Mapping pilicide anti-virulence effect in Escherichia coli, a comprehensive structure-activity study

Article abstract of DOI:10.1016/j.bmc.2012.01.048

Pilicides prevent pili formation and thereby the development of bacterial biofilms in Escherichia coli. We have performed a comprehensive structure activity relationship (SAR) study of the dihydrothiazolo ring-fused 2-pyridone pilicide central fragment by varying all open positions. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) was used to distinguish active from inactive compounds in which polarity proved to be the most important factor for discrimination. A quantitative SAR (QSAR) partial least squares (PLS) model was calculated on the active compounds for prediction of biofilm inhibition activity. In this model, compounds with high inhibitory activity were generally larger, more lipophilic, more flexible and had a lower HOMO. Overall, this resulted in both highly valuable SAR information and potent inhibitors of type 1 pili dependent biofilm formation. The most potent biofilm inhibitor had an EC₅₀ of 400 nM.

Full text of DOI:10.1016/j.bmc.2012.01.048

Bioorganic & Medicinal Chemistry 20 (2012) 3128–3142
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Mapping pilicide anti-virulence effect in Escherichia coli, a comprehensive
structure–activity study
Erik Chorell a,b, Jerome S. Pinkner b, Christoffer Bengtsson a, Thomas Sainte-Luce Banchelin a,c
,
a,c,
Sofie Edvinsson a, Anna Linusson a, Scott J. Hultgren b, , Fredrik Almqvist
⇑
⇑
a Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
b Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110, USA
c Umeå Centre for Microbial Research, Umeå University, SE-90187 Umeå, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Pilicides prevent pili formation and thereby the development of bacterial biofilms in Escherichia coli. We
have performed a comprehensive structure activity relationship (SAR) study of the dihydrothiazolo ring-
fused 2-pyridone pilicide central fragment by varying all open positions. Orthogonal projections to latent
structures discriminant analysis (OPLS-DA) was used to distinguish active from inactive compounds in
which polarity proved to be the most important factor for discrimination. A quantitative SAR (QSAR) par-
tial least squares (PLS) model was calculated on the active compounds for prediction of biofilm inhibition
activity. In this model, compounds with high inhibitory activity were generally larger, more lipophilic,
more flexible and had a lower HOMO. Overall, this resulted in both highly valuable SAR information
and potent inhibitors of type 1 pili dependent biofilm formation. The most potent biofilm inhibitor
had an EC50 of 400 nM.
Received 25 October 2011
Revised 20 January 2012
Accepted 25 January 2012
Available online 4 February 2012
Keywords:
Pilicide
Antivirulence
2-Pyridone
Peptidomimetic
Structure–activity
Biofilm inhibitor
Ó 2012 Published by Elsevier Ltd.
1. Introduction
important role in human cystitis,7 and it has been reported that
type
1 pili fulfill ‘Molecular Koch’s postulates’ of microbial
The discovery of compounds with antimicrobial activity in the
1940s resulted in tremendous advances for humanity. However,
the reduced efforts put into antibacterial research in combination
with the increasing development of bacterial resistance have re-
sulted in the re-emergence of bacterial diseases as a global health
problem. Therefore, the development of new antibacterial targets
and strategies, especially those directed towards Gram-negative
bacteria, is of great importance.1
pathogenesis.8
Biofilm formation is a severe complicating factor in bacterial
infections due to the increased resistance of bacteria within bio-
films to immune- or drug-mediated clearance, leading to persis-
tent, drug-tolerant infections.9–11 Thus, biofilms exacerbate
bacterial infections, such as urinary tract infection (UTI), causing
significant human morbidity and mortality and billions of dollars
in health care expenditures.12
Bacterial pathogens have an arsenal of virulence factors that are
critical in promoting host–pathogen interactions. One such factor is
type 1 pili, assembled by the chaperone/usher pathway (CUP),
which constitute a critical virulence factor in uropathogenic Esche-
richia coli (UPEC).2 Type 1 pili facilitate the attachment to and
invasion of the bladder epithelium and is important for IBC forma-
tion.3–6 In addition, recent studies concluded that type 1 pili play an
Type 1 pili and other CUP pili are promising targets of anti-vir-
ulence therapeutics as they are critical factors for binding and
invading the bladder tissue and forming biofilms.13,14
Pilicides are a class of small molecular weight compounds that
prevent formation of pili in UPEC.15–17 The assembly proteins of
the CUP pilus systems have a high degree of structural conservation
and compounds that target pili formation can thus potentially have
broad-spectrum activity.18 The pilicide core structure (5) is based
on a dihydrothiazolo ring-fused 2-pyridone that can be synthesized
via an acyl-ketene imine cyclocondensation of acyl-Meldrum’s acid
derivatives (3) and thiazolines (4).19,20 The acyl-Meldrum’s acid
derivatives (3) and thiazolines (4) are generally obtained from com-
mercially available carboxylic acids (1) and nitriles (2), respectively.
This synthetic procedure introduces substituent diversity in posi-
tion C-7 and C-8 already in the scaffold formation by the choice of
Abbreviations: SAR, structure activity relationship; QSAR, quantitative structure
activity relationship; PLS, partial least squares; OPLS-DA, orthogonal projections to
latent structures discriminant analysis; UTI, urinary tract infection; SMD, statistical
molecular design; PCA, principal component analysis; MRSA, methicillin-resistant
Staphylococcus aureus; UPEC, uropathogenic Escherichia coli.
⇑
Corresponding authors. Tel.: +46 90 7866925; fax: +46 90 7867655 (S.J.H.).
E-mail addresses: hultgren@borcim.wustl.edu (S.J. Hultgren), fredrik.almqvist@
chem.umu.se (F. Almqvist).
0968-0896/$ - see front matter Ó 2012 Published by Elsevier Ltd.
doi:10.1016/j.bmc.2012.01.048

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3129
carboxylic acids (1) and nitriles (2). Furthermore, various synthetic
methodologies for the introduction of substituents at the C-2 and C-
6 positions of the scaffold have been developed (Fig. 1).16,21–24
Rational alteration of the pilicide scaffolds substituents using
multivariate design could generate valuable new insights into the
intricate relationship between pilicide structure and biological
activity and ultimately result in comprehensive structure–activity
relationship (SAR) information. Multivariate design can be used to
decipher the complex correlation patterns between chemical
structures and specific biological responses and properties. In mul-
tivariate design, a representative subset of compounds is selected
from a more complete virtual set. This considerably reduces the
number of compounds to be synthesized and evaluated while
retaining much of the chemical information associated with the
full compound set. To enable this subset selection, all compounds
are described by numerical molecular descriptors. To visualize
the data set of different compounds with their corresponding
descriptors, the use of principal component analysis (PCA)25 is of-
ten applied. From this, a representative selection of a subset can be
performed by applying statistical experimental designs, that is, sta-
tistical molecular design (SMD).26,27 This results in a balanced sub-
set of compounds that encompass as much as possible of the
significant variation from the entire data set.28
identified and their chemical diversity was characterized by
molecular descriptors. Eight substituents at each position were
manually selected from the chemical space generated by PCA.
The choice of substituents was based on two known pilicides that
both had a CH2-1-naphthyl substituent in C-7 and a phenyl or
cyclopropyl in C-8 (Fig. 1).15 Hence, substituents were selected
from the chemical space in the vicinity of these substituents with
varying sizes, polarities and flexibility (Fig. 2).
All combinations of the eight C-7 and eight C-8 substituents,
resulted in a virtual set of 64 different pilicides. An SMD using
D-optimal design was used to select a balanced subset of 24 com-
pounds from this set, in which all of the substituents were repre-
sented three times (Table 1).
The 24 derivatives of the pilicide scaffold were next synthesized
in a five step synthetic sequence to the target compounds.20 In
general, the acyl-ketene imine cyclocondensation produced the de-
sired compounds in good yields (66–93%). However, the polar C-7
substituent in building block 1g proved problematic and resulted
in lower yields (15–50%). The C-8 indole building block 2f resulted
in both atropisomers, probably due to increased sterical clash with
adjacent substituents, and low yields in the acyl-ketene imine
cyclocondensation, primarily due to acylation of the indole by
the acyl-ketene.
Here we present a multivariate design strategy on di-substi-
tuted derivatives of the pilicide scaffold from which the most
promising compounds could be further substituted to give highly
active tri- and tetra-substituted derivatives. Furthermore, the set
of di-substituted derivatives could also be used to construct a reli-
able SAR model that could correctly rank the external validation
set. Overall the strategy was rewarding and significantly improved
pilicides and valuable SAR information was obtained. The results
described herein will guide future studies of these compounds as
research tools to study the biological processes they interfere with,
which ultimately may lead to novel anti-virulence therapeutics.
Before biological evaluation could be undertaken, the com-
pounds had to be hydrolyzed to the corresponding lithium carbox-
ylates. This was straightforward and all 24 target compounds were
isolated in yields above 90%. The 24 compounds were evaluated
using a pili dependent biofilm assay.29 In this assay, blocking the
formation of type 1 pili formation in the clinical isolate E. coli
strain, UTI89, completely prevents the bacteria’s ability to form
biofilm. Thus, the amount of biofilm that is formed in UTI89 grown
in the presence of pilicide is related to the potency of the com-
pound in blocking the formation of pili. The results are summa-
rized in Table 1.
We discovered that many of the di-substituted compounds effi-
ciently prevented pilus-dependent biofilm formation. In general,
the potency of the compounds turned out to be highly dependent
upon the nature of both substituents. The best compound in the
set was the C-8 indole and C-7 naphthoxy substituted 24 with an
2. Results and discussion
2.1. Synthesis and evaluation of di-substituted derivatives
EC50 of 12
lM. Compounds incorporating a thiophene or 3,4-meth-
Starting from suitable commercially available carboxylic acids
and nitriles, two sets of potential C-7 and C-8 substituents were
ylenedioxyphenyl group at C-8 (18–22) were also effective, except
Figure 1. Synthesis of the dihydrothiazolo ring-fused 2-pyridone pilicide scaffold (5) from commercially available carboxylic acids (1) and nitriles (2) via acyl-Meldrum’s acid
derivatives (3) and thiazolines (4), respectively. Firs-generation pilicides with a CH2-1-naphthyl substituent in C-7 and a cyclopropyl (6) or phenyl (7) in C-8 that forms the
basis of this work.

3130
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
compounds were correlated to their biofilm inhibition activity
using PLS.31,32 This resulted in
one-component model
C-7 building blocks
C-8 building blocks
a
(R2X ¼ 0:50; R2Y ¼ 0:62, Q2 = 0.50) that explained the relationships
between the chemical structure of the designed molecules and their
ability to prevent biofilm formation (Fig. 3b). The compounds with
high inhibitory effects were generally larger, more lipophilic, more
flexible and had lower HOMO energies compared to the analogues
with lower activity. To follow up on the results of the balanced com-
pound set, and to validate and challenge the generated QSAR model,
14 additional di-substituted derivatives of the pilicide scaffold (32–
45; Table 2) were synthesized (for predictions see Table 2 and
Fig. 3). Four derivatives of the most potent biofilm inhibitor (24)
from the tested compounds were prepared. In the first analogue
(32), the C-7 naphthoxy was replaced with the C-7 naphthyl substi-
tuent that also had proved promising. The second analogue (33) re-
tained the C-7 naphthoxy group but contained an N-methylated
indole at C-8 rather than the free N–H indole found in 24. In the
third analogue (34), the indole was similarly methylated and in
addition, the carboxylic acid was replaced with a methyl acylsulf-
onamide. The use of such groups as bioisosteres of carboxylic acids
has been reported to enhance pilicide activity.33,34 In the fourth
analogue (35), the sulfur atom in the pilicide scaffold was ex-
changed with oxygen using a one-pot procedure starting from acyl-
O
O
O
O
CN
HO
1a
O
CN
2e
HO
1e
2a
H
N
S
CN
CN
O
O
HO
HO
1f
1b
2b
2f
O
O
N
CN
N
N
N
CN
2g
ated L
-serine derivatives.19 Two additional oxygen analogues (36
HO
1c
HO
O
O
and 37) of promising compounds from the tested derivatives were
prepared using the same procedure. Furthermore, six compounds
with presumed high activities that really challenge the model
(38–43), one compound predicted to have intermediate activity
(44), and one compound that was predicted to be inactive (45) were
synthesized. All compounds (32–45) were biologically evaluated
using the pili-dependent biofilm inhibition assay (Table 2).
As predicted, several of the compounds based on the SAR data
from the first set of di-substituted compounds proved to be highly
potent inhibitors of pili-dependent biofilm formation. Considering
the differences between the first training set of compounds and the
validation set of compounds, the predicted activity correlates well
to the experimentally determined activity (Fig. 3b). The biofilm
evaluations suggest that the introduction of sterically demanding
substituents in position C-7 can greatly enhance biofilm inhibition
capacity. Moreover, N-methylation of the C-8 indole substituent in
24 to give 33 does not have a negative effect on the biological re-
sponse, which greatly facilitates the synthesis of such compounds
(Table 2). The use of a naphthoxy group as the C-7 substituent
seems to be superior to the C-7 naphthyl substituent (Table 2, 24
and 32). The introduction of the methyl acylsulfonamide carbox-
ylic acid isostere as in 34 was well tolerated, with an EC50 value
1g
2c
O
S
O
CN
O
CN
O
O
O
O
HO
HO
1h
1d
2d
2h
Figure 2. The building blocks used when constructing the library of C-7 and C-8-
substituted pilicides.
when combined with a C-7 coumarin substituent as in 17. The C-8
phenyl substituent was also favorable, but pyridine and the smaller
methoxy, cyclopropyl, and isopropyl substituents resulted in
reduced potency. The most useful C-7 substituents were the 1-
naphthylmethyl, naphthoxymethyl, 3-tolylethyl, and 2,3-dimeth-
ylphenoxymethyl groups. Exchange of the 1-naphthylmethyl
group and extension of the C-7 linker were well tolerated, but
heteroaryls were not.
of 9 lM. The oxygen analogues retain much of the biological activ-
2.2. Multivariate design
ity of the parent sulfur derivatives, which is encouraging in case
metabolic sulfur oxidation would emerge as a problem. The oxygen
analogue 36 retains all biological activity whereas 35, and 37 result
in a two and threefold decrease in activity, respectively as com-
pared to compound 33 and 18 (Table 2, and 35–37 vs 18, 22, and
33).
A structure–activity investigation was conducted based on the
balanced set of di-substituted compounds and biological responses
using a two-step modeling strategy. First, a model to distinguish ac-
tive from inactive compounds was constructed followed by a QSAR
model based on the active compounds for prediction of biofilm
inhibition activity. Consequently, all di-substituted compounds
(6–31) were characterized with descriptors (see Supplementary
data for complete list) and a OPLS-DA model was calculated, in
which fourteen of the 26 di-substituted compounds (6–9, 14, 16,
18–25) were classified as active and the remaining in-active. The
resulting two-component OPLS-DA model30 (RX2 ¼ 0:70; RY2 ¼ 0:79,
Q2 = 0.71) discriminated between the two classes of compounds
(Fig. 3a) with acceptable accuracy considering the challenge of
QSAR modeling when complex whole cell responses are used. The
polarity of the compounds appears to be the most important factor
for discrimination, where active compounds are more lipophilic
than the in-active ones. In the second step, the di-substituted
2.3. Synthesis and evaluation of tri- and tetra-substituted
derivatives
To generate more comprehensive SAR of the pilicide central
fragment, the effect of substitution at the C-2 and C-6 positions,
respectively, were evaluated by a new SMD (Table 3). The C-7
and C-8 di-substituted compounds 33, 22, and 18 were selected
as starting points for exploring C-2 and C-6 variations based on
their low molecular weight and moderate to high potency (EC50
values of 10, 21, 39 lM, respectively). The choice of substituents
in position C-2 or C-6 on the pilicide scaffold was based on both
previous studies of these positions as well as the size of the

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3131
Table 1
Chemical structures and biological evaluation of the balanced set of di-substituted compounds
ID
R8 (C-8)
R7 (C-7)
EC50
40
(l
M)a
ID
R8 (C-8)
R7 (C-7)
EC50
67
(l
M)a
O
O
8b,c
21b
S
O
O
9b,c
36
22b
21
74
O
O
O
O
NH
10b
NAd
23b
O
O
O
O
NH
NH
O
11b
NAd
24b
12
O
O
12b
13b
NAd
NAd
25b
26b
39
S
N
N
NAd
N
N
O
N
N
14b,c
100
NAd
27b
28b
NAd
NAd
N
N
N
S
O
O
15b
N
N
N
O
16b
17b
100
NAd
29b
30b
NAd
NAd
O
O
O
S
S
O
O
O
O
18b
39
14
31b,c
NAd
40
S
19b,c
7e
O
O
O
20b,c
27
6e
250
O
a
b
c
Calculated from 16–72 data points per concentration.
Compound is part of the design.
For solubility reasons these compounds were tested as carboxylic acids and not as lithium carboxylates.
d
e
Not active.
First generation pilicides that the design was based on.

3132
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
substitution increased the potency of 49 from 33 although in both
50 and 51 the same substitution reduced potency compared to
their parent compounds. Both C-6 substituents (morpholinomethyl
and hydroxymethyl) reduced the potencies of the compounds.
However, 52–57 retained the majority of their potency with C-6
substituents, which could be valuable to improve the compounds
solubility properties.
The synthesis and biological evaluation of the di-substituted
compounds showed that the incorporation of indole or 3,4-methyl-
enedioxyphenyl substituents at the C-8 position and a naphth-
oxymethyl substituent at the C-7 position of the pilicide scaffold
results in compounds with enhanced potency. Moreover, the intro-
duction of an appropriate C-2 substituent can further increase the
compounds potency, while substituents can be incorporated at the
C-6 position to improve the pilicides solubility. In using this SAR
data to synthesize tetra-substituted pilicide derivatives, 33 and
22 were used as substrates for the introduction of substituents at
both C-2 and C-6. Based on a recent study,16 we incorporated a
3-tolyl substituent at the C-2 position of the oxidized scaffold.
Our previously developed one-pot oxidation–bromination proce-
dure followed by Suzuki–Miyaura couplings was performed on
substrates 33 and 22 to obtain the C-2 substituted intermediates.16
To increase the compounds solubility properties the morpholinom-
ethyl substituent was introduced in position C-6 as described
above. After subsequent hydrolysis the tetra-substituted deriva-
tives 58 and 59 and the tri-substituted intermediates 60 and 61
were biologically evaluated for their ability to prevent pili-depen-
dent biofilm formation. The results are shown in Table 4.
We have previously described that C2/C3 oxidized pilicides
bearing a 3-tolyl C-2 substituent were more active than saturated
pilicides bearing a phenyl group at the C-2 position.16 However, the
incorporation of a 3-tolyl substituent at the C-2 positions of 60 and
61 resulted in decreased activities compared to the analogous
unsubstituted (33 and 22) and C-2 phenyl substituted (46 and
47) compounds (Tables 3 and 4). Interestingly, the introduction
of a C-6 morpholinomethyl substituent, which previously was
found to decrease activity (Table 3), resulted in 17- and 4-fold in-
creases in the respective activities of the tetrasubstituted
derivatives 58 and 59 relative to their C-6 unsubstituted counter-
parts 60 and 61 and also increased their water solubility.
Figure 3. (a) A OPLS-DA score plot showing active compounds (circles), inactive
compounds (filled circles), and the validation set (plus signs). (b) Observed versus
predicted plot of the PLS model showing calculated and predicted values of the
model set (black) and the validation set (grey) versus experimentally determined
values. The chemical structures can be seen in Tables 1 and 2.
3. Conclusion
substituent.16,17,24 Position C-2 was thus substituted with either a
phenyl or methoxy substituent and C-6 with a morpholinomethyl
or a hydroxymethyl substituent. The C-2 phenyl and methoxy sub-
stituents were introduced using a two-step process starting with
C-2/C-3 oxidation of 33, 22, and 18 followed by conjugate addi-
Various synthetic methods for the introduction of substituents
onto the basic pilicide scaffold were used to prepare a series of
51 new and highly-substituted analogues to generate more com-
prehensive pilicide SAR information. Biological testing of the 24
di-substituted compounds produced in the initial step of the de-
sign process revealed several compounds with improved potency
and important QSAR information. Three efficient di-substituted
inhibitors of biofilm formation were used to study the effects of
further substituting the C-2 and C-6 positions. A set of 14 tri-
substituted and two tetra-substituted compounds was synthe-
sized. This showed that substitution of the scaffold’s C-2 position
can increase pilicide potency and both the C-2 and C-6 positions
can be used to optimize the compounds solubility properties with
retained activity. However, the effect of C-2 and C-6 substitution is
dependent on the other substituents on the scaffold and is not sim-
ply an additive effect. Interestingly, the most potent tri-substituted
compound 48 (EC50 400 nM) was obtained from the least potent of
the three di-substituted compounds from the initial set that were
chosen for further substitution. Compounds in which the sulfur
atom in the pilicide scaffold was exchanged for oxygen retained
much of the potency of the parent compounds and will thus be
useful complements for use in oxidative environments. The use
tions to the corresponding
a,b-unsaturated derivatives to give
46–51 as the pure trans stereoisomers.22
Addition of a morpholinomethyl or a hydroxymethyl substitu-
ent in position C-6 was performed by following previously pub-
lished protocols.24 Formylation of 33, 22, and 18 gave the
corresponding aldehydes from which reduction or reductive ami-
nation gave the desired morpholinomethyl or hydroxymethyl
substituted compounds 52–57. After hydrolysis the 12 tri-substi-
tuted derivatives 46–57 were evaluated using the pili-dependent
biofilm formation assay and the results are summarized in Table 3.
The C-2 phenyl substituent was the most effective in terms of
increasing the pilicides potency. The most potent of the tri-substi-
tuted compounds was the C-2 phenyl substituted 48 with an EC50
of 400 nM, which is almost a 100-fold more potent than the C-2
unsubstituted 18 (Table 3). The incorporation of C-2 phenyl sub-
stituents in 46 and 47 resulted in almost 10- and 20-fold increased
activities, respectively, relative to 33 and 22. The C-2 methoxy

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3133
Table 2
Chemical structures and biofilm inhibition activities (predicted and experimentally determined) for the compounds synthesized to validate the QSAR model that was generated
based on the balanced set of 24 di-substituted compounds shown in Table 1
R8 (C-8)
R7 (C-7)
Pred.
M)
ID
R8 (C-8)
R7 (C-7)
Pred.
M)
.
ID
X
S
EC50
25
(l
EC50
31
(l
M)a
X
S
EC50
(l
EC50 (l
M)a
CF3
NH
c
32
41
—
3
N
N
N
N
33
S
11
10
9
42
43
44
S
S
S
3.7
2.1
4.3
39
O
O
O
O
O
O
O
O
CF3
34b
35
S
—
—
c
c
O
O
O
13
19
65
18
28
O
O
N
36
37
O
O
19
45
24
S
S
NAd
17
NAd
12
NH
O
S
117
O
O
O
N
c
38
39
40
S
S
S
—
1.1
1.9
1.4
22
18
—
S
17
58
—
21
39
—
O
CF3
S
c
—
S
O
O
9.6
—
—
—
a
b
c
Estimated from 16 to 72 data points per concentration.
In this derivative, the C-3 carboxylic acid was replaced with a methyl acylsulfonamide carboxylic acid isostere.
A reliable predicted EC50 value could not be determined because the compounds were too chemically different from the set of di-substituted compounds the model is
based upon (see Section 4 for details).
d
Not active.
of a methyl acyl sulfonamide as a carboxylic acid isostere was tol-
erated but did not substantially increase activity.
complex biological processes involved in pili and biofilm
formation.
In addition to generating potent pilicides and valuable SAR, the
generated data from the set of di-substituted compounds could be
used to construct a multivariate model. The multivariate model
could correctly rank the external validation set consisting of 16
compounds with different substituents and substitution pattern.
The herein generated comprehensive SAR information can be used
to optimize biological activity and properties of these anti-
virulence compounds, which will be highly useful both from a fu-
ture therapeutic perspective but also as research tools to study the
4. Experimental section
4.1. Multivariate design
ChemFinderACX2002Prod35 was used to search for carboxylic
acids and nitriles with molecular weights below 250. These build-
ing blocks were imported to MOE36 and molecular descriptors
were calculated. The nitrile data set was manually filtered to

3134
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
Table 3
The chemical structures and biological evaluation of tri-substituted derivatives included in the designed set to explore the C-2 and C-6 positions
R8 (C-8)
R7 (C-7)
R6 (C-6)
–H
R2 (C-2)
EC50
1.0
(l
M)a
ID
R8 (C-8)
R7 (C-7)
R6 (C-6)
R2 (C-2)
–H
EC50
88
(l
M)a
.
ID
N
S
N
O
O
O
46
54
O
N
O
OH
O
O
47
–H
1.2
55
–H
16
O
S
O
OH
48
49
50
–H
–H
–H
0.4
2.5
30
56
57
33
–H
–H
–H
30
OMe
OMe
N
S
OH
250
10
O
O
O
N
O
O
O
–H
OMe
O
S
O
51
52
53
–H
92
18
32
22
18
—
–H
–H
—
–H
–H
—
21
39
—
N
S
N
O
O
O
–H
–H
O
O
N
O
—
—
a
Estimated from 16 to 72 data points per concentration.
remove undesired substituents mainly based on chemical compat-
ibility giving 531 nitriles. The carboxylic acid data set was im-
ported to SIMCA-P37 and a PCA model was calculated with six
components having an eigenvalue over two. The principal compo-
nents were normalized to unit variance and centered. Building
blocks with a Euclidean distance over 1.5 from CH2-1-naphthyl
carboxylic acid were discarded in all principal components result-
ing in a set of 822 carboxylic acids. The carboxylic acid and the
cyanomethyl fragments were removed from the respective build-
ing blocks, as they are not part of the target compounds. The data
sets were washed and molecular descriptors were calculated
MOE.36 The filtered datasets were imported to SIMCA-P37 and
PCA models were created. The carboxylic acids gave a model with
five components with an eigenvalue over two (R2: 0.82) and the ni-
triles similarly gave a model with five components with an eigen-
value over two (R2: 0.84). From these models, eight C-7 and eight
C-8 substituents were manually selected with respect to the prop-
erties of 1a and 2a,b from the lead compounds 6 and 7. Combining
these substituents in position C-7 and C-8, respectively on the pil-
icide scaffold resulted in a set of 64 derivatives for which molecular
descriptors were calculated (see Supplementary data). The princi-
pal component data from the PCA model of the 64 derivatives
was imported to Modde38 and a D-optimal design was calculated
to select 24 compounds (all substituents represented three times).
To discriminate active from inactive compounds, an orthogonal
partial least square discriminant analysis (OPLS-DA) model was
calculated. Fourteen of the 26 di-substituted compounds (6–9,
14, 16, 18–25) were classified as active and the rest as inactive,
resulting in a two-component OPLS-DA model (R2X ¼ 0:70; RY2
¼
0:79, Q2 = 0.71). A PLS model was created with the active di-substi-
tuted compounds using the pEC50 values as response giving a one-
component model (R2X ¼ 0:50; R2Y ¼ 0:62, Q2 = 0.50). Compounds
from the validation set (32–45) with a DModX below three were
used as a prediction set to validate the models.
4.2. Synthesis
4.2.1. General remarks
All reactions were carried out under inert atmosphere with dry
solvents under anhydrous conditions, unless otherwise stated.

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3135
Table 4
J1 = 1.38 Hz, J2 = 8.95 Hz, 1H), 6.16 (s, 1H), 6.67–6.76 (m, 2H),
6.91–6.97 (m, 1H), 7.04–7.11 (m, 1H), 7.21–7.56 (m, 4H). 13C
NMR (100 MHz, MeOD) d 20.9, 31.3, 34.7, 34.8, 63.4, 113.1,
114.3, 125.0, 126.5, 128.06, 128.10, 128.7, 128.8 (2C), 129.98,
130.04, 136.4, 137.2, 140.8, 147.6, 154.0, 160.2, 169.6. HRMS (elec-
trospray ionization) calcd for [MꢀH] C23H20NO3S 390.1164, obsd
390.1161.
The chemical structure and biological evaluation of tri- and tetra-substituted
derivatives of the pilicide scaffold
R8 (C-8)
R7 (C-7)
R6 (C-6)
R2 (C-2)
EC50 (l
M)a
4.2.3. (3R)-7-((2,3-Dimethylphenoxy)methyl)-5-oxo-8-phenyl-
3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylic acid (9)
ID
N
Isolated in 77% overall yield as a light grey foam. [
a
]
D ꢀ48 (c 0.5,
DMSO); 1H NMR (400 MHz, MeOD) d 2.15 (s, 3H), 2.22 (s, 3H), 3.56
(dd J1 = 1.73 Hz, J2 = 11.83 Hz, 1H), 3.76 (dd J1 = 8.79 Hz,
J2 = 11.84 Hz, 1H), 4.56–4.68 (m, 2H), 5.66 (dd J1 = 1.68 Hz,
J2 = 8.73 Hz, 1H), 6.40 (d, J = 8.15 Hz, 1H), 6.64 (s, 1H), 6.72 (d,
J = 7.55 Hz, 1H), 6.90 (t, J = 7.88 Hz, 1H), 7.24–7.33 (m, 2H), 7.36–
7.46 (m, 3H). 13C NMR (100 MHz, MeOD) d 12.0, 20.2, 32.3, 64.6,
67.5, 109.7, 112.3, 115.5, 123.6, 125.8, 126.4, 129.4, 129.8 (2C),
130.0, 130.4, 135.6, 138.7, 149.0, 152.4, 156.4, 163.1, 170.2. HRMS
(electrospray ionization) calcd for [MꢀH] C23H20NO4S 406.1113,
obsd 406.1110.
N
O
O
O
58
5
O
O
N
O
59
60
61
33
22
5
86
20
10
21
N
–H
–H
–H
–H
O
O
O
O
O
4.2.4. (3R)-7-((7-Methoxy-2-oxo-2H-chromen-4-yl)methyl)-5-
oxo-8-phenyl-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (10)
Isolated in 70% overall yield as a light yellow non-crystalline so-
ꢀ17 (c 0.25, CHCl3); 1H NMR (400 MHz, DMSO-d6) d 3.49
N
lid. [a]
D
–H
–H
(dd, J1 = 1.79 Hz, J2 = 11.82 Hz, 1H), 3.72–3.88 (m, 6H), 5.48 (dd,
J1 = 1.63 Hz, J2 = 9.01 Hz, 1H), 5.93 (s, 1H), 6.01 (s, 1H), 6.88 (dd,
J1 = 2.50 Hz, J2 = 8.83 Hz, 1H), 6.96 (d, J = 2.49, 1H), 7.20–7.28 (m,
1H), 7.29–7.36 (m, 2H), 7.36–7.44 (m, 3H); 13C NMR (100 MHz,
DMSO-d6) d 32.4, 35.7, 56.8, 64.6, 101.9, 112.8, 113.1, 115.0,
115.3 (2C), 127.0, 129.2, 129.8 (2C), 130.8 (broad, 2C), 136.8,
149.6, 150.8, 154.0, 155.8, 160.79, 160.83, 163.3, 170.4. HRMS
(electrospray ionization) calcd for [M+H] C25H20NO6S 462.1011,
obsd 462.1018.
O
O
O
a
Estimated from 16 to 72 data points per concentration.
THF was freshly distilled from potassium, CH2Cl2 was distilled from
calcium hydride, MeCN and MeOH was dried over activated 3 Å
molecular sieves. TLC was performed on Silica Gel 60 F254 (Merck)
with detection by UV light (254 nm). Flash column chromatography
(eluents given in brackets) was performed on silica gel (Matrex,
4.2.5. (3R)-8-Cyclopropyl-7-((7-methoxy-2-oxo-2H-chromen-4-
yl)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (11)
Isolated in 65% overall yield as a light yellow non-crystalline so-
lid. [
a
]
D ꢀ58 (c 0.20, CHCl3); 1H NMR (400 MHz, DMSO-d6) d 0.51–
60 Å, 35–70
was performed on a Gradmaster parallel, Jones Chromatography
using silica gel (Matrex, 60 Å, 35–70
m, Grace Amicon). 1H and
lm, Grace Amicon). Parallel flash chromatography
0.71 (m, 2H) 0.76–0.88 (m, 2H), 1.56–1.66 (m, 1H), 3.52 (dd,
J1 = 1.76 Hz,
J2 = 11.86 Hz,
1H),
3.82
(dd,
J1 = 9.08 Hz,
l
J2 = 11.87 Hz, 1H), 3.86 (s, 3H), 4.10–4.27 (m, 2H), 5.40 (dd,
J1 = 1.75 Hz, J2 = 9.08 Hz, 1H), 5.79 (s, 1H), 6.03 (s, 1H), 6.97 (dd,
J1 = 2.55 Hz, J2 = 8.87 Hz, 1H), 7.03 (d, J = 2.51 Hz, 1H), 7.66 (d,
J = 8.88 Hz, 1H); 13C NMR (100 MHz, DMSO-d6) d 7.6, 7.8, 11.2,
32.2, 34.9, 56.5, 63.8, 101.6, 111.8, 112.4, 112.7, 112.9, 114.5,
127.0, 149.6, 152.9, 154.3, 155.6, 160.4, 160.6, 163.0, 170.1. HRMS
(electrospray ionization) calcd for [M+H] C22H20NO6S 426.1011,
obsd 426.1016.
13C NMR spectra were recorded on a Bruker DRX-400 or Bruker
DRX-360 in CDCl3 [residual CHCl3 (dH 7.26 ppm) or CDCl3 (dC
77.0 ppm) as internal standard], CD3OD [residual CD3OD (dH
3.31 ppm) or CD3OD (dC 49.0 ppm) as internal standard], DMSO-
d6 [residual DMSO (dH 2.50 ppm) or DMSO-d6 (dC 40.0 ppm) as
internal standard] or CDCl3/CD3OD mixtures using CD3OD (see
above) as internal standard at 298 K. Microwave reactions were
carried out using a monomode reactor (Smith Creator, Biotage AB)
in Teflon septa capped 0.5–2 ml or 2–5 ml Smith TM process vials
with stirring. Purities of key compounds were >95% as determined
by 1H NMR and HPLC.
4.2.6. (3R)-7-(Benzo[b]thiophen-3-ylmethyl)-8-cyclopropyl-5-
oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate
lithium salt (12)
The synthesis was performed by following previously reported
procedures.14,16,19,22,24 The acyl-ketene imine cyclocondensations
were typically performed in 0.5 mmol scale. Hydrolysis was gener-
ally performed in 0.15 mmol scale.
Isolated in 57% overall yield as a light yellow non-crystalline so-
lid. [
a]
D ꢀ99 (c 0.5, DMSO); 1H NMR (400 MHz, DMSO-d ) d 0.53–0.73 (m,
6
2H), 0.81–0.97 (m, 2H), 1.56–1.67 (m, 1H), 3.50 (dd J1 = 1.81 Hz,
J2 = 11.93 Hz, 1H), 3.78 (dd J1 = 9.12 Hz, J2 = 11.91 Hz, 1H), 4.15–
4.30 (m, 2H), 5.37 (dd J1 = 1.78 Hz, J2 = 9.10 Hz, 1H), 5.61 (s, 1H),
7.35–7.43 (m, 2H), 7.47 (s, 1H), 7.71–7.77 (m, 1H), 7.97–8.04 (m,
1H). 13C NMR (100 MHz, DMSO-d6) d 7.9, 8.4, 12.0, 33.0, 34.0,
67.2, 114.8, 115.8, 122.9, 123.8, 125.1, 125.1, 125.4, 134.5, 140.0,
141.9, 151.2, 157.2, 163.7, 174.0. HRMS (electrospray ionization)
calcd for [MꢀLi] C20H16NO3S2 382.0572, obsd 382.0578.
4.2.2. (3R)-7-(3-Methylphenethyl)-5-oxo-8-phenyl-3,5-dihydro-
2H-thiazolo[3,2-a]pyridine-3-carboxylic acid (8)
Isolated in 76% overall yield as a light grey foam. [
a]
D ꢀ16 (c 0.5,
CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, CDCl3) d 2.20 (s, 3H), 2.44–
2.62 (m, 4H), 3.43–3.51 (m, 1H), 3.76–3.85 (m, 1H), 5.49 (dd

3136
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
4.2.7. (3R)-7-((1H-Benzo[d][1,2,3]triazol-1-yl)methyl)-8-
cyclopropyl-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (13)
1H) 13C NMR (100 MHz, DMSO-d6) d 32.6, 35.8, 56.9, 65.1, 101.9,
107.1, 112.78, 112.81, 113.1, 115.5, 126.9, 128.4, 128.9, 130.4,
136.8, 151.5, 152.4, 154.2, 155.8, 160.7, 160.9, 163.3, 170.4. HRMS
(electrospray ionization) calcd for [M+H] C23H18NO6S2 468.0576,
obsd 468.0587.
Isolated in 46% overall yield as a light pink non-crystalline solid.
[a
]
D
ꢀ33 (c 0.5, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, MeOD) d
0.77–0.89 (m, 2H), 0.91–1.10 (m, 2H), 1.59–1.70 (m, 1H), 3.59
(dd J1 = 1.31 Hz, J2 = 11.34 Hz, 1H), 3.73 (dd J1 = 8.64 Hz,
J2 = 11.30 Hz, 1H), 5.34 (s, 1H), 5.37 (dd J1 = 1.36 Hz, J2 = 8.61 Hz,
1H), 5.98–6.16 (m, 2H), 7.43–7.51 (m, 1H), 7.54–7.62 (m, 1H),
7.68–7.76 (m, 1H), 8.01–8.07 (m, 1H). 13C NMR (100 MHz, MeOD)
d 8.0, 8.5, 11.3, 34.1, 50.0, 67.3, 111.6, 112.2, 113.9, 120.1, 125.9,
129.2, 134.7, 146.8, 152.46, 152.50, 163.3, 173.8. HRMS (electro-
spray ionization) calcd for [MꢀLi] C18H15N4O3S 367.0865, obsd
367.0868.
4.2.12. (3R)-7-(Naphthalen-1-ylmethyl)-5-oxo-8-(thiophen-2-
yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate
lithium salt (18)
Isolated in 81% overall yield as a light yellow non-crystalline so-
lid. [a]
D 33 (c 0.05, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, MeOD) d
3.50–3.56 (m, 1H), 3.63–3.72 (m, 1H), 4.01–4.16 (m, 2H), 5.36–5.42
(m, 1H), 5.70 (s, 1H), 7.04–7.09 (m, 2H), 7.23–7.28 (m, 1H), 7.34–
7.45 (m, 3H), 7.46–7.50 (m, 1H), 7.66–7.77 (m, 2H), 7.79–7.85
(m, 1H). 13C NMR (100 MHz, MeOD) d 34.0, 37.6, 68.2, 110.2,
114.7, 124.9, 126.5, 126.7, 127.2, 128.38, 128.41, 128.6, 128.8,
129.7, 130.5, 133.1, 135.35, 135.43, 137.9, 153.1, 156.9, 163.7,
173.8. HRMS (electrospray ionization) calcd for [MꢀLi]
4.2.8. (3R)-8-Isopropyl-7-(3-methylphenethyl)-5-oxo-3,5-
dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylic acid (14)
Isolated in 84% overall yield as a light grey foam. [
a
]
ꢀ21 (c
D
0.09, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, CD3OD) d 1.31 (m,
6H), 2.31 (s, 3H), 2.78–2.83 (m, 4H), 3.07–3.22 (m, 1H), 3.62 (dd
J1 = 1.54 Hz, J2 = 11.27 Hz, 1H), 3.72 (dd J1 = 8.45 Hz, J2 = 11.27 Hz,
1H), 5.41 (dd J1 = 1.55 Hz, J2 = 8.42 Hz, 1H), 6.12 (s, 1H), 6.97–
7.06 (m, 3H), 7.13–7.19 (m, 1H). 13C NMR (100 MHz, CD3OD) d
20.0, 21.2, 21.5, 29.7, 34.2, 36.8, 37.4, 66.6, 115.1, 121.6, 126.4,
128.0, 129.5, 130.1, 139.2, 142.2, 147.5, 156.9, 163.5, 173.9. HRMS
(electrospray ionization) calcd for [MꢀH] C20H22NO3S 356.1320,
obsd 356.1315.
C23H16NO3S2 418.0572, obsd 418.0575.
4.2.13. (3R)-7-((Naphthalen-1-yloxy)methyl)-5-oxo-8-
(thiophen-2-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (19)
Isolated in 87% overall yield as a light yellow foam. [
a
]
ꢀ23 (c
D
0.36, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, MeOD) d 3.55 (dd
J1 = 1.55 Hz, J2 = 11.90 Hz, 1H), 3.87 (dd J1 = 9.14 Hz, J2 = 11.89
Hz, 1H), 4.94–5.03 (m, 2H), 5.55 (dd J1 = 1.51 Hz, J2 = 9.05 Hz,
1H), 6.47 (s, 1H), 6.79 (d, J = 7.70 Hz, 1H), 7.11–7.15 (m, 1H),
7.18–7.20 (m, 1H), 7.34–7.40 (m, 1H), 7.47–7.57 (m, 3H), 7.64–
7.67 (m, 1H), 7.84–7.90 (m, 1H), 8.13–8.18 (m, 1H). 13C NMR
(100 MHz, MeOD) d 31.4, 63.7, 66.4, 104.8, 105.4, 112.2, 120.6,
121.4, 124.7, 125.6, 126.0, 126.6, 127.5, 127.6, 127.9, 129.2,
134.0, 135.0, 149.8, 151.0, 152.9, 159.9, 169.4. HRMS (electrospray
ionization) calcd for [MꢀH] C23H16NO4S2 434.0521, obsd 434.
0530.
4.2.9. (3R)-7-((1H-Benzo[d][1,2,3]triazol-1-yl)methyl)-8-
isopropyl-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (15)
Isolated in 13% overall yield as a light pink non-crystalline solid.
1H NMR (400 MHz, CD3OD) d 1.94–1.24 (m, 3H), 1.25–1.31 (m, 3H),
3.22–3.30 (m, 1H), 3.61–3.67 (m, 1H), 3.79 (dd J1 = 8.66 Hz,
J2 = 11.52 Hz, 1H), 5.48 (d, J = 8.77 Hz, 1H), 5.63 (br s, 1H), 5.90–
5.98 (m, 2H), 7.44–7.50 (m, 1H), 7.54–7.61 (m, 1H), 7.67–7.73
(m, 1H), 8.01–8.07 (m, 1H). 13C NMR (90 MHz, CD3OD) d 19.6,
20.9, 29.6, 34.3, 50.8, 66.7, 111.7, 114.1, 120.0, 120.2, 125.9,
129.3, 134.7, 146.8, 149.1, 149.7, 162.9, 173.5. HRMS (electrospray
ionization) calcd for [MꢀLi] C18H17N4O3S 369.1021, obsd 369.1019.
4.2.14. (3R)-8-(Benzo[d][1,3]dioxol-5-yl)-7-((2,3-
dimethylphenoxy)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (20)
Isolated in 84% overall yield as a light grey foam. [
a
]
D ꢀ9 (c 0.36,
DMSO); 1H NMR (400 MHz, CDCl3) d 2.18 (s, 3H), 2.26 (s, 3H), 3.62–
3.72 (m, 1H), 3.76–3.83 (m, 1H), 4.57–4.71 (m, 2H), 5.77–5.82 (m,
1H), 6.03 (s, 2H), 6.43–6.48 (s, 1H), 6.68–6.90 (m, 5H), 6.93–6.99
(m, 1H), 8.95 (s, 1H). 13C NMR (100 MHz, DMSO-d6) d 11.9, 20.1,
30.8, 64.8, 66.7, 101.5, 109.0, 109.2, 110.0, 112.0, 115.5, 122.8,
123.1, 123.5, 125.5, 125.7, 127.9, 138.3, 148.1, 148.6, 152.6,
155.7, 162.9, 168.5. HRMS (electrospray ionization) calcd for
[MꢀH] C24H20NO6S 450.1011, obsd 450.1006.
4.2.10. (3R)-8-Isopropyl-7-(naphthalen-1-ylmethyl)-5-oxo-3,5-
dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate lithium salt
(16)
Isolated in 56% overall yield as a light grey non-crystalline solid.
[a
]
D
ꢀ9 (c 0.5, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, CD3OD) d
1.20–1.32 (m, 6H), 3.01–3.17 (m, 1H), 3.63 (dd J1 = 1.22 Hz,
J2 = 11.29 Hz, 1H), 3.74 (dd J1 = 8.51 Hz, J2 = 11.28 Hz, 1H), 4.34 (s,
2H), 5.39 (dd J1 = 1.13 Hz, J2 = 8.33 Hz, 1H), 5.81 (s, 1H), 7.22–7.27
(m, 1H), 7.38–7.44 (m, 1H), 7.46–7.54 (m, 2H), 7.76–7.83 (m, 1H),
7.85–7.97 (m, 2H). 13C NMR (100 MHz, CD3OD) d 19.7, 20.9, 29.9,
34.3, 37.5, 66.6, 116.3, 121.8, 124.6, 126.6, 126.8, 127.3, 128.2,
128.6, 129.8, 133.1, 135.4, 135.7, 147.5, 155.8, 163.3, 173.9. HRMS
(electrospray ionization) calcd for [MꢀLi] C22H20NO3S 378.1164,
obsd 378.1166.
4.2.15. (3R)-7-(Benzo[b]thiophen-3-ylmethyl)-8-
(benzo[d][1,3]dioxol-5-yl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylate lithium salt (21)
Isolated in 72% overall yield as a light yellow non-crystalline so-
lid. [
a]
ꢀ5 (c 0.1, DMSO); 1H NMR (400 MHz, MeOD) d 3.49–3.57
D
(m, 1H), 3.68–3.78 (m, 1H), 3.80–3.92 (m, 2H), 5.42–5.49 (m, 1H),
5.84–5.97 (m, 2H), 6.07 (s, 1H), 6.64–6.81 (m, 3H), 7.14–7.19 (m,
1H), 7.24–7.34 (m, 2H), 7.45–7.53 (m, 1H), 7.78–7.86 (m, 1H). 13C
NMR (100 MHz, MeOD) d 32.2, 34.0, 68.1 (split, 68.12, 68.07),
102.6, 109.4 (split, 109.34, 109.48), 111.4 (split, 111.08, 111.73),
114.7 (split, 114.65, 114.70), 117.8, 122.7, 123.6, 124.8 (split,
124.55, 124.09), 125.0, 125.3 (2C), 131.2 (split, 131.23, 131.25),
134.1, 139.7, 141.6, 148.9 (split, 148.86, 148.95), 149.2, 151.0,
155.1 (split, 155.05, 155.09), 163.8, 174.0 (split, 173.97, 174.04).
HRMS (electrospray ionization) calcd for [MꢀLi] C24H16NO5S2
462.0470, obsd 462.0480.
4.2.11. (3R)-7-((7-Methoxy-2-oxo-2H-chromen-4-yl)methyl)-5-
oxo-8-(thiophen-2-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-
3-carboxylic acid (17)
Isolated in 72% overall yield as a light yellow non-crystalline so-
lid. [
a
]
ꢀ17 (c 0.69, CHCl3); 1H NMR (400 MHz, DMSO-d6) d 3.51
D
(dd, J1 = 1.77 Hz, J2 = 11.61 Hz, 1H), 3.78–3.83 (m, 1H), 3.85 (s,
2H), 5.43 (dd, J1 = 1.52 Hz, J2 = 9.16 Hz, 1H), 5.91 (s, 1H), 6.04 (s,
1H), 6.91 (dd, J1 = 2.56 Hz, J2 = 8.88 Hz, 1H), 6.98 (d, J = 2.54 Hz,
1H), 7.03–7.07 (m, 2H), 7.48 (d, J = 8.88 Hz, 1H), 7.56–7.60 (m,

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3137
4.2.16. (3R)-8-(Benzo[d][1,3]dioxol-5-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (22)
6.27–6.35 (m, 2H), 6.52–6.57 (m, 1H), 6.97–7.19 (m, 3H), 7.24–
7.31 (m, 1H), 7.38–7.45 (m, 1H). 13C NMR (100 MHz, MeOD) d
35.1 (maj), 35.2 (min), 42.79 (maj), 42.84 (min), 68.6, 104.7,
111.5, 112.89 (min), 112.94 (maj), 113.7 (maj), 114.0 (min),
114.1 (min), 114.3 (maj), 115.2 (min), 115.4 (maj), 117.2, 122.5
(maj), 122.6 (min), 123.1 (min), 123.3 (maj), 125.5 (min), 125.6
(maj), 125.7 (min), 12.8 (maj), 128.3 (min), 129.1 (maj), 130.2
(maj), 130.7 (min), 136.0 (maj), 136.2 (min), 140.3 (min), 140.4
(maj), 150.06 (min), 150.10 (maj), 151.6, 154.3 (maj), 154.5
(min), 162.1 (min), 162.2 (maj), 166.6 (maj), 167.5 (min), 174.2
(broad). HRMS (electrospray ionization) calcd for [MꢀLi]
Isolated in 78% overall yield as a light grey non-crystalline solid.
[
a]
D ꢀ2 (c 0.65, DMSO); 1H NMR (400 MHz, MeOD) d 3.55–3.60 (m,
1H), 3.77 (dd J1 = 8.70 Hz, J2 = 11.31 Hz, 1H), 4.88–4.99 (m, 2H),
5.49–5.53 (m, 1H), 5.97 (d, J = 13.38 Hz, 1H), 6.64 (s, 1H), 6.68 (d,
J = 7.64 Hz, 1H), 6.83–6.94 (m, 3H), 7.27–7.33 (m, 1H), 7.39–7.43
(m, 1H), 7.44–7.51 (m, 2H), 7.76–7.81 (m, 1H), 8.21–8.27 (m,
1H). 13C NMR (100 MHz, MeOD) d 34.1, 68.0, 68.1, 102.7, 106.3,
109.6 (split), 111.3 (split, 110.9, 111.6), 112.5, 115.7, 121.8,
122.8, 124.7 (split, 124.4, 125.0), 126.3, 126.82, 126.84, 127.5,
128.5, 130.3, 136.1, 149.2 (split), 149.5, 151.3, 151.9, 154.9,
163.9, 173.9 (split). HRMS (electrospray ionization) calcd for
[MꢀLi] C26H18NO6S 472.0855, obsd 472.0845.
C24H17N2O5S 445.0858, obsd 445.0863.
4.2.20. (3R)-7-((2,3-Dimethylphenoxy)methyl)-5-oxo-8-
(pyridin-3-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (26)
4.2.17. (3R)-8-(1H-Indol-3-yl)-7-(3-methylphenethyl)-5-oxo-
3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate lithium
salt (23)
Isolated in 53% overall yield as a light pink non-crystalline solid.
[
a
]
ꢀ11 (c 1.1, DMSO); 1H NMR (400 MHz, MeOD) d 2.09 (s, 3H),
D
2.22 (s, 3H), 3.60 (dd J1 = 1.17 Hz, J2 = 11.34 Hz, 1H), 3.80 (dd
J1 = 8.74 Hz, J2 = 11.25 Hz, 1H), 4.68 (s, 2H), 5.51 (dd J1 = 1.07 Hz,
J2 = 8.52 Hz, 1H), 6.50 (d, J = 8.18 Hz, 1H), 6.56 (s, 1H), 6.72 (d,
J = 7.53 Hz, 1H), 6.88–6.94 (m, 1H), 7.46–7.53 (m, 1H), 7.87–7.93
(m, 1H), 7.51–7.60 (m, 2H). 13C NMR (100 MHz, MeOD) d 11.9,
20.1, 34.3, 68.1, 68.2, 110.2, 112.0, 113.5, 123.9, 125.4, 125.9,
126.9, 134.0, 139.0, 140.1, 149.9, 151.2, 151.68, 151.75, 157.1,
163.9, 173.7. HRMS (electrospray ionization) calcd for [MꢀLi]
Isolated in 59% overall yield as a light pink non-crystalline solid.
As a 1:1.8 mixture of atropisomers. [
a]
D
ꢀ29 (c 0.8, DMSO); 1H
NMR (400 MHz, MeOD) d 2.11–2.16 (m, 3H), 2.47–2.65 (m, 4H),
3.45–3.52 (m, 1H), 3.63–3.72 (m, 1H), 5.46–5.52 (m, 1H), 6.21–
6.26 (m, 1H), 6.42–6.58 (m, 2H), 6.80–6.87 (m, 1H), 6.90–7.07
(m, 2H), 7.12–7.29 (m, 3H), 7.40–7.48 (m, 1H). 13C NMR
(100 MHz, MeOD) d 21.31 (maj), 21.33 (min), 33.68 (maj), 33.74
(min), 36.9 (maj), 37.0 (min), 37.3 (min), 37.4 (maj), 68.4 (maj),
68.5 (min), 111.18 (maj), 111.24 (min), 111.6 (min), 112.1 (maj),
112.5 (min), 112.7 (maj), 113.66 (maj), 113.69 (min), 120.1 (maj),
120.4 (min), 120.5 (maj), 120.6 (min), 122.8 (min), 122.9 (maj),
125.5 (min), 126.16 (maj), 126.19 (min), 126.6 (maj), 127.4 (maj),
127.5 (min), 127.7 (maj), 128.4 (min), 129.0, 129.88 (maj),
129.92 (min), 137.8 (min), 137.9 (maj), 138.8, 142.5, 152.2 (maj),
152.3 (min), 158.8 (min), 158.9 (maj), 164.2, 174.1 (min), 174.2
(maj). HRMS (electrospray ionization) calcd for [MꢀLi]
C
22H19N2O4S 407.1066, obsd 407.1057.
4.2.21. (3R)-7-((1H-Benzo[d][1,2,3]triazol-1-yl)methyl)-5-oxo-8-
(pyridin-3-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (27)
Isolated in 33% overall yield as a light pink non-crystalline solid.
[a]
D 0 (c 0.36, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, MeOD) d 3.58
(dd J1 = 1.12 Hz, J2 = 11.42 Hz, 1H), 3.74–3.84 (m, 1H), 5.48 (dd
J1 = 1.21 Hz, J2 = 8.56 Hz, 1H), 5.58–5.75 (m, 2H), 5.98 (s, 1H),
7.30–7.44 (m, 2H), 7.46–7.54 (m, 2H), 7.58–7.74 (m, 1H), 7.91–
7.96 (m, 1H), 8.28–8.46 (m, 2H). 13C NMR (100 MHz, MeOD) d
34.4, 49.9, 68.2, 111.4, 111.9, 114.7, 120.0, 125.4, 125.7, 129.1,
133.4, 134.4, 139.9 (split, 139.7, 140.2), 146.5, 149.0, 149.9 (split,
149.8, 150.0), 151.0 (split, 150.9, 151.1), 153.1, 163.3, 173.4. HRMS
(electrospray ionization) calcd for [MꢀLi] C20H14N5O3S 404.0817,
obsd 404.0814.
C25H21N2O3S 429.1273, obsd 429.1282.
4.2.18. (3R)-8-(1H-Indol-3-yl)-7-((naphthalen-1-yloxy)methyl)-
5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate
lithium salt (24)
Isolated in 41% overall yield as a light pink non-crystalline solid.
As a 1:1.1 mixture of atropisomers. [
a
]
D ꢀ52 (c 1, DMSO); 1H NMR
(400 MHz, DMSO-d6) d 3.45–3.53 (m, 1H), 3.77–3.90 (m, 1H), 4.80–
5.12 (m, 2H), 5.54–5.62 (m, 1H), 6.47 (s, 1H, maj), 6.48 (s, 1H, min),
6.61 (d, J = 7.67 Hz, 1H, maj), 6.70 (d, J = 7.68 Hz, 1H, min), 7.00–
7.08 (m, 1H), 7.11–7.18 (m, 1H), 7.24–7.33 (m, 1H), 7.39–7.56
(m, 6H), 7.82–7.88 (m, 1H), 8.11–8.19 (m, 1H), 11.39 (s, 1H). 13C
NMR (100 MHz, DMSO-d6) d 31.0 (maj), 31.2 (min), 63.6 (min),
63.7 (maj), 66.5 (maj), 66.7 (min), 105.0 (min), 105.3 (maj) 105.3
(maj), 105.4 (min), 108.0 (min), 108.5 (maj), 111.1 (maj), 111.3
(min), 112.0 (maj/min), 118.8 (min), 118.9 (maj), 119.1 (min),
119.3 (maj), 120.5, 121.30 (min), 121.33 (maj), 121.5 (min),
121.6 (maj), 124.7 (maj), 125.1 (min), 125.5–125.6 (2C, maj/min),
125.8 (min), 125.9 (maj), 126.0 (maj), 126.1 (min), 126.53 (maj),
126.55 (min), 127.5, 134.0, 135.9 (min), 136.0 (maj), 149.7 (maj),
149.9 (min), 150.8 (maj), 151.1 (min), 153.0, 160.2, 169.61 (maj),
169.64 (min). HRMS (electrospray ionization) calcd for [MꢀLi]
4.2.22. (3R)-7-(Benzo[d][1,3]dioxol-5-ylmethyl)-5-oxo-8-
(pyridin-3-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (28)
Isolated in 40% overall yield as a light pink non-crystalline solid.
[a
]
D
ꢀ2 (c 0.9, DMSO); 1H NMR (400 MHz, MeOD) d 3.52–3.60 (m,
3H), 3.71–3.82 (m 1H), 5.45–5.50 (m, 1H), 5.86 (s, 2H), 6.18 (s, 1H),
6.29 (d, J = 7.80 Hz, 1H), 6.37 (s, 1H), 6.59 (d, J = 7.92 Hz, 1H), 7.40–
7.47 (m, 1H), 7.62–7.70 (m, 1H), 8.21–8.31 (m, 1H), 8.46–8.51 (m,
1H). 13C NMR (100 MHz, MeOD) d 34.2, 40.1, 67.9, 102.1, 108.9,
110.0, 113.8, 115.6, 122.9, 125.1, 132.5, 134.6, 140.2 (split, 140.0,
140.4), 147.5, 149.0, 149.3 (split, 149.2, 149.4), 151.2, 151.3,
155.5, 163.7, 173.6. HRMS (electrospray ionization) calcd for
[MꢀLi] C21H15N2O5S 407.0702, obsd 407.0709.
C27H19N2O4S 467.1066, obsd 467.1056.
4.2.23. (3R)-7-(Benzo[b]thiophen-3-ylmethyl)-8-methoxy-5-
oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate
lithium salt (29)
4.2.19. (3R)-7-(Benzo[d][1,3]dioxol-5-ylmethyl)-8-(1H-indol-3-
yl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (25)
Isolated in 63% overall yield as a light yellow non-crystalline so-
lid. [
a
]
ꢀ8 (c 0.5, DMSO); 1H NMR (400 MHz, MeOD) d 3.67 (dd
D
Isolated in 27% overall yield as a light pink non-crystalline solid.
J1 = 1.48 Hz, J2 = 11.38 Hz, 1H), 3.69 (s, 3H), 3.82 (dd J1 = 8.52 Hz,
J2 = 11.35 Hz, 1H), 4.06–4.17 (m, 2H), 5.37 (dd J1 = 1.45 Hz,
J2 = 8.47 Hz, 1H), 5.89 (s, 1H), 7.31–7.40 (m, 3H), 7.72–7.77 (m,
1H), 7.85–7.90 (m, 1H). 13C NMR (100 MHz, MeOD) d 29.4, 34.7,
As a 1:1.3 mixture of atropisomers. [
a
]
D
ꢀ1 (c 0.5, CH2Cl2/MeOH
9:1); 1H NMR (400 MHz, MeOD) d 3.44–3.62 (m, 3H), 3.64–3.75
(m, 1H), 5.58 (br s, 1H), 5.79–5.85 (m, 2H), 6.07–6.13 (m, 1H),

3138
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
61.0, 67.8, 114.5, 122.9, 123.8, 125.2, 125.4, 125.5, 133.8, 138.8,
139.9, 141.8, 142.8, 151.7, 162.6, 173.6. HRMS (electrospray ioniza-
tion) calcd for [MꢀLi] C18H14NO4S2 372.0364, obsd 372.0374.
126.4 (min), 126.6, 127.5, 129.3 (min), 130.0 (maj), 134.1, 136.5
(min), 136.6 (maj), 149.8 (min), 150.0 (maj), 151.0 (min), 151.2
(maj), 153.0, 160.3, 169.6 (maj), 169.7 (min). HRMS (electrospray
ionization) calcd for [MꢀLi] C28H21N2O4S 481.1222, obsd 481.1217.
4.2.24. (3R)-8-Methoxy-7-(naphthalen-1-ylmethyl)-5-oxo-3,5-
dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate lithium salt
(30)
4.2.28. (R)-8-(1-Methyl-1H-indol-3-yl)-N-(methylsulfonyl)-7-
((naphthalen-1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxamide (34)
Isolated in 80% overall yield as a light grey non-crystalline solid.
[
a
]
D ꢀ1 (c 0.36, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, DMSO-d6) d
Isolated in 51% yield as a light grey foam starting from
3.56–3.63 (m, 1H), 3.70 (s, 3H), 3.89 (dd J1 = 8.93 Hz, J2 = 11.71 Hz,
1H), 4.24–4.36 (m, 2H), 5.31–5.39 (m, 2H), 7.41–7.58 (m, 4H),
7.85–7.99 (m, 3H). 13C NMR (100 MHz, MeOD) d 33.4, 34.7, 61.0,
67.8, 114.6, 125.1, 126.6, 126.8, 127.3, 128.7, 128.9, 129.7, 133.3,
135.3, 135.5, 138.7, 142.7, 153.0, 162.6, 173.6. HRMS (electrospray
ionization) calcd for [MꢀLi] C20H16NO4S 366.0800, obsd 366.0803.
0.08 mmol of 33. As a 1:1.9 mixture of atropisomers. [
a]
2 (c
D
0.5, DMSO); 1H NMR (400 MHz, CDCl3) d 3.32 (s, 3H), 3.52–3.68
(m, 1H), 3.75 (s, 3H, min), 3.83 (s, 3H, maj), 3.85–3.93 (m, 1H),
4.81–5.06 (m, 2H), 5.77–5.84 (m, 1H), 6.46 (d, J = 7.60 Hz, 1H,
maj), 6.50 (d, J = 7.64 Hz, 1H, min), 6.97 (s, 1H, min), 6.99 (s, 1H,
maj), 7.06 (s, 1H, min), 7.14 (s, 1H, maj), 7.15–7.54 (m, 9H),
7.74–7.80 (m, 1H), 8.30–8.38 (m, 1H). 13C NMR (100 MHz, CDCl3)
d 28.6 (maj), 29.2 (min), 33.0 (min), 33.1 (maj), 41.36 (min), 41.4
(maj), 65.6 (maj), 65.7 (min), 66.5 (maj), 66.7 (min), 105.06
(maj), 105.11 (min), 107.5 (min), 108.1 (maj), 108.6 (maj), 108.8
(min), 109.7 (min), 110.0 (maj), 111.9 (maj), 112.0 (min), 119.1
(maj), 119.6 (min), 120.26 (min), 120.33 (maj), 121.02 (maj),
121.04 (min), 122.0, 122.5 (min), 122.6 (maj), 125.39 (min, 2C),
125.43 (maj, 2C), 125.57 (maj), 125.60 (min), 126.1 (min), 126.59
(maj), 126.61 (maj), 126.7 (min), 127.4, 128.0 (min), 129.1 (maj),
134.4, 136.8 (min), 137.0 (maj), 149.9, 153.4, 153.6 (min), 153.9
(maj), 162.7 (min), 162.9 (maj), 166.1 (maj), 166.2 (min). HRMS
4.2.25. (3R)-7-(Benzo[d][1,3]dioxol-5-ylmethyl)-8-methoxy-5-
oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylic acid
(31)
Isolated in 76% overall yield as a light yellow foam. [
a
]
ꢀ1 (c
D
0.5, CH2Cl2/MeOH 9:1); 1H NMR (400 MHz, DMSO-d6) d 3.56–
3.61 (m, 4H), 3.71 (s, 2H), 3.88 (dd J1 = 8.99 Hz, J2 = 11.70 Hz, 1H),
5.37 (dd J1 = 1.24 Hz, J2 = 8.79 Hz, 1H), 5.79 (s, 1H), 5.98 (s, 2H),
6.70–6.75 (m, 1H), 6.82–6.87 (m, 2H). 13C NMR (100 MHz,
DMSO-d6) d 32.0, 34.8, 60.1, 62.9, 100.8, 108.2, 109.4, 113.5,
122.1, 131.8, 135.3, 139.7, 145.8, 147.3, 151.4, 159.1, 169.4. HRMS
(electrospray ionization) calcd for [MꢀH] C17H14NO6S 360.0542,
obsd 366.0543.
(electrospray ionization) calcd for [MꢀH]
C29H24N3O5S2
558.1158, obsd 558.1173.
4.2.26. (3R)-8-(1H-Indol-3-yl)-7-(naphthalen-1-ylmethyl)-5-
oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate
lithium salt (32)
4.2.29. (3S)-7-((Naphtalen-1-yloxy)methyl)-5-oxo-8-(1-
metyhyl-1H-indol-3-yl)-2,3-dihydro-5H-oxazolo[3,2-
a]pyridine-3-carboxylic acid (35)
Isolated in 50% overall yield as a light pink foam. As a 1:1.3 mix-
Isolated in 29% overall yield as a light pink non-crystalline solid.
ture of atropisomers. [
a
]
D
ꢀ33 (c 0.6, DMSO);1H NMR (400 MHz,
[a]
ꢀ23 (c 0.2, CHCl3/CH2Cl2/MeOH 1:1:1); 1H NMR (400 MHz,
D
MeOD) d 3.43–3.49 (m, 1H), 3.67–3.77 (m, 1H), 3.95–4.09 (m,
2H), 5.57–5.63 (m, 1H), 5.73 (s, 1H, maj), 5.76 (m, 1H, min),
7.06–7.40 (m, 7H), 7.41–7.49 (m, 2H), 7.54–7.60 (m, 1H), 7.66–
7.71 (m, 1H), 7.74–7.79 (m, 1H), 10.77 (s, 1H). 13C NMR
(100 MHz, MeOD) d 32.4 (maj), 32.5 (min), 37.7, 65.7 (maj), 65.8
(min), 111.0 (min), 111.4 (maj), 111.48 (min), 111.51 (maj),
112.8 (min), 112.9 (maj), 114.3, 120.0 (maj), 120.1 (min), 120.7
(min), 120.8 (maj), 123.0 (min), 123.1 (maj), 124.99 (min),
125.01 (maj), 125.7, 126.4 (min), 126.5 (maj), 126.56 (min),
126.62 (maj), 127.00 (maj), 127.02 (min), 127.6 (maj), 128.1
(min), 128.52 (min), 128.55 (maj), 128.8 (min), 128.9 (maj),
129.6, 133.0 (min), 133.1 (maj), 135.3, 135.7 (maj), 135.9 (min),
137.8 (min), 138.0 (maj), 151.6 (maj), 151.7 (min), 159.2 (min),
159.3 (maj), 163.81 (maj), 163.83 (min), 171.2. HRMS (electrospray
ionization) calcd for [MꢀLi] C27H19N2O3S 451.1117, obsd 451.1126.
DMSO-d6) d 3.77 (s, 3H), 4.69 (m, 1H), 4.86 (m, 1H), 5.07 (m, 3H),
6.28 (s, 1H), 6.71 (d, J = 7.52 Hz, 1H), 7.04 (m, 1H), 7.18 (m, 1H),
7.31 (m, 1H), 7.37 (m, 1H), 7.46 (m, 3H), 7.25 (m, 2H), 7.86 (m,
1H), 8.16 (m, 1H). 13C NMR (100 MHz, DMSO-d6) d 33.0, 58.2,
67.4, 72.7, 89.0, 104.3, 106.0, 107.2, 110.4, 119.6, 119.8, 120.9,
121.8, 121.8, 125.3, 126.0, 126.5, 127.0, 127.8, 128.0, 130.2,
134.5, 136.9, 153.2, 153.5, 155.7, 158.8, 169.9. HRMS (electrospray
ionization) calcd for [MꢀH] C28H21N2O5 465.1451, obsd 465.1451.
4.2.30. (3S)-7-((Naphtalen-1-yloxy)methyl)-5-oxo-8-
(benzo[d][1,3]dioxol-5-yl)-2,3-dihydro-5H-oxazolo[3,2-
a]pyridine-3-carboxylic acid (36)
Isolated in 39% overall yield as a light yellow non-crystalline so-
lid. [a]
ꢀ37 (c 0.2, CHCl3/MeOH 1:1); 1H NMR (400 MHz, DMSO-
D
d6) d 4.74 (dd, J1 = 4.01 Hz, J2 = 9.05 Hz, 1H), 4.90 (t, J = 9.31 Hz,
1H), 5.00 (d, J = 14.00 Hz, 1H), 5.10 (d, J = 14.00 Hz, 1H), 5.16 (dd,
J1 = 4.01 Hz, J2 = 9.44 Hz, 1H), 6.01 (s, 2H) 6.26 (s, 1H), 6.78 (d,
J = 7.65 Hz, 1H), 6.86 (m, 1H), 6.91 (m, 1H), 6.97 (m, 1H), 7.36
(m, 1H), 7.47 (m, 1H), 7.52 (m, 2H), 7.86 (m,1H), 8.11 (m, 1H).
13C NMR (100 MHz, DMSO-d6) d 58.1, 67.2, 72.9, 96.7, 101.5,
106.0, 107.8, 108.7, 111.3, 120.9, 121.8, 124.4, 125.3, 125.8,
126.0, 126.5, 127.0, 128.0, 134.5, 147.0, 147.7, 151.8, 153.5,
155.3, 158.6, 167.8. HRMS (electrospray ionization) calcd for
[MꢀH] C25H19NO7 456.1084, obsd 456.1079.
4.2.27 (3R)-8-(1-Methyl-1H-indol-3-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylate lithium salt (33)
Isolated in 76% overall yield as a light pink foam. As a 1:1.3 mix-
ture of atropisomers. [
a
]
D ꢀ18 (c 0.45, DMSO); 1H NMR (400 MHz,
DMSO-d6) d 3.45–3.52 (m, 1H), 3.78 (s, 3H, min), 3.79 (s, 3H, maj),
3.81–3.89 (m, 1H), 4.81–5.13 (m, 2H), 5.55–5.63 (m, 1H), 6.47–6.50
(m, 1H), 6.60 (d, J = 7.73 Hz, 1H, maj), 6.70 (d, J = 7.67 Hz, 1H, min),
7.03–7.10 (m, 1H), 7.17–7.55 (m, 8H), 7.81–7.86 (m, 1H), 8.11–8.18
(m, 1H). 13C NMR (100 MHz, DMSO-d6) d 31.0 (maj), 31.2 (min),
32.58 (maj), 32.62 (min), 63.62 (min), 63.64 (maj), 66.6 (maj),
66.7 (min), 104.7 (maj), 104.9 (min), 105.5 (maj), 105.6 (min),
107.2 (min), 107.7 (maj), 110.26 (maj), 110.31 (min), 111.08
(maj), 111.13 (min), 119.0 (min), 119.2 (maj), 119.4 (min), 119.5
(maj), 120.5, 121.35 (min), 121.37 (maj), 121.6 (min), 121.7
(maj), 124.8, 125.6, 125.94 (maj), 125.97 (min), 125.99 (maj),
4.2.31. (3S)-7-((Naphthalen-1-yloxy)methyl)-5-oxo-8-
(thiophen-2-yl)-2,3-dihydro-5H-oxazolo[3,2-a]pyridine-3-
carboxylic acid (37)
Isolated in 34% overall yield as a light grey non-crystalline solid.
[
a
]
ꢀ67 (c 0.75, CHCl3); 1H NMR (400 MHz, CDCl3) d 4.16 (d,
D
J = 17.26 Hz, 1H), 4.23 (d, J = 17.26 Hz, 1H), 4.80 (m, 1H), 5.20 (m,
1H), 5.35 (m, 1H), 5.80 (s, 1H), 7.05 (m, 1H), 7.10 (m, 1H), 7.24

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3139
(m, 1H), 7.38–7.48 (m, 4H), 7.62 (m, 1H), 7.78 (m, 1H), 7.85 (m,
1H). 13C NMR (100 MHz, CDCl3) d 37.1, 59.2, 70.8, 96.0, 109.9,
123.6, 125.5, 125.8, 126.3, 127.4, 127.4, 127.9, 128.0, 128.8,
129.5, 131.5, 131.6, 133.4, 133.9, 155.0, 160.5, 161.0, 167.5. HRMS
(electrospray ionization) calcd for [MꢀH] C23H16NO4S 402.0800,
obsd 402.0794.
(400 MHz, MeOD/CDCl3 (1:1)) d 3.48–3.56 (m, 1H), 3.63–3.75 (m,
1H), 4.20–4.38 (m, 2H), 5.36 (s, 1H), 5.41–5.50 (m, 1H), 7.32–7.43
(m, 4H), 7.65–7.94 (m, 8H), 8.27 (s, 1H); 13C NMR (100 MHz,
MeOD/CDCl3 (3:2)) d 32.4, 32.6, 65.1 (broad), 114.6, 116.0, 124.4
(2C), 124.7 (q, J = 272.8 Hz), 125.5 (2C), 126.1 (broad and split),
126.9 (2C), 127.6 (split J = 36.5 Hz), 127.84, 129.3, 129.8 (2C),
130.7, 130.9 (2C), 132.1 (2C), 132.3 (q, J = 33.5 Hz), 134.5 (split
J = 47.5 Hz), 137.9 (split J = 4.3 Hz), 149.3, 155.4, 162.8, 170.6
(broad). HRMS (electrospray ionization) calcd for [MꢀH]
4.2.32. (3R)-8-(1-Methyl-1H-indol-3-yl)-7-(3-((naphthalen-1-
yloxy)methyl)benzyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (38)
C30H19F3NO3S 530.1038, obsd 530.1038.
Isolated in 40% yield as a light grey foam in a 1:1.3 mixture of
atropisomers.
[
a
]
ꢀ30 (c 0.82, DMSO); 1H NMR (400 MHz,
4.2.36. (3R)-8-(1-Methyl-1H-indol-3-yl)-5-oxo-7-((3-
phenoxyphenoxy)methyl)-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (42)
D
DMSO-d6) d 3.47–3.68 (m, 4H), 3.71 (s, 3H, maj), 3.73 (s, 3H,
min) 5.05–5.15 (m, 2H), 5.24–5.32 (m, 1H), 5.85–5.90 (m, 1H),
6.88–7.02 (m, 4H), 7.10–7.26 (m, 4H), 7.28–7.33 (m, 1H), 7.36–
7.44 (m, 2H), 7.45–7.55 (m, 3H), 7.83–7.89 (m, 1H), 8.11–8.17
(m, 1H); 13C NMR (100 MHz, DMSO-d6) d 32.88 (maj), 32.93
(min), 33.1 (broad), 39.05 (maj), 39.09 (min), 66.8, 69.82 (min),
69.84 (maj), 106.2, 106.6 (broad and split), 109.7 (min), 110.2
(maj), 110.5, 114.1 (broad and split), 119.5, 119.6 (maj), 119.7
(min), 120.6, 121.8 (min), 121.9 (maj), 122.0, 125.5, 125.7 (broad),
125.9, 126.6 (min), 126.7 (maj), 126.9, 127.0 (maj), 127.5 (min),
127.9, 128.4 (min), 128.5 (maj), 128.8, 128.9, 129.6 (min), 130.2
(maj), 134.5, 136.8 (min), 136.9 (maj), 137.5 (split), 139.5 (maj),
139.8 (min), 150.49 (min), 150.52 (maj), 154.17 (min), 154.19
(maj), 154.7 (min), 154.8 (maj), 161.2 (broad and split), 170.1
(broad and split). HRMS (electrospray ionization) calcd for
[MꢀCO2H] C34H27N2O2S 527.1793, obsd 527.1786.
Isolated in 50% overall yield as a light pink foam in a 1:1.2 mix-
ture of atropisomers. 1H NMR (400 MHz, DMSO-d6) d 3.41–3.51 (m,
1H), 3.68–3.81(m, 4H), 4.57–4.85 (m, 2H), 5.44–5.51 (m, 1H), 6.23
(s, 1H, maj), 6.25 (s, 1H, min), 6.37 (t, J = 2.25 Hz, 1H, maj), 6.45 (t,
J = 2.24 Hz, 1H, min), 6.49–6.54 (m, 1H), 6.55–6.62 (m, 1H), 6.93–
7.04 (m, 3H), 7.12–7.25 (m, 4H), 7.35–7.41 (m, 2H), 7.43–7.49
(m, 1H); 13C NMR (100 MHz, DMSO-d6) d 32.0 (maj), 32.2 (min),
33.0 (maj), 33.1 (min), 65.0, 67.0 (maj), 67.1 (min), 104.8 (maj),
105.0 (min), 105.4 (maj), 105.6 (min), 107.7 (min), 108.2 (maj),
110.2 (min), 110.3 (maj), 110.6, 111.3 (min), 111.4 (maj), 111.7
(maj), 111.9 (min), 119.25, 119.31, 119.5, 119.7 (min), 119.9
(maj), 121.95 (min), 122.05 (maj), 124.11 (min), 124.13 (maj),
126.5 (maj), 126.9 (min), 129.7 (min), 130.3 (maj), 130.5 (2C),
131.00 (min), 131.03 (maj), 136.8 (min), 136.9 (maj), 150.4
(min), 150.60 (maj), 150.65 (min), 150.8 (maj), 156.62 (min),
156.63 (maj), 158.2 (maj), 158.3 (min), 159.4 (maj), 159.5 (min),
160.8, 170.3 (maj), 170.4 (min). HRMS (electrospray ionization)
calcd for [MꢀH] C30H23N2O5S 523.1328, obsd 523.1334.
4.2.33. (3R)-7-[3-(Naphthalen-1-yloxymethyl)-benzyl]-5-oxo-8-
(3-trifluoromethyl-phenyl)-2,3-dihydro-5H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (39)
Isolated in 35% overall yield as a colorless foam. [a] 5 (c 0.25,
D
CHCl3); 1H NMR (400 MHz, DMSO-d6) d 3.46–3.53 (m, 1H), 3.58–
3.71 (m, 2H), 3.76–3.84 (m, 1H), 5.17 (s, 2H), 5.46–5.52 (m, 1H),
6.11 (s, 1H), 6.77–6.84 (m, 1H), 6.97–7.04 (m, 2H), 7.18–7.25 (m,
1H), 7.30–7.60 (m, 8H), 7.63–7.69 (m, 1H), 7.84–7.89 (m, 1H),
8.14–8.19 (m, 1H); 13C NMR (100 MHz, DMSO-d6) d 31.7, 38.6,
63.6, 69.2, 105.7, 112.8, 114.7, 120.1, 121.5, 123.9 (q, J = 271 Hz,
1C), 124.7 (broad), 125.0, 125.4 (2C), 126.1, 126.4, 126.8 (broad
splitted), 127.4, 127.6 (broad), 128.1, 128.4, 129.3 (q, J = 31 Hz,
1C), 129.7, 134.0, 134.4, 137.1, 137.3 (broad), 138.2, 148.5, 153.0
(broad), 153.7, 160.1, 169.5. HRMS (electrospray ionization) calcd
for [MꢀH] C33H23F3NO4S 586.1300, obsd 586.1294.
4.2.37. 5-Oxo-7-((3-phenoxy-phenoxy)methyl)-8-(3-
trifluoromethyl-phenyl)-2,3-dihydro-5H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (43)
Isolated in 54% overall yield as a white non-crystalline solid.
[a
]
D
ꢀ32 (c 0.5, DMSO); 1H NMR (400 MHz, CDCl3) d 3.49–3.58
(m, 1H), 379–3.91 (m, 1H), 4.73 (s, 2H), 5.51–5.60 (m, 1H), 6.31–
6.41 (m, 2H), 6.48–6.59 (m, 2H), 6.91–7.01 (m, 2H), 7.10–7.25
(m, 2H), 7.33–7.44 (m, 2H), 7.50–7.76 (m, 4H); 13C NMR
(100 MHz, CDCl3) d 32.0, 63.9, 67.0, 105.4, 110.1, 111.5, 111.7,
113.5, 119.3, 124.1, 124.4 (q, J = 277.36 Hz), 125.4 (d, J = 3.43 Hz),
126.8 (d, J = 3.3 Hz), 130.0 (q, J = 31.93 Hz), 130.4, 130.5, 131.0,
134.4, 136.9, 149.1, 149.4, 156.6, 158.2, 159.2, 160.4, 169.9. HRMS
(electrospray ionization) calcd for [MꢀH] C28H19F3NO5S 538.0936,
obsd 538.0926.
4.2.34. (3R)-8-Cyclopropyl-7-[3-(naphthalen-1-yloxymethyl)-
benzyl]-5-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (40)
Isolated in 30% overall yield as a colorless foam. [
a
]
ꢀ17 (c
4.2.38. (3R)-8-Cyclopropyl-7-((3-phenoxy-phenoxy)methyl)-5-
oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyridine-3-carboxylic acid
(44)
D
0.25, CHCl3/MeOH 9:1); 1H NMR (400 MHz, DMSO-d6) d 0.44–
0.62 (m, 2H), 0.69–0.86 (m, 2H), 1.26–1.37 (m, 1H), 3.44–3.53
(m, 1H), 3.67–3.77 (m, 1H), 3.91–4.06 (m, 2H), 5.38 (m, 1H), 5.86
(s, 1H), 7.00–7.06 (m, 1H), 7.19–7.24 (m, 1H), 7.34–7.55 (m, 7H),
7.84–7.89 (m, 1H), 8.17–8.23 (m, 1H);13C NMR (100 MHz, DMSO-
d6) d 7.4, 7.7, 10.9, 31.3, 38.2, 62.8, 69.3, 105.8, 111.8, 114.2,
120.1, 121.5, 125.0, 125.4, 125.5, 126.1, 126.5, 127.5, 128.1,
128.5, 128.7, 134.1, 137.4, 138.9, 148.4, 153.6, 156.2, 160.1,
169.7. HRMS (electrospray ionization) calcd for [MꢀH] C29H24NO4S
482.1426, obsd 482.1416.
Isolated in 61% overall yield as a grey non-crystalline solid. [a]
D
ꢀ44 (c 0.5, DMSO); 1H NMR (400 MHz, CDCl3) d 0.49–0,63 (m, 2H),
0.78–0.84 (m, 2H), 1.58–1.64 (m, 1H), 3.50–3.55 (m, 1H), 3.75–3.82
(m, 1H), 5.14 (s, 2H), 5.38–5.43 (m, 1H), 6.14 (s, 1H), 6.55–6.59 (m,
1H), 6.65 (s, 1H), 6.77–6.81 (m, 1H), 7.00–7.05 (m, 2H), 7.13–7.18
(m, 1H), 7.27–7.33 (m, 1H) 7.36–7.42 (m, 2H). 13C NMR
(100 MHz, CDCl3) d 6.7, 6.8, 9.8, 31.4, 62.7, 66.1, 105.1, 109.7,
109.9, 110.8, 111.3, 119.0, 123.7, 130.0, 130.6, 148.5, 151.7,
156.1, 158.0, 159.2, 160.0, 169.6. HRMS (electrospray ionization)
calcd for [MꢀH] C24H20NO5S 434.1062, obsd 434.1051.
4.2.35. (3R)-7-(Anthracen-9-ylmethyl)-5-oxo-8-(3-
(trifluoromethyl)phenyl)-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (41)
4.2.39. 8-Cyclopropyl-7-indol-1-ylmethyl-5-oxo-2,3-dihydro-
5H-thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (45)
Isolated in 21% overall yield as a yellow non-crystalline solid.
Isolated in 57% overall yield as a white non-crystalline solid by
following a previously published procedure and the use of naph-
thalene-1-boronic acid.
[a]
ꢀ4 (c 0.5, DMSO); 1H NMR
[a
]
D
ꢀ22 (c 0.33, CHCl3/MeOH 9:1); 1H NMR (400 MHz, CDCl3) d
D

3140
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
0.83–0.78 (m, 2H), 1.07–0.91 (m, 2H), 1.75–1.69 (m, 1H), 3,58 (d,
J = 11.36 Hz, 1H), 3.75–3.68 (m, 1H), 5.22 (s, 1H), 5.35 (d,
J = 8.59 Hz, 1H), 5.49 (s, 2H), 6.53 (d, J = 3.10 Hz, 1H), 7.07–7.01
(m, 1H), 7.16–7.09, (m, 1H), 7.28–7.23 (m, 2H), 7.57 (d,
J = 7.88 Hz, 1H); 13C NMR (100 MHz, CDCl3) d 7.9, 8.4, 11.25,
34.1 (2C), 67.1, 102.8, 110.7, 111.7, 113.9, 120.6, 121.8, 122.8,
129.7, 130.2, 137.8, 151.3, 155.5, 163.7, 173.9. HRMS (electro-
spray ionization) calcd for [MꢀLi] C20H17N2O3S 365.0960, obsd
365.0970.
4.2.43. 2-Methoxy-8-(1-methyl-1H-indol-3-yl)-7-((naphthalen-
1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-
3-carboxylic acid (49)
Isolated in 65% yield starting from 0.4 mmol of methylester pro-
tected 33. As a light pink foam in a 1:1.5 mixture of atropisomers.
1H NMR (400 MHz, CDCl3) d 3.34 (s, 3H, maj), 3.38 (s, 3H, min), 3.81
(s, 3H, min), 3.83 (s, 3H, maj), 4.84–5.06 (m, 2H), 5.70 (s, 1H, maj),
5.71 (s, 1H, min), 5.89 (s, 1H, maj), 5.92 (s, 1H, min), 6.46 (d,
J = 7.64 Hz, 1H, maj), 6.52 (d, J = 7.73 Hz, 1H, maj), 7.03–7.24 (m,
4H), 7.28–7.53 (m, 6H), 7.75–7.81 (m, 1H), 8.30–8.36 (m, 1H),
9.11 (br s, 1H). 13C NMR (100 MHz, CDCl3/MeOD (70:30)) d 33.07
(maj), 33.09 (min), 56.4 (maj), 56.6 (min), 67.1 (maj), 67.3 (min),
71.8, 87.9 (maj), 88.3 (min), 105.48 (maj), 105.51 (min), 107.89
(min), 107.93 (maj), 108.1 (min), 108.5 (maj), 110.06 (min),
110.14 (maj), 112.2 (maj), 112.6 (min), 119.7, 120.2 (min), 120.3
(maj), 121.09 (maj), 121.13 (min), 122.1, 122.56 (min), 122.63
(maj), 125.62 (maj), 125.64 (min), 125.7, 125.8, 126.66 (maj),
126.73 (maj), 126.74 (min), 127.2 (min), 127.7, 128.7 (min),
129.5 (maj), 134.8, 137.1 (min), 137.3 (maj), 148.0 (maj), 148.1
(min), 153.0 (min), 153.3 (maj), 153.77 (min), 153.79 (maj),
162.7, 167.5. HRMS (electrospray ionization) calcd for [MꢀH]
4.2.40. 8-(1-Methyl-1H-indol-3-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-2-phenyl-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (46)
Isolated in 54% yield over three steps starting from 0.4 mmol
of 33. As a light pink foam in a 1:1.5 mixture of atropisomers.
1H NMR (400 MHz, CDCl3) d 3.78 (s, 3H, min), 3.80 (s, 3H, maj),
4.85–5.07 (m, 2H), 5.29–5.33 (m, 1H), 5.84–5.90 (m, 1H), 6.49
(d, J = 7.66 Hz, 1H, maj), 6.54 (d, J = 7.62 Hz, 1H, min), 7.06–7.54
(m, 15H), 7.75–7.81 (m, 1H), 8.33–8.39 (m, 1H), 8.76 (br s, 1H).
13C NMR (100 MHz, CDCl3) d 33.0, 48.9 (maj), 49.3 (min), 66.7
(maj), 66.9 (min), 72.5 (min), 72.7 (maj), 105.1 (maj), 105.2
(min), 107.5 (min), 108.0 (min), 108.3 (maj), 108.5 (min), 109.7
(min), 109.9 (maj), 112.0 (maj), 112.3 (min), 119.0 (maj), 119.6
(min), 120.30 (min), 120.31 (maj), 121.0 (maj), 121.1 (min),
121.98 (min), 122.02 (maj), 122.5, 125.4 (min), 125.46 (maj),
125.49 (min), 125.5 (maj, 2C), 126.2 (maj), 126.4, 126.5 (2C),
126.7 (min), 127.41 (maj), 127.45 (min), 128.1, 128.69 (maj),
128.74 (min), 129.1, 129.2 (maj), 129.3 (min), 134.46 (maj),
134.48 (min), 136.8 (min), 137.0 (maj), 139.6 (maj), 139.7 (min),
149.8 (min), 149.9 (maj), 153.47 (maj), 153.50 (min), 153.8
(min), 154.2 (maj), 163.1 (min), 163.3 (maj), 167.99 (min),
168.04 (maj). HRMS (electrospray ionization) calcd for [MꢀH]
C29H23N2O5S 511.1328, obsd 511.1335.
4.2.44. 8-(Benzo[d][1,3]dioxol-5-yl)-2-methoxy-7-((naphthalen-
1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-
3-carboxylic acid (50)
Isolated in 65% yield as a light grey foam starting from 0.4 mmol
of methylester protected 22. 1H NMR (400 MHz, CDCl3) d 3.36 (s,
3H), 4.73–4.91 (m, 2H), 5.63 (s, 1H), 5.89 (s, 1H), 5.98–6.04 (m,
2H), 6.54–6.60 (m, 1H), 6.64–6.89 (m, 2H), 6.99 (s, 1H), 7.24–7.30
(m , 1H), 7.39–7.51 (m, 3H), 7.74–7.80 (m, 1H), 8.26–8.33 (m,
1H), 11.81 (br s, 1H). 13C NMR (100 MHz, CDCl3) d 56.6, 66.6,
71.9, 87.9, 101.4, 105.1, 109.0 (split, 108.9, 109.0), 109.8 (split,
109.4, 110.1), 112.6, 115.8, 121.1, 122.0, 123.3 (split, 123.0,
123.6), 125.4, 125.5, 125.6, 126.6, 127.4, 127.9 (split, 127.8,
127.9), 134.5, 146.9, 148.0 (split), 148.2 (split), 151.8, 153.5,
162.8, 166.7. HRMS (electrospray ionization) calcd for [MꢀH]
C34H25N2O4S 557.1535, obsd 557.1543.
4.2.41. 8-(Benzo[d][1,3]dioxol-5-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-2-phenyl-3,5-dihydro-2H-thiazolo[3,2-
a]pyridine-3-carboxylic acid (47)
C27H20NO7S 502.0961, obsd 502.0948.
Isolated in 62% yield as a grey foam starting from 0.4 mmol of
methylester protected 22. 1H NMR (400 MHz, CDCl3) d 4.76–4.93
(m, 2H), 5.23 (s, 1H), 5.84 (s, 1H), 5.98 (s, 2H), 6.60 (d,
J = 7.29 Hz, 1H), 6.67–6.87 (m, 3H), 7.04 (s, 1H), 7.24–7.35 (m,
6H), 7.40–7.53 (m, 3H), 7.75–7.81 (m, 1H), 8.31–8.37 (m, 1H),
11.87 (br s, 1H). 13C NMR (100 MHz, CDCl3) d 50.0 (split, 50.01,
50.09), 65.6, 71.9 (split, 71.88, 71.93), 101.4, 105.1, 109.0, 109.7
(split, 109.4, 110.1), 112.5, 114.9, 121.1, 122.0, 123.2 (split, 122.9,
123.6), 125.4, 125.5, 125.6, 126.4, 126.5, 126.6, 127.4, 127.8,
128.7, 129.2 (2C), 134.5, 139.3 (split, 139.3, 139.4), 148.0, 148.1
(split, 148.1, 148.2), 148.4, 151.9, 153.5, 162.7, 168.6. HRMS (elec-
trospray ionization) calcd for [MꢀH] C32H22NO6S 548.1168, obsd
548.1170.
4.2.45. 2-Methoxy-7-((naphthalen-1-yloxy)methyl)-5-oxo-8-
(thiophen-2-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (51)
Isolated in 65% yield as a light grey foam starting from 0.4 mmol
of methylester protected 18. 1H NMR (400 MHz, DMSO-d6) d 3.36
(s, 3H), 4.01–4.22 (m, 2H), 5.60 (s, 1H), 5.74 (s, 1H), 5.93 (s, 1H),
7.01–7.10 (m, 2H), 7.19–7.23 (m, 1H), 7.35–7.49 (m, 4H), 7.62–
7.68 (m, 1H), 7.73–7.78 (m, 1H), 7.81–7.87 (m, 1H). 13C NMR
(100 MHz, MeOD) d 37.7, 56.8, 72.8, 89.6, 111.2, 115.3, 124.8,
126.5, 126.8, 127.3, 128.6, 128.7, 128.79, 128.83, 129.7, 130.7,
133.0, 135.1, 135.4, 137.2, 150.3, 157.9, 163.4, 168.2. HRMS (elec-
trospray ionization) calcd for [MꢀH] C24H18NO4S2 448.0677, obsd
448.0691.
4.2.42. 7-((Naphthalen-1-yloxy)methyl)-5-oxo-2-phenyl-8-
(thiophen-2-yl)-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (48)
4.2.46. (3R)-8-(1-Methyl-1H-indol-3-yl)-6-(morpholinomethyl)-
7-((naphthalen-1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (52)
Isolated in 65% yield starting from 0.4 mmol of methylester pro-
tected 33. As a pink non-crystalline solid as a 1:1.4 mixture of
Isolated in 65% yield as a light yellow foam starting from
0.4 mmol of methylester protected 18. 1H NMR (400 MHz, CDCl3)
d 4.10–4.24 (m, 2H), 5.27 (d, J = 2.07 Hz, 1H), 5.66 (d, J = 2.19 Hz,
1H), 5.96 (s, 1H), 7.06–7.10 (m, 2H), 7.23–7.36 (m, 6H), 7.39–7.50
(m, 4H), 7.67–7.72 (m, 1H), 7.76–7.80 (m, 1H), 7.83–7.88 (m, 1H),
9.04 (br s, 1H). 13C NMR (100 MHz, CDCl3) d 36.9, 49.4, 72.5,
110.4, 114.8, 123.7, 125.5, 125.8, 126.4, 126.6 (2C), 127.6,
127.7, 128.0 (2C), 128.8 (2C), 129.29 (2C), 129.33, 131.7, 133.2,
133.9, 135.6, 139.1, 150.2, 157.4, 162.7, 167.8. HRMS (electro-
spray ionization) calcd for [MꢀH] C29H20NO3S2 494.0885, obsd
494.0892.
atropisomers. [
a
]
D ꢀ58 (c 0.27, DMSO); 1H NMR (400 MHz, MeOD)
d 2.36–2.54 (m, 4H), 3.37–3.56 (m, 8H), 3.59–3.74 (m, 3H), 4.80–
5.32 (m, 2H), 5.56–5.62 (m, 1H), 6.51 (d, J = 7.62 Hz, 1H maj),
6.61 (d, J = 7.65 Hz, 1H, min), 6.83–6.51 (m, 9H), 7.71–7.78 (m,
1H), 8.04–8.09 (m, 1H). 13C NMR (100 MHz, MeOD) d 32.6 (min),
32.7 (maj), 33.4 (maj), 33.7 (min), 53.9 (maj), 54.1 (min), 54.67
(2C, min), 54.70 (2C, maj), 65.9 (min), 66.0 (maj), 67.95 (2C,
min), 67.99 (2C, maj), 69.1 (min), 69.2 (maj), 105.7 (maj), 105.9

E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
3141
(min), 110.3 (min), 110.4 (maj), 110.5 (min), 110.8 (maj), 111.1
(min), 111.3 (maj), 120.3 (min), 120.4 (maj), 120.5 (maj), 121.2,
121.3 (min), 122.8, 122.85 (maj), 122.87 (min), 122.92 (maj),
122.94 (min), 126.0 (maj), 126.2 (min), 126.71 (maj), 126.75
(min), 126.81 (maj), 126.9 (min), 127.27 (maj), 127.35 (min),
128.38 (min), 128.42 (maj), 128.5 (maj), 128.6 (min), 130.1
(min), 131.0 (maj), 135.88 (maj), 135.92 (min), 138.0 (min),
138.1 (maj), 150.4 (min), 150.7 (maj), 151.5 (min), 151.7 (maj),
155.6 (min), 155.7 (maj), 163.99 (maj), 164.03 (min), 173.9
(min), 174.0 (maj). HRMS (electrospray ionization) calcd for [MꢀLi]
spray ionization) calcd for [MꢀLi] C29H23N2O5S 511.1328, obsd
511.1335.
4.2.50. (3R)-8-(Benzo[d][1,3]dioxol-5-yl)-6-(hydroxymethyl)-7-
((naphthalen-1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (56)
Isolated in 50% yield as a yellow non-crystalline solid starting
from 0.4 mmol of methylester protected 22. [
a
]
ꢀ10 (c 0.45,
D
DMSO); 1H NMR (400 MHz, DMSO-d6) d 3.50 (dd J1 = 2.08 Hz,
J2 = 11.80 Hz, 1H), 3.84 (dd J1 = 9.11 Hz, J2 = 11.78 Hz, 1H), 4.51–
4.59 (m, 2H), 4.96–5.06 (m, 2H), 5.57 (dd J1 = 2.02 Hz,
J2 = 9.04 Hz, 1H), 5.80–6.00 (m, 2H), 6.70–6.90 (m, 4H), 7.30–7.37
(m, 1H), 7.42–7.53 (m, 3H), 7.80–7.86 (m, 1H), 7.96–8.02 (m,
1H). 13C NMR (100 MHz, DMSO-d6) d 31.3, 54.6, 64.1, 64.3 (split,
64.28, 64.35), 101.1, 105.3, 108.3 (split, 123.4), 124.7, 125.3,
126.0 (2C), 126.4, 127.3, 129.9 (split, 129.8, 129.9), 133.9, 145.3
(split, 145.23, 145.80), 146.8 (split, 146.79, 146.86), 147.2, 147.5,
153.6, 160.3, 169.5. HRMS (electrospray ionization) calcd for
[MꢀLi] C27H20NO7S 502.0961, obsd 502.0964.
C33H30N3O5S 580.1906, obsd 580.1929.
4.2.47. (3R)-8-(Benzo[d][1,3]dioxol-5-yl)-6-
(morpholinomethyl)-7-((naphthalen-1-yloxy)methyl)-5-oxo-
3,5-dihydro-2H-thiazolo[3,2-a]pyridine-3-carboxylate lithium
salt (53)
Isolated in 56% yield as a light pink non-crystalline solid start-
ing from 0.4 mmol of methylester protected 22. [
a
]
ꢀ29 (c 0.22,
D
DMSO); 1H NMR (400 MHz, DMSO-d6) d 2.23 (br s, 4H), 3.35 (br
s, 4H), 3.46–3.60 (m, 3H), 3.78–3.89 (m, 1H), 4.97–5.17 (m, 2H),
5.53–5.60 (m, 1H), 5.82–5.99 (m, 2H), 6.70–6.92 (m, 4H), 7.31–
7.37 (m, 1H), 7.40–7.53 (m, 3H), 7.80–7.86 (m, 1H), 7.94–8.00
(m, 1H). 13C NMR (100 MHz, DMSO-d6) d 31.0, 52.1, 52.9 (2C),
64.0, 64.5, 65.8 (2C), 100.9, 105.0, 108.0 (split, 108.0, 108.1),
109.9 (split, 109.8, 110.0), 140.1, 120.0, 121.3, 121.7, 123.3,
124.7, 125.0, 125.8, 126.2, 127.1, 129.9, 133.8, 146.4, 146.6,
147.0, 147.5, 153.7, 160.7, 169.2. HRMS (electrospray ionization)
calcd for [MꢀLi] C31H27N2O7S 571.1539, obsd 571.1535.
4.2.51. (3R)-6-(Hydroxymethyl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-8-(thiophen-2-yl)-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (57)
Isolated in 53% yield as a yellow non-crystalline solid starting
from 0.4 mmol of methylester protected 18. [
a
]
D ꢀ3 (c 1.0, DMSO);
1H NMR (400 MHz, MeOD) d 3.59 (dd J1 = 1.45 Hz, J2 = 11.36 Hz,
1H), 3.77 (dd J1 = 8.83 Hz, J2 = 11.40 Hz, 1H), 4.28–4.48 (m, 4H),
5.59 (dd J1 = 1.41 Hz, J2 = 8.70 Hz, 1H), 6.68–6.77 (m, 2H), 7.05–
7.09 (m, 1H), 7.18–7.21 (m, 1H), 7.32–7.37 (m, 1H), 7.41–7.47
(m, 2H), 7.67–7.73 (m, 1H), 7.80–7.89 (m, 2H). 13C NMR
(100 MHz, MeOD) d 33.5, 33.9, 57.8, 68.9, 110.9, 123.8, 125.1,
126.0, 126.5, 126.7, 127.1, 127.7, 127.9, 128.0, 129.6, 130.2,
132,9, 135.1, 136.1, 138.3, 152.8, 153.4, 163.5, 174.0. HRMS (elec-
trospray ionization) calcd for [MꢀLi] C24H18NO4S2 448.0677, obsd
448.0673.
4.2.48. (3R)-6-(Morpholinomethyl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-8-(thiophen-2-yl)-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (54)
Isolated in 47% yield as a light pink non-crystalline solid start-
ing from 0.4 mmol of methylester protected 18. [
a
]
ꢀ7 (c 0.5,
D
DMSO); 1H NMR (400 MHz, DMSO-d6) d 2.24 (br s, 4H), 3.19–
3.33 (m, 6H), 3.52 (dd J1 = 1.71 Hz, J2 = 11.78 Hz, 1H), 3.86 (dd
J1 = 9.17 Hz, J2 = 11.76 Hz, 1H), 4.21–4.49 (m, 2H), 5.57 (dd
J1 = 1.65 Hz, J2 = 9.17 Hz, 1H), 6.79–6.87 (m, 2H), 6.96 (d,
J = 6.99 Hz, 1H), 7.37–7.43 (m, 2H), 7.46–7.53 (m, 2H), 7.73–7.78
(m, 1H), 7.87–7.98 (m, 2H). 13C NMR (100 MHz, DMSO-d6) d 31.1,
31.7, 52.6, 52.9 (2C), 64.7, 65.7 (2C), 107.4, 120.5, 122.7, 123.9,
125.2, 125.5, 125.9, 126.3, 126.7, 127.2, 128.3, 128.7, 131.1,
133.0, 135.0, 136.8, 149.6, 152.2, 160.8, 169.3. HRMS (electrospray
4.2.52. 8-(1-Methyl-1H-indol-3-yl)-6-(morpholinomethyl)-7-
((naphthalen-1-yloxy)methyl)-5-oxo-2-m-tolyl-5H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (58)
Isolated in 34% yield as a yellow non-crystalline solid starting
from 0.5 mmol of methylester protected 33. 1H NMR (400 MHz,
MeOD) d 2.30 (s, 3H), 2.48 (br s, 4H), 3.48–3.54 (m, 7H), 3.79 (s,
2H), 5.07–5.40 (m, 2H), 6.61 (d, J = 7.71 Hz, 1H), 6.93–6.98 (m,
1H), 7.11–7.24 (m, 5H), 7.28–7.49 (m, 6H), 7.53 (s, 1H), 7.72–
7.76 (m, 1H), 7.99–8.04 (m, 1H). 13C NMR (100 MHz, MeOD) d
21.3, 32.8, 54.3, 54.7 (2C), 66.2, 68.0 (2C), 106.1, 109.7, 110.3,
110.8, 118.6, 120.3, 120.7, 121.4, 122.8, 123.2, 125.2, 126.1,
126.5, 126.8, 126.9, 127.3, 128.0, 128.5, 129.79, 129.84, 130.6,
130.8, 131.4, 135.7, 135.9, 138.4, 139.9, 147.0, 149.9, 155.7,
161.4, 167.9. HRMS (electrospray ionization) calcd for [MꢀCO2Li]
ionization) calcd for [MꢀLi]
C28H25N2O4S2 517.1256, obsd
517.1270.
4.2.49. (3R)-6-(Hydroxymethyl)-8-(1-methyl-1H-indol-3-yl)-7-
((naphthalen-1-yloxy)methyl)-5-oxo-3,5-dihydro-2H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (55)
Isolated in 62% yield starting from 0.4 mmol of methylester pro-
tected 33. As a pink non-crystalline solid in a 1:1.2 mixture of
C39H34N3O3S 624.2321, obsd 624.2307.
atropisomers. [
a]
D
ꢀ21 (c 0.5, DMSO); 1H NMR (400 MHz, DMSO-
d6) d 3.44–3.50 (m, 1H), 3.56 (s, 3H, min), 3.62 (s, 3H, maj), 3.74–
3.80 (m, 1H), 4.54–4.68 (m, 2H), 4.88–5.18 (m, 2H), 5.51–5.58
(m, 1H), 6.63 (d, J = 7.69 Hz, maj), 6.72 (d, J = 7.65 Hz, min), 6.87–
7.00 (m, 1H), 7.07–7.15 (m, 1H), 7.18–7.27 (m, 2H), 7.31–7.51
(m, 5H), 7.77–7.82 (m, 1H), 7.93–8.02 (m, 1H). 13C NMR
(100 MHz, DMSO-d6) d 31.0 (maj), 31.2 (min), 32.3, 54.91 (min),
54.93 (maj), 64.5, 64.57 (min), 64.62 (maj), 105.3 (maj), 105.5
(min), 106.9 (maj), 107.0 (min), 108.6 (min), 109.2 (maj), 109.9
(maj), 110.1 (min), 119.1 (2C), 120.18 (maj), 120.2 (min), 121.5
(2C), 124.8, 125.27 (min), 125.29 (maj), 125.8 (min), 125.89
(maj), 125.93, 126.37, 126.41 (maj), 126.7 (min), 127.3, 129.0
(min), 129.9 (maj), 133.9, 136.15 (min), 136.24 (maj), 146.5
(min), 146.6 (maj), 148.6 (min), 148.7 (maj), 153.65 (min),
153.70 (maj), 160.50 (min), 160.53 (maj), 169.6. HRMS (electro-
4.2.53. 8-(Benzo[d][1,3]dioxol-5-yl)-6-(morpholinomethyl)-7-
((naphthalen-1-yloxy)methyl)-5-oxo-2-m-tolyl-5H-
thiazolo[3,2-a]pyridine-3-carboxylate lithium salt (59)
Isolated in 42% yield as a yellow non-crystalline solid starting
from 0.5 mmol of methylester protected 22. 1H NMR (400 MHz,
MeOD) d 2.34 (s, 3H), 2.45 (s, 4H), 3.48 (s, 4H), 3.72 (s, 2H),
5.19–5.29 (m, 2H), 5.85 (d, J = 36.04 Hz, 2H), 6.72–6.76 (m, 1H),
6.78–6.82 (m, 1H), 6.85–6.92 (m, 2H), 7.17–7.21 (m, 1H), 7.24–
7.32 (m, 2H), 7.37–7.48 (m, 3H), 7.50–7.55 (m, 1H), 7.58 (s, 1H),
7.75–7.80 (m, 1H), 8.00–8.06 (m, 1H). 13C NMR (100 MHz, MeOD)
d 21.4, 54.2, 54.6 (2C), 65.8, 68.0 (2C), 102.7, 106.0, 109.8, 111.4,
116.8, 118.8, 121.6, 122.8, 124.9, 125.0, 126.2, 126.6, 126.8,
126.9, 127.4, 128.5, 129.87, 129.94, 130.96, 130.98, 131.3, 135.7,
136.0, 140.0, 145.6, 148.9, 149.3, 149.6, 155.7, 161.2, 167.7. HRMS

3142
E. Chorell et al. / Bioorg. Med. Chem. 20 (2012) 3128–3142
(electrospray ionization) calcd for [MꢀCO2Li] C37H31N2O5S
References and notes
615.1954, obsd 615.1969.
1. Boucher, H. W.; Talbot, G. H.; Bradley, J. S.; Edwards, J. E.; Gilbert, D.; Rice, L. B.;
Scheld, M.; Spellberg, B.; Bartlett, J. Clin. Infect. Dis. 2009, 48, 1.
2. Wiles, T. J.; Kulesus, R. R.; Mulvey, M. A. Exp. Mol. Pathol. 2008, 85, 11.
3. Anderson, G. G.; Palermo, J. J.; Schilling, J. D.; Roth, R.; Heuser, J.; Hultgren, S. J.
Science 2003, 301, 105.
4. Mulvey, M. A.; Lopez-Boado, Y. S.; Wilson, C. L.; Roth, R.; Parks, W. C.; Heuser, J.;
Hultgren, S. J. Science 1998, 282, 1494.
5. Mulvey, M. A.; Schilling, J. D.; Hultgren, S. J. Infect. Immun. 2001, 69, 4572.
6. Schilling, J. D.; Lorenz, R. G.; Hultgren, S. J. Infect. Immun. 2002, 70, 7042.
7. Norinder, B. S.; Köves, B.; Yadav, M.; Brauner, A.; Svanborg, C. Microb. Pathog.
2012, 52, 10.
8. Snyder, J. A.; Lloyd, A. L.; Lockatell, C. V.; Johnson, D. E.; Mobley, H. L. T. Infect.
Immun. 2006, 74, 1387.
9. Costerton, J. W.; Stewart, P. S.; Greenberg, E. P. Science 1999, 284, 1318.
10. Davies, D. Nat. Rev. Drug Disc. 2003, 2, 114.
11. Xu, K. D.; McFeters, G. A.; Stewart, P. S. Microbiology UK 2000, 146, 547.
12. Litwin, M. S.; Saigal, C. S.; Yano, E. M.; Avila, C.; Geschwind, S. A.; Hanley, J. M.;
Joyce, G. F.; Madison, R.; Pace, J.; Polich, S. M.; Wang, M. J. Urol. 2005, 173, 933.
13. Pratt, L. A.; Kolter, R. Mol. Microbiol. 1998, 30, 285.
14. Cegelski, L.; Pinkner, J. S.; Hammer, N. D.; Cusumano, C. K.; Hung, C. S.; Chorell,
E.; Aberg, V.; Walker, J. N.; Seed, P. C.; Almqvist, F.; Chapman, M. R.; Hultgren, S.
J. Nat. Chem. Biol. 2009, 5, 913.
15. Aberg, V.; Almqvist, F. Org. Biomol. Chem. 2007, 5, 1827.
16. Chorell, E.; Pinkner, J. S.; Phan, G.; Edvinsson, S.; Buelens, F.; Remaut, H.;
Waksman, G.; Hultgren, S. J.; Almqvist, F. J. Med. Chem. 2010, 53, 5690.
17. Pinkner, J. S.; Remaut, H.; Buelens, F.; Miller, E.; Åberg, V.; Pemberton, N.;
Hedenström, M.; Larsson, A.; Seed, P.; Waksman, G.; Hultgren, S. J.; Almqvist, F.
Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 17897.
18. Nuccio, S. P.; Baumler, A. J. Microbiol. Mol. Biol. Rev. 2007, 71, 551.
19. Chorell, E.; Edvinsson, S.; Almqvist, F. Tetrahedron Lett. 2010, 51, 2461.
20. Emtenäs, H.; Alderin, L.; Almqvist, F. J. Org. Chem. 2001, 66, 6756.
21. Aberg, V.; Sellstedt, M.; Hedenstrom, M.; Pinkner, J. S.; Hultgren, S. J.; Almqvist,
F. Bioorg. Med. Chem. 2006, 14, 7563.
22. Chorell, E.; Das, P.; Almqvist, F. J. Org. Chem. 2007, 72, 4917.
23. Pemberton, N.; Aberg, V.; Almstedt, T.; Westermark, A.; Almqvist, F. J. Org.
Chem. 2004, 69, 7830.
24. Pemberton, N.; Pinkner, J. S.; Jones, J. M.; Jakobsson, L.; Hultgren, S. J.; Almqvist,
F. Tetrahedron Lett. 2007, 48, 4543.
4.2.54. 8-(1-Methyl-1H-indol-3-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-2-m-tolyl-5H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (60)
Isolated in 66% yield as a yellow foam starting from 0.5 mmol of
methylester protected 33. 1H NMR (400 MHz, DMSO-d6) d 2.26 (s,
3H), 3.83 (s, 3H), 4.96–5.18 (m, 2H), 6.55 (s, 1H), 6.66 (d,
J = 7.61 Hz, 1H), 7.02–7.09 (m, 1H), 7.14–7.18 (m, 1H), 7.19–7.30
(m, 3H), 7.36–7.56 (m, 7H), 7.62 (s, 1H), 7.82–7.87 (m, 1H), 8.12–
8.18 (m, 1H). 13C NMR (100 MHz, CDCl3/MeOD (9:20)) d 21.4,
33.2, 67.3, 105.8, 107.4, 107.9, 108.3, 110.6, 119.6, 120.7, 121.4,
122.1, 123.0, 125.95, 125.99, 126.1, 126.2, 126.4, 126.7, 127.2,
128.0, 129.35, 129.42, 129.44 (2C), 130.0, 130.8, 135.2, 137.8,
139.4, 149.0, 150.1, 154.1, 160.7, 167.5. HRMS (electrospray ioniza-
tion) calcd for [MꢀCO2H] C34H25N2O2S 525.1637, obsd 525.1630.
4.2.55. 8-(Benzo[d][1,3]dioxol-5-yl)-7-((naphthalen-1-
yloxy)methyl)-5-oxo-2-m-tolyl-5H-thiazolo[3,2-a]pyridine-3-
carboxylic acid (61)
Isolated in 67% yield as a yellow foam starting from 0.5 mmol of
methylester protected 22. 1H NMR (400 MHz, DMSO-d6) d 2.31 (s,
3H), 5.11 (s, 2H), 6.08 (s, 2H), 6.54 (s, 1H), 6.81 (d, J = 7.59 Hz,
1H), 6.99–7.06 (m, 2H), 7.13 (s, 1H), 7.22–7.28 (m, 1H), 7.30–7.39
(m, 2H), 7.40–7.57 (m, 5H), 7.84–7.90 (m, 1H), 8.12–8.18 (m,
1H). 13C NMR (100 MHz, CDCl3/MeOD (9:20)) d 21.4, 40.4, 67.3,
102.3, 105.9, 108.7, 110.0, 110.3, 114.2, 121.6, 122.3, 123.9,
125.9, 126.1, 126.2, 126.2, 127.1, 128.0, 128.4, 129.0, 129.6,
129.7, 129.8, 131.5, 135.3, 139.7, 148.0, 148.4, 149.1, 149.4,
154.1, 160.3, 163.5. HRMS (electrospray ionization) calcd for
[MꢀCO2H] C32H22NO4S 516.1270, obsd 516.1263.
25. Wold, S.; Esbensen, K.; Geladi, P. Chemom. Intell. Lab. Syst. 1987, 2, 37.
26. Eriksson, L.; Johansson, E.; Kettaneh-Wold, N.; Wikstrom, C.; Wold, S. Design of
Experiments, Principles and Applications; Umetrics Academy, 2000.
27. St. John, R. C.; Draper, N. R. Technometrics 1975, 17, 15.
28. Linusson, A.; Elofsson, M.; Andersson, I. E.; Dahlgren, M. K. Curr. Med. Chem.
2001, 17.
Acknowledgments
F.A. was supported by the Swedish Research Council (Grant
621-2010-4730), the Knut and Alice Wallenberg Foundation, JC
Kempe Foundation (SJCKMS), S.H. was supported by NIH grants
AI048689, AI049950, and AI029549, and A.L. was supported by
the Swedish Research Council (Grant 2008-3672).
29. O’Toole, G. A.; Kolter, R. Mol. Microbiol. 1998, 28, 449.
30. Bylesjo, M.; Rantalainen, M.; Cloarec, O.; Nicholson, J. K.; Holmes, E.; Trygg, J. J.
Chemometr. 2006, 20, 341.
31. Wold, S.; Ruhe, A.; Wold, H.; Dunn, W. J. SIAM J. Sci. Stat. Comp. 1984, 5, 735.
32. Wold, S.; Sjostrom, M.; Eriksson, L. Chemom. Intell. Lab. Syst. 2001, 58, 109.
33. Aberg, V.; Das, P.; Chorell, E.; Hedenstrom, M.; Pinkner, J. S.; Hultgren, S. J.;
Almqvist, F. Bioorg. Med. Chem. Lett. 2008, 18, 3536.
34. Aberg, V.; Hedenstrom, M.; Pinkner, J. S.; Hultgren, S. J.; Almqvist, F. Org.
Biomol. Chem. 2005, 3, 3886.
35. ChemACX2002, CamebridgeSoft; Cambridge, MA, 2002.
Supplementary data
36. MOE; Chemical Computing Group Inc.: Montreal, Quebec, Cananda, 2004.
37. SIMCA-P+, 12.0; Umetrics AB: Box 7960, Umeå, Sweden, 2008.
38. MODDE, 7.0; Umetrics AB: Box 7960, Umeå, Sweden.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2012.01.048.