines: human ovarian A121, human lung
NSCLC A549, human colon HT-29, and human
breast MCF7. As shown in Table 1, the 7-(6-
amino-6-deoxy-ꢀ-d-glucofuranosyl)pyrrolo[2,3-d]-
pyrimidines (22, 23) showed inhibitory activity
against these cell lines ranging from 3.9 to 11.5 mM;
the other compounds tested were much less active.
In contrast, sangivamycin itself inhibited cell
growth at 0.006 ꢁM. That greater inhibition
0
0
constant J1 2 2.43 Hz, which is within the accep-
table limits for ꢀ-ribonucleosides as predicted by
the Karplus equation [16]. This assignment was
in harmony with stereocontrol exercised by the

B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
323
Scheme 4.
Table 1
compounds on PKA, PKC, and cyclin-dependent
kinase activity will be determined and reported
elsewhere.
The e€ect of newly synthesized aminonucleosides on the
growth of some tumor cells in vitro during continuous
exposure a
IC50 [mM]
Compound
A121
A549
HT-29
MCF7
3. Experimental
22
23
26
28
3.9
4.2
33
4.8
11.5
53
>100
NT b
0.006
5.0
7.8
154
>100
67
0.009
4.0
8.5
59
General methods.ÐThin-layer chromatography
was performed on EM Separations silica gel alu-
minum-backed plates F254. Solvent A: 3:1 petro-
leum ether (PE)±EtOAc, solvent B: 1:1 PE±EtOAc,
solvent C: 20:2:2:1 EtOAc±EtOH±Me2O±H2O,
solvent D: 8:2:1 MeOH±EtOAc±concd NH3±H2O.
Column chromatography was carried out on silica
gel (230±400 mesh) from E. Merck Co. Melting
points were taken on a Mel-Temp capillary point
block and are uncorrected. Elemental analyses
were performed by Robertson Laboratories,
>100
51
0.004
>100
64
0.005
29
Sangivamycin
a The tumor cells were maintained in complete RPMI 1640
medium. Cell growth inhibition was determined, and these
results are the average of at least two separate determinations
performed with duplicate cultures.
b Not tested.
derived from the fact that phosphorylation in the
intact cell allows this compound to interfere with
nucleic acids as well as with other metabolic
sites [18,19]. The e€ects of the newly prepared
1
Madison, NJ. H NMR spectra were recorded on
either a Varian 390 (90 MHz) or a Bruker AM 400
(400 MHz) spectrometer. IR spectra were recorded

324
B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
on Perkin±Elmer Models 457 and 710B spectro-
meters. Evaporations were carried out under
reduced pressure at water bath temperature below
35 ꢀC.
(d, 1 H, H-1, J 3.5 Hz); IR (neat) ꢄ 2150 (N3), 1750
(C ˆ O) cm .
1
Method B. To an ice-cooled solution of 5 (2.20 g,
6.30 mol) in CH2Cl2 (25 mL) and pyridine
(2.50 mL) was added dropwise benzoyl chloride
(0.95 mL, 7.92 mmol), and the mixture was stirred
at rt overnight and then poured into a vigorously
stirred mixture of ice±water (25 mL) and NaHCO3
(1.40 g). The organic phase was washed with H2O
(3Â20 mL), dried (MgSO4), evaporated, and chro-
matographed to give 6 (2.45 g, 86%), which was
identical by TLC and NMR spectrum with the
product of Method A.
3,5-Di-O-benzoyl-1,2-O-isopropylidene-6-O-p-tol-
uenesulfonyl-a-d-glucofuranose (4).ÐTo an ice-
cooled solution of 3 [7] (52.58 g, 0.11 mol) in
CH2Cl2 (400 mL) and pyridine (44 mL) was added
dropwise benzoyl chloride (15.6 mL, 0.13 mol), and
the mixture was stirred at rt overnight and then
poured into a vigorously stirred mixture of ice±
water (300 mL) and NaHCO3 (21.8 g). The organic
layer was washed with H2O (3Â200 mL), dried
(MgSO4), evaporated, and chromatographed to
Methyl 6-azido-3,5-di-O-benzoyl-6-deoxy-a,b-d-
glucofuranoside (7).ÐA solution of 6 (34.6 g,
0.076 mol) in 1% I2 in MeOH (400 mL) was heated
at re¯ux for 16 h. The solution was then con-
centrated to half of the volume and poured into a
stirred aqueous solution of Na2S2O3 (1%, 600 mL).
The mixture was extracted with ethyl acetate
(3Â200 mL), and the extract was washed with H2O
(3Â200 mL), dried (MgSO4), evaporated and chro-
matographed to give 7 (27.7 g, 85%); Rf 0.24 (sol-
vent A). 1H NMR (CDCl3) ꢀ:ꢂ ꢁ2:1, ꢃ 3.35 (s, 3 H,
OCH3), 3.66 (m, 2 H, H-6), 4.25 (s, 1 H, OH), 4.87
(m, 1 H), 5.17±5.51 (m, 4 H), 7.15±7.41 (m, 6 H,
aromatic), 7.73±7.80 (m, 4 H, aromatic); IR (neat)
1
give 4 (57.3 g, 89%); Rf 0.36 (solvent A). H NMR
(CDCl3) ꢃ 1.23, 1.46 (2 s, 6 H, CMe2), 2.20 (s, 3 H,
CH3), 4.33±4.69 (m, 4 H), 5.34±5.43 (m, 2 H), 5.83
(d, 1 H, H-1, J 3.0 Hz), 7.0±7.86 (m, 14 H, aro-
1
matic); IR (neat) ꢄ 1780 (C ˆ O) cm .
6-Azido-3-O-benzoyl-6-deoxy-1,2-O-isopropyl-
idene-a-d-glucofuranose (5).ÐA mixture of 3
(3.60 g, 7.53 mmol) and LiN3 (3.69 g, 75.4 mmol) in
DMF (40 mL) was stirred at rt for 36 h and eva-
porated. The residue was triturated with ether
(50 mL), and the ether solution was washed with
H2O (3Â20 mL), dried (MgSO4), evaporated, and
chromatographed to give 5 as a syrup (1.88 g,
1
1
72%); Rf 0.55 (solvent A). H NMR (CDCl3) ꢃ
ꢄ 3200±3600 (OH), 2180 (N3), 1770 (C ˆ O) cm .
1.27, 1.49 (2 s, 6 H, CMe2), 3.30±3.43 (m, 3 H, H-6,
OH), 3.60±4.30 (m, 2 H, H-4,5), 4.59 (d, 1 H, J
3.0 Hz, H-2), 5.46 (d, 1 H, H-3), 5.86 (d, 1 H, J1,2
3.0 Hz, H-1), 7.30±7.53 (m, 3 H, aromatic), 7.89±
8.05 (m, 2 H, aromatic); lit. [7] 1H NMR (60 MHz,
CDCl3) ꢃ 1.43, 1.57 (2 s, 6 H, CMe2), 3.43±3.6 (m,
H-6, OH), 4.7 (d, 1 H, J1,2 4.0 Hz, H-2), 5.52 (d, 1
H, J3,4 2.5 Hz, H-3), 5.97 (d, 1 H, J1,2 4.0 Hz, H-1);
IR (neat) ꢄ 3200±3600 (OH), 2160 (N3), 1760
Methyl 6-azido-2,3,5-tri-O-benzoyl-6-deoxy-a,b-
d-glucofuranoside (8).ÐThe title compounds were
prepared by benzoylation of 7 as previously repor-
1
ted [9]: Rf 0.64 (solvent A); H NMR (CDCl3) ꢃ
3.46 (s, 3 H, OCH3), 3.76±4.86 (m, 3 H, H-5,6),
5.10±5.59 (m, 3 H, H-2,3,4), 5.83 (d, 1 H, H-1, J
6.0 Hz), 7.15±7.41 (m, 9 H, aromatic), 7.73±7.80
(m, 6 H, aromatic); IR (neat) ꢄ 2160 (N3), 1760
1
(C ˆ O) cm .
1
(C ˆ O) cm .
1-O-Acetyl-6-azido-2,3,5-tri-O-benzoyl-6-deoxy-
a,b-d-glucofuranose (9).ÐTo an ice-cooled solution
of 8 (29.3 g, 0.055 mol) in CH2Cl2 (200 mL) and
acetic anhydride (33.5 mL) was added dropwise
sulfuric acid (1.35 mL), and the mixture was kept at
5 ꢀC overnight. Sodium acetate (11 g) was added at
rt, and the mixture was then stirred for 20 min, ®l-
tered, and the ®ltrate was evaporated. The residue
was dissolved in ethyl acetate (200 mL), and the
solution was washed with saturated NaHCO3
solution (3Â100 mL), H2O (3Â100 mL), dried
(MgSO4), evaporated, and chromatographed to
provide 9 (21.3 g, 69%) as an oil which solidi®ed on
6-Azido-3,5-di-O-benzoyl-6-deoxy-1,2-O-isopropyl-
idene-a-d-glucofuranose (6).ÐMethod A: A mix-
ture of 4 (56.7 g, 0.097 mol) and LiN3 (21.2 g,
0.43 mol) in DMF (250 mL) was stirred at 75±80ꢀC
for 1 h and evaporated. The residue was sequen-
tially taken up into ether (250 mL), washed with
H2O (3Â100 mL), dried (MgSO4), evaporated, and
chromatographed to yield 6 as a yellow syrup
(34.6 g, 78.3%); Rf 0.68 (solvent A). 1H NMR
(CDCl3) ꢃ 1.26, 1.51 (2 s, 6 H, CMe2), 3.66 (m, 2 H,
H-6), 4.50±4.73 (m, 2 H, H-2,4), 5.34±5.50 (m, 2 H,
H-3,5), 5.87 (d, 1 H, H-1, J 3.0 Hz), 7.20±7.46 (m, 6
H, aromatic), 7.76±7.89 (m, 4 H, aromatic); lit. [9]
1H NMR (CDCl3) ꢃ 1.34 and 1.61 (2 s, CMe2), 5.98
1
standing; Rf 0.52 (solvent A). H NMR (CDCl3) ꢃ
2.10 (s, 3 H, CH3), 3.73±3.86 (m, 2 H, H-6), 3.92±

B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
325
5.10 (m, 1 H, H-5), 5.54±5.66 (m, 2 H, H-3,4), 5.86
(d, 1 H, H-2, J 4.5 Hz), 6.40 (d, 1 H, H-1, J 4.5 Hz),
7.26±7.50 (m, 9 H, aromatic), 7.76±8.07 (m, 6 H,
aromatic); IR (neat) ꢄ 2125 (N3), 1750 (C ˆ O)
ture of ice±water (300 mL) and NaHCO3 (16.8 g),
and the organic phase was washed with H2O
(3Â200 mL), dried (MgSO4), and evaporated. The
residue was chromatographed to give 14 (20.1 g,
94%), which wasꢀcrystallized from petroleum ether±
1
cm . Anal. Calcd for C29H25N3O9 (559.5): C,
1
62.25; H, 4.47; N, 7.51. Found: C, 61.98; H, 4.43;
N, 7.48.
3-Azidomethyl-3-deoxy-1,2,5,6-di-O-isopropyl-
ether: mp 68±69 C; Rf 0.48 (solvent A). H NMR
(CDCl3) ꢃ 1.38, 1.54 (2 s, 6 H, CMe2), 2.40 (m, 1 H,
H-3), 3.26 (m, 1 H), 4.16 (m, 2 H), 4.80 (m, 3 H),
5.53 (m, 1 H), 5.86 (d, 1 H, H-1, J 3.0 Hz), 7.46 (m,
6 H, aromatic), 8.0 (m, 4 H, aromatic); IR (neat) ꢄ
idene-a-d-allofuranose
chloride (27.5 g, 18.6 mL, 0.24 mol) was added
(12).ÐMethanesulfonyl
ꢀ
1
dropwise at 0 C to a solution of 10 [11] (25.5 g,
2150 (N3), 1720 (C ˆ O) cm . Anal. Calcd for
0.093 mol) in pyridine (350 mL), and the mixture
was stirred at 0 ꢀC for 20 h. The solvent was
removed by evaporation, and the residue was dis-
solved in CH2Cl2 (500 mL). The solution was
washed with saturated NaHCO3 (3Â200 mL), H2O
(3Â200 mL), dried (MgSO4), and evaporated to
give a yellowish solid (11), which was used in the
next step without puri®cation. A solution of 11 and
lithium azide (45.5 g, 0.93 mol) in DMF (600 mL)
C24H25N3O7 (467.5): C, 61.67; H, 5.35; N, 8.99.
Found: C, 61.62; H, 5.36; N, 9.07.
Methyl 3-azidomethyl-5,6-di-O-benzoyl-3-deoxy-
a,b-d-allofuranoside (15).ÐA solution of 14
(19.92 g, 42.6 mmol) in I2±MeOH (1% w/v,
300 mL) was heated at re¯ux for 16 h and evapo-
rated to half of the volume, and then poured into a
stirred solution of Na2S2O3 (1%, 450 mL). The
mixture was extracted with ethyl acetate
(3Â200 mL), and the extract was washed with H2O
(3Â200 mL), dried (MgSO4), evaporated, and
chromatographed to give 15 (16.1 g, 86%); Rf 0.21,
ꢀ
was stirred at 95 C for 2 h and evaporated. The
residue was sequentially dissolved in CH2Cl2
(500 mL), washed with H2O (3Â200 mL), dried
(MgSO4), and evaporated to give 12 (24.2 g, 81%).
An analytical sample was obtained by chromato-
graphy of 12; Rf 0.57 (solvent A). 1H NMR
(CDCl3) ꢃ 1.36, 1.41, 1.53 (3 s, 12 H, 2 CMe2), 2.17
(m, 1 H, H-3), 3.53±4.13 (m, 6 H, H-4,5,6, CH2),
4.73 (dd, 1 H, H-2, J1,2 3.0 Hz, J2,3 3.5 Hz), 5.74 (d,
1
(solvent A). H NMR (CDCl3) ꢃ 2.56 (m, 1 H, H-
3), 3.02 (s, 1 H, OH), 3.33 (s, 3 H, Me), 3.46 (m, 2
H), 4.20 (m, 2 H), 4.53±4.80 (m, 3 H), 5.41 (m, 1 H,
H-1), 7.40 (m, 6 H, aromatic), 7.96 (m, 4 H, aro-
matic); IR (neat) ꢄ 3200±3600 (OH), 2150 (N3),
1
1750 (C ˆ O) cm . Anal. Calcd for C22H23N3O7
1
1 H, H-1, J 3.0 Hz); IR (neat) ꢄ 2150 (N3) cm .
(441.4): C, 59.86; H, 5.21; N, 9.52. Found: C,
59.89; H, 5.22; N, 9.51.
Anal. Calcd for C13H21N3O5 (299.3): C, 52.17; H,
7.02; N, 14.04. Found: C, 52.42; H, 7.02; N, 13.98.
3-Azidomethyl-3-deoxy-1,2-O-isopropylidene-a-
d-allofuranose (13).ÐA solution of 12 (24.2 g,
0.08 mol) in 200 mL of 75% acetic acid was stirred
at rt for 20 h and evaporated. The residue was co-
evaporated with toluene (3Â100 mL) and then
chromatographed to give 13 (17.8 g, 85%); Rf 0.23
Methyl 3-azidomethyl-2,5,6-tri-O-benzoyl-3-de-
oxy-a,b-d-allofuranoside (16).ÐTo an ice-cooled
solution of 15 (15.8 g, 35.8 mmol) in CH2Cl2
(100 mL) and pyridine (8 mL) was added dropwise
benzoyl chloride (4.5 mL, 37.5 mmol), and the
mixture was stirred at rt overnight, and then
poured into a vigorously stirred mixture of ice±
water (100 mL) and NaHCO3 (6.6 g). The organic
phase was washed with H2O (3Â100 mL), dried
(MgSO4), evaporated, and chromatographed to
give 16 (18.3 g, 94%); Rf 0.48 (solvent A). 1H
NMR (CDCl3) ꢃ 3.0 (m, 1 H, H-3), 3.46 (s, 3 H,
Me), 3.60 (m, 2 H, CH2), 4.30±4.83 (m, 5 H), 5.46
(m, 1 H, H-1), 7.46 (m, 6 H, aromatic), 8.0 (m, 4 H,
aromatic); IR (neat) ꢄ 2150 (N3), 1740 (C ˆ O)
1
(solvent B). H NMR (CDCl3) ꢃ 1.26, 1.45 (2 s, 6
H, CMe2), 2.13 (m, 1 H, H-3), 3.07 (br s, 1 H, OH),
3.36 (br s, 1 H, OH), 3.61 (m, 6 H, H-4,5,6, CH2),
4.63 (t, 1 H, H-2), 5.69 (d, 1 H, H-1, J 3.0 Hz); IR
1
(neat) ꢄ 3200±3600 (OH), 2150 (N3) cm . Anal.
Calcd for C10H17N3O5 (259.3): C, 46.33; H, 6.56;
N, 16.22. Found: C, 46.32; H, 6.62; N, 15.99.
3-Azidomethyl-5,6-di-O-benzoyl-3-deoxy-1,2-O-
isopropylidene-a-d-allofuranose (14).ÐTo a stirred
and ice-cooled solution of 13 (11.83 g, 45.6 mmol)
in CH2Cl2 (200 mL) and pyridine (13 mL) was
added dropwise benzoyl chloride (11.7 mL,
0.10 mol), and the mixture was kept at rt overnight.
It was then poured into a vigorously stirred mix-
1
.
cm . Anal. Calcd for C29H27N3O8 H2O (563.5):
C, 61.75; H, 4.79; N, 7.45. Found: C, 62.06; H,
4.81; N, 7.37.
1-O-Acetyl-3-azidomethyl-2,5,6-tri-O-benzoyl-3-
deoxy-b-d-allofuranose (17).ÐTo an ice-cooled
solution of 16 (14.2 g, 26.0 mmol) in CH2Cl2

326
B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
(150 mL) and acetic anhydride (15.6 mL) was
added dropwise and with stirring sulfuric acid
(0.63 mL), and the mixture was kept at 5 C over-
with toluene (3Â20 mL) to give a crystalline
residue of silylated nucleosides. To this residue
were added 1,2-dichloroethane (20 mL), followed
by Me3SiOTf (0.39 mL, 2.0 mmol), and the mixture
was heated at re¯ux for 3 h. Workup as above gave
the N-7 isomer 18 (385 mg, 52%); Rf 0.47 (solvent
ꢀ
night. Sodium acetate (6.3 g) was added to the
mixture with stirring, and after 20 min the mixture
was ®ltered and evaporated. The residue was dis-
solved in ethyl acetate (200 mL), washed with
saturated NaHCO3 solution (3Â100 mL), H2O
(3Â100 mL), dried (MgSO4), and evaporated. The
residue was puri®ed by chromatography to give
17 (12.9 g, 86%), which was then crystallized from
petroleum ether±ether: mp 105±106 ꢀC; Rf 0.43
(solvent A). 1H NMR (CDCl3) ꢃ 2.0 (s, 3 H,
COMe), 2.92 (m, 1 H, H-3), 3.56 (m, 2 H, CH2),
4.33±4.83 (m, 3 H), 5.50 (m, 2 H), 6.25 (s, 1 H,
H-1), 7.34 (m, 6 H, aromatic), 7.95 (m, 4 H,
aromatic); IR (neat) ꢄ 2130 (N3), 1740 (C ˆ O)
1
B). H NMR (CDCl3) ꢃ 3.65±4.10 (m, 2H), 5.0
(m, 1 H), 6.05 (m, 2 H), 6.33 (d, 1 H, H-10), 6.80
(m, 1 H), 7.46 (m, 9 H, aromatic), 8.0 (m, 7 H,
aromatic, H-2); IR (KBr) ꢄ 3200±3600 (NH),
1
2280 (CN), 2150 (N3), 1750 (C ˆ O) cm . Anal.
Calcd for C34H25BrN8O7 (737.5): C, 55.37; H,
3.42; N, 15.19. Found: C, 55.36; H, 3.60; N,
14.78.
4-Amino-7-(6-azido-6-deoxy-b-d-glucofuranosyl)-
6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine (20).Ð
Method A: A solution of 18 (770 mg, 1.04 mmol)
in methanolic ammonia (35 mL) was kept at rt for
24 h and evaporated. The residue was triturated
with ether (2Â20 mL) and ®ltered, and the solid
was dried and recrystallized from ethanol to give
390 mg (88%) of 20; Rf 0.59 (solvent C); mp 205±
1
cm . Anal. Calcd for C30H27N3O9 (573.5): C,
62.83; H, 4.71; N, 7.33. Found: C, 62.64; H, 4.89;
N, 7.33.
4-Amino-7-(6-azido-2,3,5-tri-O-benzoyl-6-deoxy-
b-d-glucofuranosyl)-6-bromo-5-cyanopyrrolo[2,3-d]
pyrimidine (18).Ð4-Amino-6-bromo-5-cyanopyr-
rolo[2,3-d]pyrimidine (2.50 g, 10.5 mmol) was dried
ꢀ
206 C, dec. 1H NMR (Me2SO-d6) ꢃ 3.20 (dd, 1 H,
H-6a0, J5 ,6a 6.26 Hz, J6a ,6b 12.85 Hz), 3.30 (dd, 1
0
0
0
0
ꢀ
H, H-6b0, J5 ,6b 2.61 Hz, J6a ,6b 12.94 Hz), 3.90 (dd,
0
0
0
0
at 50 C and 0.1 Torr for 3 h. The apparatus was
1 H, H-40, J4 ,5 3.61 Hz, J
0
0
40,30
8.37 Hz), 4.02±4.07
¯ushed with N2 and hexamethyldisilazane (HMDS,
35 mL), followed by chlorotrimethylsilane (0.5 mL),
were added through a septum, and the mixture was
heated at re¯ux for 12 h. The solution was evapo-
rated, and the residue was co-evaporated with dry
toluene (3Â10 mL) at 0.1 mmHg to give a yellow
solid. A solution of 9 (4.90 g, 8.54 mmol) in 1,2-
dichloroethane (100 mL) was added to this solid,
(m, 2 H, H-30, 50), 4.66 (dd, H-20, J1 ,2 3.12 Hz, J2 ,3
1.50 Hz), 5.40 (bs, 1 H, OH), 5.71 (d, 1 H, H-10,
0
0
0
0
0
0
J1 ,2 3.05 Hz), 5.95 (bs, 1 H, OH), 6.78 (d, 1 H,
OH), 7.20 (bs, 2 H, NH2), 8.22 (s, 1 H, H-2); IR
(KBr) ꢄ 3200±3600 (NH), 2250 (CN), 2120 (N3)
1
cm ; UV ꢅmax pH 1, 282, 234, EtOH, 286, 218,
pH 11, 285, 215 nm. Anal. Calcd for C13H13BrN8
O4 (425.1): C, 36.70; H, 3.08; N, 26.36. Found: C,
36.56; H, 2.96; N, 25.65.
ꢀ
and the mixture was cooled (0 C), and then tri-
methylsilyl tri¯uoromethanesulfonate (Me3SiOTf)
(2.03 mL, 10.5 mmol) in 1,2-dichloroethane
(10 mL) was added dropwise. The mixture was
sequentially stirred at 0 ꢀC for 30 min, at rt for 1 h,
at 50 ꢀC overnight, and then at 75±80 ꢀC for 3 h. It
was then chilled, and diluted with CH2Cl2
(200 mL), and poured into a stirred mixture of ice±
water and solid NaHCO3 (4.0 g). The organic
phase was washed with H2O (3Â100 mL), dried
(MgSO4), evaporated, and chromatographed to
give a mixture of 18 and its N-1 isomer (19) (4.99 g,
79.2%). A portion of this mixture (0.74 g,
1.0 mmol) was co-evaporated with toluene
(3Â10 mL) and dried at 50 ꢀC and 0.1 Torr for 3 h.
HMDS (20 mL), xylene (20 mL), and chloro-
trimethylsilane (50 ꢁL) were added, and the mix-
ture was heated at re¯ux for 12 h. The solvent was
evaporated, and the residue was co-evaporated
Method B.ÐThe mixture of 18 and 19 (7.7 g,
10.4 mmol) was kept in methanolic ammonia
(350 mL) at rt for 24 h and evaporated. The residue
was crystallized from water to give an isomeric
mixture (3.0 g, 67%) of 20 and 4-amino-1-(6-azido-
6-deoxy-ꢀ-d-glucofuranosyl)-6-bromo-5-cyano-
pyrrolo[2,3-d]pyrimidine (21). Recrystallization of
this mixture from ethanol gave pure 20 (1.2 g).
Evaporation of the mother liquor and chromato-
graphy of the residue gave 21 (1.8 g); Rf 0.65 (sol-
vent C); mp 136±138 C. H NMR (Me2SO-d6) ꢃ
4.02±4.30 (m, 3 H, H-20,30,50), 5.52 (bs, 1 H, OH),
6.06 (s, 1 H, H-10), 7.82 (bs, 2 H, NH2), 8.41 (s, 1 H,
H-2); UV ꢅmax pH 1, 289, 261, 221, EtOH, 285, 259,
215, pH 11, 285, 259, 214 nm. Anal. Calcd For
C13H13BrN8O4 (425.1): C, 36.70; H, 3.08; N, 26.36.
Found: C, 36.79; H, 2.92; N, 26.10.
ꢀ
1

B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
327
4-Amino-7-(6-amino-6-deoxy-b-d-glucofuranosyl)-
5-cyanopyrrolo[2,3-d]pyrimidine (22).ÐA suspen-
sion of 20 (160 mg, 0.38 mmol) in methanol
(30 mL) was warmed to obtain a solution and then
cooled to rt. Triethylamine (0.5 mL) followed by
10% Pd/C (100 mg) (Caution: Extreme ®re hazard)
were added to this solution, and the mixture was
stirred under atmospheric pressure H2 for 20 h. It
was then ®ltered and the catalyst was washed with
hot methanol. The combined ®ltrate was evapo-
rated and chromatographed to give 104 mg
(86.3%) of 22; Rf 0.42 (solvent D). 1H NMR
(Me2SO-d6) ꢃ 2.60, 2.82, 4.00 (3 m, 5 H, H-
30,40,50,6a0,6b0), 4.16 (s, 1 H, H-20), 6.05 (s, 1 H, H-
10), 6.84 (bs, 2 H, NH2), 8.20 (s, 1 H, H-6), 8.22 (s,
1 H, H-2); IR (neat) ꢄ 3200±3600 (OH, NH), 2280
and chromatographed to give 7.47 g (68%) of an
isomeric mixture of 24 and 25. A portion (0.50 g,
0.67 mmol) of this mixture was co-evaporated
with toluene (3Â10 mL) and dried at 50 ꢀC/
0.1 Torr for 3 h. HMDS (15 mL), xylene (15 mL)
and chlorotrimethylsilane (50 (L) were added to
the residue, and the mixture was heated at re¯ux for
12 h. The solvent was evaporated and the residue
was co-evaporated with toluene (3Â10 mL) to give
a crystalline mixture of silylated nucleosides. To
this mixture were added 1,2-dichloroethane (15 mL)
followed by Me3SiOTf (0.26 mL, 1.34 mmol), and
the mixture was heated at re¯ux for 3 h. Workup
as above gave 24 (280 mg, 56%); Rf 0.57 (solvent
1
B). H NMR (CDCl3) ꢃ 3.83 (m, 3 H), 4.33±4.92
(m, 3 H), 5.80±6.0 (m, 3 H), 6.13 (d, 1 H, H-10, J
3.0 Hz), 6.33 (m, 1 H), 7.50 (m, 9 H, aromatic), 8.0
(m, 6 H, aromatic), 8.20 (s, 1 H, H-2); IR (KBr) ꢄ
1
(CN) cm ; UV ꢅmax pH 1, 276, 234, EtOH, 280,
231, 205, pH 11, 278, 210 nm. Anal. Calcd for
C13H16N6O4 (320.3): C, 48.75; H, 5.00; N, 26.25.
Found: C, 48.63, H, 4.89, N, 26.02.
1
2250 (CN), 2130 (N3), 1740 (C ˆ O) cm . Anal.
.
Calcd for C35H27BrN8O7 H2O (769.6): C, 54.57; H,
4-Amino-7-(6-amino-6-deoxy-b-d-glucofuranosyl)-
5-carboxamidopyrrolo[2,3-d]pyrimidine (23).ÐA
solution of 22 (200 mg, 0.6 mmol) in concd ammo-
nium hydroxide (30 mL) was treated with 30%
H2O2 (3.0 mL) at rt for 5 h and evaporated. The
residue was co-evaporated with ethanol and chro-
matographed to give 140 mg (66.4%) of 23; Rf 0.27
3.77; N, 14.55. Found: C, 54.61; H, 3.52; N, 14.49.
4-Amino-7-(3-azidomethyl-3-deoxy-b-d-allofur-
anosyl)-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine
(26).ÐMethod A: A solution of 24 (800 mg,
1.06 mmol) in methanolic ammonia (35 mL) was
kept at rt for 24 h and evaporated. The residue was
triturated with ether (2Â20 mL), ®ltered, and
washed with ethanol (3Â10 mL) to give a white
solid (400 mg, 85.5%). An analytical sample was
obtained by recrystallizing this solid from 1,4-
1
(solvent D). H NMR (Me2SO-d6) ꢃ 2.70±4.16 (m,
5 H, H-30,40,50,6a0, 6b0), 4.21 (s, 1 H, H-20), 5.93 (s,
1 H, H-10), 8.07 (s, 1 H, H-6), 8.11 (s, 1 H, H-2); IR
(KBr) ꢄ 3200±3600 (OH, NH), 1630 (CONH2)
ꢀ
dioxane; Rf 0.45 (solvent C); mp 213±216 C, dec.
1
cm ; UV ꢅmax pH 1, 277, 231, EtOH, 281, 229,
1H NMR (Me2SO-d6) ꢃ 2.90, 3.20 (2 m, 6 H, H-
30,50,60a,b, CH2), 3.56 (t, 1 H, H-20, J 5.15 Hz), 4.09 (t,
1 H, OH), 4.66 (m, 1 H, H-40), 5.12, 5.38 (2 d, 2 OH),
5.48 (d, 1 H, H-10, J 5.36 Hz), 6.62 (bs, 2 H, NH2),
7.75 (s, 1 H, H-2); IR (KBr) ꢄ 3200±3600 (NH),
205, pH 11, 279, 228, 210 nm. Anal. Calcd for
C13H18N6O5 (338.3): C, 46.15; H, 5.32; N, 24.85.
Found: C, 45.78, H, 5.29, N, 24.76.
4-Amino-7-(3-azidomethyl-2,5,6-tri-O-benzoyl-3-
deoxy-b-d-allofuranosyl)-6-bromo-5-cyanopyrrolo-
[2,3-d]pyrimidine (24).Ð4-Amino-6-bromo-5-cyano-
pyrrolo[2,3-d]pyrimidine (3.94 g, 16.5 mmol) was
silylated with HMDS (50 mL) and chloro-
trimethylsilane (0.5 mL) as described above for 18.
To the silylated base was added a solution of 17
(8.6 g, 15.0 mmol) in 1,2-dichloroethane (200 mL),
and the solution was cooled in ice±water.
Me3SiOTf (3.45 mL, 18.0 mmol) was added drop-
wise to this solution, which was then stirred
1
2225 (CN), 2100 (N3) cm ; UV ꢅmax pH 1, 282,
231, 207, EtOH, 286, 219, 204, pH 11, 285, 216 nm.
Anal. Calcd for C14H15BrN8O4 (439.2): C, 38.29; H,
3.44; N, 25.51. Found: C, 38.45; H, 3.42; N, 25.50.
Method B.ÐThe mixture of 24 and 25 (8.0 g,
11 mmol) was kept in methanolic ammonia
(400 mL) at rt for 24 h and evaporated. The residue
was triturated with ether to give a mixture of 26
and 27 (4.0 g, 85.5%). Recrystallization of this
mixture from 1,4-dioxane gave pure 26 (2.4 g). The
isomeric 27 (1.5 g) was obtained from the mother
liquor by chromatography. For 27: Rf 0.50 (solvent
ꢀ
ꢀ
sequentially at 0 C fꢀor 30 min, rt for 1 h, 50 C
overnight, and 75±80 C for 3 h. The mixture was
chilled and diluted with CH2Cl2 (200 mL) and then
poured into a stirred mixture of ice±water and solid
NaHCO3 (7.0 g). The organic phase was washed
with H2O (3Â100 mL), dried (MgSO4), evaporated,
1
C); H NMR (Me2SO-d6) ꢃ 4.02±4.07 (m, 2 H, H-
30,50), 5.24 (bs, 1 H, OH), 5.78 (d, 1 H, H-10, J1 ,2
0
0
3.3 Hz), 7.15 (bs, 2 H, NH2), 7.95 (s, 1 H, H-2); UV
max pH 1, 288, 260, 222, EtOH, 286, 260, 214, pH
ꢅ

328
B.-G. Huang, M. Bobek/Carbohydrate Research 308 (1998) 319±328
11, 285, 258, 215 nm. Anal. Calcd for C14H15
BrN8O4 (439.2): C, 38.29; H, 3.44; N, 25.51.
Found: C, 38.10; H, 3.40; N, 25.45.
References
[1] M. Sharma, H. Wikiel, R. Hromchak, A. Bloch,
and M. Bobek, Nucleosides Nucleotides, 12 (1993)
295±304
[2] M. Bobek and A. Bloch, Nucleosides Nucleotides,
13 (1994) 429±435
[3] P.D. Davis, L.H. Elliott, W. Harris, C.H. Hill, S.A.
Hurst, E. Keech, M.K.H. Kumar, G. Lawton, J.S.
Nixon, and S.E. Wilkinson, J. Med. Chem., 35
(1992) 994±1001
[4] T. Iimori, Y. Murai, Y. Wakizaka, Y. Ohtsuka, S.
Ohuchi, Y. Kodama, and T. Oishi, Chem. Pharm.
Bull., 41 (1993) 775±777
[5] M. Sharma, A. Bloch, and M. Bobek, Nucleosides
Nucleotides, 12 (1993) 643±648
[6] H. Vorbruggen, K. Krolikiewicz, and B. Bennua,
Chem. Ber., 114 (1981) 1234±1255
[7] W. Meyer zu Reckendorf and U. Spohr, Liebigs
Ann. Chem., (1982) 137±149.
[8] A. Holy, Collect. Czech. Chem. Commun., 47
(1982) 2969±2988
[9] K. Kefurt, K. Capek, Z. Kefurtova, and J. Jary,
Collect. Czech. Chem. Commun., 51 (1986) 391±400
[10] W.A. Szarek, A. Zamojski, K.N. Tiwari, and E.R.
Ison, Tetrahedron Lett., 27 (1986) 3827±3830
[11] (a) G. Legler and S. Pohl, Carbohydr. Res., 155
(1986) 119±129; (b) E.M. Acton, R.N. Goerner,
H.S. Uh, K.J. Ryan, D.W. Henry, C.E. Cass, and
G.A. LePage, J. Med. Chem., 22 (1979) 518±525.
[12] A. Billich, U. Stockhorve, and H. Witzel, Nucleic
Acids Res., 11 (1983) 7611±7624
[13] E.E. Swayze, J.M. Hinkley, and L.B. Townsend, in
L.B. Townsend and R.S. Tipson (Eds.), Nucleic
Acids Research, Part 4, Wiley-Interscience, New
York, 1991, pp 16±18.
[14] R.L. Tolman, R.K. Robins, and L.B. Towsend, J.
Am. Chem. Soc., 91 (1969) 2102±2108
4-Amino-7-(3-aminomethyl-3-deoxy-b-d-allofur-
anosyl)-5-cyanopyrrolo[2,3-d]pyrimidine (28).ÐA
suspension of 26 (380 mg, 0.87 mmol) in 1,4-diox-
ane (60 mL) was warmed to obtain a solution
which was then cooled to rt. Triethylamine
(1.0 mL), followed by 10% Pd/C (300 mg), were
added and the mixture was hydrogenated at rt for
24 h. It was then ®ltered and the catalyst was
washed with hot 1,4-dioxane. The combined ®ltrate
was evaporated and chromatographed to give
1
250 mg (86.5%) of 28; Rf 0.52 (solvent D). H
NMR (Me2SO-d6) ꢃ 2.65 (m, 1 H, H-30), 3.00±4.57
(m, 7 H), 6.07 (d, 1 H, H-10, J 2.87 Hz), 6.88 (bs, 2
H, NH2), 8.34 (s, 1 H, H-6), 8.37 (s, 1 H, H-2); IR
1
(neat) ꢄ 3200±3600 (OH, NH), 2210 (CN) cm ;
UV ꢅmax pH 1, 274, 232, 201, EtOH, 281, 204, pH
11, 278, 210 nm. Anal. Calcd for C14H18N6O4
(334.3): C, 50.30; H, 5.43; N, 25.14. Found: C,
50.05; H, 5.39; N, 24.82.
4-Amino-7-(3-aminomethyl-3-deoxy-b-d-allofur-
anosyl)-5-carboxamidopyrrolo[2,3-d]pyrimidine (29).Ð
A solution of 28 (150 mg, 0.45 mmol) in concd
ammonium hydroxide (21 mL) was treated with
30% H2O2 (2.1 mL) at rt for 5 h. The solvent was
evaporated, and the residue was co-evaporated
with ethanol and chromatographed to give 118 mg
(75%) of 29; Rf 0.29 (solvent D). 1H NMR
(Me2SO-d6) ꢃ 2.42 (m, 1 H, H-30), 2.76±3.60 (m, 4
H), 3.93 (t, 1 H), 4.42 (m, 1 H, H-20), 6.02 (d, 1 H,
H-10, J 2.43 Hz), 6.63 (s, 1 H, OH), 7.32, 7.25 (2 s, 2
H, NH2), 8.04 (s, 1 H, H-6), 8.07 (s, 1 H, H-2); IR
(KBr) ꢄ 3200±3600 (OH, NH), 1630 (CONH2)
1
cm ; UV ꢅmax pH 1, 274, 232, EtOH, 280, 230,
[15] M. Sharma, Y.X. Li, M. Ledvina, and M. Bobek,
Nucleosides Nucleotides, 14 (1995) 1831±1852
[16] M. Karplus, J. Chem. Phys., 30 (1959) 11±15
[17] H. Vorbruggen, Acc. Chem. Res., 28 (1995) 509±
520
205, pH 11, 274, 231, 210 nm. Anal. Calcd for
C14H20N6O5 (352.3): C, 47.73; H, 5.72; N, 23.86.
Found: C, 47.60; H, 5.65; N, 23.75.
[18] R.J. Suhadolnik, in R.J. Suhadolnik (Ed.),
Nucleoside Antibiotics, Vol. 1, Wiley-Interscience,
New York, 1970, pp 298±353.
[19] P.S. Ritch and R.I. Glaser, in R.I. Glaser (Ed.),
Pyrrolo[2,3-d]pyrimidine Nucleosides. Develop-
ments and Cancer Chemotherapy, CRC Press, 1984,
pp 1±33.
Acknowledgements
We thank Dr Bernacki and his co-workers for
performing the cytotoxicity studies. This study was
aided in part by grant CA 13038 from the National
Cancer Institute.