Exploring structure-activity relationships of transition state analogues of human purine nucleoside phosphorylase

Article abstract of DOI:10.1021/jm030145r

The aza-C-nucleosides, Immucillin-H and Immucillin-G, are transition state analogue inhibitors of purine nucleoside phosphorylase, a therapeutic target for the control of T-cell proliferation. Immucillin analogues modified at the 2′-, 3′-, or 5′-positions of the azasugar moiety or at the 6-, 7-, or 8-positions of the deazapurine, as well as methylene -bridged analogues, have been synthesized and tested for their inhibition of human purine nucleoside phosphorylase. All analogues were poorer inhibitors, which reflects the superior capture of transition state features in the parent immucillins.

Full text of DOI:10.1021/jm030145r

3412
J . Med. Chem. 2003, 46, 3412-3423
Exp lor in g Str u ctu r e-Activity Rela tion sh ip s of Tr a n sition Sta te An a logu es of
Hu m a n P u r in e Nu cleosid e P h osp h or yla se
Gary B. Evans,† Richard H. Furneaux,† Andrzej Lewandowicz,‡ Vern L. Schramm,‡ and Peter C. Tyler*,†
Carbohydrate Chemistry, Industrial Research Limited, P. O. Box 31310, Lower Hutt, New Zealand, and
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
Received April 1, 2003
The aza-C-nucleosides, Immucillin-H and Immucillin-G, are transition state analogue inhibitors
of purine nucleoside phosphorylase, a therapeutic target for the control of T-cell proliferation.
Immucillin analogues modified at the 2′-, 3′-, or 5′-positions of the azasugar moiety or at the
6-, 7-, or 8-positions of the deazapurine, as well as methylene-bridged analogues, have been
synthesized and tested for their inhibition of human purine nucleoside phosphorylase. All
analogues were poorer inhibitors, which reflects the superior capture of transition state features
in the parent immucillins.
In tr od u ction
will lead to reduced binding to the enzyme. However,
we wished to explore the consequences of functional
group changes in the hope that additional or altered
binding modes to the human enzyme might be discov-
ered.
Purine nucleoside phosphorylase (PNP) has been
identified as a therapeutic target for the control of T-cell
proliferative disorders such as organ transplant rejec-
tion, T-cell cancers, rheumatoid arthritis, psoriasis, and
some other autoimmune diseases.1-5 We have used
knowledge of the transition state characteristics of the
phosphorolysis catalyzed by bovine PNP6-8 to design
and synthesize transition state analogue inhibitors.9-11
Immucillin-H 1 and Immucillin-G 2 are exceedingly
potent inhibitors of bovine and human PNP12,13 as well
as PNP from Plasmodium falciparum14 and Mycobac-
terium tuberculosis.15 Immucillin-H has been shown to
inhibit the proliferation of human T lymphocytes16-18
and has entered clinical trials for the control of T-cell
malignancies.
Mod ifica tion s of th e Im in or ibitol Moiety. Some
analogues of 1 modified in the iminoribitol moiety,
namely the 2′-deoxy-, 5′-deoxy- and 5′-deoxy-5′-fluoro
derivatives, have been described.10 For this study we
wished to focus on the synthesis of derivatives modified
at the 2′- and 3′-positions. The protected immucillin
derivative 3 is readily available,11 and mild acid hy-
drolysis followed by treatment with di-tert-butyl dicar-
bonate afforded triol 4 which was tritylated to give diol
5 (Scheme 1). This diol could be monoprotected with
moderate regioselectivity using stannylene methodol-
ogy22 generating the allyl ethers 6 and 7, and the
4-methoxybenzyl ethers 8 and 9 with the 2-O-ethers
predominating in each case by a ratio of ∼2:1. The
regioisomers were distinguished by 2D-NMR experi-
ments on the isomers and/or their derived monoacetates.
The 2-O-allyl ether 6 was readily converted into the 3-O-
(4-methoxybenzyl) derivative 9.
Deoxygenation of the 2-O-(4-methoxybenzyl) ether 8
was achieved by treatment with thiocarbonyl diimida-
zole followed by tributyltin hydride (Scheme 2), and the
3′-deoxy product was deprotected by acid hydrolysis to
give 3′-deoxy-immucillin-H 10. O-Methylation of the
3-O-allyl derivative 7 followed by deprotection afforded
2′-O-methyl-immucillin-H 11. Oxidation of 9 followed
by reduction with sodium borohydride generated the 2′-
epimer as the only product. Acid hydrolysis then gave
the arabino-immucillin-H 12.
Several attempts were made to introduce fluorine at
the 2′-position by treating 7, 9, their 2′-epimers, or the
derived ketones with DAST, but no discrete products
could be obtained. Consequently the 2-deoxy-2,2-difluo-
roiminoribitol derivative 13 (Scheme 3) was prepared
with the intention of converting it into the corresponding
immucillin analogue. The parent iminoribitol 1423,24 was
selectively functionalized via the tetraisopropyldisilox-
ane derivative 15 to the alcohol 16. Oxidation of this
We report here the synthesis and structure-activity
relationships of some immucillin analogues applied to
human PNP.
Resu lts a n d Discu ssion
The immucillins were designed to possess features of
the transition state of the enzyme-catalyzed reaction,
and X-ray crystallography of the inhibitors bound in the
active site of bovine19,20 and Mycobacterium tuberculo-
sis21 PNP’s has revealed a network of many hydrogen
bonds between inhibitor and enzyme. It is likely, there-
fore, that disruption of any one of these hydrogen bonds
* To whom correspondence should be addressed. Phone: 64-4-
9313062. Fax: 64-4-9313055. E-mail: p.tyler@irl.cri.nz.
† Industrial Research.
‡ AECOM.
10.1021/jm030145r CCC: $25.00 © 2003 American Chemical Society
Published on Web 06/20/2003

Purine Nucleoside Phosphorylase Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15 3413
Sch em e 1a
Sch em e 3a
a
Reagents: i, aq TFA; ii, (Boc)2O; iii, TipsCl2, imid.; iv, MomBr,
iPr2NEt; v, Bu4NF; vi, NaH, BnBr; vii, TFA, H2O, THF; viii,
Cl3CCH2OCOCl, Et3N; ix, TFAA, DMSO, Et3N; x, DAST; xi, Zn,
HOAc.
Sch em e 4a
a
Reagents: i, aq TFA, THF; ii, (Boc)2O, Et3N; iii, TrCl, iPr2NEt,
DMAP, CH2Cl2; iv, Bu2SnO, toluene, reflux, then Bu4NBr and allyl
bromide or 4-MeO-benzyl chloride; v, NaH, 4-MeO-benzyl chloride,
DMF; vi, DABCO, (Ph3P)3RhCl, EtOH, reflux; vii, HgO, HgCl2,
aq acetone.
Sch em e 2a
a
Reagents: i, BrCF2CO2Et, Zn, THF; ii, H2, Pd/C; iii, aq TFA;
iv, NaH, BnBr.
to be highly stereoselective affording products with the
desired anti stereochemistry.26 When a Reformatsky
reaction employing ethyl bromodifluoroacetate was ap-
plied to this aldehyde under standard conditions27 only
one product, 19, was obtained in moderate yield. Depro-
tection and then benzylation of the resulting lactam
gave 17.
Lithiation of the 9-bromo-9-deazahypoxanthine de-
rivative 2011 by bromine-lithium exchange and then
addition of lactam 17 to the reaction mixture afforded
a product, presumably 21 (Scheme 5). Reduction of this
crude material using sodium cyanoborohydride afforded
a separable mixture of 22 and 23 in a 1:3 ratio as well
as some recovered lactam. The minor isomer, when
deprotected by hydrogenolysis and acid hydrolysis, gave
2′-deoxy-2′,2′-difluoro-immucillin-H 24. The stereochem-
istry of this compound was confirmed by NMR experi-
ments whereby a NOESY pulse sequence showed cor-
relations between H-1′ and H-4′ as well as between H-3′
and H-5′. The other isomer, 25, demonstrated NOESY
correlations between H-1′ and H-3′ as well as H-3′ and
H-5′. These experiments provide evidence for the ster-
eochemistry at C-1′ and C-3′.
Mod ifica tion of th e Dea za p u r in e Moiety. The
6-O-methyl- and 7-N-methyl-immucillin derivatives 26
and 27 were prepared from 2811 by selective hydrolysis,
and methylation followed by acid hydrolysis, respec-
tively (Scheme 6). Treatment of immucillin-H 1 with di-
tert-butyl dicarbonate and acetylation gave triacetate
29, which, after exposure to Lawesson’s reagent followed
a
Reagents: i, thiocarbonyldiimidazole; ii, Bu3SnH; iii, concd
HCl, reflux; iv, NaH, MeI; v, DABCO, (Ph3P)3RhCl, EtOH, reflux;
vi, HgO, HgCl2, aq acetone, vii, DMSO, TFAA, CH2Cl2, -70 °C,
then Et3N, viii, NaBH4, EtOH.
alcohol to the ketone and treatment with DAST afforded
the difluoroiminoribitol 13. Generation of a 1,N-imine
from this material was possible using standard tech-
niques10,11 but it was unstable, and attempts to add a
9-lithio-9-deazapurine derivative or lithiated acetonitrile
to it did not afford discrete products.
The difluoropentonolactam 17 was then prepared
(Scheme 4) from D-serine via the known aldehyde 18.25
The addition of organometallic reagents to 18 is known

3414 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15
Evans et al.
Sch em e 5a
Sch em e 6a
a
Reagents: i, BuLi, THF, -70 °C, then 17; ii, NaBH3CN, HOAc,
MeOH; iii, H2, Pd/C; iv, aq HCl, MeOH.
by saponification and acid hydrolysis afforded the 6-thio-
immucillin 30.
a
Reagents: i, MeOH, 2 M aq HCl; ii, NaH, MeI; iii, MeOH,
concd aq HCl, reflux; iv, (Boc)2O; v, Ac2O, py; vi, Lawesson’s
reagent, toluene, reflux; vii, NH3/MeOH; viii, 1 M aq HCl.
When the fully protected derivative 3111 was allowed
to react with n-butyllithium at -70 °C and then
quenched with CD3OD, deuterium incorporation was
observed by 1H NMR spectroscopy only at H-8 (Scheme
7). Similar treatment of a 6-chloropurine riboside de-
rivative, but with LDA as base, has shown that both
the 2- and 8-positions of the purine were readily
lithiated.28 Consequently it might have been expected
that lithiation of the 9-deazapurine derivative 31 would
occur at C-2 rather than the observed C-8. The 8-lithio
intermediate was allowed to react with methyl iodide
to give 32, which on hydrogenolysis and acid hydrolysis
afforded 8-methylimmucillin-H 33. Similarly, treatment
of the 8-lithio derivative with N-fluorobenzenesulfon-
imide generated an 8-fluoro derivative, but the strong
acid conditions required for deprotection resulted in
partial hydrolysis of the heteroaryl fluoride moiety. The
alternative 6-O-tert-butyl compound 34 was prepared
in an analogous manner to the 6-O-methyl derivative
31, and successfully converted into the 8-fluoro deriva-
tive 35 as above. Hydrogenolysis and a mild acid hy-
drolysis then afforded 36. The 8-trimethylsilyl deriva-
tive 37 was synthesized in order to block the 8-position
from lithiation. However, treatment of this material
with n-butyllithium at -70 °C did not result in any
detectable C-2 lithiation and under more forcing condi-
tions resulted only in degradation.
Sch em e 7a
a
Reagents: i, BuLi, THF, -70 °C; ii, MeI or (PhSO2)2NF or
Me3SiCl, HMPA; iii, H2, Pd/C; iv, MeOH, concd aq HCl, reflux,
(for 33), or MeOH, 2 M aq HCl (for 36).
Syn th esis of “Meth ylen e-Br id ged ” An a logu es.
Addition of lithiated tert-butyl acetate to the imine 38
successfully afforded the adduct 39 (Scheme 8). With a
view toward synthesizing immucillins 40 and 41 with
a methylene bridge between the deazapurine and imi-
noribitol moieties, 39 was converted into the propioni-

Purine Nucleoside Phosphorylase Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15 3415
Sch em e 8a
a
t
Reagents: i, LDA, CH3CO2 Bu; ii, (Boc)2O; iii, Bu4NF; iv, NaH, BnBr; v, DIBAH; vi, MsCl, iPr2NEt; vii, KCN, DMF; viii, tBuOCH(NMe2)2,
DMF; ix, THF, HOAc, H2O; x, NaOAc, H2NCH2CO2Et, MeOH; xi, DBU, MeOCOCl, then, for 46, MeOH; xii, NaOAc, H2NCH2CN, MeOH;
xiii, K2CO3, MeOH; xiv, formamidine, EtOH, reflux; xv, H2, Pd(OH)2/C, EtOH, xvi, 2 M aq HCl.
Sch em e 9a
Sch em e 10a
a
Reagents: i, BuLi, DMF; ii, NaBH3CN, 14, MeOH; iii, H2, Pd/
C, EtOH; iv, concd HCl; MeOH, reflux.
trile derivative 42 via 43. This was then functionalized
to the enamine 44 and then pyrroles 45 and 46, using
standard methods,10 from which the methylene bridged
immucillins 40 and 41 were obtained. The N-linked
methylene-bridged compound 47 was readily prepared
(Scheme 9) by a reductive amination applied to the
9-deaza-9-formylpurine 48, itself available from 49.11
The compound 50 with the iminoribitol directly N-linked
to the 9-deazapurine, was synthesized (Scheme 10) from
the acetonitrile adduct 51 using the standard chemistry
for building up a 9-deazapurine moiety, but in poor
overall yield. A standard reductive amination between
immucillin-H 1 and propionaldehyde has afforded the
N-propyl immucillin 52.
a
i
Reagents: i, Pr2NEt, BrCH2CN; ii, as in Scheme 8 for the
conversion of 42 to 40; iii, H2, Pd/C, EtCHO.
recently reported on the inhibitory properties of the 2′-
deoxy, 53 and 54, and 5′-modified 55-57 derivatives
against bovine PNP.10,19 In these cases the 2′-deoxy
inhibitors 53 and 54 showed good activity, as might be
expected since 2′-deoxy nucleosides are excellent sub-
strates for the enzyme, whereas changes at the 5′-
position proved deleterious to binding. This is perhaps
not surprising since the X-ray crystal structure of bovine
PNP complexed with 1 showed the 5′-hydroxy group
engaged in a strong hydrogen bonding pattern with
enzyme and the 4′-nitrogen.20 This pattern of activity
of the 2′- and 5′-modified compounds is repeated for the
human enzyme except that the 2′-deoxy-immucillins
Biologica l Resu lts. While some preliminary assays
of immucillin analogues against bovine PNP have been
reported, it is of more interest to study the clinically
relevant human PNP as presented here. We have

3416 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15
Evans et al.
Ta ble 1. Inhibition of Human PNP by Immucillinsa
compd Ki, nM
Ki*, nM
compd
Ki, nM
Ki*, nM
1
2
3.3 ( 0.2 0.056 ( 0.015
0.54 ( 0.1 0.042 ( 0.006
40
41
47
50
52
53
54
55
57
58
250 ( 7
>30 000
2.84 ( 0.06
12 700 ( 1700
415 ( 86
0.25 ( 0.06
0.22 ( 0.02
25 ( 7
ND
ND
ND
ND
ND
ND
ND
ND
7 ( 2
10
11
12
24
26
27
30
33
36
9.5 ( 1.6
5.9 ( 1.4
3.5 ( 0.3
1.4 ( 0.2
4.7 ( 0.5
4.7 ( 0.3
24.7 ( 1.1
10.1 ( 1.6
5.6 ( 0.7
ND
ND
ND
ND
ND
ND
ND
ND
81 ( 5
1.4 ( 0.2
0.18 ( 0.02
0.39 ( 0.02
a
Ki is the initial rate constant and Ki* is the equilibrium
dissociation constant obtained after slow-onset inhibition.12 ND
indicates that no slow-onset phase was observed.
Assays used inosine and inorganic phosphate as substrates.
The hypoxanthine product was converted to uric acid in a
coupled assay that detects the UV absorbance of uric acid at
293 nm. Details of the assay and experimental determination
of Ki and Ki* have been described.12
were slightly poorer inhibitors than the parent com-
pounds (Table 1). Other changes engendered at the 2′-
position such as inversion of stereochemistry 12, methyl
ether formation 11, and fluorination 24, as well as 3′-
deoxygenation 10, all resulted in relatively poor inhibi-
tion compared to the extremely potent immucillin-H 1
and immucillin-G 2. The 2′,2′-difluoro derivative 24
appeared to decompose in the presence of the enzyme
but this was not further investigated.
In the cases of the immucillins modified in the
deazapurine ring, the 6-O-methyl 26 and 7-N-methyl
derivatives 27 exhibited a ∼100 fold loss of activity,
whereas the 6-thio derivative 30 suffered a ∼400-fold
loss of activity. Substitution at the 8-position (com-
pounds 33 and 36) again reduced activity, although the
8-fluoro derivative 36 was <10 times less active. The
8-aza compound 5830 on the other hand retained most
of the activity of the parent compound.
(1S)-1-(7-N-Ben zyloxym et h yl-9-d ea za -6-O-m et h ylh y-
p oxa n t h in -9-yl)-N-ter t-b u t oxyca r b on yl-1,4-d id eoxy-1,4-
im in o-D-r ibitol (4). A solution of 311 (2.25 g, 5.1 mmol) in
THF (30 mL), trifluoroacetic acid (4 mL), and water (12 mL)
was heated under reflux for 1.5 h and then concentrated to
dryness. The crude residue in methanol (20 mL) was treated
with triethylamine (1.43 mL, 10.3 mmol) and di-tert-butyl
dicarbonate (1.67 g, 7.7 mmol). After 1 h the solution was
concentrated to dryness and chromatography afforded 4 as a
1
syrup (2.28 g, 4.56 mmol, 88%). H NMR (at 50 °C after D2O
shake) δ 8.24 (bs, 1H), 7.40 (bs, 1H), 7.32-7.25 (m, 5H), 5.72-
5.65 (m, 2H), 4.70 (d, J ) 7.6 Hz, 1H), 4.65 (s, 1H), 4.55-4.46
(m, 2H), 4.21 (s, 1H), 4.15-4.10 (m, 1H), 4.07 (s, 3H), 3.99 (s,
1H), 3.66 (d, J ) 12.2 Hz, 1H), 1.13 (bs, 9H); 13C NMR (at 50
°C) δ 157.1, 149.7, 148.1, 137.6, 132.9, 129.1, 128.6, 128.3,
117.0, 80.5, 77.7, 76.9, 74.1, 71.1, 68.4, 63.6, 60.4, 54.3, 28.9.
HRMS (MH+) calcd for C25H33N4O7: 501.2349. Found: 501.2388.
(1S)-1-(7-N-Ben zyloxym et h yl-9-d ea za -6-O-m et h ylh y-
p oxa n t h in -9-yl)-N-ter t-b u t oxyca r b on yl-1,4-d id eoxy-1,4-
im in o-5-O-tr ip h en ylm eth yl-D-r ibitol (5). A solution of 4
(1.74 g, 3.48 mmol) in dichloromethane (20 mL) containing
N,N-diisopropylethylamine (2.4 mL, 13.8 mmol), 4-(dimeth-
ylamino)pyridine (0.13 g, 1.06 mmol), and chlorotriphenyl-
methane (1.17 g, 4.2 mmol) was allowed to stand at room
temperature for 16 h. Additional chlorotriphenylmethane (1.0
g, 3.6 mmol) was added, and after a further 6 h, the solution
was washed with water and aq NaHCO3 and processed
normally. Chromatography afforded 5 (2.27 g, 3.06 mmol, 88%)
as a colorless foam. 1H NMR (C6D6 at 70 °C) δ 8.40 (s, 1H),
7.56 (d, J ) 1.1 Hz, 1H), 7.39-7.35 (m, 6H), 7.05-6.90 (m,
14H), 5.46 (d, J ) 6.8 Hz, 1H), 5.24 (s, 2H), 5.03 (dd, J ) 6.7,
4.3 Hz, 1H), 4.54 (bs, 1H), 4.46 (d, J ) 4.0 Hz, 1H), 4.11 (s,
2H), 3.76 (s, 3H), 3.60 (dd, J ) 9.4, 5.7 Hz, 1H), 3.35 (dd, J )
9.4, 3.3 Hz, 1H), 3.22 (bs, 1H), 1.42 (s, 9H); 13C NMR (C6D6 at
70 °C) δ 156.7, 156.5 (C), 149.8 (CH), 149.6, 144.7, 137.8 (C),
132.1 (CH), 118.7, 116.1, 87.6, 79.8 (C), 77.8 (CH), 77.2 (CH2),
74.3 (CH), 70.2 (CH2), 67.0 (CH), 64.5 (CH2), 61.6 (CH), 53.2,
28.6 (CH3), some aromatic signals were obscured by the
solvent. HRMS (MH+) calcd for C44H47N4O7: 743.3445.
Found: 743.3419.
1(S)-2-O-Allyl-1-(7-N -b e n zyloxym e t h yl-9-d e a za -6-O-
m e t h ylh yp oxa n t h in -9-yl)-N -t er t -b u t oxyca r b on yl-1,4-
d id eoxy-1,4-im in o-5-O-tr ip h en ylm eth yl-D-r ibitol (6) a n d
1(S)-3-O-Allyl-1-(7-N-ben zyloxym eth yl-9-d ea za -6-O-m eth -
ylh yp oxa n th in -9-yl)-N-ter t-bu toxyca r bon yl-1,4-d id eoxy-
1,4-im in o-5-O-tr ip h en ylm eth yl-D-r ibitol (7). A solution of
5 (1.9 g, 2.56 mmol) in toluene (50 mL) was heated under reflux
with dibutyltin oxide (0.64 g, 2.57 mmol) in a Dean-Stark
apparatus for 1 h, tetrabutylammonium bromide (0.82 g, 2.55
mmol) and allyl bromide (4 mL, 46.2 mmol) were added,
refluxing was continued for 4 h, and then the solution was
concentrated to dryness. Chromatography of the residue
At the transition state of nucleoside phosphorolysis
catalyzed by PNP there is reduced bond order between
the ribose and the departing purine. Synthesis of
analogues with greater distance between the ribose
mimic and the deazapurine explored this feature of the
transition state. Such “methylene-bridged” analogues 40
and 47 were not an improvement. The N-linked 50 and
N-propyl 52 derivatives were exceedingly poor inhibitors
in comparison to 1 and 2.
Con clu sion
Immucillin analogues modified in the iminoribitol and
deazapurine moieties as well as “methylene-bridged”
derivatives have been prepared and assayed as inhibi-
tors of human purine nucleoside phosphorylase. All were
poorer inhibitors than the potent transition state ana-
logues 1 and 2.
Exp er im en ta l Section
Gen er a l Meth od s. Aluminum-backed silica gel sheets
(Merck or Riedel de Haen) were used for TLC. Column
chromatography was performed on silica gel (230-400 mesh,
Merck). Chromatography solvents were distilled prior to use.
Anhydrous solvents were obtained from Aldrich or Acros. NMR
spectra were recorded at 300 MHz (1H) and 75 MHz (13C) in
CDCl3 with tetramethylsilane as internal standard unless
otherwise indicated.
Hu m a n P NP a n d Assa ys. The cDNA for human PNP was
inserted into a pCRT7/NT-TOPO vector and expressed in E.
coli with an N-terminal His-tag. Protein was purified to >98%
homogeneity and used as the His-tagged product. Full char-
acterization of the human enzyme will be reported elsewhere.

Purine Nucleoside Phosphorylase Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15 3417
afforded the 2-ether 6 (1.14 g, 1.46 mmol, 57%) followed by
the 3-ether 7 (0.61 g, 0.78 mmol, 30%) as syrups. For 6; 1H
NMR (C6D6 at 70 °C) δ 8.57 (s, 1H), 7.61-7.57 (m, 7H), 7.15-
6.99 (m, 14H), 5.79-5.68 (m, 1H), 5.55 (d, J ) 3.6 Hz, 1H),
5.32 (d, J ) 10.4 Hz, 1H), 5.14 (dd, J ) 17.2, 1.6 Hz, 1H), 5.05
(d, J ) 10.4 Hz, 1H), 4.96-4.92 (m, 3H), 4.34-4.29 (m, 1H),
4.18 (d, J ) 1.7 Hz, 2H), 4.16-4.03 (m, 3H), 3.85 (dd, J ) 9.4,
3.8 Hz, 1H), 3.80 (s, 3H), 2.55 (d, J ) 5.7 Hz, 1H), 1.30 (s,
9H); 13C NMR (C6D6 at 70 °C) δ 156.6, 155.8(C), 150.2 (CH),
149.9, 145.0, 138.0 (C), 135.1, 133.7 (CH), 116.9 (CH2), 116.5,
87.6 (C), 82.1 (CH), 79.5 (C), 77.4 (CH2), 72.1 (CH), 71.3, 70.3
(CH2), 64.8 (CH), 63.2 (CH2), 58.7 (CH), 53.0, 28.6 (CH3).
HRMS (MH+) calcd for C47H51N4O7: 783.3758. Found: 783.3795.
For 7; 1H NMR (C6D6 at 70 °C) δ 8.49 (s, 1H), 7.55 (s, 1H),
7.48 (d, J ) 7.5 Hz, 6H), 7.12-6.97 (m, 14H), 5.93-5.82 (m,
1H), 5.45 (d, J ) 5.4 Hz, 1H), 5.29-5.23 (m, 4H), 5.17 (d, J )
10.4 Hz, 1H), 5.05 (d, J ) 10.4 Hz, 1H), 4.57-4.49 (m,
2H), 4.21-4.08 (m, 3H), 4.04 (bs, 1H), 3.88-3.79 (m, 1H), 3.77
(s, 3H), 3.65 (dd, J ) 9.4, 3.8 Hz, 1H), 1.34 (s, 9H); 13C NMR
(C6D6 at 70 °C) δ 156.6, 156.1 (C), 150.0 (CH), 149.7, 144.9,
137.9 (C), 135.6, 133.3 (CH), 116.7 (CH2), 116.3, 87.5 (C), 80.6
(CH), 79.5 (C), 77.3 (CH2), 75.4 (CH), 71.5, 70.2, 63.8 (CH2),
63.6, 61.6 (CH), 53.0, 28.6 (CH3). HRMS (MH+) calcd for
solution was heated under reflux for 4 h. The same quantities
of reagents were added again, and refluxing was continued
for another 4 h. The solution was concentrated to dryness and
the residue was dissolved in 10 % aq acetone (30 mL). Yellow
mercuric oxide (1.0 g, 4.6 mmol) and mercuric chloride (0.6 g,
2.2 mmol) were added to the stirred solution, and after 1 h
the same quantities of reagents were added again. After
another 1 h the mixture was concentrated to dryness. Chlo-
roform (100 mL) was added, and the mixture was filtered. The
filtrate was washed twice with water and processed normally
to give, after chromatography, 9 as a syrup (1.02 g, 1.18 mmol,
1
81%) with the same H and 13C NMR spectra described above.
(1S)-1-(9-Dea za h yp oxa n t h in -9-yl)-1,3,4-t r id eoxy-1,4-
im in o-D-er yth r o-p en titol Hyd r och lor id e (10‚HCl). A solu-
tion of the 2-O-(4-methoxybenzyl) derivative 8 (0.36 g, 0.418
mmol) in toluene (5 mL) containing thiocarbonyl diimidazole
(0.148 g, 0.83 mmol) was heated under reflux for 1 h.
Tributyltin hydride (1.2 mL, 4.45 mmol) was added directly
to the refluxing solution, and refluxing was continued for 1 h.
The solution was concentrated to dryness, the residue was
dissolved in acetonitrile (10 mL), and this solution was washed
twice with light petroleum. The acetonitrile phase was con-
centrated to dryness and chromatography afforded a colorless
foam (0.204 g). This material was suspended in concentrated
HCl (5 mL), and the mixture was heated under reflux for 1 h,
cooled, and concentrated to dryness. The residue was redis-
solved in water, and this solution was washed twice with
chloroform. The aqueous phase was concentrated to dryness
and chromatography (CH2Cl2/MeOH/a NH3 5:4:1) afforded a
syrup which was treated with 2M aq HCl (2 mL) and the
solution was lyophilized to give 10‚HCl as a white solid (0.065
g, 0.22 mmol, 52%) which decomposed at ∼270 °C without
melting. 1H NMR (D2O) δ 7.95 (s, 1H), 7.68 (s, 1H), 4.95-4.84
(m, 2H), 4.24-4.17 (m, 1H), 3.97 (dd, J ) 12.6, 3.8 Hz, 1H),
3.83 (dd, J ) 12.6, 6.7 Hz, 1H), 2.50-2.40 (m, 1H), 2.34-2.25
(m, 1H); 13C NMR (D2O) δ 157.5, 146.0 (C), 145.3, 131.4 (CH),
120.4, 110.8 (C), 76.2, 63.8 (CH), 63.1 (CH2), 62.7 (CH), 36.6
(CH2). HRMS (MH+) calcd for C11H15N4O3: 251.1144. Found:
251.1133.
C
47H51N4O7: 783.3758. Found: 783.3741.
(1S )-1-(7-N -B e n zy lox y m e t h y l-9-d e a za -6-O-m e t h yl-
h yp oxa n t h in -9-yl)-N-ter t-b u t oxyca r b on yl-1,4-d id eoxy-
1,4-im in o-2-O-(4-m et h oxyb en zyl)-5-O-t r ip h en ylm et h yl-
D-r ibit ol (8) a n d (1S)-1-(7-N-Ben zyloxym et h yl-9-d ea za -
6-O-m eth ylh yp oxa n th in -9-yl)-N-ter t-bu toxyca r bon yl-1,4-
d id eoxy-1,4-im in o-3-O-(4-m eth oxyben zyl)-5-O-tr ip h en yl-
m eth yl-D-r ibitol (9). A solution of 5 (0.50 g, 0.67 mmol) in
benzene (15 mL) was treated as described above in the
preparation of 6 and 7 except that 4-methoxybenzyl chloride
(0.18 mL, 1.33 mmol) was used in place of allyl bromide, and
the reaction was heated under reflux for 18 h. Chromatography
afforded the 2-ether 8 (0.377 g, 0.44 mmol, 65%) followed by
the 3-ether 9 (0.143 g, 0.17 mmol, 25%) as syrups. For the
1
2-ether 8; H NMR (500 MHz) (DMSO-d6 at 90 °C) δ 8.23 (s,
1H), 7.49 (s, 1H), 7.40-7.37 (m, 6H), 7.30-7.22 (m, 12H),
7.15-7.10 (m, 4H), 6.72 (d, J ) 8.5 Hz, 2H), 5.61 (d, J ) 10.4
Hz, 1H), 5.35 (d, J ) 10.4 Hz, 1H), 5.00 (d, J ) 5.1 Hz, 1H),
4.54 (d, J ) 12.0 Hz, 1H), 4.49-4.46 (m, 2H), 4.43 (d, J ) 12.0
Hz, 1H), 4.37 (d, J ) 12.0 Hz, 1H), 4.34 (d, J ) 12.0 Hz, 1H),
4.06 (s, 3H), 4.94-4.91 (m, 1H), 3.70 (s, 3H), 3.58 (dd, J ) 9.4,
6.9 Hz, 1H), 3.40 (dd, J ) 9.4, 4.1 Hz, 1H), 1.18 (s, 9H); 13C
NMR (DMSO-d6) δ 158.9, 155.9, 154.9, 149.3, 148.7, 144.1,
137.5, 130.4, 129.4, 128.7, 128.5, 128.2, 127.9, 127.7, 127.3,
115.2, 113.6, 86.4, 79.5, 79.0, 77.2, 70.8, 69.7, 64.1, 62.0, 57.1,
55.3, 53.7, 28.2. HRMS (MH+) calcd for C52H55N4O8: 863.4020.
Found: 863.4052. For the 3-ether 9 1H NMR (C6D6 at 70 °C)
δ 8.51 (s, 1H), 7.55 (s, 1H), 7.51-7.44 (m, 6H), 7.29 (d, J ) 8.6
Hz, 2H), 7.11-6.90 (m, 14H), 6.83-6.75 (m, 2H), 5.49 (d, J )
5.3 Hz, 1H), 5.28 (m, 2H), 5.16 (d, J ) 10.4 Hz, 1H), 4.71-
4.67 (m, 3H), 4.54 (bs, 1H), 4.17 (s, 2H), 3.88-3.81 (m, 1H),
3.78 (s, 3H), 3.66 (dd, J ) 9.4, 3.8 Hz, 1H), 3.37 (s, 3H), 1.35
(s, 9H); 13C NMR (C6D6 at 70 °C) δ 160.1, 156.6, 156.1 (C),
150.0 (CH), 149.7, 144.9, 137.9, 117.9 (C), 114.5 (CH), 87.5 (C),
80.3 (CH), 79.6 (C), 77.3 (CH2), 75.3 (CH), 72.3, 70.3, 63.8
(CH2), 63.5, 61.6 (CH), 55.0, 53.0, 28.6 (CH3) some aromatic
peaks were obscured by the solvent. HRMS (MH+) calcd for
(1S)-1-(9-Deazah ypoxan th in -9-yl)-1,4-dideoxy-1,4-im in o-
2-O-m eth yl-D-r ibitol (11). Sodium hydride (0.03 g, 60%, 0.75
mmol) was added to a solution of the 3-O-allyl derivative 7
(0.20 g, 0.26 mmol) and methyl iodide (32 µL, 0.51 mmol) in
DMF (3 mL), and the mixture was stirred at room temperature
for 1 h. A small amount of ethanol was added followed by
toluene (15 mL), and the solution was washed twice with water
and processed normally. The crude product in ethanol (5 mL),
benzene (1.5 mL), and water (0.5 mL) was treated with
DABCO (0.06 g, 0.53 mmol) and tris(triphenylphosphine)-
rhodium(I) chloride (0.05 g, 0.054 mmol), and the solution was
heated under reflux for 8 h. Additional reagents as above were
added, and reflux was continued for 2 h. The solution was
concentrated to dryness and redissolved in 10% aq acetone (10
mL). Yellow mercuric oxide (0.30 g) and mercuric chloride (0.25
g) were added to the stirred solution, and after 1 h the mixture
was concentrated to dryness. Chloroform (50 mL) was added,
the solids were removed, and the filtrate was washed with
water and processed normally followed by chromatography to
give 0.12 g of syrupy material. This was dissolved in concen-
trated HCl (10 mL), and the solution was heated under reflux
for 1 h then concentrated to dryness. A solution of the residue
in water was washed twice with chloroform, and the aq phase
was evaporated to dryness. Chromatography of the residue
(MeOH:CHCl3:concentrated aq NH3 100:100:1) afforded 11 as
an amorphous powder (0.025 g, 0.09 mmol, 34%). 1H NMR
(D2O) δ 7.97 (s, 1H), 7.62 (s, 1H), 4.57 (d, J ) 8.2 Hz, 1H),
4.41 (dd, J ) 5.2, 4.3 Hz, 1H), 4.18 (dd, J ) 8.2, 5.3 Hz, 1H),
3.86-3.76 (m, 2H), 3.45 (dd, J ) 9.1, 4.8 Hz, 1H), 3.41 (s, 3H);
13C NMR (D2O) δ 158.1, 146.3 (C), 145.0, 131.0 (CH), 120.7,
115.8 (C), 87.0, 72.9, 68.2 (CH), 64.1 (CH2), 60.8 (CH3), 58.1
(CH). HRMS (MH+) calcd for C12H17N4O4: 281.1250. Found:
281.1249.
C
52H55N4O8: 863.4020. Found: 863.4014.
(1S)-1-(7-N-Ben zyloxym et h yl-9-d ea za -6-O-m et h ylh y-
p oxa n t h in -9-yl)-N-ter t-b u t oxyca r bon yl-1,4-d id eoxy-1,4-
im in o-3-O-(4-m eth oxyben zyl)-5-O-tr ip h en ylm eth yl-D-r ib-
itol (9). Sodium hydride (0.117 g, 60%, 2.9 mmol) was added
slowly to a solution of the 2-O-allyl compound 6 (1.14 g, 1.46
mmol) and 4-methoxybenzyl chloride (0.3 mL, 2.1 mmol) in
DMF (15 mL), and the mixture was stirred at room temper-
ature for 4 h. A little ethanol was added followed by toluene
(30 mL), and the mixture was washed with water. Normal
processing afforded a syrup which was dissolved in a mixture
of ethanol (30 mL), benzene (9 mL), and water (3 mL). DABCO
(0.326 g, 2.91 mmol) and tris(triphenylphosphine)rhodium(I)
chloride (0.15 g, 0.16 mmol) were added, and the resulting
(1S)-1-(9-Deazah ypoxan th in -9-yl)-1,4-dideoxy-1,4-im in o-
D-a r a bin itol (12). A solution of DMSO (0.24 mL, 3.38 mmol)

3418 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15
Evans et al.
in dichloromethane (10 mL) was cooled to -70 °C, and
trifluoroacetic anhydride (0.24 mL, 1.73 mmol) was added to
the stirred solution. After 10 min a solution of the 3-O-
methoxybenzyl ether 9 (0.31 g, 0.36 mmol) in dichloromethane
(5 mL) was added followed by triethylamine (0.4 mL, 5.4 mmol)
after a further 15 min. The solution was allowed to warm to
room temperature and processed normally. The crude product
in methanol (5 mL) was cooled to 0 °C, and sodium borohy-
dride (0.1 g, 2.5 mmol) was added to the stirred solution.
After 30 min the solution was concentrated to dryness, and
chromatography afforded a syrup, presumably (1S)-1-(7-N-
benzyloxymethyl-9-deaza-6-O-methylhypoxanthin-9-yl)-N-tert-
butoxycarbonyl-1,4-dideoxy-1,4-imino-3-O-(4-methoxybenzyl)-
5-O-triphenylmethyl-D-arabinitol (0.22 g, 0.255 mmol, 70%).
Some of this material (0.16 g, 0.186 mmol) was dissolved in
concentrated HCl, and the solution was heated under reflux
for 1 h and then concentrated to dryness. Chromatography
(CH2Cl2/MeOH/aq NH3 5:4:1) afforded 12 as a solid (0.038 g,
0.143 mmol, 77%) which decomposed at ∼210 °C without
melting. 1H NMR (D2O) δ 7.86 (s, 1H), 7.57 (s, 1H), 4.68
(d, J ) 3.8 Hz, 1H), 4.30 (dd, J ) 3.8, 1.5 Hz, 1H), 4.10
(dd, J ) 4.2, 1.5 Hz, 1H), 3.93 (dd, J ) 11.8, 5.0 Hz, 1H), 3.86
(dd, J ) 11.8, 6.8 Hz, 1H), 3.36-3.31 (m, 1H); 13C NMR (D2O)
δ 157.7, 145.6 (C), 144.8, 131.7 (CH), 119.9, 113.1 (C), 81.5,
80.9, 69.1 (CH), 64.2 (CH2), 59.9 (CH). HRMS (MH+) calcd for
69.0 and 68.2, 61.5 and 61.1, 52.7 and 52.3. HRMS (MH+) calcd
for C22H25NO535Cl237Cl: 490.0769. Found: 490.0757.
3,5-Di-O-ben zyl-1,2,4-tr id eoxy-2,2-d iflu or o-1,4-im in o-D-
er yth r o-p en titol (13). A solution of 16 (1.0 g, 2.04 mmol) in
dichloromethane (20 mL) containing DMSO (1.0 mL, 14 mmol)
was cooled to -70 °C, and trifluoroacetic anhydride (1.0 mL,
7.2 mmol) was added slowly. After 0.5 h at -70 °C, triethyl-
amine (2.0 mL, 15 mmol) was added, and the solution was
warmed to ambient temperature, then processed normally.
DAST (1.5 mL, 11.4 mmol) was added to the crude product in
dry chloroform (20 mL), and the solution was heated under
reflux for 4 h, then washed with aq NaHCO3 and processed
normally. Chromatography afforded a syrup (0.94 g) which was
stirred with zinc dust (1.0 g) in acetic acid (30 mL) for 1 h.
The solids and solvent were removed, and the residue in
chloroform was washed with aq NaHCO3 and dried and
concentrated to dryness. Chromatography gave syrupy title
compound 13 (0.535 g, 1.61 mmol, 78%). 1H NMR δ 7.37-7.23
(m, 10H), 4.83 (d, J ) 11.6 Hz, 1H), 4.52-4.40 (m, 3H), 3.88-
3.78 (m, 1H), 3.65-3.61 (m, 1H), 3.54-3.49 (m, 1H), 3.35 (dt,
J ) 13.3, 6.9 Hz, 1H), 3.23-3.08 (m, 2H); 13C NMR δ 138.2,
137.8 (C), 128.8, 128.5, 128.4, 128.2, 128.1 (CH), 80.4, (dd, J C,F
) 29, 18 Hz, CH), 73.7, 73.2, 68.7 (CH2), 63.3 (d, J C,F ) 6 Hz,
CH), 53.9 (t, J C,F ) 28 Hz, CH2). HRMS (MH+) calcd for
C
19H22F2NO2: 334.1619. Found: 334.1611.
4-Am in o-4-N-ben zyl-3,5-d i-O-ben zyl-2,4-d id eoxy-2,2-d i-
C
11H15N4O4: 267.1093. Found: 267.1092.
flu or o-D-er yth r o-p en ton ola cta m (17). To a stirred suspen-
sion of zinc dust (2.73 g, 41.7 mmol) in THF (100 mL) was
added 1,2-dibromoethane (0.273 mL, 3.17 mmol), and the
mixture was briefly heated to reflux. After the mixture was
cooled to 40 °C, chlorotrimethylsilane (0.35 mL, 2.76 mmol)
was added, and the stirred mixture was maintained at ∼40
°C for 10 min before being cooled to room temperature. Ethyl
bromodifluoroacetate (4.35 mL, 33.9 mmol) was added to the
stirred mixture with cooling to keep the reaction temperature
e30 °C. When the exothermic reaction was complete, the
mixture was stirred at room temperature for 0.5 h and then
cooled to 0 °C. A solution of 1825 (crude product from oxidation
of the corresponding propan-1-ol derivative; 4.35 g, 11.3 mmol)
in THF (15 mL) was added, and the resulting mixture was
allowed to warm to room temperature and stirred for 16 h.
Ether (200 mL) was added, and the mixture was washed with
water and filtered through a pad of Celite. Normal processing
and chromatography gave, presumably, ethyl 4-amino-4-N,N-
dibenzyl-5-O-tert-butyldimethylsilyl-2,4-dideoxy-2,2-difluoro-
D-erythro-pentanoate (19) (2.32 g, 4.6 mmol). A solution of this
material (1.0 g, 1.97 mmol) in ethanol (30 mL) was stirred
under hydrogen in the presence of 10% Pd/C (0.5 g) for 1 h.
The solids and solvent were removed, and the residue was
dissolved in 25% aq trifluoroacetic acid (10 mL). After 3 h, the
solution was concentrated to dryness, and a solution of the
residue in THF (10 mL) and DMF (2.5 mL) was treated with
benzyl bromide (1.17 mL, 9.8 mmol) and sodium hydride (0.40
g, 60%, 10 mmol). The mixture was stirred at room temper-
ature for 16 h and then quenched carefully with ethanol.
Chloroform (100 mL) was added, and normal processing
followed by chromatography afforded syrupy title compound
17 (0.50 g, 1.14 mmol). 1H NMR δ 7.39-7.05 (m, 15H), 5.05
(d, J ) 15.2 Hz, 1H), 4.83 (d, J ) 11.5 Hz, 1H), 4.51 (d, J )
11.5 Hz, 1H), 4.37 (d, J ) 12.0 Hz, 1H), 4.28 (d, J ) 11.9 Hz,
1H), 4.22-4.13 (m, 1H), 3.91 (dd, J ) 15.2, 1.5 Hz, 1H), 3.50
(m, 1H), 3.43 (m, 1H), 3.34 (m, 1H); 13C NMR δ 163.3 (t, J C,F
) 30 Hz, C), 137.4, 136.9, 135.0 (C), 129.3, 129.0, 128.7, 128.6,
128.5, 128.4, 128.3 (CH), 115.6 (t, J C,F ) 255 Hz, C), 74.5 (dd,
3,5-Di-O-ben zyl-1,4-d id eoxy-1,4-im in o-N-(2,2,2-tr ich lo-
r oeth oxyca r bon yl)-D-r ibitol (16). A solution of 1424 (2.41
g, 8.4 mmol) in 10% aq trifluoroacetic acid (30 mL) was allowed
to stand at room temperature for 16 h and then was concen-
trated to dryness. A solution of the residue in methanol (30
mL) was treated with triethylamine (2.3 mL, 16.6 mmol) and
then di-tert-butyl dicarbonate (2.38 g, 10.9 mmol), and after
standing at room temperature for 2 h the solution was
concentrated to dryness. Chromatography of the residue
afforded N-tert-butoxycarbonyl-1,4-dideoxy-1,4-imino-D-ribitol
(1.68 g, 86%). A cold (-20 °C) solution of this material (2.16
g, 9.27 mmol) and imidazole (3.78 g, 55.6 mmol) in dry N,N-
dimethylformamide (25 mL) was treated with 1,3-dichlorotet-
raisopropyldisiloxane (3.11 mL, 9.73 mmol), and after 0.5 h
the solution was allowed to warm to room temperature.
Toluene (40 mL) was added, and the solution was washed twice
with water. Normal processing followed by chromatograpgy
gave 15 (4.02 g, 82%). Bromomethyl methyl ether (1.2 mL, 14.7
mmol) was then added to a solution of this material (2.25 g,
4.74 mmol) in THF (30 mL) containing diisopropylethylamine
(5.0 mL, 28.7 mmol), and the mixture was heated under reflux
for 1 h and cooled, and then methanol (20 mL) and tetrabu-
tylammonium fluoride (15 mL, 1 M in THF) were added. After
16 h, the solution was concentrated to dryness. A solution of
the crude material in dry DMF (10 mL) was treated with
benzyl bromide (2.0 mL, 16.7 mmol) and sodium hydride (0.6
g, 60%, 15.6 mmol), and the mixture was stirred for 2 h. The
reaction was quenched with a little methanol, toluene (30 mL)
was added, and the solution was washed (×2) with water.
Normal processing and chromatography afforded syrupy 3,5-
di-O-benzyl-N-tert-butoxycarbonyl-1,4-dideoxy-1,4-imino-2-O-
methoxymethyl-D-ribitol (1.71 g, 78%). A solution of this
material (1.6 g, 3.5 mmol) in THF (20 mL), water (10 mL),
and TFA (10 mL) was heated under reflux for 1.5 h and then
concentrated to dryness. The residue was dissolved in metha-
nol (20 mL) containing triethylamine (2.4 mL, 17.3 mmol), and
then trichloroethyl chloroformate (0.75 mL, 5.4 mmol) was
added slowly with stirring. After 1 h, chloroform (30 mL) was
added, and the solution was processed normally followed by
chromatography to give title compound 16 as a syrup (1.58 g,
3.23 mmol, 92%). 1H NMR δ 7.35-7.23 (m, 10H), 4.84-4.53
(m, 4H), 4.46 (s, 2H), 4.42-4.32 (m, 1H), 4.15-4.09 (m, 1H),
J C,F ) 25, 17 Hz, CH), 73.6, 73.5, 64.7 (CH2), 58.3 (d, J C,F
)
7.0 Hz, CH), 44.8 (CH2). HRMS (MH+) calcd for C26H26F2NO3:
438.1881. Found: 438.1886.
(1S)-1-(9-Dea za h yp oxa n th in -9-yl)-1,2,4-tr id eoxy-2,2-d i-
flu or o-1,4-im in o-D-er yth r o-p en titol Hyd r och lor id e (24‚
HCl). A solution of 2011 (2.6 g, 7.6 mmol) in ether (100 mL)
and anisole (35 mL) was cooled to -70 °C, and butyllithium
(4.8 mL, 7.6 mmol) was added. After 10 min, a solution of
lactam 17 (1.6 g, 3.66 mmol) in ether (10 mL) was added, and
the resulting solution was stirred at -40 °C for 30 min before
4.02 (m, 1H), 3.80-3.50 (m, 4H), 2.66 (t, J ) 7.9 Hz, 1H); 13
C
NMR (many of the peaks are doubled due to slow intercon-
version of rotamers) δ 153.6 and 153.4, 138.4 and 138.3, 137.5,
129.0, 128.8, 128.7, 128.4, 128.2, 128.1, 128.0, 96.1 and 95.9,
81.3 and 80.4, 75.3 and 75.2, 73.8, 72.7 and 72.5, 69.4 and 68.9,

Purine Nucleoside Phosphorylase Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15 3419
water was added. Normal processing afforded a syrup which
was dissolved in methanol (50 mL) and acetic acid (1 mL), and
sodium cyanoborohydride (1 g) was added to the stirred
solution. After 1 h, the solution was partitioned between
chloroform and aq sodium bicarbonate. The organic phase was
processed normally, and then chromatography gave first
recovered lactam 17 (0.45 g, 1.03 mmol) and then the C-1
epimer 23 of the desired product (0.81 g, 1.42 mmol) followed
by 22 (0.261 g, 0.46 mmol). A solution of this material 22 (0.17
g, 0.3 mmol) in ethanol (10 mL) with 10% Pd/C (200 mg) was
stirred under H2 for 3 days. The solids and solvent were
removed, and chromatography of the residue afforded fully
debenzylated material (0.015 g). A solution of this material in
methanol (3 mL) and concentrated aq HCl (3 mL) was heated
under reflux for 3 h and then concentrated to dryness. The
residue was redissolved in water and lyophilized to give title
compound 24‚HCl as an amorphous solid (0.015 g, 0.047
mmol). 1H NMR (D2O) δ 8.33 (s, 1H), 7.84 (d, J ) 2.1 Hz, 1H),
5.44 (dd, J ) 19.1, 8.2 Hz, 1H), 4.60-4.52 (m, 1H), 4.07-3.95
(m, 2H), 3.92-3.84 (m, 1H); 13C NMR δ 154.5 (C), 144.3 (CH),
140.6 (C), 131.2 (d, J ) 4.7 Hz, CH), 118.3, 100.9 (C), 70.8
(dd, J ) 33, 18.9 Hz, CH), 63.9 (CH), 58.3 (CH2), 55.7 (dd, J )
34.8, 25.9 Hz, CH). HRMS (MH+) calcd for C11H13F2N4O3:
287.0956. Found: 287.0934.
170.1, 155.0, 154.5, 142.8 (C), 140.5, 127.5 (CH), 118.1, 114.7,
81.2 (C), 75.1, 72.2 (CH), 62.6 (CH2), 60.6, 57.0 (CH), 28.3, 20.8
(CH3). Anal. Calcd for C22H28N4O9: C, 53.65; H, 5.73; N, 11.38.
Found: C, 53.99; H, 5.65; N, 11.20.
(1S)-1-(9-Dea za -6-t h ioh yp oxa n t h in -9-yl)-1,4-d id eoxy-
1,4-im in o-D-r ibitol Hyd r och lor id e (30‚HCl). A solution of
29 (0.215 g, 0.437 mmol) and Lawesson’s reagent [2,4-bis(4-
methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide]
(0.265 g, 0.65 mmol) in dry toluene (15 mL) was heated under
reflux for 1.5 h. The cooled solution was washed with water
and processed normally followed by chromatography to give,
presumably, the 6-thio analogue (0.22 g). This material was
dissolved in 2 M NH3 in methanol (15 mL), and the solution
was stored at room temperature for 18 h before being concen-
trated to dryness. Chromatography of the residue gave deacety-
lated material (0.11 g) which was dissolved in 1 M aq HCl (5
mL). After 2 h the solution was lyophilized to give 30‚HCl as
a pale yellow solid (0.087 g, 0.273 mmol, 62%) which decom-
1
posed at ∼250 °C without melting. H NMR (D2O) δ 8.19 (s,
1H), 7.95 (s, 1H), 4.99 (d, J ) 8.2 Hz, 1H), 4.83 (dd, J ) 8.2,
4.9 Hz, 1H), 4.49 (t, J ) 4.4 Hz, 1H), 4.04-3.98 (m, 2H), 3.93-
3.88 (m, 1H); 13C NMR (D2O) δ 167.6 (C), 142.6 (CH), 139.5
(C), 133.1 (CH), 129.7, 108.0 (C), 73.7, 71.0, 65.6 (CH), 59.0
(CH2), 57.0 (CH). Anal. Calcd for C11H15ClN4O3S: C, 41.44;
H, 4.74; Cl, 11.12; N, 17.58; S, 10.06. Found: C, 41.42; H, 4.87;
Cl, 10.74; N, 16.99; S, 9.89.
(1S )-1-(9-D e a za -6-O -m e t h y lh y p o x a n t h in -9-y l)-1,4-
d id eoxy-1,4-im in o-D-r ibitol Bis-Hyd r och lor id e (26‚2HCl).
A solution of 2811 (0.395 g, 0.94 mmol) in methanol (6 mL)
and 2 M aq HCl (6 mL) was allowed to stand at room
temperature for 4 h and was then concentrated to dryness.
The residue was recrystallized from aq acetone to give 26‚
2HCl as a white solid (0.20 g, 0.57 mmol, 60%) which charred
7-N-Ben zyloxym eth yl-9-br om o-6-O-ter t-bu tyl-9-d ea za -
h yp oxa n th in e. A mixture of 6-chloro-9-deazapurine29 (5.0 g,
32.6 mmol) and benzyl chloromethyl ether (6.0 mL, 43.1 mmol)
in THF (100 mL) was stirred in an ice bath while sodium
hydride (1.7 g, 60%, 42.4 mmol) was added portionwise. When
the addition was complete, the mixture was stirred for 1 h,
and then tert-butyl alcohol (20 mL) and N,N-dimethylforma-
mide (20 mL) were added followed by more sodium hydride
(1.5 g, 60%, 37.5 mmol). The cooling bath was removed, and
the mixture was stirred at room temperature for 18 h and then
diluted with chloroform and washed twice with water. Normal
processing afforded a dark syrup which was dissolved in
chloroform (50 mL), and the resulting solution was stirred in
an ice bath while NBS was added until TLC analysis indicated
complete conversion to a less polar product. Chromatography
then afforded the title compound as a white solid (5.8 g, 14.9
mmol, 46%). Recrystallized from ethyl acetate/petroleum ether
it had mp 91-93 °C; 1H NMR δ 8.55 (s, 1H), 7.41 (s, 1H), 7.34-
7.20 (m, 5H), 5.73 (s, 2H), 4.48 (s, 2H), 1.69 (s, 9H); 13C NMR
δ 156.3 (C), 151.1 (CH), 148.7, 137.1 (C), 131.4, 128.9, 128.4,
127.8 (CH), 117.0, 92.6, 84.0 (C), 77.6, 70.5 (CH2), 29.0 (CH3).
Anal. Calcd for C18H20BrN3O2: C, 55.40; H, 5.17; N, 10.77.
Found: C, 55.46; H, 5.18; N, 10.80.
1
at 240 °C without melting. H NMR (D2O) δ 8.87 (s, 1H), 8.22
(s, 1H), 5.08 (d, J ) 9.0 Hz, 1H), 4.79 (dd, J ) 9.0, 4.9 Hz,
1H), 4.47 (dd, J ) 4.7, 3.1 Hz, 1H), 4.35 (s, 3H), 3.99-3.92 (m,
3H); 13C NMR δ 162.1 (C), 149.4 (CH), 141.0 (C), 137.2 (CH),
119.5, 106.3 (C), 76.6, 73.5, 68.8 (CH), 61.5 (CH2), 59.3 (CH3),
58.2 (CH). Anal. calcd for C12H18Cl2N4O4: C, 40.81; H, 5.14;
Cl, 20.08; N, 15.86. Found: C, 41.06; H, 5.10; Cl, 19.85; N,
15.86.
(1S )-1-(9-D e a za -7-N -m e t h y lh y p o x a n t h in -9-y l)-1,4-
d id eoxy-1,4-im in o-D-r ibitol Hyd r och lor id e (27‚HCl). A
stirred solution of 2811 (0.43 g, 0.80 mmol) in THF (10 mL)
containing methyl iodide (75 µL, 1.20 mmol) was cooled in an
ice bath while sodium hydride (0.050 g, 60%, 1.25 mmol) was
added, and then the mixture was stirred at room temperature
for 1 h. Normal processing and chromatography afforded a
syrup (0.427 g). This material in methanol (4 mL) and
concentrated HCl (4 mL) was heated under reflux for 2 h and
then concentrated to dryness. The solid residue was recrystal-
lized from aq acetone to give 27‚HCl as a white solid (0.188 g,
0.59 mmol, 73%) which charred at ∼270 °C without melting.
1H NMR (D2O) δ 7.89 (s, 1H), 7.54 (s, 1H), 4.87 (d, J ) 8.2 Hz,
1H), 4.41 (t, J ) 4.4 Hz, 1H), 3.98-3.91 (m, 5H), 3.87-3.80
(1S)-1-(7-N-Ben zyloxym et h yl-6-O-ter t-b u t yl-9-d ea za -
h yp oxa n t h in -9-yl)-N-ter t-b u t oxyca r b on yl-5-O-ter t-b u -
t yld im et h ylsilyl-1,4-d id eoxy-1,4-im in o-2,3-O-isop r op y-
lid en e-D-r ibitol (34). n-Butyllithium (2.9 mL, 2.4 M, 6.96
mmol) was added to a stirred solution of 7-N-benzyloxymethyl-
9-bromo-6-O-tert-butyl-9-deazahypoxanthine (2.7 g, 6.9 mmol)
in anisole (20 mL) and ether (40 mL) at -60 °C, and then a
solution of imine 3811 (1.6 g, 5.6 mmol) in ether (5 mL) was
added. The resulting solution was allowed to warm to 10 °C
and washed with water. Normal processing afforded a crude
syrup which was dissolved in chloroform (20 mL) containing
di-tert-butyl dicarbonate (1.05 g, 4.8 mmol). After 0.5 h, the
solution was concentrated to dryness and after chromatogra-
(m, 1H) one of the signals was obscured by the HOD peak; 13
C
NMR (D2O) δ 155.7, 144.1 (C), 143.0, 133.5 (CH), 118.3, 106.6
(C), 73.8, 71.0, 65.6 (CH), 59.0 (CH2), 57.0 (CH), 36.3 (CH3).
Anal. Calcd for C12H17ClN4O4: C, 45.50; H, 5.41; Cl, 11.19; N,
17.69. Found: C, 45.68; H, 5.52; Cl, 11.37; N, 17.62.
(1S)-2,3,5-Tr i-O-a cetyl-N-ter t-bu toxyca r bon yl-1-(9-d e-
azah ypoxan th in -9-yl)-1,4-dideoxy-1,4-im in o-D-r ibitol (29).
Di-tert-butyl dicarbonate (2.0 g, 9.2 mmol) and triethylamine
(1.5 mL, 20.5 mmol) were added to a solution of 1‚HCl11 (1.5
g, 4.96 mmol) in water (20 mL) and methanol (40 mL). After
30 min the solution was concentrated to dryness. Pyridine (10
mL) and acetic anhydride (15 mL) were added to the residue,
and the resulting solution was allowed to stand at room
temperature for 16 h. The solution was poured onto water (200
mL), and after 30 min the mixture was extracted twice with
chloroform. The combined extracts were processed normally
followed by chromatography to give 29 as a foam (1.42 g, 2.89
mmol, 58%). 1H NMR δ 7.66 (bs, 1H), 7.31 (d, J ) 2.6 Hz, 1H),
5.95 (bs, 1H), 5.63 (t, J ) 3.8 Hz, 1H), 5.19 (bs, 1H), 4.67 (bs,
1H), 4.48 (dd, J ) 11.4, 3.8 Hz, 1H), 4.20 (bs, 1H), 2.14 (s,
3H), 2.09 (s, 3H), 2.07 (s, 3H), 1.46 (bs, 9H); 13C NMR δ 170.7,
1
phy 34 was obtained as a syrup (2.17 g, 3.12 mmol, 56%). H
NMR (C6D6) δ 8.65 (s, 1H), 7.52 (s, 1H), 7.07-7.02 (m, 5H),
5.91 (bs, 1H), 5.74 (bs, 1H), 5.62 (bs, 1H), 5.38 (bs, 1H), 5.20-
5.05 (m, 1H), 4.52 (bs, 1H), 4.30-4.05 (m, 3H), 3.94 (bs, 1H),
1.57 (s, 3H), 1.56 (s, 9H), 1.41 (s, 9H), 1.30 (s, 3H), 0.97 (s,
9H), 0.11 (s, 6H); 13C NMR (C6D6) δ 156.2, 154.6 (C), 149.8
(CH), 149.2, 137.8 (C), 134.6 (CH), 131.9, 116.9, 115.5, 111.8
(C), 85.4 and 84.2, 83.9 and 83.2 (CH), 82.3, 79.4 (C), 77.0,
69.8 (CH2), 67.5 (CH), 63.1 (CH2), 61.6 (CH), 28.6, 28.5, 27.7,
26.2, 25.5 (CH3), 18.6 (C), -4.9, -5.1 (CH3) some aromatic
signals were obscured by the solvent. HRMS (MH+) calcd for
C
37H57N4O7Si: 697.3997. Found: 697.3989.

3420 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15
Evans et al.
(1S)-1-(7-N-Ben zyloxym eth yl-6-O-ter t-bu tyl-9-d ea za -8-
flu or oh yp oxa n th in -9-yl)-N-ter t-bu toxyca r bon yl-5-O-ter t-
b u t yld im et h ylsilyl-1,4-d id eoxy-1,4-im in o-2,3-O-isop r o-
p ylid en e-D-r ibitol (35). n-Butyllithium (1.2 mL, 2.4M, 2.88
mmol) was added to a stirred solution of 34 (1.25 g, 1.80 mmol)
in THF (30 mL) at -70 °C. After 10 min, N-fluorobenzene-
sulfonimide (1.42 g, 4.5 mmol) was added to the red/brown
solution which resulted in an immediate decolorization to a
yellow solution. After 20 min, water was added, and the
solution was extracted with chloroform and processed normally
to give, after chromatography, 35 as a syrup (0.67 g, 0.94
mmol) followed by recovered 34 (0.40 g, 0.57 mmol). For 35,
1H NMR (C6D6) δ 8.58 (s, 1H), 7.12-7.00 (m, 5H), 5.7-5.1 (m,
5H), 4.8-4.05 (m, 5H), 1.55 (s, 9H), 1.54 (s, 3H), 1.39 (s, 9H),
1.27 (s, 3H), 1.01 (s, 9H), 0.17 (s, 6H); 13C NMR (C6D6) δ 155.3,
154.4 (C), 150.3 (CH), 147.7, 137.7, 112.0, 110.7 (C), 85.3, 83.8
(CH), 82.5, 79.6 (C), 72.4, 70.5 (CH2), 67.1 (CH), 63.0 (CH2),
59.3 (CH), 28.6, 28.5, 27.8, 26.2, 25.6 (CH3), 18.6 (C), -4.8,
-5.0 (CH3) some aromatic signals were obscured by the
solvent. HRMS (MH+) calcd for C37H56FN4O7Si: 715.3902.
Found: 715.3916.
(m, 2H), 3.96 (m, 1H), 2.54 (s, 3H); 13C NMR (D2O) δ 155.7
(C), 146.2 (CH), 145.7, 141.3, 119.4, 104.8 (C), 75.7, 73.8, 68.6
(CH), 61.9 (CH2), 59.4 (CH), 14.5 (CH3). Anal. Calcd for C12H17
-
ClN4O4: C, 45.50; H, 5.41; Cl, 11.19; N, 17.69. Found: C, 45.38;
H, 5.41; Cl, 11.50; N, 17.80.
(1S)-1-(7-N-Ben zyloxym eth yl-9-d ea za -6-O-m eth yl-8-tr i-
m eth ylsilylh yp oxa n th in -9-yl)-N-ter t-bu toxyca r bon yl-5-
O-ter t-b u t yld im et h ylsilyl-1,4-d id eoxy-1,4-im in o-2,3-O-
isop r op ylid en e-D-r ibitol (37). n-Butyllithium (2.0 mL, 1.3
M in hexanes, 2.6 mmol) was added to a stirred solution of 31
(0.75 g, 1.15 mmol) in THF (15 mL) at -70 °C. After 15 min,
HMPA (0.57 mL) was added followed by chlorotrimethylsilane
(0.63 mL, 5.0 mmol), and 45 min later the reaction was
quenched with water. Normal processing followed by chroma-
tography gave 37 as a syrup (0.447 g, 0.62 mmol, 54%). 1H
NMR (C6D6 at 70 °C) δ 8.64 (s, 1H), 7.10-7.02 (m, 5H), 5.76
(d, J ) 2.9 Hz, 1H), 5.72 (d, J ) 10.5 Hz, 1H), 5.61 (d, J )
10.5 Hz, 1H), 5.50 (d, J ) 5.9 Hz, 1H), 5.40 (dd, J ) 5.5, 2.8
Hz, 1H), 4.89 (dd, J ) 10.6, 9.4 Hz, 1H), 4.49 (dd, J ) 10.6,
4.7 Hz, 1H), 4.34-4.25 (m, 3H), 3.74 (s, 3H), 1.58 (s, 3H), 1.30
(s, 9H), 1.29 (s, 3H), 1.07 (s, 9H), 0.71 (s, 9H), 0.24 (s, 6H); 13
C
NMR (C6D6 at 70 °C) δ 156.4, 155.2, 150.0 (C), 149.5 (CH),
146.3, 138.5, 120.3, 112.2 (C), 85.8, 84.4 (CH), 79.6 (C), 76.8,
70.3 (CH2), 68.0 (CH), 63.8 (CH2), 62.9 (CH), 53.1, 28.8, 28.3,
26.6, 26.0 (CH3), 19.0 (C), 2.5, -4.4, -4.6 (CH3). Some aromatic
signals were obscured by the solvent. HRMS (MH+) calcd for
(1S)-1-(9-Dea za -8-flu or oh yp oxa n th in -9-yl)-1,4-d id eoxy-
1,4-im in o-D-r ib it ol H yd r och lor id e (36‚H Cl). Tetrabutyl-
ammonium fluoride (1 M in THF, 5 mL) was added to a
solution of 35 (0.20 g, 0.28 mmol) in methanol (5 mL) and THF
(5 mL). After 18 h, toluene (20 mL) was added, and the solution
was washed twice with water, dried and concentrated to
dryness. A solution of the crude residue in ethanol (10 mL)
C
37H59N4O7Si2: 727.3922. Found: 727.3921.
(1S)-5-O-ter t-Bu tyld im eth ylsilyl-1-ter t-bu toxyca r bon -
containing 10% Pd/C (0.2 g) was stirred in
a hydrogen
ylm eth yl-1,4-d id eoxy-1,4-im in o-2,3-O-isop r op ylid en e-D-
r ibitol (39). tert-Butyl acetate (40 mL, 297 mmol) was added
dropwise to a stirred solution of LDA (200 mL, 1.5 M, 300
mmol) in diethyl ether such that the reaction temperature was
maintained below -65 °C. The resulting solution was left to
stir for 20 min after which time a solution of imine 3811 (17.0
g, 60 mmol) was added at such a rate that the reaction
temperature was maintained below -65 °C, and the resulting
solution was then allowed to warm to room temperature. The
reaction was quenched by the addition of saturated aq am-
monium chloride (200 mL), and the organic layer was sepa-
rated and processed normally. Chromatography then afforded
atmosphere for 2 d. The solids and solvent were removed, and
chromatography of the residue afforded two compounds, the
more polar of which appeared by NMR to have lost the tert-
butyl group. A solution of this mixture (0.102 g) in methanol
(2 mL) and 2 M aq HCl (2 mL) was allowed to stand at room
temperature for 2.5 h and then concentrated to dryness. The
residue was recrystallized from aq acetone to give 36‚HCl as
a cream solid (0.043 g, 0.13 mmol, 46%) which charred at ∼250
1
°C without melting. H NMR (D2O) δ 8.04 (s, 1H), 4.97-4.88
(m, 2H), 4.48 (t, J ) 4.1 Hz, 1H), 4.05-3.99 (m, 2H), 3.89 (dd,
J ) 9.1, 4.6 Hz, 1H); 13C NMR (D2O) δ 157.2, 155.2 (d, J )
250 Hz), (C), 146.6 (CH), 146.2 (d, J ) 9.2 Hz), 113.1, 89.5 (d,
J ) 6.6 Hz), (C), 74.9, 73.3, 68.2 (CH), 61.6 (CH2), 57.7 (CH).
Anal. Calcd for C11H14ClFN4O4: C, 41.20; H, 4.40; Cl, 11.05;
N, 17.47. Found: C, 41.01; H, 4.37; Cl, 11.11; N, 17.17.
1
39 as an oil (15.7 g, 39 mmol, 65%). H NMR δ 4.31 (dd, J )
7.0, 4.6 Hz, 1H), 4.18 (t, J ) 6.1 Hz, 1H), 3.71 (dd, J ) 10.2,
4.1 Hz, 1H), 3.57 (dd, J ) 10.2, 5.7 Hz, 1H), 3.32 (quintet, J )
5.0 Hz), 3.15 (1H, q, J ) 4.7 Hz), 2.54 (dd, J ) 15.9, 4.8 Hz,
1H), 2.34 (dd, J ) 15.9, 8.2 Hz, 1H), 1.44 (s, 3H), 1.38 (s, 9H),
1.24 (s, 3H), 0.83 (s, 9H), 0.01 (s, 6H); 13C NMR δ 171.4, 114.1
(C), 85.1, 85.2 (CH), 81.1 (C), 65.8 (CH), 64.7 (CH2), 61.3 (CH),
39.9 (CH2), 28.5, 27.8, 26.3, 25.8, -5.5, -5.6 (CH3). HRMS
(MH+) calcd for C20H40NO5Si: 402.2661. Found: 402.2676.
(1S)-1-(9-Deaza-8-m eth ylh ypoxan th in -9-yl)-1,4-dideoxy-
1,4-im in o-D-r ibitol Hyd r och lor id e (33‚HCl). n-Butyllithi-
um (0.40 mL, 2.4M, 0.96 mmol) was added to a stirred solution
of 31 (0.29 g, 0.44 mmol) in THF (7 mL) at -70 °C. After 10
min, methyl iodide (0.25 mL, 4.0 mmol) was added, and 10
min later the reaction was quenched with water. Normal
processing followed by chromatography afforded 1-(S)-1-(7-N-
benzyloxymethyl-9-deaza-8-methyl-6-O-methylhypoxanthin-9-
yl)-N-tert-butoxycarbonyl-5-O-tert-butyldimethylsilyl-1,4-dideoxy-
1,4-imino-2,3-O-isopropylidene-D-ribitol (32) as a syrup (0.164
g, 0.25 mmol, 55%). 1H NMR (C6D6 at 70 °C) δ 8.66 (s, 1H),
7.10-7.00 (m, 5H), 5.70 (d, J ) 5.9 Hz, 1H), 5.57 (s, 1H), 5.52
(d, J ) 5.0 Hz, 1H), 5.39 (d, J ) 10.9 Hz, 1H), 5.32 (d, J )
10.9 Hz, 1H), 4.56-4.44 (m, 2H), 4.25 (s, 2H), 4.06 (dd, J )
8.2, 4.3 Hz, 1H), 3.77 (s, 3H), 2.63 (s, 3H), 1.58 (s, 3H), 1.40 (s,
9H), 1.32 (s, 3H), 1.03 (s, 9H), 0.18 (s, 3H), 0.17 (s, 3H); 13C
NMR (C6D6 at 70 °C) δ 155.4, (C), 149.7 (CH), 149.5, 143.0,
138.3, 116.0, 114.3, 111.8 (C), 85.5, 84.6 (CH), 79.5 (C), 74.4,
70.1 (CH2), 68.5 (CH), 63.6 (CH2), 61.6 (CH), 52.9, 28.7, 28.0,
26.3, 25.8 (CH3), 18.7 (C), 10.8, -4.8, -4.9 (CH3). Some
aromatic signals were obscured by the solvent. A solution of
this material in ethanol (5 mL) containing 10% Pd/C (0.1 g)
was stirred in a hydrogen atmosphere for 2 d. The solids and
solvent were removed, and a solution of the residue in
methanol (3 mL) and concd HCl (3 mL) was heated under
reflux for 2 h. The solution was concentrated to dryness, and
trituration of the residue with ethanol afforded 33‚HCl as a
white solid (0.061 g, 0.19 mmol, 76%) which charred at ∼260
(1S)-5-O-Ben zyl-N-ter t-bu toxyca r bon yl-1-ter t-bu toxy-
ca r b on ylm et h yl-1,4-d id eoxy-1,4-im in o-2,3-O-isop r op y-
lid en e-D-r ibitol (43). Di-tert-butyl dicarbonate (13.0 g, 60
mmol) was added, portionwise, to a stirred solution of amine
39 (15.7 g, 39 mmol) in methanol (100 mL) at room temper-
ature. The reaction was monitored by TLC and on completion
tetrabutylammonium fluoride in THF (40 mL, 1.0 M, 40
mmol) was added dropwise and the resulting solution left to
stir for 14 h. The reaction was then concentrated in vacuo,
the resulting residue (15 g) was dissolved in DMF (100 mL)
and benzyl bromide (18.5 mL, 155 mmol) at 0 °C, and so-
dium hydride (2 g, 60%, 50 mmol) was added portionwise,
keeping the reaction temperature e0 °C. The reaction mixture
was allowed to warm to room temperature and then was
diluted with toluene (500 mL) and washed with water and then
brine and processed normally. The crude material was purified
by chromatography to afford 43 as an oil (15.0 g, 31.4 mmol,
80%). 1H NMR δ 7.36-7.27 (m, 5H), 4.69 (d, J 5.8 Hz, 1H),
4.56-4.52 (m, 3H), 4.35-4.01 (m, 2H), 3.60-3.46 (m, 2H),
2.85-2.49 (m, 2H), 1.46 (s, 3H), 1.43 (s, 18H), 1.31 (s, 3H); 13
C
NMR δ 170.9, 154.1, 138.1 (C), 128.8, 128.1 (CH), 111.9 (C),
85.3, 84.7, 82.8, 82.2 (CH), 81.0, 80.4 (C), 73.9, 70.5 (CH2), 64.7
(CH), 62.6, 62.3 (CH), 39.5, 38.5 (CH2), 28.8, 28.5, 27.6, 25.7
(CH3). HRMS (MH+) calcd for C26H40NO7: 478.2805. Found:
478.2791.
1
°C without melting. H NMR (D2O) δ 8.46 (s, 1H), 4.96 (dd, J
) 9.4, 4.6 Hz, 1H), 4.89 (d, J ) 9.5 Hz, 1H), 4.51 (m, 1H), 4.07

Purine Nucleoside Phosphorylase Inhibitors
J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15 3421
(1S)-5-O-Ben zyl-N-ter t-bu toxycar bon yl-1-(2-cyan oeth yl)-
1,4-d id eoxy-1,4-im in o-2,3-O-isop r op ylid en e-D-r ibitol (42).
Diisobutylaluminum hydride (1.0 M in toluene, 120 mL, 120
mmol) was added dropwise to a stirred solution of 43 (15.0 g,
39 mmol) in THF (150 mL) at 0 °C under argon. After 3 h, the
reaction was quenched with water (100 mL) and diluted with
toluene (500 mL). The organic layer was separated, washed
with dilute HCl (10% v/v, 100 mL), water (100 mL), and brine
(100 mL), and processed normally. Methanesulfonyl chloride
(3.0 mL, 39 mmol) was added dropwise to a stirred solution of
the crude residue (10.4 g, 36 mmol) and diisopropylethylamine
(13.3 mL, 76 mmol) in dichloromethane (100 mL) at 0 °C under
an inert atmosphere. The reaction was allowed to warm to rt,
diluted with dichloromethane (250 mL), washed with water
(100 mL) and brine (100 mL), and processed normally. The
residue was dissolved in DMF (100 mL), and potassium
cyanide (12.6 g, 195 mmol) was added. The resulting suspen-
sion was stirred at 80 °C for 14 h, diluted with toluene (500
mL), washed with water (100 mL) and brine (100 mL), dried
(MgSO4), and concentrated in vacuo. Chromatography of the
resulting residue afforded 42 as an oil (6.5 g, 15.6 mmol, 40%).
1H NMR δ 7.39-7.26 (m, 5H), 4.68 (d, J ) 5.7 Hz, 1H), 4.51
(dd, J ) 11.8, 5.7 Hz, 2H), 4.34 (brd, J ) 5.0 Hz, 1H), 3.95
(brs, 1H), 3.56 (s, 2H), 2.35 (m, 2H), 1.84 (sextet, J ) 6.5 Hz,
1H), 1.60 (d, J ) 5.5 Hz, 1H), 1.44 (s, 12H), 1.30 (s, 3H); 13C
NMR δ 154.7, 137.9 (C), 128.9, 128.3 (CH), 119.5, 112.3 (C),
84.9, 84.4, 82.6, 82.0 (CH), 79.9 (C), 73.6, 70.5 (CH2), 65.4, 64.2
(CH), 29.7 (CH2), 28.8, 27.7, 25.8 (CH3), 14.6 (CH2). HRMS
(MH+) calcd for C23H32N2O5: 417.2389. Found: 417.2391.
(C), 128.9, 128.4, 127.0 (CH), 113.5, 112.1 (C), 84.3, 83.0 (CH),
81.9 (C), 74.0, 70.4 (CH2), 65.0, 64.3 (CH), 60.0 (CH2), 54.1
(CH3), 28.7 (CH3), 28.4 (CH2), 27.5, 25.6, 14.9 (CH3). HRMS
(MH+) calcd for C30H42N3O9: 588.2921. Found: 588.2901.
(1S)-1-(3-Am in o-2-cya n op yr r ol-4-yl)m eth yl-5-O-ben zyl-
N-ter t-b u t oxyca r b on yl-1,4-d id eoxy-1,4-im in o-2,3-O-iso-
p r op ylid en e-D-r ibitol (46). A solution of the enamine 44 (6.1
g, 12.6 mmol) in THF/acetic acid/water (1:1:1, v/v/v, 45 mL)
was stirred at room temperature for 1.5 h, diluted with
chloroform (150 mL), washed with water (2 × 50 mL) and
saturated aqueous sodium bicarbonate, dried, and concen-
trated in vacuo. Sodium acetate (10.0 g, 122 mmol) and
aminoacetonitrile hydrochloride (8.0 g, 86.4 mmol) were added
to a solution of the residue in methanol (100 mL). The mixture
was stirred at room temperature for 16 h, concentrated in
vacuo, and partitioned between chloroform (200 mL) and water
(100 mL). The organic layer was washed with water (50 mL)
and brine (50 mL), dried, and concentrated in vacuo. The crude
residue was redissolved in dichloromethane (50 mL) and
treated with DBU (15 mL, 100 mmol) and then methyl
chloroformate (5 mL, 65 mmol) and the resulting solution
heated under reflux for 16 h. The reaction solution was cooled
and diluted with methanol (50 mL), and the resulting solution
was stirred for an additional 1 h, diluted with dichloromethane
(250 mL), washed with dilute aqueous HCl and aqueous
sodium bicarbonate, dried, and concentrated in vacuo. Chro-
matography of the residue afforded 46 as a syrup (2.35 g, 4.87
mmol, 39%). 1H NMR δ 8.51 (brs, 1H), 7.39-7.29 (m, 5H), 6.35
(d, J ) 3.0 Hz, 1H), 4.74 (d, J ) 5.9 Hz, 1H), 4.53 (s, 2H), 4.41
(d, J ) 5.9 Hz, 1H), 3.95 (m, 2H), 3.58 (m, 1H), 3.53 (m, 1H),
2.71-2.36 (m, 2H), 1.45 (s, 12H), 1.28 (s, 3H); 13C NMR δ 154.6,
148.9143.5, 138.1 (C), 128.9, 128.4, 122.3 (CH), 112.1, 109.3
(C), 84.4, 83.0 (CH), 80.1 (C), 74.0, 70.6 (CH2), 65.5, 64.9 (CH),
28.8 (CH3), 28.0 (CH2), 27.6, 25.7 (CH3). HRMS (MH+) calcd
for C26H35N4O5: 482.2529. Found: 482.2549.
(1S)-5-O-Ben zyl-N-ter t-b u t oxyca r b on yl-1-(2-cya n o-3-
d im eth yla m in oa llyl)-1,4-d id eoxy-1,4-im in o-2,3-O-isop r o-
p ylid en e-D-r ibitol (44). A solution of nitrile 42 (6.4 g, 15.4
mmol) and tert-butoxybis(dimethylamino)methane (15 mL,
72.6 mmol) in DMF (50 mL) was heated at 70 °C under an
inert atmosphere for 72 h and then cooled to r.t., diluted with
toluene (250 mL), washed with water (100 mL) and brine (100
mL), dried (MgSO4), and concentrated in vacuo. Chromatog-
raphy of the resulting residue afforded 44 as an oil (6.1 g, 12.9
(1S)-1-(9-Dea za h yp oxa n th in -9-yl)m eth yl-1,4-d id eoxy-
1,4-im in o-D-r ibitol Bis-Hyd r och lor id e (40‚2HCl). Carbam-
ate 45 (120 mg, 0.20 mmol) was dissolved in ethanol (5 mL),
potassium carbonate (100 mg) was added, and the resulting
suspension was stirred at rt for 16 h. The reaction mixture
was concentrated in vacuo, the residue suspended in chloro-
form (50 mL) and filtered, and the filtrate concentrated in
vacuo. The crude residue was redissolved in ethanol (5 mL),
formamidine acetate (400 mg, 3.8 mmol) was added, and the
resulting suspension was heated under reflux for 16 h. The
mixture was concentrated to dryness, and chromatography of
the residue afforded an oil which was not characterized but
redissolved in ethanol and stirred with Pearlman’s catalyst
(50 mg) under a hydrogen atmosphere for 16 h. The crude
reaction was filtered through Celite, 2 M HCl was added, and
the resulting solution was stirred for an additional 2 h and
then concentrated in vacuo to afford 40‚2HCl as the solid
monohydrate (45 mg, 69%) which decomposed between 269
1
mmol, 84%). H NMR δ 7.36-7.27 (m, 5H), 6.23, 5.86 (s, 1H),
4.71 (brs, 1H), 4.51 (m, 3H), 4.23 (brs, 1H), 3.96 (m, 1H), 3.58
(m, 2H), 2.97 (s, 6H), 2.43 (m, 1H), 2.04 (m, 1H), 1.49 (s, 3H),
1.45 (s, 9H), 1.33 (s, 3H); 13C NMR δ 154.7, 153.2 (C), 152.1,
151.0 (CH), 138.3 (C), 128.8, 128.2 (CH), 122.5, 112.0 (C), 84.9,
84.1, 83.0, 82.1 (CH), 80.4 (C), 73.9, 70.6 (CH2), 69.2, 67.3, 64.4
(CH), 42.1 (CH3), 37.0, 35.7 (CH2), 28.8, 27.7, 25.9 (CH3).
HRMS (MH+) calcd for C26H37N3O5: 471.2733. Found: 471.2709.
(1S)-1-(3-Am in o-2-eth oxyca r bon yl-1-N-m eth oxyca r bo-
n ylpyr r ol-4-yl)m eth yl-5-O-ben zyl-N-ter t-bu toxyca r bon yl-
1,4-d id eoxy-1,4-im in o-2,3-O-isop r op ylid en e-D-r ibitol (45).
A solution of enamine 44 (260 mg, 0.55 mmol) in THF/acetic
acid/water (1:1:1, v/v/v, 6 mL) was stirred at room temperature
for 1.5 h. The solution was then diluted with chloroform (100
mL), washed with water (2 × 25 mL) and saturated aqueous
sodium bicarbonate, and then dried and concentrated in vacuo.
The crude residue was redissolved in methanol (5 mL), and
sodium acetate (500 mg, 6.1 mmol) and ethyl glycinate
hydrochloride (300 mg, 2.2 mmol) were added consecutively.
The mixture was stirred at room temperature for 16 h and
then concentrated in vacuo and partitioned between chloroform
(100 mL) and water (50 mL). The organic layer was separated,
washed with water (25 mL) and then brine (25 mL), dried,
and concentrated in vacuo. The crude residue was redissolved
in dichloromethane (5 mL) and treated with DBU (2.25 mL,
15 mmol) and then methyl chloroformate (0.6 mL, 7.6 mmol)
and the resulting solution heated under reflux for 1 h. The
reaction was cooled and diluted with dichloromethane (250
mL), washed with dilute aqueous HCl and aqueous sodium
bicarbonate, dried, and concentrated in vacuo. Chromatogra-
phy of the residue afforded 45 as a syrup (120 mg, 0.204 mmol,
1
and 270 °C without melting. H NMR δ 8.79 (s, 1H), 7.60 (s,
1H), 4.23 (t, J ) 7.3 Hz, 1H), 4.13 (t, J ) 5.3 Hz, 1H), 3.83 (m,
3H), 3.65 (q, J ) 5.3 Hz, 1H), 3.20 (dq, J ) 15.7, 6.9 Hz, 2H);
13C NMR δ 153.1 (C), 144.3 (CH), 133.2 (C), 130.7 (CH), 118.2,
108.0 (C), 73.4, 70.44, 65.0, 62.9 (CH), 58.4, 24.2 (CH2). HRMS
(MH+) calcd for C12H17N4O4: 281.1250. Found: 281.1259. Anal.
Calcd for C12H16N4O4.2HCl‚H2O requires C, 38.83; H, 5.43; N,
15.09; Cl, 19.10; Found C, 39.17; H, 5.42; N, 14.97; Cl, 19.15.
(1S)-1-(9-Dea za a d en in -9-yl)m eth yl-1,4-d id eoxy-1,4-im i-
n o-D-r ibitol Tr is-Hyd r och lor id e (41‚3HCl). Pyrrole 46 (100
mg, 0.20 mmol) was dissolved in ethanol (2 mL), formamidine
acetate (35 mg, 0.3 mmol) was added, and the resulting
suspension was heated under reflux for 16 h. The mixture was
concentrated to dryness, and chromatography of the residue
afforded an oil which was not characterized but redissolved
in ethanol and stirred with Pearlman’s catalyst (40 mg) under
a hydrogen atmosphere for 16 h. The crude reaction was
filtered through Celite, 2 M HCl was added, and the resulting
solution was stirred for an additional 2 h and then concen-
trated in vacuo to afford solid 41‚3HCl (42 mg, 59%) with mp
1
37%). H NMR δ 7.38-7.28 (m, 5H), 6.98 (brs, 1H), 5.46 (brs,
1H), 4.75 (d, J ) 5.8 Hz, 1H), 4.53 (s, 2H), 4.38 (brd, J ) 5.8
Hz, 1H), 4.28 (q, J ) 7.1 Hz, 2H), 4.05 (m, 2H), 3.88 (s, 3H),
3.50 (m, 2H), 2.51 (m, 2H), 1.42 (s, 12H), 1.32 (t, J ) 7.1 Hz,
3H), 1.28 (s, 3H); 13C NMR δ 162.0, 154.6, 153.9, 151.6, 138.0
1
254-257 °C. H NMR (D2O) δ 8.38 (s, 1H), 7.75 (s, 1H), 4.26

3422 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 15
Evans et al.
(t, J ) 5.3 Hz), 4.16 (q, J ) 5.3, 1H), 3.88 (m, 3H), 3.66 (q, J
) 5.4 Hz, 1H), 3.26 (m, 2H); 13C NMR δ 150.5 (C), 144.0 (CH),
136.5 (C), 132.6 (CH), 112.9, 107.3 (C), 73.4, 70.4, 65.0, 62.9
(CH), 58.4, 24.1 (CH2). HRMS (MH+) calcd for C12H18N5O3:
280.1410. Found: 280.1405. Anal. Calcd for C12H17N5O3.3HCl
requires C, 37.08; H, 5.19; N, 18.02; Cl, 27.36. Found: C, 36.88;
H, 5.25; N, 18.29; Cl, 27.19.
7-N-Ben zyloxym eth yl-9-d ea za -9-for m yl-6-O-m eth ylh y-
p oxa n th in e (48). A solution of 4911 (1.0 g, 2.87 mmol) in
anisole (10 mL) and ether (25 mL) was cooled to -70 °C, and
n-butyllithium (2.4 mL, 1.2 M) was added to the resulting
suspension. After 10 min, dry N,N-dimethylformamide (1.1
mL, 14.2 mmol) was added to the clear solution which was
stirred at -70 °C for 30 min and then quenched with water.
Normal processing afforded a solid, which after trituration
with ethanol gave title compound 48 as a white solid (0.67 g,
2.26 mmol, 78%) with mp 100-101 °C. 1H NMR δ 10.30 (s,
1H), 8.67 (s, 1H), 8.00 (s, 1H), 7.35-7.21 (m, 5H), 5.77 (s, 2H),
4.55 (s, 2H), 4.14 (s, 3H); 13C NMR δ 184.7 (CH), 157.0 (C),
153.0 (CH), 150.0 (C), 136.9 (CH), 136.5 (C), 129.0, 128.7, 128.1
(CH), 118.6, 116.7 (C), 78.3, 71.4 (CH2), 54.3 (CH3). HRMS
(MH+) calcd for C19H21N3O3 340.1661 found: 340.1652.
56.1 (CH2). HRMS (M+) calcd For C11H15N4O4: 267.1093.
Found: 267.1101.
(1S)-1-(9-Deazah ypoxan th in -9-yl)-1,4-dideoxy-1,4-im in o-
N-p r op yl-D-r ibitol Hyd r och lor id e (52‚HCl). A solution of
1‚HCl (0.21 g, 0.69 mmol) and propionaldehyde (0.25 mL, 3.46
mmol) in water (10 mL) was stirred with 10% Pd/C (0.08 g) in
a hydrogen atmosphere for 16 h, and then the solids and
solvent were removed to give a white solid residue (0.24 g) of
title compound 52‚HCl. This material was very hygroscopic
and became an oil on exposure to air. 1H NMR (D2O) δ 8.38
(s, 1H), 7.84 (s, 1H), 4.85 (d, J ) 9.7 Hz, 1H), 4.41 (dd, J )
4.4, 2.1 Hz, 1H), 3.99 (dd, J ) 12.7, 4.1 Hz, 1H), 3.91 (dd, J )
12.7, 3.7 Hz, 1H), 3.83 (m, 1H), 3.36-3.19 (m, 2H), 1.74-1.52
(m, 2H), 0.80 (t, J ) 7.3 Hz, 3H) (the peaks for one proton
were obscured under the HOD peak); 13C NMR δ 154.4 (C),
144.3 (CH), 139.9 (C), 130.9 (CH), 118.5, 105.6 (C), 74.0, 73.7,
71.7, 64.6 (CH), 59.0, 58.5, 18.2 (CH2), 10.5 (CH3). HRMS (M+)
calcd For C14H21N4O4: 309.1563. Found: 309.1566.
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N-(9-Dea za h yp oxa n t h in -9-yl)m et h yl-1,4-d id eoxy-1,4-
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concentrated to dryness. Chromatography of the residue
afforded, presumably, N-(7-N-benzyloxymethyl-9-deaza-6-O-
methylhypoxanthin-9-yl)methyl-5-O-tert-butyldimethylsilyl-
1,4-dideoxy-1,4-imino-2,3-O-isopropylidene-D-ribitol as a syrup
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1
47‚HCl as a powder (80 mg, 0.25 mmol, 80%). H NMR (D2O)
δ 8.57 (m, 1H), 7.78 (s, 1H), 4.66 (s, 1H), 4.56 (s, 1H), 4.29 (m,
1H), 4.13 (m, 1H), 3.76 (m, 2H), 3.61 (m, 2H), 3.34 (dd, J )
13.0, 3.4 Hz, 1H); 13C NMR δ 153.6 (C), 144.8 (CH), 136.7 (C),
133.2 (CH), 118.5, 103.3 (C), 71.3, 70.3, 68.9 (CH), 57.4, 57.1,
50.1 (CH2). HRMS (M+) calcd For C12H17N4O4: 281.1250.
Found: 281.1260.
5-O-ter t-Bu tyldim eth ylsilyl-N-cyan om eth yl-1,4-dideoxy-
1,4-im in o-2,3-O-isop r op ylid en e-D-r ibitol (51). Bromoac-
etonitrile (1.46 mL, 20.9 mmol) and ethyldiisopropylamine
(5.46 mL, 56.9 mmol) were added to a solution of 1424 (3.0 g,
10.45 mmol) in acetonitrile (20 mL). After 1 h, the solution
was concentrated to dryness, and chromatography of the
residue afforded title compound 51 as a syrup (3.4 g, 10.4
mmol, 99%). 1H NMR δ 4.58 (dt, J ) 6.4, 4.3 Hz, 1H), 4.20
(dd, J ) 6.8, 4.2 Hz, 1H), 3.88 (d, J ) 17 Hz, 1H), 3.79 (dd, J
) 10.9, 3.0 Hz, 1H), 3.58 (m, 1H), 3.56 (d, J ) 17 Hz, 1H),
3.19 (dd, J ) 9.8, 6.1 Hz, 1H), 2.85 (m, 1H), 2.75 (dd, J ) 9.8,
4.3 Hz, 1H), 1.44 (s, 3H), 1.23 (s, 3H), 0.82 (s, 9H), 0.09 (s,
3H), 0.08 (s, 3H); 13C NMR δ 115.6, 113.6 (C), 82.2, 78.3, 68.6
(CH), 64.7, 59.3, 41.0 (CH2), 27.6, 26.2, 25.6 (CH3), 18.5 (C).
HRMS (MH+) calcd For C16H31N2O3Si: 327.2104. Found:
327.2097.
N-(9-Dea za h yp oxa n th in -9-yl)-1,4-d id eoxy-1,4-im in o-D-
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compound by the same sequence of reactions described previ-
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powder (0.07 g, 0.23 mmol, 15%). 1H NMR (D2O) δ 8.24 (s,
1H), 7.71 (s, 1H), 4.43 (m, 1H), 4.29-4.17 (m, 2H), 3.96 (m,
1H), 3.82-3.71 (m, 3H); 13C NMR δ 154.2 (C), 144.3 (CH), 133.0
(C), 124.0 (CH), 117.8, 115.9 (C), 73.4, 70.4, 68.9 (CH), 62.9,
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