5′-O-[(N-acyl)sulfamoyl]adenosines as antitubercular agents that inhibit MbtA: An adenylation enzyme required for siderophore biosynthesis of the mycobactins

Article abstract of DOI:10.1021/jm070905o

A study of the structure - activity relationships of 5′-O-[N- (salicyl)sulfamoyl]adenosine (6), a potent inhibitor of the bifunctional enzyme salicyl-AMP ligase (MbtA, encoded by the gene Rv2384) in Mycobacterium tuberculosis, is described, targeting the salicyl moiety. A systematic series of analogues was prepared exploring the importance of substitution at the C-2 position revealing that a hydroxy group is required for optimal activity. Examination of a series of substituted salicyl derivatives indicated that substitution at C-4 was tolerated. Consequently, a series of analogues at this position provided 4-fluoro derivative, which displayed an impressive MIC ₉₉ of 0.098 μM against whole-cell M. tuberculosis under iron-limiting conditions. Examination of other heterocyclic, cycloalkyl, alkyl, and aminoacyl replacements of the salicyl moiety demonstrated that these nonconserative modifications were poorly tolerated, a result consistent with the fairly strict substrate specificities of related non-ribosomal peptide synthetase adenylation enzymes.

Full text of DOI:10.1021/jm070905o

6080
J. Med. Chem. 2007, 50, 6080-6094
5′-O-[(N-Acyl)sulfamoyl]adenosines as Antitubercular Agents that Inhibit MbtA: An
Adenylation Enzyme Required for Siderophore Biosynthesis of the Mycobactins
Chunhua Qiao,† Amol Gupte,† Helena I. Boshoff,‡ Daniel J. Wilson,† Eric M. Bennett,† Ravindranadh V. Somu,†
Clifton E. Barry, III,‡ and Courtney C. Aldrich*,†
Center for Drug Design, Academic Health Center, UniVersity of Minnesota, Minneapolis, Minnesota 55455, and Tuberculosis Research
Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892
ReceiVed July 26, 2007
A study of the structure-activity relationships of 5′-O-[N-(salicyl)sulfamoyl]adenosine (6), a potent inhibitor
of the bifunctional enzyme salicyl-AMP ligase (MbtA, encoded by the gene RV2384) in Mycobacterium
tuberculosis, is described, targeting the salicyl moiety. A systematic series of analogues was prepared
exploring the importance of substitution at the C-2 position revealing that a hydroxy group is required
for optimal activity. Examination of a series of substituted salicyl derivatives indicated that substitution
at C-4 was tolerated. Consequently, a series of analogues at this position provided 4-fluoro derivative,
which displayed an impressive MIC99 of 0.098 µM against whole-cell M. tuberculosis under iron-limiting
conditions. Examination of other heterocyclic, cycloalkyl, alkyl, and aminoacyl replacements of the
salicyl moiety demonstrated that these nonconserative modifications were poorly tolerated, a result con-
sistent with the fairly strict substrate specificities of related non-ribosomal peptide synthetase adenylation
enzymes.
Introduction
Iron is an essential micronutrient for almost all known
organisms including M. tuberculosis where it serves as an
obligate cofactor for numerous metalloproteins.2 A particular
exception is Borrelia burgdorferi, the causative agent of Lyme
disease, which apparently has evolved to utilize manganese
instead of iron.3 Notwithstanding this anomaly, iron acquisition
is critical for bacterial pathogenesis, and bacteria have evolved
a variety of mechanisms to obtain this vital nutrient. The most
common mechanism involves the synthesis, secretion, and
reuptake of small molecule iron-chelators termed siderophores.2
In a mammalian host, siderophore production is crucial since
the concentration of free iron is approximately 10-24 M, which
is far too low to support bacterial colonization and growth.4
Thus, inhibition of siderophore biosynthesis represents a logical
strategy for the development of a new class of antibiotics.5 An
alternate strategy pioneered by Miller and co-workers involves
antagonism of siderophore function using synthetic siderophore
analogues that likely cannot be taken up by the bacterial
siderophore transport system.32
M. tuberculosis produces two series of structurally related
siderophores, collectively known as the mycobactins, that are
critical for virulence and growth (Figure 1).6,7 Mycobactin
biosynthesis is initiated by MbtA, an adenylate-forming enzyme
that catalyzes a two-step reaction and is responsible for
incorporating salicylic acid into the mycobactins (Figure 1).8
MbtA first binds its substrates salicylic acid and ATP then
catalyzes their condensation to afford acyladenylate 2 and
pyrophosphate. The acyladenylate remains tightly bound whereas
pyrophosphate dissociates. Next, MbtA binds the N-terminal
aryl carrier domain of MbtB and catalyzes the transfer of the
salicyl moiety onto the nucleophilic sulfur atom of the phos-
phopantetheinyl cofactor of MbtB to afford thioester tethered-
MbtB 3 that is elaborated to the mycobactins by a mixed
nonribosomal peptide synthetase polyketide synthase (NRPS-
PKS) assembly line.8
Tuberculosis (TBa) is the leading cause of infectious disease
mortality by a bacterial pathogen.1 TB is extremely difficult to
treat since the etiological agent, Mycobacterium tuberculosis,
is slow growing, is capable of switching its metabolism to a
latent or nonreplicating state, and possesses a nearly impen-
etrable cell wall, which provides a permeability barrier that limits
the uptake of many antibiotics. As a result of these factors,
effective therapy requires prolonged treatment with 3-4 anti-
biotics. A combination of poor patient compliance and the
inevitable evolution of drug resistance has resulted in the
development of multidrug resistant tuberculosis (MDR-TB)
defined as resistance to both the first-line agents isoniazid and
rifampin. Further, co-infection with HIV/AIDS is a deadly
combination, and over one-third of HIV-related deaths are due
to TB or related mycobacterial infections. Despite the tremen-
dous advances in TB chemotherapy made in the 20th century,
TB has now reemerged as one of the most significant threats to
global public health; thus there is a great demand for new drugs
to combat TB. The Global Alliance for TB Drug Development
(http://www.tballiance.org) recommends that an ideal new TB
drug should shorten the duration of effective treatment, improve
the treatment of MDR-TB, and provide more effective treatment
of latent TB infection. Additionally, drugs that are specific
antitubercular agents as opposed to broad-spectrum antibiotics
may be advantageous to prevent disturbance to beneficial
commensal bacteria as well as minimize the potential develop-
ment of cross-resistance.
* To whom correspondence should be addressed. Phone: 612-625-7956.
Fax: 612-626-5173. E-mail: aldri015@umn.edu.
† University of Minnesota.
‡ National Institute of Allergy and Infectious Diseases.
a Abbreviations: CDI, carbonyl diimidazole; DBU, 1,8-diazabicyclo-
[5.4.0]undec-7-ene; MDR-TB, multidrug resistant tuberculosis; MIC,
minimum inhibitory concentration; NHS, N-hydroxysuccinimide; NRPS,
nonribosomal peptide synthetase; PAS, para-aminosalicylic acid; PDB,
protein data bank; PKS, polyketide synthase; SAR, structure-activity
relationships; TB, tuberculosis; TBAF, tetrabutylammonium fluoride; TBS,
tert-butyldimethylsilyl; TFA, trifluoroacetic acid.
Acyladenylates have been shown to bind several orders of
magnitude more tightly than the substrate acids since they
simultaneously occupy both substrate binding pockets.9,10 Thus
10.1021/jm070905o CCC: $37.00 © 2007 American Chemical Society
Published on Web 10/30/2007

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6081
Figure 1. Biosynthesis of the mycobactins and carboxymycobactins.6 The depicted lipid side chain is a representative as both 4 and 5 are isolated
as a suite of compounds with various length lipid residues.
explore the importance of the ortho-hydroxy group, to define
the steric requirements of the shallow aryl acid binding pocket
of MbtA, and to assess the potential for interacting with specific
residues within the active site such as C240. Additionally, a
number of heteroaryl, cycloalkyl, alkyl, and aminoalkyl modi-
fications were targeted. The syntheses of 6,11,14,16 7,11,16 8,11
9,16 21,16 and 2217 were disclosed previously, but 8 and 21 were
synthesized by alternate routes in improved overall yields. The
other 22 inhibitors were synthesized through three related
synthetic routes as described below.
Salicyl acid derivatives 12-20 and 23 were prepared ac-
cording to the method described by Tan, Quadri, and co-workers
from the corresponding acids 34a-j by direct activation with
CDI to afford intermediate cyclic anhydrides 35a-j, which were
not isolated but subsequently reacted with either protected 5′-
O-(sulfamoyl)adenosine derivatives 36 or 37 employing either
DBU or Cs2CO3 as base to afford 38a-j (Scheme 1).14 Catalytic
hydrogenation of 38h provided p-aminosalicyl derivative 39.
Final deprotection of the isopropylidene acetal (80% aq TFA)
or TBS ethers (TBAF) furnished bisubstrate inhibitors 12-20
and 23. Anthranoyl analogue 8 was prepared analogously from
isatoic anhydride and 36 (not shown, see Experimental Section).
The tert-butyldimethylsilyl (TBS) protected nucleosides were
preferred for compounds, such as nicotinyl derivative 23, that
decomposed under acidic conditions. Compounds 15-18 and
23, which were initially isolated as the tetrabutylammonium
salts, were converted to the corresponding sodium salts by ion-
exchange with a strong cation exchange resin in the sodium
form.
Figure 2. Bisubstrate inhibitors of MbtA. The expanded portion of
the figure shows the Ar modifications described herein.
acyladenylate analogues that incorporate a stabile linker as a
bioisostere of the labile acylphosphate function provide potent
adenylation enzyme inhibitors. The general inhibitor scaffold
is comprised of four domains (aryl, linker, glycosyl, and base)
as depicted in Figure 2. The most crucial portion of the inhibitor
scaffold is the linker domain since this must be metabolically
stable and appropriately position both the aryl and nucleoside
moieties in their respective binding pockets. We have previously
explored both the molecular geometry and polarity of the linker
pharmacophore with the preparation of â-ketophosphonate,
acylsulfamate, acylsulfamide, sulfamate, â-ketosulfonamide,
R,R-difluoro-â-ketosulfonamide, acyltriazole, and vinylsulfona-
mide linkages as surrogates for the labile acylphosphate
linkage.11-13 Inhibitors incorporating the acylsulfamate and
acylsulfamide linkages were found to be the most potent with
low nanomolar apparent inhibition constants and possessed sub-
micromolar antitubercular activity against whole-cell M. tuber-
culosis rivaling the first-line agent isoniazid.11,14 Next, we
systematically examined the glycosyl domain and found that
both the 3′-hydroxy and 4′-ribofuranose ring oxygen were
dispensable for bioactivity while modifications making the sugar
either more or less flexible were detrimental.15 In this article,
we explore the importance of the aryl ring of the bisubstrate
inhibitor scaffold.
Direct CDI activation of aryl acids lacking a 2-hydroxy group
was much less efficient. In these cases the acyl imidazolidate
that forms in situ is substantially less reactive than the cyclic
anhydride species (see compound 35, Scheme 1) formed with
salicylic acid derivatives. For most other aryl-, heteoaryl-, and
alkyl carboxylic acids (40a-k), the corresponding preformed
N-hydroxysuccinimide (NHS) esters provided superior coupling
yields. Thus, coupling of NHS esters 41a-k to 36 or 37
mediated by either DBU or Cs2CO3 afforded acylsulfamate
derivatives 42a-k (Scheme 2).18 Catalytic hydrogenation of 42c
provided 2,3-dihydroxybenzoyl derivative 43. In general Cs2-
CO3 as base is favored since in a few instances, such as 42a,
DBU salts of the coupled products were obtainedsthe DBU
could not removed by an acid wash, ion-exchange, or by
chromatography (coeluting with 1% Et3N). Deprotection of the
isopropylidene acetal (80% aq TFA) or the TBS ethers (TBAF)
of 42a-b, 42d-k, and 43 yielded the final bisubstrate inhibitors
10, 11, 21, 24, 25, 27-29, and 31-33. Compounds 27-29 and
31, which were initially isolated as tetrabutylammonium salts,
were converted to the corresponding sodium salts by ion-
exchange chromatography. The acetonide protected nucleosides
were preferred for compounds, such as 4-azido-2,3,5,6-tetrafluo-
rphenyl derivative 32, that decomposed under the fluoride
mediated conditions (TBAF or HF‚pyr) required for TBS
deprotection.
Results and Discussion
Chemistry. Since NRPS adenylation domains exhibit a fairly
strict substrate specificity, bisubstrate inhibitors containing a
number of conservative aryl modifications were prepared to

6082 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
Scheme 1a
a Reaction conditions: (a) CDI, MeCN, 60 °C; (b) 36 or 37, DBU or Cs2CO3, DMF; (c) 80% aq TFA, 0 °C; or TBAF, THF; (d) H2, Pd/C.
Scheme 2a
a Reaction conditions: (a) DCC, NHS, THF; (a) 36 or 37, DBU or Cs2CO3, DMF; (c) 80% aq TFA or TBAF, THF; (d) H2, Pd/C.
Scheme 3a
Attempts to prepare a morpholine derivative from the
corresponding NHS ester 44 and 5′-O-sulfamoyladenosine
derivative 37 did not afford the anticipated product 45 but rather
46 which was deprotected with TBAF to provide 47 in 56%
overall yield from 44 (Scheme 3). The â-alanine fragment in
47 was confirmed by HRMS and NMR.19 The â-alanine moiety
of compound 46 is hypothesized to arise from a sequential series
of reactions as depicted in Scheme 3 above. Initial nucleophilic
attack of sulfamate 37 onto the succinimidyl carbonyl of 44
followed by opening of the imide affords acylhydroxamate
intermediate 48, which in turn undergoes Lo¨ssen rearrangement
to provide isocyanate 49 and expulsion of the carbamic acid of
morpholine. Decarboxylation of the carbamic acid affords
morpholine that condenses with isocyanate 49 to provide the
observed â-alanine urea derivative 46. Precedent exists for
opening of the succinimide by a nucleophile.20 Failure to obtain

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6083
Scheme 6a
Scheme 4a
a Reaction conditions: (a) CH2Cl2, pPyr; (b) 53, MeCN; (c) 80% aq
TFA; (d) ion-exchange, 4% overall.
a Reaction conditions: (a) ref 22, 92%; (b) Boc2O, NaH, DMF/THF (4:
1), 16 h, 76%; (c) H2 (1 atm), Pd/C, MeOH, 95%; (d) (i) CDI, DBU, DMF,
(ii) chromone-3-carboxylic acid; (e) 80% aq TFA, 20% (2 steps).
Scheme 5a
Scheme 7a
a Reaction conditions: (a) MeCN, CDI; (b) MeOH, Et3N; (c) 80% aq
TFA; (d) ion-exchange, 64% overall.
a Reaction conditions: (a) (COCl)2, CH2Cl2, 50 °C, 3 h; (b) 56, MeCN,
16 h, 88%; (c) H2, Pd/C, 51%; (d) 80% aq TFA, 70%.
the desired product arises from the attenuated electrophilicity
of the N-(morpholinyl)carbonyl group, which favors addition
at the more reactive imide carbonyls.
Enzyme Assay. Enzyme assays were performed at 37 °C with
recombinant MbtA expressed in E. coli in a buffer of 75 mM
Tris-HCl, pH 7.5, 10 mM MgCl2, 2 mM DTT, 250 µM salicylic
acid, 10 mM ATP, and 1 mM PPi.15 The initial rates of
pyrophosphate exchange (e10% reaction) were monitored using
an enzyme concentration (typically 5-10 nM) by measuring
the amount of [32P]ATP formed after addition of [32P]PPi. The
enzyme concentration was determined by active-site titration
with inhibitor 6. The apparent inhibition constants (KIapp) were
determined by fitting the concentration-response plots either
to the Hill equation (eq 1, see Experimental Section) or to the
Morrison equation (eq 2, see Experimental Section). The
Morrison equation was employed in cases where the inhibitors
exhibited tight-binding behavior (KIapp e 100[E]). This class
of inhibitors has been shown to exhibit reversible and competi-
tive inhibition toward MbtA with respect to both salicylic acid
and ATP.15 Attempts to determine the true inhibition constants
(KI) have been hampered by the tight-binding nature of the
inhibitors, which has precluded assessment of the KI by
traditional steady-state kinetic methods.23 The KIapp of the parent
inhibitor 6 is 6.6 nM (measured at 250 µM salicylic acid, 10
mM ATP). If one accounts for the competitive substrate salicylic
acid, which is held at 250 µM or 120KM, then the KI is 55 pM.
However, this analysis still neglects the effect of the nonvaried
substrate ATP, which is held at 10 mM, or 55KM, thus the true
KI for 6 is estimated at approximately 1 pM, a value that has
been independently confirmed by isothermal calorimetry (Daniel
Wilson, Thomas Anderson, unpublished results). All of the KIapp
values reported are uncorrected for substrate concentrations and
represent an upper limit of the true dissociation constant.
Although the KIapp reported herein are not a measure of the true
inhibitor potency, the differences are reflective of free energy
differences associated with inhibitor binding to MbtA, presum-
ing equivalent modalities of inhibition.
On the basis of the above synthetic considerations, morpholine
analogue 26 was successfully prepared by simply interchanging
the electrophile. Thus, treatment of chlorosulfonylisocyanate 51
with morpholine 50 provided chlorosulfonylurea 52 (Scheme
4). This intermediate was not isolated but condensed with 2′,3′-
O-isopropylideneadenosine 53 to afford 54; subsequent ac-
etonide deprotection (80% aq TFA) and ion-exchange to the
sodium salt afforded 26.
Treatment of 5′-O-(sulfamoyl)adenosine derivative 36 with
carbonyl diimidazole afforded [(imidazolyl)carbonyl]sulfamate
55 (Scheme 5). This intermediate was not isolated but treated
with methanol and triethylamine, and subsequent acetonide
deprotection (80% aq TFA) and ion-exchange to the sodium
salt afforded 30.
Bicyclic chromone 58 was prepared as both structural and
modeling studies suggested that the ortho-hydroxy group of 6
internally hydrogen bonds with the sulfamate nitrogen.12,21 This
analogue simultaneously explores modifications to both the aryl
and linker domains of the inhibitor scaffold and was synthesized
from 2′,3′-O-isopropylideneadenosine 53 by interconversion of
the 5′-alcohol to an azide, Boc protection of the N6-amine of
adenine, and hydrogenation to afford 56 (Scheme 6).22 CDI
mediated coupling of chromone-3-carboxylic acid provided 57
that was deprotected with aqueous TFA to furnish 58.
Finally, acylurea analogue 63 was prepared in order to
examine the importance of the sulfonyl group of the linker
domain of 6 (Figure 2). Acylurea 63 was prepared from
2-benzyloxybenzamide 59 by treatment with oxalyl chloride to
provide intermediate acylisocyanate 60 (Scheme 7). After
complete removal of the solvent and excess oxalyl chloride, a
solution of 5-aminoadenosine derivative 56 in acetonitrile was
added to provide 61, which was sequentially deprotected with
aqueous TFA to 62 and hydrogenated to afford acylurea 63.

6084 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
Table 1
a Value ( std error. b Grown in GAST media without added Fe3+ c Grown in GAST media supplemented with Fe3+ d See ref 15.
. .
the DhbE X-ray structure, residues are numbered as in DhbE).
The 2-fluoro analogue, which notably lacks the metabolically
labile phenol function, displayed the smallest destabilization of
binding, consistent with its ability to adopt a coplanar arrange-
ment in quantum calculations. Unfortunately, the bicyclic
chromone analogue 58 that mimics the postulated planar
conformation of 6 was inactive. The related acyclic acylurea
derivative 63 exhibited a profound 329-fold loss in potency
relative to acylsulfamide 64 (Table 2). Modeling suggests that
twisting of the urea functionality of 63 is required for binding,
partially explaining its decreased activity relative to 6. Cycliza-
tion as in 58 imposes even greater energy penalties for this
twisting, which likely explains the further loss of potency of
this compound.
Figure 3. Schematic diagram of key nucleoside/protein interactions
for analogue 6 based on docking.
Aryl Ring SAR Study. To explore the significance of the
ortho-hydroxy group, a systematic series of analogues was
prepared bearing substitution at the 2-position. Several important
trends emerged from this series. Deletion of the hydroxy
afforded benzoyl analogue 7 and resulted in a concomitant 14-
fold loss of binding affinity (Table 1). Substitution of the ortho-
hydroxy group reduced potency in all cases but by widely
varying amounts: by 6-fold for 2-fluoro 9, 117-fold for 2-amino
8, 1100 fold for 2-nitro 11, and 2700-fold for 2-chloro 10.
Docking studies of the parent ligand 6 into a homology model
of MbtA as well as quantum mechanics calculations free from
the constraints of the active site show that 6 adopts a coplanar
conformation that is stabilized by an internal hydrogen bond
where the phenol acts as a hydrogen bond donor to the sulfamate
nitrogen (pKa ∼ 1), which is deprotonated (Figure 3).11 The
X-ray cocrystal structure of DhbE with adenylated 2,3-dihy-
droxybenzoic acid also shows a similar coplanar arrangement.21
Molecular mechanics simulations of 10 and 11 show that the
bulky nitro- and chloro- substituents disfavor the required
coplanar conformation and additionally are unable to form an
internal hydrogen bond. The 117-fold loss of activity when the
aryl hydroxy is replaced by an amino group suggests that the
carboxamide side chain of N235 in MbtA must present the
amino group to the inhibitor (for ease of interpretation using
Analogues 12-14 were prepared to define the steric require-
ments of the shallow binding pocket and to identify potential
sites for further modification. A homology model of MbtA
reveals a shallow hydrophobic binding pocket for salicylic acid
consisting of F236, C240, G307, V329, G331, and L337. The
chlorine atom is isosteric with a methyl group and importantly
can be modified by standard palladium mediated coupling
reactions. The SAR from this chloro-scan showed that substitu-
tion at the 4-position of the aryl ring was most tolerated,
resulting in a modest 2-fold decrease in potency relative to 6
whereas substitution at the 3- and 5-positions reduced inhibitor
potency 3- and 9-fold, respectively (Table 1). Since the optimal
position was found to be the 4-position, several additional
substituents (F, Br, CH3, CF3, and NH2) were examined at this
position. None of the analogues in this series (15-19) exceeded
the potency of 4-Cl 13, and strongly electron-withdrawing
substituents were strongly disfavored. Thus, 4-CF3 18 exhibited
a remarkable 313-fold loss of potency relative to the 4-CH3 17.
Additionally, modeling suggested that a 6-substituent might be
able to accept a poor-geometry hydrogen bond from the

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6085
Table 2
the 2-OH pyridyl 23 suffered a 560-fold loss in potency relative
to 6, a result that can be partially reconciled since 23 exists
exclusively as the keto tautomer. The lack of any apparent trend
with 24 and 25 suggests that multiple effects are responsible
for the observed activity.
In order to explore the tolerance for nonaromatic groups, a
small set of alkyl derivatives 27-29 were prepared. The trend
from this small series shows that larger alkyl substituents led
to an increase activity. This series was not further explored
systematically since the best compound 28 exhibited a 2600-
fold loss in potency relative to 6. In docking studies, all low-
energy conformations of 28 showed unfavorable contacts
between the cyclohexyl hydrogens and residues Phe236 and
Gly331, which are on opposite faces of the aryl binding pocket,
suggesting the pocket is not tall enough to accommodate
saturated ring systems. However, methoxy analogue 30 was
found to exhibit a greater than 40-fold increase in activity
relative to methyl analogue 29, and this unexpected increase in
activity warrants further investigation.
Incorporation of a methylene spacer between the linkage
carbonyl and the phenyl group in benzyl analogue 31 led to
complete loss of activity (>1000-fold decrease in potency
relative to 7). 4-Azido-2,3,5,6-tetrafluorophenyl derivative 32
was prepared as a potential photoaffinity probe, but it was found
to be completely inactive.26 Finally, the phenylalanine derived
inhibitor 33 was evaluated to probe the selectivity of MbtA
toward aminoacyl adenylate inhibitors. Surprisingly, compound
33 exhibited moderate micromolar activity suggesting that the
amino group of 33 is able to favorably interact with MbtA.
a Value ( std error. b Grown in GAST media without added Fe3+
.
c Grown in GAST media supplemented with Fe3+
11.
.
d See ref 15. e See ref
backbone amide of G307. The only 6-substituted compound in
the series, 6-fluorosalicyl 20, showed activity nearly identical
to the parent compound.
Since many siderophores contain an aryl-capped residue
derived from 2,3-dihydroxybenzoic acid, inhibitor 21 was
evaluated against MbtA and found to possess a 20-fold loss in
potency relative to the parent compound 6. Bacillus subtilis uses
the adenylating enzyme DhbE in the synthesis of the 2,3-
dihydroxybenzoic acid-capped siderophore bacillibactin, and
compounds 6 and 21 were shown to possess KIapp values toward
DhbE of 106 and 85 nM respectively; however, this analysis
neglected the tight-binding nature of the inhibitors and thus
underestimated both the inhibitor potency as well as selectiv-
ity.16,24 MbtA shares 42% overall sequence identity to DhbE
but significantly higher homology in the ligand binding site.
Of the 21 residues contacting the adenylate ligand in the X-ray
cocrystal structure of DhbE (within 4 Å), 16 are identical in
MbtA and the remaining 5 residues represent conservative
changes (Y236F, S240C, A308S, V337L, T411S).21 In DhbE,
the 3-hydroxy hydrogen bonds to S240, which is a cysteine in
MbtA and therefore a weaker hydrogen-bonding partner. In
addition, the nearby V337L substitution reduces the space
available for the meta-hydroxyl. Therefore residues S240 and
V337 probably contribute to the specificity differences between
DhbE and MbtA. Bacillus anthracis incorporates native substrate
3,4-dihydroxybenzoic acid to make the siderophore petrobac-
tin.25 Accordingly, compound 22 was prepared to probe the
MbtA active site compatibility for 3,4-dihydroxybenzoic acid.
3,4-Dihydroxybenzoyl analogue 22 was a modest nanomolar
inhibitor of AsbC (IC50 ) 250 nM17), but displayed no activity
toward MbtA, indicating an important active site difference
between the two adenylation enzymes.
Inhibition of M. tuberculosis H37Rv. Compounds 6-33,
58, and 63-64 were evaluated for whole-cell activity against
M. tuberculosis H37Rv under iron-limiting and iron-rich condi-
tions. The minimum inhibitory concentrations (MIC99) that
inhibited >99% of cell growth are shown in Tables 1 and 2.
The MIC99 for 6-8 and 64 have been previously reported under
iron-deficient conditions, but the MIC99 under iron-rich condi-
tions have not yet been disclosed.11 In general, the MIC99 values
were approximately 100-fold greater than the corresponding
KIapp values. The strong correlation between in vitro enzyme
inhibition and whole-cell biological activity provides support
for the designed mechanism of action. 4-Fluorosalicyl derivative
15 displayed the most potent activity with an impressive MIC99
of 0.098 µM under iron-deficient conditions, which is 4-fold
more potent that the parent compound 6. Although the 2-hy-
droxy group is required for optimal activity, the finding that
this can be replaced with a fluoro in analogue 9 and still maintain
respectable biological activity may be useful to increase the
metabolic stability due to potential glucuronidation of the
phenol. Interestingly, chromone derivative 58 displayed modest
activity with a MIC99 of 12.5-25 µM under iron-deficient
conditions despite no apparent enzyme inhibition. However, it
should be recognized that the inhibition studies were conducted
under supersaturating concentrations of substrates, which un-
derestimate compound potency by more than 1000-fold.
Another consideration is inhibitor selectivity since siderophore
production is not essential under iron-rich conditions, suggesting
that activity under iron-rich conditions is due to off-target
binding and subsequent inhibition of alternate biochemical
pathways.14 The parent inhibitor 6 has an MIC99 of 0.39 µM
under iron-deficient conditions and 1.56 µM under iron-rich
conditions. The ratio of MIC99s of iron-rich/iron-deficient
(MIC99Fe+/MIC99Fe-) is a measure of the inhibitor selectivity,
and the selectivity ratio for 6 is only 4. By contrast, the first-
line antitubercular agent isoniazid, which disrupts cell-well
Incorporation of a nitrogen at the 3-position in pyridyl
analogue 23-25 was explored because of the S240C and V337L
substitutions. A nitrogen internal to the aryl ring would avoid
any steric issues present with a 3-hydroxyl group, and molecular
modeling of 24 and 25 showed that C240 can potentially donate
a hydrogen bond to the 3-nitrogen. The carbon to nitrogen
substitutions in 2-Cl pyridyl 25 provided an 103-fold increase
in potency relative to 2-Cl phenyl 10, while 2-F pyridyl 24
decreased activity 76-fold relative to 2-F phenyl 9. Additionally,

6086 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
General Procedure for CDI Mediated Acylation.14,18
A
solution of 34a-j (3.0 mmol, 3.0 equiv) and CDI (3.6 mmol, 3.6
equiv) in DMF (10 mL) was stirred at 60 °C for 2 h. The solution
was cooled to rt, a mixture of either 3611 or 3714 (1.0 mmol, 1.0
equiv) and either DBU or Cs2CO3 (1.5 mmol, 1.5 equiv) was then
added, and the reaction mixture was stirred a further 3 h at rt. The
reaction mixture was concentrated in vacuo and purified by flash
chromatography to afford the title compound.
biosynthesis, was found to be equipotent under iron-rich and
Fe+
Fe-
iron-deficient conditions (MIC99
) MIC99
) 0.19 µM).
p-Aminosalicyl derivative 19 displayed improved selectivity
showing a 16-fold increase in potency under iron-deficient
conditions, suggesting that this modification reduced off-target
binding. Compound 6 was previously shown to exhibit moderate
activity against Yerinia pseudotuberculosis with an MIC99 of
20 µM and >400 µM under iron-deficient and iron-rich
conditions respectively.15 Bioinformatic analysis of M. tuber-
culosis and Y. pseudotuberculosis suggests that the observed
phenotypic difference between these organisms elicited by 6
may be due to the presence of over 30 functionally related fatty
acid adenylating (FadD) enzymes found in M. tuberculosis.27
Many of these FadD enzymes catalyze essential reactions in
the biosynthesis M. tuberculosis lipids and may represent
potential off-target proteins inhibited by this class of adenylation
inhibitors.28
General Procedure for Synthesis of NHS Esters. Method A:
To a solution of carboxylic acid 40a-e and 40j-k, (1.0 mmol,
1.0 equiv) in THF (10 mL) at 0 °C were added N-hydroxysuccin-
imide (1.0 mmol, 1.0 equiv) and DCC (1.0 mmol, 1.0 equiv). The
resulting mixture was stirred for 30 min at 0 °C then 2 h at rt. The
reaction mixture was filtered to remove the DCU precipitate, and
the filtrate was concentrated under reduced pressure. Purification
by flash chromatography afforded the desired N-hydroxysuccin-
imdyl aroyl ester.
Method B: To a solution of acid chloride/anhydride 40f-i (1.0
mmol, 1.0 equiv) in THF (10 mL) at 0 °C were added N-
hydroxysuccinimide (1.0 mmol, 1.0 equiv) and pyridine (1.0 mmol,
1.0 equiv). The resulting mixture was stirred for 30 min at 0 °C
then 2 h at rt. The reaction mixture was filtered, and the filtrate
was concentrated under reduced pressure. The product was used
without further purification.
Conclusion
A series of 5′-O-[(N-acyl)sulfamoyl]adenosines was prepared
and evaluated for inhibition of MbtA and activity against whole-
cell M. tuberculosis under iron-deficient and iron-rich conditions.
A comprehensive and systematic evaluation of the acyl group
revealed that a benzoyl substituent is required for antitubercular
activity and potent enzyme inhibition. Modifications of the
benzoyl group indicated that a hydroxy or fluoro group at C-2
is necessary and that small substituents at C-4 are tolerated.
4-Fluorosalicyl 15 was found to exhibit the most antitubercular
activity, while p-aminosalicyl 19 was the first analogue that
exhibited improved selectivity against M. tuberculosis under
iron-rich conditions. Overall, the collective SAR demonstrated
that the aryl domain is poorly tolerant to modification in accord
with the fairly strict specificity of NRPS adenylation enzymes;
however, minor modifications were found to provide incremental
enhancement in both potency and selectivity of this new class
of adenylation inhibitors.
General Procedure for NHS Ester Mediated Acylation.11,18
To a solution of N-hydroxysuccinimdyl ester 41a-k (1.0 mmol)
in DMF (10 mL) at 0 °C were added 36 or 37 (1.5 mmol, 1.5
equiv) and DBU or Cs2CO3 (2.0 mmol, 2.0 equiv). The reaction
mixture was warmed to rt and stirred 16 h. The reaction was
concentrated under reduced pressure and the residue taken up in
EtOAc and filtered. The solids were washed with additional EtOAc
(100 mL), and the combined filtrate was concentrated. Purification
by flash chromatography (EtOAc/MeOH/Et3N) afforded the title
compound.
General Procedure for TFA Deprotection. To a solution of
5′-O-[N-acyl(sulfamoyl)]-2′,3′-O-isopropylideneadenosine triethy-
lammonium salt (0.2 mmol) was added 80% aq TFA (2.5 mL).
The resulting solution was stirred for 30 min at 0 °C then
concentrated under reduced pressure. Purification by flash chro-
matography (EtOAc/MeOH/Et3N) afforded the title compound.
General Procedure for TBS Deprotection. To a solution of
5′-O-[N-acyl(sulfamoyl)]-2′,3′-O-di-(tert-butyldimethylsilyl)adenos-
ine triethylammonium salt (0.1 mmol, 1 equiv) in THF (5 mL) at
rt was added TBAF (1.0 M in THF, 0.25 mmol, 2.5 equiv). The
reaction mixture was stirred 30 min then concentrated in vacuo.
Purification by flash chromatography (EtOAc/MeOH/Et3N) afforded
the title compound.
General Procedure for Ion-Exchange. A solution of a nucleo-
side tetrabutylammonium or triethylammonium salt (0.25 mmol, 1
equiv) in H2O (0.5 mL) was added to a short column (10 × 50
mm, Dowex 50WX8-100-Na+) and incubated for 10 min before
eluting with H2O (20 mL). The fractions containing the product
were lyophilized to afford the sodium salt as a flocculant white
solid. The Dowex cation exchange resin was converted to the
sodium form by sequentially washing the column with MeOH (50
mL), H2O (50 mL), 1 N aq NaOH (25 mL), and H2O (100 mL).
5′-O-[N-(2-Aminobenzoyl)sulfamoyl]-2′,3′-O-isopropylidene-
adenosine Triethylammonium Salt. To a solution of isatoic
anhydride (47 mg, 0.284 mmol, 1.1 equiv) in DMF (1.0 mL) at rt
was added 36 (100 mg, 0.26 mmol, 1.0 equiv) and Cs2CO3 (169
mg, 0.52 mmol, 2.0 equiv). The reaction was stirred 12 h at rt then
concentrated in vacuo. Purification by flash chromatography (100:
25:1 EtOAc/MeOH/TEA) afforded the title compound (135 mg,
86%). 1H NMR, 13C NMR, and HRMS agreed with literature
values.11 This compound was deprotected as described.11
N-Hydroxysuccinimdyl 2-chlorobenzoate (41a). This was
prepared from 2-chlorobenzoic acid (780 mg, 5.0 mmol) using the
general procedure for NHS ester synthesis. Purification by flash
chromatography (1:1 hexanes/EtOAc) afforded the title compound
(880 mg, 70%): Rf 0.5 (1:1 hexanes/EtOAc); 1H NMR (600 MHz,
CDCl3) δ 2.91 (s, 4H), 7.39 (ddd, J ) 7.8, 6.0, 1.8 Hz, 1H), 7.53-
Experimental Section
General Procedures. All commercial reagents (Sigma-Aldrich,
Acros), 4-bromosalicylic acid (ABCR), and 4-trifluormethylsalicylic
acid (TCI America) were used as provided unless otherwise
indicated. An anhydrous solvent dispensing system (J. C. Meyer)
using two packed columns of neutral alumina was used for drying
THF, Et2O, and CH2Cl2 while two packed columns of molecular
sieves were used to dry DMF, and the solvents were dispensed
under argon. Anhydrous grade DME, MeOH, and MeCN were
purchased from Aldrich. Pyridine was freshly distilled from KOH;
Et3N was distilled from CaH2. Flash chromatography was performed
with Silia P grade silica gel 60 (Silicycle) with the indicated solvent
system. All reactions were performed under an inert atmosphere
of dry Ar or N2 in oven-dried (150 °C) glassware. 1H and 13C NMR
spectra were recorded on a Varian 600 MHz spectrometer. Proton
chemical shifts are reported in ppm from an internal standard of
residual chloroform (7.26 ppm) or methanol (3.31 ppm), and carbon
chemical shifts are reported using an internal standard of residual
chloroform (77.3 ppm) or methanol (49.1 ppm). Proton chemical
data are reported as follows: chemical shift, multiplicity (s )
singlet, d ) doublet, t ) triplet, q ) quartet, p ) pentet, m )
multiplet, br ) broad), coupling constant, integration. High-
resolution mass spectra were obtained on an Agilent TOF II TOF/
MS instrument equipped with either an ESI or APCI interface.
Analytical HPLC were obtained on a Agilent 1100 Series HPLC
system with a PDA detector. Optical rotations were measured on
Rudolph Autopol III polarimeter. Melting points were measured
on electrothermal Mel-Temp manual melting point apparatus and
are uncorrected.

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6087
7.57 (m, 2H), 8.10 (dd, J ) 7.8, 1.8 Hz, 1H); 13C NMR (150 MHz,
CDCl3) δ 25.9, 124.8, 127.1, 131.8, 132.6, 134.8, 135.8, 160.4,
169.2; MS (ESI+) calcd for C11H9ClNO4 [M + H]+ 254.0, found
254.0.
5′-O-[N-(3-Chloro-2-hydroxybenzoyl)sulfamoyl]-2′,3′-O-iso-
propylideneadenosine (38a). This was prepared from 3-chloro-
salicylic acid (170 mg, 1.0 mmol) using the general procedure for
CDI mediated acylation. Purification by flash chromatography (100:
5:1 EtOAc/MeOH/TEA) afforded the title compound (83 mg,
15%): Rf 0.15 (100:5:1 EtOAc/MeOH/TEA); [R]D21 -32.3 (c 2.00,
5′-O-[N-(2-Chlorobenzoyl)sulfamoyl]-2′,3′-O-isopropylidene-
adenosine (42a). This was prepared from 41a (126 mg, 0.50 mmol)
using the general procedure for NHS ester mediated acylation.
Purification by flash chromatography (100:10:1 EtOAc/MeOH/
TEA) afforded the title compound (58 mg, 22%): Rf 0.2 (100:10:1
EtOAc/MeOH/TEA); [R]D21 -102 (c 2.79, MeOH); 1H NMR (600
MHz, CD3OD) δ 1.36 (s, 3H), 1.59 (s, 3H), 4.35 (d, J ) 1.8 Hz,
2H), 4.58 (d, J ) 1.8 Hz, 1H), 5.20 (d, J ) 6.0 Hz, 1H), 5.37 (dd,
J ) 6.0, 3.0 Hz, 1H), 6.24 (d, J ) 3.0 Hz, 1H), 7.24 (t, J ) 7.2
Hz, 1H), 7.28 (t, J ) 7.2 Hz, 1H), 7.33 (d, J ) 7.8 Hz, 1H), 7.46
(d, J ) 7.8 Hz, 1H), 8.18 (s, 1H), 8.46 (s, 1H); 13C NMR (150
MHz, CD3OD) δ 24.4, 26.3, 68.9, 82.1, 84.5, 84.6, 90.7, 114.1,
118.9, 126.4, 128.9, 129.6, 129.8, 130.7, 139.5, 140.3, 149.3, 152.8,
156.1, 174.7; HRMS (APCI+) calcd for C20H22ClN6O7S [M + H]+
525.0959, found 525.0953 (error 1.1 ppm).
1
MeOH); H NMR (600 MHz, CD3OD) δ 1.31 (s, 3H), 1.55 (s,
3H), 4.32-4.34 (m, 2H), 4.54 (br s, 1H), 5.09-5.11 (m, 1H), 5.34
(dd, J ) 6.0, 3.0 Hz, 1H), 6.20 (d, J ) 3.0 Hz, 1H), 6.71 (t, J )
7.8 Hz, 1H), 7.35 (d, J ) 7.8 Hz, 1H), 7.83 (d, J ) 7.8 Hz, 1H),
8.14 (s, 1H), 8.39 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 24.3,
26.2, 68.9, 82.1, 84.5, 84.6, 90.8, 114.1, 118.0, 119.0, 120.8, 121.3,
128.7, 133.3, 140.2, 149.2, 152.7, 156.1, 156.8, 172.9; HRMS
(ESI+) calcd for C20H22ClN6O8S [M + H]+ 541.0903, found
541.0903 (error 0 ppm).
5′-O-[N-(3-Chloro-2-hydroxybenzoyl)sulfamoyl]adenosine Tri-
ethylammonium Salt (12). This was prepared form 38a (30 mg,
0.060 mmol) using the general procedure for TFA deprotection.
Purification by flash chromatography (100:15:1 EtOAc/MeOH/
TEA) afforded the title compound (20 mg, 65%): Rf 0.17 (100:
15:1 EtOAc/MeOH/TEA); [R]D21 -32.8 (c 0.570, MeOH); 1H NMR
(600 MHz, CD3OD) δ 1.28 (t, J ) 7.2 Hz, 9H), 3.18 (q, J ) 7.2
Hz, 6H), 4.34-4.35 (m, 1H), 4.39-4.46 (m, 3H), 4.74 (t, J ) 5.4
Hz, 1H), 6.11 (d, J ) 6.0 Hz, 1H), 6.76 (t, J ) 7.8 Hz, 1H), 7.40
(dd, J ) 7.8, 1.2 Hz, 1H), 7.91 (dd, J ) 7.8, 1.2 Hz, 1H), 8.20 (s,
1H), 8.53 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.1, 46.6, 68.5,
71.1, 74.8, 83.3, 87.9, 117.9, 118.9, 120.9, 121.3, 128.7, 133.1,
139.8, 149.6, 152.6, 156.0, 156.7, 172.6; HRMS (ESI+) calcd for
C17H18ClN6O8S [M + H]+ 501.0595, found 501.0585 (error 2.0
ppm).
5′-O-[N-(2-Chlorobenzoyl)sulfamoyl]adenosine (10). This was
prepared from 42a (29 mg, 0.050 mmol) using the general procedure
for TFA deprotection. Purification by flash chromatography afforded
the title compound (22 mg, 93%): Rf 0.18 (100:15:2 MeOH/EtOAc/
21
1
TEA); [R]D -18.7 (c 0.83, MeOH); H NMR (600 MHz, CD3-
OD) δ 4.37 (br s, 1H), 4.49 (t, J ) 4.8 Hz, 1H), 4.62-4.70 (m,
3H), 6.11 (d, J ) 4.8 Hz, 1H), 7.34-7.37 (m, 1H), 7.44-7.47 (m,
3H), 8.36 (s, 1H), 8.51 (s, 1H); 13C NMR (150 MHz, CD3OD) δ
70.3, 71.5, 74.5, 82.4, 89.3, 119.3, 127.1, 128.9, 130.2, 130.9, 132.4,
133.5, 142.7, 144.3, 148.9, 150.8, 165.7; HRMS (ESI+) calcd for
C17H18ClN6O7S [M + H]+ 485.0641, found 485.0649 (error 0.2
ppm).
5′-O-[N-(4-Chloro-2-hydroxybenzoyl)sulfamoyl]-2′,3′-O-iso-
propylideneadenosine Triethylammonium Salt (38b). This was
prepared from 4-chlorosalicylic acid (43 mg, 0.25 mmol) using the
general procedure for CDI mediated acylation. Purification by flash
chromatography (100:10:1 EtOAc/MeOH/TEA) afforded the title
compound (94 mg, 70%): Rf 0.15 (100:10:1 EtOAc/MeOH/TEA);
N-Hydroxysuccinimdyl 2-Nitrobenzoate (41b). This was pre-
pared from 2-nitrobenzoic acid (835 mg, 5.0 mmol) using the
general procedure for NHS ester synthesis. Purification by flash
chromatography (6:4 hexanes/EtOAc) afforded the title compound
1
(1.10 g, 85%): Rf 0.2 (6:4 hexanes/EtOAc); H NMR (600 MHz,
21
1
[R]D -88.4 (c 1.86, MeOH); H NMR (600 MHz, CD3OD) δ
1.24 (t, J ) 7.8 Hz, 9H), 1.34 (s, 3H), 1.58 (s, 3H), 3.09 (q, J )
7.8 Hz, 6H), 4.29 (dd, J ) 10.8, 4.2 Hz, 1H), 4.32 (dd, J ) 10.8,
3.6 Hz, 1H), 4.53-4.54 (m, 1H), 5.11 (dd, J ) 6.0, 1.8 Hz, 1H),
5.37 (dd, J ) 6.0, 3.0 Hz, 1H), 6.21 (d, J ) 3.0 Hz, 1H), 6.72-
6.80 (m, 2H), 7.83 (d, J ) 9.0 Hz, 1H), 8.14 (s, 1H), 8.41 (s, 1H);
13C NMR (150 MHz, CD3OD) δ 8.3, 24.2, 26.2, 46.6, 68.8, 82.2,
84.51, 84.53, 90.8, 114.1, 115.9, 116.6, 118.3, 118.4, 131.6, 138.3,
140.2, 149.2, 152.8, 156.1, 161.7, 172.6; MS (ESI+) calcd for
C20H22ClN6O8S [M + H]+ 541.09, found 541.08.
CDCl3) δ 2.89 (s, 4H), 7.76-7.79 (m, 2H), 7.92-7.95 (m, 1H),
8.06-8.08 (m, 1H); 13C NMR (150 MHz, CDCl3) δ 25.9, 123.2,
124.8, 130.9, 133.6, 133.7, 147.9, 161.2, 168.7; MS (ESI+) calcd
for C11H9N2O6 [M + H]+ 265.0, found 264.9.
2′,3′-O-Isopropylidene-5′-O-[N-(2-nitrobenzoyl)sulfamoyl]ad-
enosine Triethylammonium Salt (42b). This was prepared from
41b (133 mg, 0.50 mmol) using the general procedure for NHS
ester mediated acylation. Purification by flash chromatography (100:
10:1 EtOAc/MeOH/TEA) afforded the title compound (75 mg,
28%): Rf 0.17 (100:10:1 EtOAc/MeOH/TEA); [R]D21 -142 (c 2.38,
MeOH); 1H NMR (600 MHz, CD3OD) δ 1.23 (t, J ) 7.2 Hz, 9H),
1.36 (s, 3H), 1.59 (s, 3H), 3.13 (q, J ) 7.2 Hz, 6H), 4.32-4.35
(m, 2H), 4.58 (br s, 1H), 5.18 (d, J ) 6.0, 1H), 5.37-5.39 (m,
1H), 6.23 (d, J ) 2.4, 1H), 7.52 (t, J ) 7.2 Hz, 1H), 7.62 (t, J )
8.4 Hz, 1H), 7.66 (d, J ) 7.2 Hz, 1H), 7.82 (d, J ) 8.4 Hz, 1H),
8.18 (s, 1H), 8.45 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.0,
24.4, 26.3, 46.7, 68.8, 82.2, 84.5, 84.6, 90.7, 114.1, 118.9, 123.4,
129.3, 129.7, 132.6, 135.5, 140.2, 148.1, 149.3, 152.8, 156.1, 172.6;
HRMS (ESI+) calcd for C20H22N7O9S [M + H]+ 536.1199, found
536.1201 (error 0.4 ppm).
5′-O-[N-(2-Nitrobenzoyl)sulfamoyl]adenosine Triethylammo-
nium Salt (11). This was prepared from 42b (55 mg, 1.0 mmol)
using the general procedure for TFA deprotection. Purification by
flash chromatography (100:25:2.5 EtOAc/MeOH/TEA) afforded the
title compound (11 mg, 22%): Rf 0.15 (100:25:2.5 EtOAc/MeOH/
TEA); [R]D21 -99.7 (c 0.290, MeOH); 1H NMR (600 MHz, CD3-
OD) δ 1.24 (t, J ) 7.8 Hz, 9H), 3.14 (q, J ) 7.8 Hz, 6H), 4.31-
4.34 (m, 1H), 4.40 (t, J ) 3.6 Hz, 2H), 4.45 (dd, J ) 3.6 Hz, 1H),
4.72 (t, J ) 6.0 Hz, 1H), 6.09 (d, J ) 6.0 Hz, 1H), 7.52 (t, J ) 8.4,
1H), 7.61 (t, J ) 7.2 Hz, 1H), 7.68 (d, J ) 7.2 Hz, 1H), 7.83 (d,
J ) 8.4 Hz, 1H), 8.18 (s, 1H), 8.49 (s, 1H); 13C NMR (150 MHz,
CD3OD) δ 8.0, 46.7, 68.5, 71.3, 74.9, 83.5, 87.9, 118.9, 123.4,
129.3, 129.5, 132.7, 135.7, 139.8, 147.9, 149.7, 152.7, 156.1, 172.7;
HRMS (APCI+) calcd for C17H18N7O9S [M + H]+ 496.0876, found
496.0904 (error 5.6 ppm).
5′-O-[N-(4-Chloro-2-hydroxybenzoyl)sulfamoyl]adenosine Tri-
ethylammonium Salt (13). This was prepared from 38b (35 mg,
0.060 mmol) using the general procedure for TFA deprotection.
Purification by flash chromatography (100:15:1 EtOAc/MeOH/
TEA) afforded the title compound (19 mg, 60%): Rf 0.14 (100:
15:1 EtOAc/MeOH/TEA); [R]D21 -23.3 (c 1.81, MeOH); 1H NMR
(600 MHz, CD3OD) δ 1.24 (t, J ) 7.8 Hz, 9H), 3.13 (q, J ) 7.8
Hz, 6H), 4.30 (dd, J ) 6.6, 3.0 Hz, 1H), 4.34-4.42 (m, 3H), 4.70
(t, J ) 5.4 Hz, 1H), 6.07 (d, J ) 5.4 Hz, 1H), 6.74 (dd, J ) 8.4,
1.2 Hz, 1H), 6.79 (d, J ) 1.2 Hz, 1H), 7.88 (d, J ) 8.4 Hz, 1H),
8.16 (s, 1H), 8.47 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.1,
46.7, 60.3 68.5, 71.2, 74.8, 83.3, 88.1, 116.6, 118.3, 119.0, 131.5,
138.3, 139.9, 149.7, 152.7, 156.1, 161.7, 172.6; HRMS (ESI+)
calcd for C17H18ClN6O8S [M + H]+ 501.0595, found 501.0592
(error 0.6 ppm).
5′-O-[N-(5-Chloro-2-hydroxybenzoyl)sulfamoyl]-2′,3′-O-iso-
propylideneadenosine (38c). This was prepared from 5-chloro-
salicylic acid (86 mg, 0.50 mmol) using the general procedure for
CDI mediated acylation. Purification by flash chromatography (100:
5:1.5 EtOAc/MeOH/TEA) afforded the title compound (33 mg,
21
12%): Rf 0.18 (100:5:1.5 EtOAc/MeOH/TEA); [R]D -96.0 (c
1
1.26, MeOH); H NMR (600 MHz, CD3OD) δ 1.33 (s, 3H), 1.56
(s, 3H), 4.30-4.33 (m, 2H), 4.53 (br s, 1H), 5.10 (d, J ) 6.0 Hz,
1H), 5.35 (dd, J ) 6.0, 2.4 Hz, 1H), 6.19 (d, J ) 2.4 Hz, 1H), 6.75
(d, J ) 8.4 Hz, 1H), 7.22 (dd, J ) 8.4, 2.4 Hz, 1H), 7.84 (d, J )

6088 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
2.4 Hz, 1H), 8.13 (s, 1H), 8.39 (s, 1H); 13C NMR (150 MHz, CD3-
OD) δ 24.2, 26.2, 60.3, 68.9, 82.1, 84.5, 84.6, 90.8, 104.7, 114.1,
118.5, 120.5, 122.7, 129.3, 132.8, 140.2, 152.7, 156.0, 159.5, 172.4;
HRMS (ESI+) calcd for C20H22ClN6O8S [M + H]+ 541.0903,
found 541.0914 (error 2.0 ppm).
1H), 8.51 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 20.7, 68.6,
71.5, 75.2, 83.7, 88.3, 117.1, 119.3, 119.5, 130.4, 140.2, 144.4,
150.0, 152.9, 156.4, 161.1, 174.4 (missing 1 C); HRMS (ESI-)
calcd for C18H19N6O8S [M - H]- 479.0990, found 479.1009 (error
4.0 ppm).
5′-O-[N-(5-Chloro-2-hydroxybenzoyl)sulfamoyl]adenosine Tri-
ethylammonium Salt (14). This was prepared from 38c (28 mg,
0.050 mmol) using the general procedure for TFA deprotection.
Purification by flash chromatography (100:20:1.5 EtOAc/MeOH/
TEA) afforded the title compound (15 mg, 59%): Rf 0.15 (100:
5′-O-[N-(4-Trifluoromethyl-2-hydroxybenzoyl)sulfamoyl]ad-
enosine Sodium Salt (18). This was prepared from 4-trifluoro-
methylsalicylic acid (20.6 mg, 0.10 mmol) using the general
procedure for CDI mediated acylation to afford 38g. The crude
product was used directly for the next step.
21
20:1.5 EtOAc/MeOH/TEA); [R]D -23.3 (c 1.72, MeOH); 1H
Crude 38g prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (80:20:1 EtOAc/MeOH/TEA) followed by conversion to the
sodium salt using the general procedure for ion-exchange afforded
the title compound (27 mg, 48% overall yield): Rf 0.25 (8:2 EtOAc/
MeOH); [R]D21 -0.04 (c 0.25, CH3OH); 1H NMR (600 MHz, CD3-
OD) δ 4.30-4.33 (m, 1H), 4.37-4.45 (m, 3H), 4.70 (t, J ) 5.4
Hz, 1H), 6.09 (d, J ) 6.0 Hz, 1H), 7.02 (d, J ) 7.8 Hz, 1H), 7.04
(s, 1H), 8.08 (d, J ) 7.8 Hz, 1H), 8.17 (s, 1H), 8.51 (s, 1H); 13C
NMR (150 MHz, CD3OD) δ 68.8, 71.5, 75.2, 83.7, 88.3, 114.0,
114.3, 119.3, 123.0, 131.4, 136.3, 140.2, 150.0, 153.0, 156.4, 161.3,
172.5 (missing 1 aryl C and CF3); HRMS (ESI-) calcd for
C18H16F3N6O8S [M - H]- 533.0707, found 533.0714 (error 1.1
ppm).
NMR (600 MHz, CD3OD) δ 1.17 (t, J ) 7.2 Hz, 9H), 2.90 (q, J
) 7.2 Hz, 6H), 4.31-4.42 (m, 4H), 4.68 (t, J ) 5.4 Hz, 1H), 6.06
(d, J ) 5.4 Hz, 1H), 6.76 (d, J ) 8.4 Hz, 1H), 7.22 (d, J ) 8.4 Hz,
1H), 7.87 (s, 1H), 8.15 (s, 1H), 8.44 (s, 1H); 13C NMR (150 MHz,
CD3OD) δ 8.8, 46.3, 60.4, 68.5, 71.1, 74.8, 83.2, 88.3, 116.8, 118.0,
118.4, 120.6, 129.4, 132.8, 139.9, 152.7, 156.1, 159.5, 172.4; HRMS
(ESI+) calcd for C17H18ClN6O8S [M + H]+ 501.0595, found
501.0594 (error 0.2 ppm).
5′-O-[N-(4-Fluoro-2-hydroxybenzoyl)sulfamoyl]adenosine So-
dium Salt (15). This was prepared from 4-fluorosalicylic acid (16
mg, 0.10 mmol) using the general procedure for CDI mediated
acylation to afford 38d. The crude product was used directly for
the next step.
Crude 38d prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (80:20:1 EtOAc/MeOH/TEA) followed by conversion to the
sodium salt using the general procedure for ion-exchange afforded
the title compound (25 mg, 48% overall yield): Rf 0.21 (8:2 EtOAc/
MeOH); [R]D21 -0.05 (c 0.33, CH3OH); 1H NMR (600 MHz, CD3-
OD) δ 4.29-4.31 (m, 1H), 4.35 (dd, J ) 10.8, 3.0 Hz, 1H), 4.38-
4.40 (m, 2H), 4.69 (t, J ) 5.4 Hz, 1H), 6.07 (d, J ) 6.0 Hz, 1H),
6.47-6.50 (m, 2H), 7.94 (t, J ) 7.8 Hz, 1H), 8.15 (s, 1H), 8.49 (s,
1H); 13C NMR (150 MHz, CD3OD) δ 69.5, 72.4, 76.0, 84.6, 89.2,
104.1 (d, JC-F ) 23.4), 106.5 (d, JC-F ) 21.8), 120.1, 133.44,
133.51, 141.1, 150.9, 153.8, 157.2, 164.1, 167.2 (d, JC-F ) 247.8),
174.0; HRMS (ESI-) calcd for C17H16FN6O8S [M - H]- 483.0739,
found 483.0758 (error 3.9 ppm).
5′-O-[N-(4-Bromo-2-hydroxybenzoyl)sulfamoyl]adenosine So-
dium Salt (16). This was prepared from 4-bromosalicylic acid (60
mg, 0.28 mmol) using the general procedure for CDI mediated
acylation to afford 38e. The crude product was used directly for
the next step.
4-Benzyloxycarbonylamino-2-hydroxybenzoic Acid (34h). To
a solution of 4-aminosalicylic acid (2.0 g, 13.1 mmol) in THF (40
mL) was added saturated aq NaHCO3 (40 mL) followed by benzyl
chloroformate (2.04 mL, 14.4 mmol, 1.1 equiv). The reaction was
stirred for 16 h at rt then concentrated to remove THF. The
remaining aqueous layer was acidified with 6 N HCl to pH 3-4
then extracted with EtOAc (3 × 50 mL). The combined organic
layers were dried (Na2SO4) and concentrated to afford the title
compound (2.30 g, 61%) as a light brown solid: 1H NMR (600
MHz, CD3OD) δ 5.17 (s, 2H), 6.91 (dd, J ) 9.0, 1.8 Hz, 1H), 7.14
(d, J ) 1.8 Hz, 1H), 7.29-7.39 (m, 5H), 7.72 (d, J ) 9.0 Hz, 1H),
9.57 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 66.6, 105.2, 107.2,
109.3, 127.9, 128.0, 128.3, 131.1, 136.6, 145.9, 154.0, 163.1, 172.0;
HRMS (ESI-) calcd for C15H12NO5 [M - H]- 286.0721, found
286.0727 (error 2.1 ppm)
2
2
5′-O-[N-(4-Benzyloxycarbonylamino-2-hydroxybenzoyl)sulfa-
moyl]-2′,3′-O-isopropylideneadenosine (38h). This was prepared
from 34h (71 mg, 0.25 mmol) using the general procedure for CDI
mediated acylation. Purification by flash chromatography (100:7
MeOH/EtOAc) afforded the title compound (75 mg, 38%) as a
Crude 38e prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (80:20:1 EtOAc/MeOH/TEA) followed by conversion to the
sodium salt using the general procedure for ion-exchange afforded
the title compound (116 mg, 74% overall yield): Rf 0.23 (8:2
21
white solid: Rf 0.20 (100:7 MeOH/EtOAc); [R]D 86.1 (c 1.29,
1
CH3OH); H NMR (600 MHz, CD3OD) δ 1.32 (s, 3H), 1.56 (s,
3H), 4.30 (t, J ) 4.2 Hz, 2H), 4.54 (br s, 1H), 5.10 (d, J ) 5.4 Hz,
1H), 5.15 (s, 2H), 5.35 (br s, 1H), 6.20 (d, J ) 3.0 Hz, 1H), 6.81
(d, J ) 8.4 Hz, 1H), 7.28 (t, J ) 7.2 Hz, 1H), 7.34 (t, J ) 7.2 Hz,
2H), 7.38 (d, J ) 7.2 Hz, 2H), 7.66 (s, 1H), 7.80 (d, J ) 8.4 Hz,
1H), 8.13 (s, 1H), 8.40 (s, 1H); 13C NMR (150 MHz, CD3OD) δ
24.2, 26.2, 66.4, 68.7, 82.2, 84.5, 90.8, 105.6, 108.8, 114.1, 119.0,
121.4, 127.8, 127.9, 128.3, 130.9, 135.1, 136.8, 140.2, 143.9, 149.2,
152.7, 154.2, 156.1, 161.8, 173.9; HRMS (ESI+) calcd for
C28H30N7O10S [M + H]+ 656.1769, found 656.1707 (error 9.4 ppm).
5′-O-[N-(4-Amino-2-hydroxybenzoyl)sulfamoyl]-2′,3′-O-iso-
propylideneadenosine Triethylammonium Salt (39). To a solution
of compound 38h (120 mg, 0.18 mmol) in MeOH (5 mL) was added
10% Pd/C (12 mg, 10% by wt), and the reaction mixture was stirred
under H2 (1 atm) for 12 h. The reaction mixture was then filtered
through a plug of Celite. Purification by flash chromatography (100:
10:1 MeOH/EtOAc/TEA) afforded the title compound (84 mg,
89%) as a white solid: Rf 0.10 (100:10:1 MeOH/EtOAc/TEA);
[R]D21 -153 (c 1.88, MeOH); 1H NMR (600 MHz, CD3OD) δ 1.18
(t, J ) 7.2 Hz, 9H), 1.33 (s, 3H), 1.58 (s, 3H), 2.97 (q, J ) 7.2 Hz,
6H), 4.27 (d, J ) 3.6 Hz, 2H), 4.55 (br s, 1H), 5.11 (d, J ) 6.0 Hz,
1H), 5.37 (dd, J ) 6.0, 2.4 Hz, 1H), 6.02 (d, J ) 2.4 Hz, 1H), 6.11
(dd, J ) 8.4, 1.8 Hz, 1H), 6.20 (d, J ) 1.8 Hz, 1H), 7.64 (d, J )
8.4 Hz, 1H), 8.15 (s, 1H), 8.48 (s, 1H); 13C NMR (150 MHz, CD3-
OD) δ 8.6, 24.2, 26.2, 46.4, 68.6, 82.3, 84.4, 84.5, 90.8, 100.3,
106.2, 108.9, 114.1, 118.9, 131.5, 131.7, 140.2, 149.3, 152.8, 153.8,
21
1
EtOAc/MeOH); [R]D -0.13 (c 0.53, CH3OH); H NMR (600
MHz, CD3OD) δ 4.31-4.32 (m, 1H), 4.35-4.37 (m, 1H), 4.40-
4.42 (m, 2H), 4.70 (t, J ) 5.4 Hz, 1H), 6.08 (d, J ) 6.0 Hz, 1H),
6.91 (dd, J ) 7.8 Hz, 1.8 Hz, 1H), 6.97 (d, J ) 1.8, 1H), 7.81 (d,
J ) 7.8 Hz, 1H), 8.17 (s, 1H), 8.50 (s, 1H); 13C NMR (150 MHz,
CD3OD) δ 69.7, 72.4, 76.1, 84.6, 89.3, 119.9, 120.2, 120.9, 122.5,
127.8, 132.8, 141.1, 150.9, 153.9, 157.3, 162.9, 174.1; HRMS
(ESI-) calcd for C17H16BrN6O8S [M - H]- 542.9939, found
542.9945 (error 1.1 ppm).
5′-O-[N-(2-Hydroxy-4-methylbenzoyl)sulfamoyl]adenosine So-
dium Salt (17). This was prepared from 4-methylsalicylic acid (76
mg, 0.50 mmol) using the general procedure for CDI mediated
acylation to afford 38f. The crude product was used directly for
the next step.
Crude 38f prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (80:20:1 EtOAc/MeOH/TEA) followed by conversion to the
sodium salt using the general procedure for ion-exchange afforded
the title compound (113 mg, 45% overall yield): Rf 0.20 (8:2
21
1
EtOAc/MeOH); [R]D -0.15 (c 0.56, CH3OH); H NMR (600
MHz, CD3OD) δ 2.27 (s, 3H), 4.31-4.32 (m, 1H), 4.34-4.37 (m,
1H), 4.39-4.42 (m, 2H), 4.71 (t, J ) 5.4 Hz, 1H), 6.08 (d, J ) 6.0
Hz, 1H), 6.59-6.61 (m, 2H), 7.81 (d, J ) 7.8 Hz, 1H), 8.17 (s,

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6089
156.1, 162.7; HRMS (ESI+) calcd for C20H24N7O8S [M + H]+
522.1402, found 522.1385 (error 3.3 ppm).
7.00-7.06 (m, 2H), 7.06-7.10 (m, 1H), 7.14-7.22 (m, 3H), 7.26-
7.36 (m, 3H), 7.38-7.46 (m, 4H), 8.17 (s, 1H), 8.44 (s, 1H); 13C
NMR (150 MHz, CD3OD) δ 10.2, 25.6, 27.5, 47.3, 69.8, 72.0, 76.6,
83.2, 85.6, 85.7, 91.8, 115.2, 116.1, 120.2, 121.8, 125.1, 128.6,
128.9, 129.0, 129.1, 129.5, 129.6, 137.7, 138.5, 139.4, 141.4, 146.8,
150.5, 153.5, 153.9, 157.3, 176.4; HRMS (ESI-) calcd for
C34H33N6O9S [M - H]- 701.2035, found 701.2082 (error 6.7 ppm).
5′-O-[N-(2,3-Dihydroxybenzoyl)sulfamoyl]adenosine Triethy-
lammonium Salt (21). Compound 42c (0.45 g, 0.56 mmol) was
treated with 10% Pd/C (90 mg, 20% by wt) at rt under H2 (1 atm)
in MeOH (20 mL) for 12 h. The reaction mixture was filtered
through Celite and concentrated to afford 43. The crude product
was used directly for the next step.
5′-O-[N-(4-Amino-2-hydroxybenzoyl)sulfamoyl]adenosine (19).
This was prepared from 39 (50 mg, 0.090 mmol) using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (100:30:3 MeOH/EtOAc/TEA) afforded the title compound
(15 mg, 35%) as a white solid: Rf 0.10 (100:30:3 MeOH/EtOAc/
21
1
TEA); [R]D -55.1 (c 3.75, MeOH); H NMR (600 MHz, CD3-
OD) δ 1.18 (t, J ) 7.2 Hz, 9H), 3.17 (q, J ) 7.2 Hz, 6H), 4.29-
4.40 (m, 4H), 4.72 (t, J ) 6.0 Hz, 1H), 6.02 (br s, 1H), 6.08 (d, J
) 6.0 Hz, 1H), 6.10 (d, J ) 9.0 Hz, 1H), 7.66 (d, J ) 9.0 Hz, 1H),
8.16 (s, 1H), 8.50 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.0,
46.4, 68.2, 71.3, 74.9, 83.5, 88.0, 100.3, 106.2, 109.0, 118.9, 131.7,
139.9, 149.7, 152.7, 153.8, 156.1, 162.7, 177.8; HRMS (ESI-)
calcd for C17H18N7O8S [M - H]- 480.0943, found 480.0941 (error
0.4 ppm).
Compound 43 prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (25:75:1 MeOH/EtOAc/ Et3N) afforded the title compound
5′-O-[N-(6-Fluoro-2-hydroxybenzoyl)sulfamoyl]-2′,3′-O-iso-
propylideneadenosine Triethylammonium Salt (38i). This was
prepared from 6-fluorosalicylic acid (70 mg, 0.50 mmol) using the
general procedure for CDI mediated acylation. Purification by flash
chromatography (100:7.5:1 EtOAc/MeOH/TEA) afforded the title
compound (157 mg, 60%): Rf 0.15 (100:7.5:1 EtOAc/MeOH/TEA);
(287 mg, 88%) as a white solid: mp 138-140 °C; Rf 0.2 (1:1
1
MeOH/EtOAc); [R]20 -23.5 (c 0.480, MeOH); H NMR (600
D
MHz, CD3OD) δ 1.24 (t, J ) 7.8 Hz, 9H), 3.12 (q, J ) 7.8 Hz,
6H), 4.26-4.50 (m, 4H), 4.71 (t, J ) 4.8 Hz, 1H), 6.08 (d, J ) 5.4
Hz, 1H), 6.61 (t, J ) 7.8 Hz, 1H), 6.84 (d, J ) 7.8 Hz, 1H), 7.43
(d, J ) 7.8 Hz, 1H), 8.16 (s, 1H), 8.50 (s, 1H); 13C NMR (150
MHz, CD3OD) δ 9.3, 47.8, 69.6, 72.4, 76.0, 84.6, 89.2, 118.6, 119.3,
120.2, 120.9, 121.9, 141.1, 146.1, 146.8, 150.9, 153.9, 157.3, 175.0;
HRMS (ESI+) calcd for C17H19N6O9S [M + H]+ 483.0929, found
483.0917 (error 2.5 ppm).
21
1
[R]D -52.8 (c 0.420, MeOH); H NMR (600 MHz, CD3OD) δ
1.23 (t, J ) 7.2 Hz, 9H), 1.35 (s, 3H), 1.58 (s, 3H), 3.08 (q, J )
7.2 Hz, 6H), 4.31 (dd, J ) 10.8, 4.2 Hz, 1H), 4.35 (dd, J ) 10.8,
4.2 Hz, 1H), 4.54 (dd, J ) 4.2, 1.8 Hz, 1H), 5.14 (dd, J ) 3.0, 1.8
Hz, 1H), 5.37 (dd, J ) 6.0, 3.0 Hz, 1H), 6.22 (d, J ) 3.0 Hz, 1H),
6.44-6.50 (m, 1H), 6.58-6.62 (m, 1H), 7.17-7.22 (m, 1H), 8.15
(s, 1H), 8.42 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.2, 24.3,
26.3, 46.6, 68.9, 82.2, 84.5, 90.8, 106.1 (d, JC-F ) 24 Hz), 111.9,
2′,3′-O,O-Bis(t-butyldimethylsilyl)-5′-O-[N-(2-pyridon-1-yl)-
sulfamoyl]adenosine Triethylammonium Salt (38j). This was
prepared from 2-hydroxynicotinic acid (83 mg, 0.60 mmol) using
the general procedure for CDI mediated acylation. Purification by
flash chromatography (100:10:2 MeOH/EtOAc/TEA) afforded the
title compound (62 mg, 15%): Rf 0.27 (100:10:2 MeOH/EtOAc/
112.6, 114.1, 119.0, 131.8 (d, JC-F ) 11.7 Hz), 132.3 (d, JC-F
)
12.2 Hz), 140.2, 149.3, 152.8, 156.1, 162.0 (d, J ) 131 Hz), 164.2,
170.7 (d, JC-F ) 2.7 Hz); HRMS (ESI+) calcd for C20H22FN6O8S
[M + H]+ 525.1198, found 525.1215 (error 3.2 ppm).
21
1
TEA); [R]D -148 (c 4.20, MeOH); H NMR (600 MHz, CD3-
OD) δ -0.39 (s, 3H), -0.07 (s, 3H), 0.13 (s, 3H), 0.15 (s, 3H),
0.69 (s, 9H), 0.95 (s, 9H), 1.27 (t, J ) 7.2 Hz, 9H), 3.18 (q, J )
7.2 Hz, 6H), 4.31 (br s, 1H), 4.44-4.47 (m, 3H), 4.87 (dd, J )
7.2, 4.8 Hz, 2H), 6.10 (d, J ) 7.2 Hz, 1H), 6.76 (br s, 1H), 7.98
5′-O-[N-(6-Fluoro-2-hydroxybenzoyl)sulfamoyl]adenosine Tri-
ethylammonium Salt (20). This was prepared from 38i (50 mg,
0.10 mmol) using the general procedure for TFA deprotection.
Purification by flash chromatography (100:16:3 EtOAc/MeOH/
TEA) afforded the title compound (36 mg, 76%): Rf 0.09 (100:
16:3 EtOAc/MeOH/TEA); [R]D21 -47.0 (c 0.340, MeOH); 1H NMR
(600 MHz, CD3OD) δ 1.14 (t, J ) 7.2 Hz, 9H), 2.85 (q, J ) 7.2
Hz, 6H), 4.33 (dd, J ) 6.6, 3.0 Hz, 1H), 4.38-4.45 (m, 3H), 4.69
(t, J ) 5.4 Hz, 1H), 6.08 (d, J ) 5.4 Hz, 1H), 6.47 (dd, J ) 11.4,
8.4 Hz, 1H), 6.60 (d, J ) 8.4 Hz, 1H), 7.16-7.21 (m, 1H), 8.15 (s,
1H), 8.41 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.9, 46.2, 68.6,
(br s, 1H), 8.18 (s, 1H), 8.34 (d, J ) 6.0 Hz, 1H), 8.57 (s, 1H); 13
C
NMR (150 MHz, CD3OD) δ -5.1, -4.2, -4.17, -4.11, 9.4, 18.7,
19.0, 26.3, 26.5, 47.8, 69.7, 74.8, 77.5, 86.1, 88.6, 105.9, 114.1
(br), 120.3, 141.6 (br), 142.9, 148.0 (br), 151.1, 154.0, 157.5, 166.0
(br), 172.6; HRMS (ESI-) calcd for C28H44N7O8SSi2 [M - H]-
694.2516, found 694.2548 (error 4.6 ppm).
5′-O-[N-(2-Pyridon-1-yl)sulfamoyl]adenosine Triethylammo-
nium Salt (23). This was prepared from 38j (35 mg, 0.050 mmol)
using the general procedure for TBAF deprotection. Purification
by flash chromatography (90:5:7 MeOH/EtOAc/TEA) afforded the
title compound (6.1 mg, 87%): Rf 0.03 (90:5:7 MeOH/EtOAc/
TEA); [R]D21 -105 (c 0.760, MeOH); 1H NMR (600 MHz, DMSO-
d6) δ 1.15 (t, J ) 6.6 Hz, 9H), 2.95 (q, J ) 6.6 Hz, 6H), 4.11-
4.17 (m, 2H), 4.19 (dd, J ) 7.8, 4.2 Hz, 1H), 4.24 (dd, J ) 10.8,
4.2 Hz, 1H), 4.60 (q, J ) 6.0 Hz, 1H), 5.38 (d, J ) 4.2 Hz, 1H),
5.53 (d, J ) 6.0 Hz, 1H), 5.92 (d, J ) 6.0 Hz, 1H), 6.82 (br s, 1H),
7.31 (br s, 2H), 8.11 (s, 1H), 8.12-8.18 (br m, 1H), 8.39 (s, 1H);
13C NMR (150 MHz, DMSO-d6) δ 9.3, 45.7, 68.3, 70.7, 73.5, 82.4,
86.9, 115.3, 118.9, 139.1 (br), 139.3, 149.6, 151.4 (br), 152.7, 156.1,
165.4, 169.6 (missing one aryl carbon); HRMS (ESI-) calcd for
C16H16N7O8S [M - H]- 466.0787, found 466.0767 (error 4.3 ppm).
N-Hydroxysuccinimdyl 2-Fluoropyridine-3-carboxylate (41d).
This was prepared from 2-fluoronicotinic acid (300 mg, 2.1 mmol)
using the general procedure for NHS ester synthesis. Purification
by flash chromatograpy (1:1 EtOAc/hexane) afforded the title
compound (250 mg, 50%): Rf 0.18 (1:1 EtOAc/hexane); 1H NMR
(600 MHz, CDCl3) δ 2.91 (s, 4H), 7.38 (t, J ) 6.0 Hz, 1H), 8.49-
8.52 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 23.3, 107.0 (d, 2JC-F
71.1, 74.8, 83.2, 88.3, 106.1 (d, JC-F ) 24 Hz), 109.8 (d, JC-F
)
9.0 Hz), 112.7 (d, JC-F ) 3.3 Hz), 119.1, 132.4 (d, JC-F ) 12.3
Hz), 139.9, 149.5, 152.7, 156.1, 162.0 (d, JC-F ) 125 Hz), 164.1,
171.1 (d, J ) 3.3 Hz); HRMS (ESI+) calcd for C17H18FN6O8S [M
+ H]+ 485.0891, found 485.0906 (error 3.1 ppm).
N-Hydroxysuccinimdyl-2,3-dibenzyloxybenzoate (41c). This
was prepared from 2,3-dibenzyloxybenzoic acid29 (1.00 g, 2.99
mmol, 1.0 equiv) using the general procedure for NHS ester
synthesis. Purification by flash chromatography (4:1 EtOAc/
hexanes) afforded the title compound (0.80 g, 62%): Rf 0.85
1
(EtOAc); H NMR (600 MHz, CDCl3) δ 4.49 (m, 4H), 5.13 (s,
4H), 7.12 (t, J ) 8.4 Hz, 1H), 7.20-7.30 (m, 4H), 7.32-7.39 (m,
4H), 7.39-7.44 (m, 3H), 7.85 (dd, J ) 8.4, 1.2 Hz, 1H); 13C NMR
(150 MHz, CDCl3) δ 25.9, 71.6, 76.1, 120.4, 121.3, 123.9, 124.4,
127.8, 128.2, 128.4, 128.5, 128.8, 128.9, 136.5, 137.2, 150.1, 153.2,
160.9, 169.4.
5′-O-[N-(2,3-Dibenzyloxybenzoyl)sulfamoyl]-2′,3′-O-isopropy-
lideneadenosine Triethylammonium Salt (42c). This was prepared
from 41c (837 mg, 1.88 mmol, 2.50 equiv) using the general
procedure for NHS mediated acylation. Purification by flash
chromatography (95:5:1 MeOH/EtOAc/Et3N) afforded the title
4
3
) 25.1 Hz), 119.4 (d, JC-F ) 5.0 Hz), 141.4, 151.4 (d, JC-F
)
3
1
compound (460 mg, 77%): Rf 0.30 (1:5 MeOH/EtOAc); [R]20
15.6 Hz), 155.9 (d, JC-F ) 15.6 Hz), 159.0 (d, JC-F ) 251 Hz),
166.4; HRMS (ESI+) calcd for C10H8FN2O4 [M + H]+ 239.0463,
found 239.0469 (error 2.5 ppm).
D
1
-43.5 (c 0.540, MeOH); H NMR (600 MHz, CD3OD) δ 1.08 (t,
J ) 7.2 Hz, 9H), 1.32 (s, 3H), 1.57 (s, 3H), 2.77 (q, J ) 7.2 Hz,
6H), 4.24 (d, J ) 3.6 Hz, 2H), 4.40-4.48 (m, 1H), 5.04-5.12 (m,
5H), 5.29 (dd, J ) 5.4, 3.0 Hz, 1H), 6.19 (d, J ) 3.0 Hz, 1H),
5′-O-{N-[(2-Fluoropyridin-3-yl)carbonyl]sulfamoyl}-2′,3′-O-
isopropylideneadenosine (42d). This was prepared from 41d (100

6090 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
mg, 0.40 mmol) using the general procedure for NHS ester mediated
acylation. Purification by flash chromatography (1:7 MeOH/EtOAc)
afforded the title compound (58 mg, 27%): Rf 0.17 (1:7 MeOH/
EtOAc); [R]D21 -63.0 (c 2.50, MeOH); 1H NMR (600 MHz, CD3-
OD) δ 1.36 (s, 3H), 1.59 (s, 3H), 4.32 (d, J ) 3.6 Hz, 2H), 4.56-
4.58 (m, 1H), 5.15 (dd, J ) 6.0, 2.4 Hz, 1H), 5.37 (dd, J ) 6.0,
3.0 Hz, 1H), 6.22 (d, J ) 3.0 Hz, 1H), 7.26-7.30 (m, 1H), 8.16 (s,
1H), 8.17-8.23 (m, 2H), 8.45 (s, 1H); 13C NMR (150 MHz, CD3-
OD) δ 24.3, 26.3, 68.7, 82.1, 84.5, 84.6, 90.7, 114.1, 118.9, 121.4,
dropwise to a solution of chlorosulfonyl isocyanate (54 µL, 3.0
mmol, 1.0 equiv) in CH2Cl2 (15 mL) at -20 °C. The reaction
mixture was stirred at -15 °C to -20 °C for 4 h, then the solvent
was evaporated in vacuo, and the crude product 52 was used for
the subsequent step without any further workup.
To the above intermediate 52 was added a solution of 2′,3′-O-
isopropylideneadenosine (155 mg, 2 mmol, 0.66 equiv) and pyridine
(48 µL, 3 mmol, 1 equiv) in MeCN (38 mL). The resulting solution
was stirred at rt for 20 h. The solvent was evaporated in vacuo,
and purification by flash column chromatography (70:30:1 EtOAc/
MeOH/TEA) afforded 2′,3′-O-isopropylidene-5′-O-{N-[(morpholino)-
carbonyl]sulfamoyl}adenosine triethylammonium salt 54 that was
140.2, 142.2, 148.2, 148.3, 149.3, 152.7, 156.1, 170.1 (d, 1JC-F
)
252 Hz), 173.7; HRMS (ESI-) calcd for C19H19FN7O7S [M - H]-
508.1056, found 508.1059 (error 0.6 ppm).
1
5′-O-{N-[(2-Fluoropyridin-3-yl)carbonyl]sulfamoyl}-
adenosine Triethylammonium Salt (24). This was prepared from
42d (30 mg, 0.060 mmol) using the general procedure for TFA
deprotection. Purification by flash chromatography (100:20:1.5
MeOH/EtOAc/TEA) afforded the title compound (14 mg, 50%):
approximately 50-75% pure based on H NMR.
Crude 54 prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash column
chromatography (70:30:1 EtOAc/MeOH/TEA) followed by conver-
sion to the sodium salt using the general procedure for ion-exchange
afforded the title compound (12 mg, 4% overall yield): Rf 0.29
(6:4 EtOAc/MeOH); [R]D21 -0.06 (c 0.22, CH3OH); 1H NMR (600
MHz, CD3OD) δ 3.40-3.60 (m, 4H), 3.58-3.60 (m, 4H), 4.25-
4.30 (m, 3H), 4.41-4.43 (m, 1H), 4.70 (t, J ) 5.4 Hz, 1H), 6.09
(d, J ) 6.0 Hz, 1H), 8.19 (s, 1H), 8.54 (s, 1H); 13C NMR (150
MHz, CD3OD) δ 49.7, 68.1, 68.8, 72.5, 76.3, 85.0, 89.1, 120.2,
141.4, 151.0, 154.0, 157.4, 162.4; HRMS (ESI-) calcd for
C15H20N7O8S [M - H]- 458.1099, found 458.1106 (error 1.4 ppm).
2′,3′-O,O-Bis(t-butyldimethylsilyl)-5′-O-{N-[(cyclopentyl)-
carbonyl]sulfamoyl}adenosine Triethylammonium Salt (42f).
Cyclopentanecarbonyl chloride (920 µL, 7.54 mmol) was converted
to the NHS ester 41f using the general procedure B for NHS ester
synthesis. The crude NHS ester was used directly for the next step.
The title compound was prepared from 41f (126 mg, 0.60 mmol)
using the general procedure for NHS ester mediated acylation.
Purification by flash chromatography (80:20:1 EtOAc/MeOH/TEA)
afforded the title compound (270 mg, 67% overall yield): Rf 0.23
(6:4 EtOAc/MeOH); [R]D21 -64.7 (c 0.34, MeOH); 1H NMR (600
MHz, CD3OD) δ -0.37 (s, 3H), -0.01 (s, 3H), 0.16 (s, 3H); 0.17
(s, 3H), 0.71 (s, 9H), 0.98 (s, 9H), 1.23 (t, J ) 7.2 Hz, 9H), 1.54-
1.57 (m, 2H), 1.70-1.72 (m, 2H), 1.80-1.84 (m, 4H), 2.65 (p, J
) 8.4 Hz, 1H), 3.03 (q, J ) 7.2 Hz, 6H), 4.29-4.34 (m, 3H), 4.45
(d, J ) 4.2 Hz, 1H), 4.84-4.86 (m, 1H, obscured by CD3OD:
assigned by gCOSY as H-2′), 6.12 (d, J ) 7.2 Hz, 1H), 8.18 (s,
1H), 8.57 (s, 1H); 13C NMR (600 MHz, CD3OD) δ -5.2, -4.2,
-4.14 (2C), 9.8, 18.8, 19.0, 26.3, 26.5, 27.1, 31.9, 32.0 47.8, 69.1,
75.4, 77.7, 86.6, 88.3, 120.2, 141.7, 151.2, 154.0, 157.5, 186.9;
MS (ESI-) calcd for C28H49N6O7SSi2 [M - H]- 669.3, found
669.3.
21
Rf 0.17 (100:20:1.5 MeOH/EtOAc/TEA); [R]D -69.6 (c 2.55,
MeOH); 1H NMR (600 MHz, CD3OD) δ 1.24 (t, J ) 7.2 Hz, 9H),
3.13 (q, J ) 7.2 Hz, 6H), 4.31-4.32 (m, 1H), 4.32-4.43 (m, 3H),
4.70 (t, J ) 4.8 Hz, 1H), 6.08 (d, J ) 5.4 Hz, 1H), 7.27-7.29 (m,
1H), 8.16 (s, 1H), 8.18 (d, J ) 4.2 Hz, 1H), 8.24-8.27 (m, 1H),
8.50 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 8.1, 46.5, 68.4, 71.2,
74.8, 83.4, 87.9, 118.9, 121.5 (d, JC-F ) 4.5 Hz), 122.1 (d, JC-F
)
25.7 Hz), 139.9, 142.2 (d, JC-F ) 2.7 Hz), 148.3 (d, JC-F ) 14.0
Hz), 149.6, 152.7, 156.1, 160.6 (d, JC-F ) 243 Hz), 170.1 (d, JC-F
) 6.2 Hz); HRMS (ESI-) calcd for C16H15FN7O7S [M - H]-
468.0743, found 468.0740 (error 0.6 ppm).
N-Hydroxysuccinimdyl 2-Chloropyridine-3-carboxylate (41e).
This was prepared from 2-chloronicotinic acid (780 mg, 5.00 mmol)
using the general procedure for NHS ester synthesis. Purification
by flash chromatography (1:1 EtOAc/hexane) afforded the title
compound (660 mg, 52%): Rf 0.21 (1:1 EtOAc/hexane); 1H NMR
(600 MHz, CDCl3) δ 2.92 (s, 4H), 7.41 (t, J ) 7.8 Hz, 1H), 8.42
(dd, J ) 7.8, 1.8 Hz, 1H), 8.63 (dd, J ) 7.8, 1.8 Hz, 1H); 13C
NMR (150 MHz, CDCl3) δ 25.9, 122.1, 122.4, 141.4, 151.7, 153.9,
159.6, 168.9; HRMS (ESI+) calcd for C10H8ClN2O4 [M + H]+
255.0167, found 255.0163 (error 1.6 ppm).
5′-O-{N-[(2-Chloropyridin-3-yl)carbonyl]sulfamoyl}-2′,3′-O-
isopropylideneadenosine Triethylammonium Salt (42e). This was
prepared from 41e (50 mg, 0.20 mmol) using the general procedure
for NHS mediated acylation. Purification by flash chromatography
(100:10:1 EtOAc/MeOH/TEA) afforded the title compound (86 mg,
21
82%): Rf 0.15 (100:10:1 EtOAc/MeOH/TEA); [R]D -94.3 (c
1
0.340, MeOH); H NMR (600 MHz, CD3OD) δ 1.27 (t, J ) 7.8
Hz, 9H), 1.36 (s, 3H), 1.59 (s, 3H), 3.16 (q, J ) 7.8 Hz, 6H), 4.33-
4.35 (m, 2H), 4.57 (dd, J ) 5.4, 2.4 Hz, 1H), 5.20 (dd, J ) 6.0,
2.4 Hz, 1H), 5.39 (dd, J ) 6.0, 3.0 Hz, 1H), 6.24 (d, J ) 3.0 Hz,
1H), 7.35 (dd, J ) 7.8, 4.8 Hz, 1H), 7.90 (dd, J ) 7.8, 1.8 Hz,
5′-O-{N-[(Cyclopentyl)carbonyl]sulfamoyl}adenosine Sodium
Salt (27). This was prepared from 42f (270 mg, 0.40 mmol) using
the general procedure for TBS protection. Purification by flash
chromatography (80:20:1 EtOAc/MeOH/TEA) followed by conver-
sion to the sodium salt using the general procedure for ion-exchange
afforded the title compound (96 mg, 55%): Rf 0.25 (8:2 EtOAc/
MeOH); [R]D21 -0.23 (c 0.49, CH3OH); 1H NMR (600 MHz, CD3-
OD) δ 1.52-1.54 (m, 2H), 1.66-1.68 (m, 2H), 1.72-1.77 (m, 2H),
1.80-1.83 (m, 2H), 2.63 (p, J ) 8.4 Hz, 1H), 4.24-4.31 (m, 3H),
4.38-4.39 (m, 1H), 4.69 (t, J ) 6.0 Hz, 1H), 6.08 (d, J ) 6.0 Hz,
1H), 8.19 (s, 1H), 8.48 (s, 1H); 13C NMR (150 MHz, CD3OD) δ
27.1, 27.1, 31.3, 31.9, 69.2, 72.5, 76.2, 84.8, 89.3, 120.3, 141.3,
151.0, 154.0, 157.4, 186.3; HRMS (ESI-) calcd for C16H21N6O7S
[M - H]- 441.1197, found 441.1183 (error 3.2 ppm).
1H), 8.19 (s, 1H), 8.32 (dd, J ) 4.8, 1.8 Hz, 1H), 8.45 (s, 1H); 13
C
NMR (150 MHz, CD3OD) δ 8.0, 24.4, 26.3, 46.7, 68.9, 82.1, 84.5,
84.6, 90.7, 114.2, 119.0, 122.7, 136.1, 138.3, 140.2, 147.3, 149.0,
149.3, 152.8, 156.1, 172.3; HRMS (ESI+) calcd for C19H21Cl
N7O7S [M + H]+ 526.0906, found 526.0909 (error 0.6 ppm).
5′-O-{N-[(2-Chloropyridin-3-yl)carbonyl]sulfamoyl}-
adenosine Triethylammonium Salt (25). This was prepared from
42e (40 mg, 0.080 mmol) using the general procedure for TFA
deprotection. Purification by flash chromatography (100:20:1
EtOAc/MeOH/TEA) afforded the title compound (21 mg, 53%):
21
Rf 0.10 (100:20:1 EtOAc/MeOH/TEA); [R]D -64.7 (c 0.340,
MeOH); 1H NMR (600 MHz, CD3OD) δ 1.26 (t, J ) 7.8 Hz, 9H),
3.15 (q, J ) 7.8 Hz, 6H), 4.33 (dd, J ) 6.6, 3.0 Hz, 1H), 4.39-
4.46 (m, 3H), 4.73 (t, J ) 6.0 Hz, 1H), 6.09 (d, J ) 4.8 Hz, 1H),
7.35 (dd, J ) 7.2, 4.2 Hz, 1H), 7.94 (dd, J ) 7.2, 1.8 Hz, 1H),
8.19 (s, 1H), 8.31 (dd, J ) 4.2, 1.8 Hz, 1H), 8.49 (s, 1H); 13C
NMR (150 MHz, CD3OD) δ 8.1, 46.7, 68.5, 71.2, 74.8, 83.4, 88.1,
119.0, 122.6, 136.2, 138.3, 139.9, 147.3, 148.9, 149.7, 152.7, 156.1,
172.4; HRMS (ESI+) calcd for C16H17ClN7O7S [M + H]+
486.0593, found 486.0598 (error 1.0 ppm).
2′,3′-O,O-Bis(t-butyldimethylsilyl)-5′-O-{N-[(cyclohexyl)-
carbonyl]sulfamoyl}adenosine Triethylammonium Salt (42g).
Cyclohexanecarbonyl chloride (930 µL, 6.82 mmol) was converted
to the NHS ester 41g using the general procedure B for NHS ester
synthesis. The crude NHS ester was used directly for the next step.
The title compound was prepared from 41g (88 mg, 0.39 mmol)
using the general procedure for NHS ester mediated acylation.
Purification by flash chromatography (80:20:1 EtOAc/MeOH/TEA)
afforded the title compound (230 mg, 87%): Rf 0.22 (6:4 EtOAc/
MeOH); 1H NMR (600 MHz, CD3OD) δ -0.37 (s, 3H), -0.01 (s,
3H), 0.16 (s, 3H), 0.17 (s, 3H), 0.71 (s, 9H), 0.98 (s, 9H), 1.23 (t,
5′-O-{N-[(Morpholino)carbonyl]sulfamoyl}adenosine Sodium
Salt (26). Morpholine (54 µL, 3.0 mmol, 1.0 equiv) was added

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6091
21
1
J ) 7.2 Hz, 9H), 1.28-1.33 (m, 3H), 1.43-1.46 (m, 2H), 1.65-
1.66 (m, 1H), 1.75-1.76 (m, 2H), 1.86-1.88 (m, 2H), 2.16 (tt, J
) 11.4, 3.0 Hz, 1H), 3.06 (q, J ) 7.2 Hz, 6H), 4.30-4.33 (m,
3H), 4.45 (d, J ) 4.2 Hz, 1H), 4.84-4.86 (m, 1H, obscured by
CD3OD: assigned by gCOSY as H-2′), 6.11 (d, J ) 7.8 Hz, 1H),
8.18 (s, 1H), 8.56 (s, 1H); 13C NMR (150 MHz, CD3OD) δ -5.3,
-4.33, -4.28 (2C), 9.7, 18.6, 18.9, 26.2, 26.4, 27.0, 27.4, 31.25,
31.29, 47.6, 69.0, 74.9, 77.5, 86.4, 88.2, 120.1, 141.5, 151.1, 153.9,
157.3, 185.8; MS (ESI-) calcd for C29H51N6O7SSi2 [M - H]-
683.3, found 683.3.
5′-O-{N-[(Cyclohexyl)carbonyl]sulfamoyl}adenosine Sodium
Salt (28). This was prepared from 42g (230 mg, 0.33 mmol) using
the general procedure for TBS protection. Purification by flash
chromatography (80:20:1 EtOAc/MeOH/TEA) followed by conver-
sion to the sodium salt using the general procedure for ion-exchange
afforded the title compound (82 mg, 51%): Rf 0.22 (8:2 EtOAc/
MeOH); [R]D21 -0.26 (c 0.50, CH3OH); 1H NMR (600 MHz, CD3-
OD) δ 1.17-1.30 (m, 3H), 1.37-1.42 (m, 2H), 1.63-1.65 (m, 1H)
1.73-1.74 (m, 2H), 1.82-1.84 (m, 2H), 2.14 (tt, J ) 11.4, 3.0 Hz,
1H), 4.23-4.30 (m, 3H), 4.37-4.39 (m, 1H), 4.69 (t, J ) 6.0 Hz,
1H), 6.08 (d, J ) 6.0 Hz, 1H), 8.19 (s, 1H), 8.48 (s, 1H); 13C NMR
(150 MHz, CD3OD) δ 27.2, 27.3, 31.27, 31.28, 69.2, 72.6, 76.2,
84.8, 89.3, 120.3, 141.3, 151.0, 153.9, 157.4, 186.4; HRMS (ESI-)
calcd for C17H23N6O7S [M - H]- 455.1354, found 455.1348 (error
1.3 ppm).
Rf 0.20 (7:3 EtOAc/MeOH); [R]D -0.16 (c 0.58, CH3OH); H
NMR (600 MHz, CD3OD) δ 3.56 (s, 3H), 4.23-4.31 (m, 3H),
4.36-4.38 (m, 1H), 4.65 (t, J ) 5.4 Hz, 1H), 6.08 (d, J ) 6.0 Hz,
1H), 8.18 (s, 1H), 8.48 (s, 1H); 13C NMR (150 MHz, CD3OD) δ
51.8, 68.2, 71.4, 75.3, 83.8, 88.3, 119.3, 140.2, 145.0, 153.0, 156.4,
161.2; HRMS (ESI-) calcd for C17H23N6O7S [M - H]- 403.0677,
found 403.0690 (error 3.1 ppm).
5′-O-{N-[(Benzyl)carbonyl]sulfamoyl}adenosine Sodium Salt
(31). Phenylacetic acid (1.00 g, 7.3 mmol) was converted to the
NHS ester 41i using the general procedure A for NHS ester
synthesis. The crude NHS ester was used directly for the next step.
Compound 41i (85 mg, 0.37 mmol) prepared above was treated
with 36 using the general procedure for NHS ester mediated
acylation to afford crude 2′,3′-O,O-bis(t-butyldimethylsilyl)-5′-O-
{N-[(benzyl)carbonyl]sulfamoyl}triethylammonium salt that was
used directly for the next step.
2′,3′-O,O-Bis(t-butyldimethylsilyl)-5′-O-{N-[(benzyl)carbonyl]-
sulfamoyl}triethylammonium salt prepared above was deprotected
using the general procedure for TBS deprotection. Purification by
flash chromatography (75:25:1 EtOAc/MeOH/TEA) followed by
conversion to the sodium salt using the general procedure for ion-
exchange afforded the title compound (110 mg, 65% overall
21
yield): Rf 0.29 (7:3 EtOAc/MeOH); [R]D -0.14 (c 0.43, CH3-
OH); 1H NMR (600 MHz, CD3OD) δ 3.48 (s, 2H), 4.18-4.20 (m,
1H), 4.22-4.26 (m, 2H), 4.29-4.30 (m, 1H), 4.62 (t, J ) 5.4 Hz,
1H), 6.06 (d, J ) 6.0 Hz, 1H), 7.13 (t, J ) 7.2 Hz, 1H), 7.21 (t, J
) 7.8 Hz, 2H), 7.30 (d, J ) 7.8 Hz, 2H), 8.19 (s, 1H), 8.45 (s,
1H); 13C NMR (150 MHz, CD3OD) δ 47.2, 69.3, 72.4, 76.2, 84.6,
89.3, 120.3, 127.3, 129.3, 130.4, 138.5, 141.2, 150.9, 154.0, 157.4,
181.1; HRMS (ESI-) calcd for C18H19N6O7S [M - H]- 463.1041,
found 463.1046 (error 1.1 ppm).
2′,3′-O,O-Bis(t-butyldimethylsilyl)-5′-O-[(N-(acetyl)sulfamoyl]-
adenosine Triethylammonium Salt (42h). Acetic anhydride (920
µL, 9.8 mmol) was converted to the NHS ester 41h using the
general procedure B for NHS ester synthesis. The crude NHS ester
was used directly for the next step.
The title compound was prepared from 41h (96 mg, 0.61 mmol)
using the general procedure for NHS ester mediated acylation.
Purification by flash chromatography (70:30:1 EtOAc/MeOH/TEA)
afforded the title compound (350 mg, 93%): Rf 0.20 (85:15 EtOAc/
MeOH); 1H NMR (600 MHz, CD3OD) δ -0.35 (s, 3H), -0.01 (s,
3H), 0.16 (s, 3H), 0.17 (s, 3H), 0.71 (s, 9H), 0.98 (s, 9H), 1.29 (t,
J ) 7.2 Hz, 9H), 1.96 (s, 3H), 3.17 (q, J ) 7.2 Hz, 6H), 4.46 (d,
J ) 4.2 Hz, 1H), 4.30-4.35 (m, 3H), 4.82-4.84 (1H, m, obscured
by CD3OD: assigned by gCOSY as H-2′), 6.12 (d, J ) 7.2 Hz,
1H), 8.19 (s, 1H), 8.56 (s, 1H); 13C NMR (150 MHz, CD3OD) δ
-5.2, -4.24, -4.20, -4.17, 9.5, 18.8, 19.0, 26.2, 26.3, 26.5, 47.9,
69.2, 74.9, 77.7, 86.4, 88.3, 120.2, 141.6, 151.2, 154.0, 157.5, 180.4;
MS (ESI-) calcd for C24H43N6O7SSi2 [M - H]- 615.2, found
615.2.
5′-O-[N-(4-Azido-2,3,5,6-tetrafluorobenzoyl)sulfamoyl]ad-
enosine Triethylammonium Salt (32). N-Hydroxysuccinimidyl-
4-azidotetrafluorobenzoate26 (235 mg, 1.0 mmol, 1.0 equiv) was
treated with 36 using the general procedure for NHS ester mediated
acylation. Purification by flash column chromatography (80:20:1
EtOAc/MeOH/Et3N) afforded 5′-O-[N-(4-azido-2,3,5,6-tetrafluo-
robenzoyl)sulfamoyl]-2′,3′-O-isopropylideneadenosine triethylam-
monium salt (141 mg, 39%).
5′-O-[N-(4-Azido-2,3,5,6-tetrafluorobenzoyl)sulfamoyl]-2′,3′-O-
isopropylideneadenosine triethylammonium salt (105 mg, 0.2 mmol)
prepared above was deprotected using the general procedure for
TFA deprotection. Purification by flash column chromatography
(80:20:1 EtOAc/MeOH/Et3N) afforded the title compound (62 mg,
21
5′-O-[N-(Acetyl)sulfamoyl]adenosine Sodium Salt (29). This
was prepared from 42h (350 mg, 0.57 mmol) using the general
procedure for TBS protection. Purification by flash chromatography
(80:20:1 EtOAc/MeOH/TEA) followed by conversion to the sodium
salt using the general procedure for ion-exchange afforded the title
47%): Rf 0.29 (8:2 EtOAc/MeOH); [R]D -0.11 (c 0.37, CH3-
OH); H NMR (600 MHz, CD3OD) δ 1.29 (t, J ) 7.8 Hz, 9H),
1
3.21 (q, J ) 7.8 Hz, 6H), 4.32-4.42 (m, 4H), 4.70 (t, J ) 5.4 Hz,
1H), 6.09 (d, J ) 5.4 Hz, 1H), 8.19 (s, 1H), 8.48 (s, 1H); 13C NMR
(150 MHz, CD3OD) δ 9.3, 48.1, 69.9, 72.5, 76.1, 84.7, 89.3, 120.3,
141.2, 151.0, 154.0, 157.4, 166.1 (missing three aryl carbons and
CdO); HRMS (ESI-) calcd for C17H12F4N9O7S [M - H]-
562.0522, found 562.0548 (error 4.6 ppm).
21
compound (148 mg, 74%): Rf 0.26 (7:3 EtOAc/MeOH); [R]D
1
-0.25 (c 0.56, CH3OH); H NMR (600 MHz, CD3OD) δ 1.95 (s,
3H), 4.26-4.33 (m, 3H), 4.38-4.39 (m, 1H), 4.66 (t, J ) 6.0 Hz,
1H), 6.08 (d, J ) 6.0 Hz, 1H), 8.19 (s, 1H), 8.49 (s, 1H); 13C NMR
(150 MHz, CD3OD) δ 26.2, 69.2, 72.4, 76.2, 84.7, 89.3, 120.3,
141.2, 151.0, 154.0, 157.4, 180.8, HRMS (ESI-) calcd for
C16H21N6O7S [M - H]- 387.0728, found 387.0722 (error 1.5 ppm).
5′-O-{N-[(Methoxy)carbonyl]sulfamoyl}adenosine Sodium Salt
(30). A solution of 36 (80 mg, 0.2 mmol, 1.0 equiv) and CDI (65
mg, 0.4 mmol, 2 equiv) in MeCN (10 mL) was stirred at rt for 2
h. Next, MeOH (3 mL) and Et3N (55 µL, 0.4 mmol, 2.0 equiv)
were added, and the reaction mixture was stirred for an additional
2 h and then concentrated in vacuo. Purification by flash column
chromatography (80:20:1 EtOAc/MeOH/Et3N) afforded 2′,3′-O-
isopropylidene-5′-O-{N-[(methoxy)carbonyl]sulfamoyl}-
adenosine triethylammonium salt.
2′,3′-O-Isopropylidene-5′-O-{N-[(methoxy)carbonyl]sulfamoyl}-
adenosine triethylammonium salt prepared above was deprotected
using the general procedure for TFA deprotection. Purification by
flash chromatography (70:30:1 EtOAc/MeOH/TEA) followed by
conversion to the sodium salt using the general procedure for ion-
exchange afforded the title compound (84 mg, 64% overall yield):
N-Hydroxysuccinimdyl N-(t-Butyloxycarbonyl)-L-phenylala-
nine (41k). This was prepared from N-(t-butyloxycarbonyl)-L-
phenylalanine (795 mg, 3.00 mmol) using the general procedure
for NHS ester synthesis. Purification by flash chromatography (2:5
EtOAc/hexane) afforded the title compound (800 mg, 74%): Rf
0.33 (3:1 hexane/EtOAc); [R]D21 -37.1 (c 0.730, MeOH); 1H NMR
(600 MHz, CDCl3) δ 1.39 (s, 9H), 2.84 (s, 4H), 3.18 (dd, J )
13.2, 5.4 Hz, 1H), 3.30 (dd, J ) 13.2, 5.4 Hz, 1H), 4.90 (t, J ) 5.4
Hz, 1H), 7.25-7.33 (m, 5H); 13C NMR (150 MHz, CDCl3) δ 25.8,
28.2, 38.4, 52.8, 80.8, 127.6, 128.9, 129.9, 134.9, 154.8, 167.9,
168.7; MS (ESI+) C13H15N2O4 [M + H] calcd 263.1, found 263.1.
5′-O-{N-[N-(t-Butyloxycarbonyl)-L-phenylalanyl]sulfamoyl}-
2′,3′-O-isopropylideneadenosine (42k). This was prepared from
41k (363 mg, 1.00 mmol) using the general procedure for NHS
mediated acylation. Purification by flash chromatography (100:10:1
EtOAc/MeOH/TEA) afforded the title compound (600 mg, 95%):
21
1
Rf 0.16 (10:1 EtOAc/MeOH); [R]D -19.1 (c 1.00, MeOH); H
NMR (600 MHz, CD3OD) δ 1.33 (s, 9H), 1.36 (s, 3H), 1.58 (s,
3H), 2.84 (dd, J ) 13.2, 9.0 Hz, 1H), 3.10 (dd, J ) 13.2, 4.8 Hz,

6092 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
Qiao et al.
1H), 4.16-4.23 (m, 3H), 4.47-4.51 (m, 1H), 5.06 (d, J ) 6.0 Hz,
1H), 5.32 (br s, 1H), 6.21 (br s, 1H), 7.11-7.22 (m, 5H), 8.19 (s,
1H), 8.41 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 25.1, 26.3,
27.5, 57.9, 80.5, 82.0, 84.4, 84.6, 85.3, 85.9, 90.7, 92.3, 114.1,
118.9, 126.2, 128.1, 129.4, 139.4, 140.3, 149.1, 149.3, 152.7, 156.0;
HRMS (ESI+) calcd for C27H36N7O9S [M]+ 634.2295, found
634.2309 (error 3.0 ppm).
5′-Amino-N6-t-butoxycarbonyl-5′-deoxy-2′,3′-O-isopropylide-
neadenosine (56). To a solution of 5′-azido-N6-tert-butoxycarbonyl-
5′-deoxy-2′,3′-O-isopropylideneadenosine (150 mg, 0.35 mmol, 1.0
equiv) in MeOH (5.0 mL) was added 10% Pd/C (10 mg, 7% by
wt) in MeOH (0.5 mL), and the reaction mixture was stirred under
H2 (2.5 atm) for 12 h. The reaction mixture was then filtered through
a plug of Celite. Purification by flash chromatography (100:17:1
EtOAc/MeOH/TEA) afforded the title compound 132 mg, 94%).
1H NMR, 13C NMR, and HRMS agreed with literature values.11
5′-Amino-5′-N-[(chromon-3-yl)carbonyl]adenosine (58). A
solution of chromone 3-carboxylic acid (74 mg, 0.39 mmol) and
CDI (63.3 mg, 0.39 mmol, 1.0 equiv) in DMF (6 mL) was stirred
at 60 °C for 2 h. The solution was cooled to rt, a mixture of 56
(100 mg, 0.32 mmol, 0.8 equiv) and DBU (92 µL, 0.62 mmol, 1.5
equiv) were then added, and the reaction mixture was stirred
overnight at rt. The reaction mixture was then concentrated in vacuo
and purified by flash chromatography to afford 57. The crude
product was used directly for the next step.
5′-O-[N-(L-Phenylalanyl)sulfamoyl]adenosine Sodium Salt
(33). This was prepared from 42k (200 mg, 0.32 mmol) using the
general procedure for TFA deprotection. Purification by HPLC
(Microsorb C18 Dynamax preparative HPLC column, 41.4 × 250
mm, pore size 100 Å, 20-80% A in 45 min, A ) 40 mM TEAB
buffer, B ) 70% CH3CN in H2O, flow rate ) 40 mL/min,
monitored at 254 nm) and lypholization of the pooled fractions
followed by conversion to the sodium salt using the general
procedure for ion-exchange afforded the title compound (90 mg,
58%): tR ) 12.7 min; [R]D21 -7.5 (c 0.74, MeOH); 1H NMR (600
MHz, CD3OD) δ 2.87 (dd, J ) 13.2, 5.4 Hz, 1H), 3.17 (dd, J )
13.2, 5.4 Hz 1H), 3.64 (t, J ) 6.6 Hz, 1H), 4.22-4.29 (m, 3H),
4.36 (t, J ) 4. 2 Hz, 1H), 4.62 (t, J ) 4.8 Hz, 1H), 6.07 (d, J ) 5.4
Hz, 1H), 7.13-7.15 (m, 1H), 7.22-7.25 (m, 4H), 8.18 (s, 1H),
8.50 (s, 1H); 13C NMR (150 MHz, CD3OD) δ 41.6, 58.5, 67.9,
70.9, 75.1, 83.2, 88.3, 119.0, 126.2, 128.2, 129.3, 138.4, 140.1,
149.6, 152.7, 156.1, 181.6 (missing 2C’s); HRMS (ESI+) calcd
for C19H24N7O7S [M + H]+ 494.1458 found 494.1489 (error 0.6
ppm).
Crude 57 prepared above was deprotected using the general
procedure for TFA deprotection. Purification by flash chromatog-
raphy (60:40 EtOAc/MeOH) afforded the title compound (29 mg,
21
20% overall yield): Rf 0.22 (7:3 EtOAc/MeOH); [R]D -31.7 (c
0.11, MeOH); 1H NMR (600 MHz, DMSO) δ 3.97 (br s, 1H), 4.08
(dd, J ) 5.4, 4.8 Hz, 1H), 4.16 (dd, J ) 6.6, 3.6 Hz, 1H), 4.22 (br
s, 1H), 4.67-4.71 (m, 1H), 5.43 (br s, 1H), 5.57 (br s, 1H), 5.92
(d, J ) 6.0 Hz, 1H), 7.26-7.30 (m, 4H), 7.63 (t, J ) 7.8 Hz, 1H),
7.88 (t, J ) 7.8 Hz, 1H), 8.10 (br s, 1H), 8.33 (s, 1H), 8.43-8.45
(m, 1H), 10.39 (br s, 1H); 13C NMR (150 MHz, DMSO) δ 51.7,
70.8, 72.7, 82.1, 87.7, 96.0, 116.9, 119.3, 120.2, 123.9, 125.3, 134.3,
139.9, 149.3, 152.6, 154.2, 156.1, 162.6, 163.2, 179.4; MS (APCI-)
calcd for C20H18N6O6 [M - H]- 437.1215, found 437.1378.
5′-O-[N-(3-{[(Morpholino)carbonyl]amino}propanoyl)-
sulfamoyl]adenosine Sodium Salt (47). Morpholinocarbonyl
chloride (0.77 mg, 6.7 mmol) was converted to the NHS ester 44
using the general procedure B for NHS ester synthesis. The crude
NHS ester was used directly for the next step.
Compound 44 (82 mg, 0.36 mmol) prepared above was treated
with 37 using the general procedure for NHS mediated acylation.
The crude product 46 was used directly for the next step.
2-Benzyloxybenzamide (59). To a solution of 2-hydroxyben-
zamide (2.74 g, 20 mmol, 1.0 equiv) and K2CO3 (3.30 g, 24 mmol,
1.2 equiv) in acetone (100 mL) was added benzyl bromide (2.80
mL, 24 mmol, 1.2 equiv), and the reaction mixture was heated at
reflux for 16 h. After cooling to rt, the solution was filtered and
the filtrate was concentrated under reduced pressure. The crude
solid was recrystallized from acetone to afford the title compound
(2.89 g, 62%) as a white solid: 1H NMR (CDCl3, 600 MHz) δ
5.19 (s, 2H), 5.92 (br s, 1H), 7.05 (d, J ) 8.4 Hz, 1H), 7.09 (t, J
) 8.4 Hz, 1H), 7.36-7.48 (m, 6H), 7.73 (br s, 1H), 8.23 (d, J )
7.8 Hz, 1H); 13C NMR (CDCl3, 150 MHz) δ 71.5, 112.9, 121.3,
121.8, 128.1, 129.0, 129.2, 132.9, 133.6, 135.8, 157.4, 167.2; HRMS
(APCI+) calcd for C14H14NO2 [M + H]+ 228.1019, found 228.1042
(error 10.0 ppm).
5′-Amino-5′-N-{[(2-benzyloxybenzoyl)amino]carbonyl}-N6-t-
butoxycarbonyl-5′-deoxy-2′,3′-O-isopropylideneadenosine (61).
To a stirred solution of 59 (114 mg, 0.50 mmol, 1.0 equiv) in CH2-
Cl2 (20 mL) was added oxalyl chloride (129 µL, 1.5 mmol, 3 equiv)
dropwise at rt. The solution was then heated at 50 °C for 3 h. After
cooling to rt, the reaction mixture was concentrated in vacuo to
afford a light yellow solid. Next, a solution of 56 (244 mg, 0.6
mmol, 1.2 equiv) in CH3CN (10 mL) was added, and the resulting
mixture was stirred for 16 h at rt. The crude reaction was
concentrated in vacuo, and the residue was partitioned between CH2-
Cl2 (25 mL) and H2O (25 mL). The aqueous layer was extracted
with CH2Cl2 (2 × 25 mL). The combined organic extracts were
dried (Na2SO4) and concentrated under reduced pressure. Purifica-
tion by flash chromatography (7:3 EtOAc/hexane) afforded the title
compound (290 mg, 88%) as a white solid: Rf 0.10 (6:4 EtOAc/
hexane); 1H NMR (CDCl3, 600 MHz) δ 1.35 (s, 3H), 1.54 (s, 9H),
1.59 (s, 3H), 3.64-3.71 (m, 2H), 4.41-4.44 (m, 1H), 4.99 (dd, J
) 6.0, 3.6 Hz, 1H), 5.28 (s, 2H), 5.37 (dd, J ) 6.0, 3.0 Hz, 1H),
6.12 (d, J ) 3.0 Hz, 1H), 7.05 (d, J ) 8.4 Hz, 1H), 7.10 (t, J ) 7.8
Hz, 1H), 7.35-7.37 (m, 1H), 7.40-7.43 (m, 4H), 7.48 (dt, J )
8.4, 1.2 Hz, 1H), 8.05 (br s, 1H, NH), 8.12 (dd, J ) 7.8, 1.2 Hz,
1H), 8.18 (s, 1H), 8.74 (s, 1H), 8.85 (t, J ) 6.0 Hz, 1H, NH), 9.97
(s, 1H, NH); 13C NMR (CDCl3, 150 MHz) δ 25.7, 27.5, 28.3, 41.5,
71.8, 81.9, 82.5, 84.2, 85.3, 90.4, 113.5, 115.2, 119.9, 122.1, 122.3,
127.7, 129.1, 129.2, 132.9, 134.9, 135.0, 141.7, 149.7, 150.2, 150.7,
Compound 46 prepared above was deprotected using the general
procedure for TBS deprotection. Purification by flash chromatog-
raphy (70:30:1 EtOAc/MeOH/TEA) followed by conversion to the
sodium salt using the general procedure for ion-exchange afforded
the title compound (107 mg, 56% overall yield): Rf 0.21 (6:4
21
1
EtOAc/MeOH); [R]D -0.08 (c 0.42, CH3OH); H NMR (600
MHz, CD3OD) δ 2.40 (t, J ) 6.6 Hz, 2H), 3.29 (t, J ) 4.8 Hz,
4H), 3.42 (t, J ) 6.6 Hz, 2H), 3.58 (t, J ) 4.8 Hz, 4H), 4.27-4.33
(m, 3H), 4.39 (t, J ) 4.2 Hz, 1H), 4.66 (t, J ) 5.4 Hz, 1H), 6.08
(d, J ) 5.4 Hz, 1H), 8.20 (s, 1H), 8.51 (s, 1H), 13C NMR (150
MHz, CD3OD) δ 38.8, 40.3, 45.2, 67.7, 69.2, 72.4, 76.3, 84.6, 89.4,
120.3, 141.3, 150.9, 154.0, 157.4, 160.2, 181.4; HRMS (ESI-)
calcd for C18H25N8O9S [M - H]- 529.1470, found 529.1489 (error
3.5 ppm).
5′-Azido-N6-butyloxylcarbonyl-5′-deoxy-2′,3′-O-isopropylide-
neadenosine. To a solution of 5′-azido-5′-deoxy-2′,3′-O-isopropy-
lideneadenosine22 (146 mg, 0.44 mmol, 1.0 equiv) in THF/DMF
(4:1, 10 mL) was added sodium hydride (60% dispension in mineral
oil, 20 mg, 0.5 mmol, 1.15 equiv) at rt. The resulting solution was
stirred for 30 min, and then solid di-tert-butyl dicarbonate (106
mg, 0.48 mmol, 1.1 equiv) was added in one portion. The reaction
was monitored by TLC until complete consumption of the amine
was observed (3 h). The solution was diluted with CH2Cl2 (20 mL)
and washed with saturated aq NaHCO3 (20 mL). The aqueous phase
was back-extracted with CH2Cl2 (2 × 10 mL), and the combined
organic phase was washed with H2O (20 mL) and saturated aq NaCl
(30 mL), dried (Na2SO4), and concentrated. Purification by flash
chromatography (4:6 hexane/EtOAc) afforded the title compound
(144 mg, 60%): Rf 0.55 (1:2 hexane/EtOAc); [R]D21 -33.1 (c 0.972,
CH3OH); 1H NMR (600 MHz, CDCl3) δ 1.35 (s, 3H), 1.53 (s, 9H),
1.58 (s, 3H), 3.54 (d, J ) 5.4 Hz, 2H), 4.36 (dd, J ) 3.6, 5.4 Hz,
1H), 5.01 (dd, J ) 6.6, 3.6 Hz, 1H), 5.42 (dd, J ) 6.6, 2.4 Hz,
1H), 6.13 (d, J ) 2.4 Hz, 1H), 8.09 (s, 1H), 8.74 (s, 1H); 13C NMR
(150 MHz, CDCl3) δ 25.5, 27.3, 28.3, 52.4, 82.0, 82.6, 84.2, 85.8,
90.9, 115.1, 122.3, 141.8, 149.8, 150.3, 150.4, 153.2; MS (APCI+)
calcd for C18H25O5N8 [M + H]+ 433.2, found 433.2.

5′-O-[(N-Acyl)sulfamoyl]adenosines
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24 6093
153.4, 153.9, 157.2, 165.9; HRMS (ESI+) calcd for C33H38N7O8
[M + H]+ 660.2776, found 660.2667 (error 16.5 ppm).
µL/well), and growth was recorded by measurement of optical
density at 620 nm.
5′-Amino-5′-N-{[(2-benzyloxybenzoyl)amino]carbonyl}-5′-
deoxyadenosine (62). This was prepared from 61 (100 mg, 0.15
mmol) using the general procedure for TFA deprotection. Purifica-
tion by flash chromatography (500:3 EtOAc/MeOH) afforded the
Docking Studies. The homology model and docking runs were
configured as described,12 except that the side chains of
residues 235, 240, 329, and 337 were allowed to move along with
the ligand.
1
title compound (55 mg, 70%): Rf 0.3 (500:3 EtOAc/MeOH); H
NMR (CD3OD, 600 MHz) δ 3.64 (dt, J ) 14.4, 4.8 Hz, 1H), 3.76
(dt, J ) 14.4, 6.0 Hz, 1H), 4.18 (q, J ) 4.8 Hz, 1H), 4.40 (t, J )
5.4 Hz, 1H), 4.72 (t, J ) 5.4 Hz, 1H), 5.31 (s, 2H), 5.99 (d, J )
5.4 Hz, 1H), 7.09 (t, J ) 7.8 Hz, 1H), 7.24 (d, J ) 8.4 Hz, 1H),
7.30 (t, J ) 7.2 Hz, 1H), 7.36 (t, J ) 7.8 Hz, 2H), 7.46 (d, J ) 7.8
Hz, 2H), 7.54 (t, J ) 7.2 Hz, 1H), 7.91 (d, J ) 7.8 Hz, 1H), 8.15
(s, 1H), 8.29 (s, 1H), 8.96 (br t, J ) 6.0 Hz, 1H, 5′-NH); 13C NMR
(CD3OD, 150 MHz) δ 40.7, 71.2, 71.4, 74.0, 83.2, 89.2, 113.8,
119.4, 120.5, 121.5, 127.6, 128.3, 128.7, 131.6, 134.6, 135.8,
140.7, 149.4, 151.8, 154.7, 155.5, 157.2, 166.6; HRMS (ESI-)
calcd for C25H24N7O6 [M - H]- 518.1794, found 518.1795 (error
0.1 ppm).
Acknowledgment. This research is supported by a grant
from the NIH (R01AI070219) and funding from the Center for
Drug Design in the Academic Health Center of the University
of Minnesota to C.C.A. We thank the Minnesota Supercom-
puting Institute VWL lab for computer time.
Supporting Information Available: Table of HPLC purities
of the inhibitors disclosed herein. This material is available free of
charge via the Internet at http://pubs.acs.org.
References
5′-Amino-5′-deoxy-5′-N-{[(2-hydroxybenzoyl)amino]carbonyl}-
adenosine (63). To a solution of 62 (50 mg, 0.096 mmol) in MeOH
(10 mL) was added 10% Pd/C (10 mg, 20% by wt), and the reaction
mixture was stirred at rt under H2 (1 atm). After 2 h, the reaction
mixture was filtered through Celite, and the filtrate was concentrated
under reduced pressure. Purification by flash chromatography (10:2
EtOAc/MeOH) afforded the title compound (21 mg, 51%): Rf 0.12
(100:20 EtOAc/MeOH); 1H NMR (CD3OD, 600 MHz) δ 3.66 (dd,
J ) 14.4, 4.2 Hz, 1H), 3.80 (dd, J ) 14.4 Hz, 4.8 Hz, 1H), 4.20
(q, J ) 4.8 Hz, 1H), 4.42 (t, J ) 4.8 Hz, 1H), 4.74 (t, J ) 4.8 Hz,
1H), 6.00 (d, J ) 4.8 Hz, 1H), 6.90 (ovlp t, J ) 7.8 Hz, 1H), 6.91
(ovlp d, J ) 7.8 Hz, 1H), 7.40 (t, J ) 7.8 Hz, 1H), 7.91 (d, J ) 7.8
Hz, 1H), 8.16 (s, 1H), 8.32 (s, 1H); 13C NMR (CD3OD, 150 MHz)
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(ESI-) calcd for C18H18N7O6 [M - H]- 428.1324, found 428.1327
(error 0.7 ppm).
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6094 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 24
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