Identification of an orally efficacious matrix metalloprotease 12 inhibitor for potential treatment of asthma

Article abstract of DOI:10.1021/jm900809r

MMP-12 plays a significant role in airway inflammation and remodeling. Increased expression and production of MMP-12 have been observed in the lungs of asthmatic patients. Compound 27 was identified as a potent and selective MMP-12 inhibitor possessing go

Full text of DOI:10.1021/jm900809r

5408 J. Med. Chem. 2009, 52, 5408–5419
DOI: 10.1021/jm900809r
Identification of an Orally Efficacious Matrix Metalloprotease 12 Inhibitor for
Potential Treatment of Asthma
Wei Li,*,† Jianchang Li,† Yuchuan Wu,† Fabio Rancati,^ Stefania Vallese,^ Luca Raveglia,^ Junjun Wu,†
Rajeev Hotchandani,† Nathan Fuller,† Kristina Cunningham,† Paul Morgan,‡ Susan Fish,‡ Rustem Krykbaev,‡ Xin Xu,§
Steve Tam,† Samuel J. Goldman,‡ William Abraham, Cara Williams,‡ Joseph Sypek,‡ and Tarek S. Mansour†
†Chemical Sciences and ‡Inflammation and §Drug Safety and Metabolism, Wyeth Research, 200 Cambridge Park Drive, Cambridge,
Massachusetts 02140, Mount Sinai Medical Center, 4300 Alton Road, Miami Beach, Florida 33140, and ^NiKem Research S.r.L.,
Via Zambeletti 25, 20021 Baranzate (MI), Italy
Received April 27, 2009
MMP-12 plays a significant role in airway inflammation and remodeling. Increased expression and
production of MMP-12 have been observed in the lungs of asthmatic patients. Compound 27 was
identified as a potent and selective MMP-12 inhibitor possessing good physicochemical properties. In
pharmacological studies, the compound was orally efficacious in an MMP-12 induced ear-swelling
inflammation model in the mouse with a good dose response. This compound also exhibited oral
efficacy in a naturally Ascaris-sensitized sheep asthma model showing significant inhibition of the late
phase response to allergen challenge. This compound has been considered for further development as a
treatment therapy for asthma.
Introduction
and airway hyper-responsiveness in response to allergen.9,10
These mice also have less peribronchial fibrosis accompanied
by reduced levels of R-smooth muscle actin and collagen type
III deposition as detected by immunohistochemistry (IHC).11
Furthermore, transgenic animals that overexpress IL-13 de-
velop alveolar and lung enlargements, compliance alterations,
respiratory failure, and death that are, in part, mediated by
MMP-12. MMP-12 also makes a critical contribution to the
accumulation of eosinophils and macrophages within the
lungs of these mice and plays an important role in the IL-
13-mediated induction of mRNA for MMP-2, -9, -13, and
-14.12 Significant increases in the expression of MMP-12
following antigen challenge or IL-13 exposure have been
observed in both mouse and rat models of allergen-induced
asthma.13-15 IHC analyses in these studies revealed that
MMP-12 was primarily expressed in airway epithelia and
alveolar macrophages.16 These findings are consistent with
in vitro data that both human bronchial epithelial cells17 and
human airway smooth muscle cells18 can also express and
secrete MMP-12 upon stimulation with pro-inflammatory
cytokines. Moreover, as detected by IHC, significantly in-
creased levels of MMP-12 have been noted within airway
smooth muscle of large airways in human fatal asthmatic
patients when compared to nonasthmatics.19 Collectively,
these findings provide support for the potential involvement
of MMP-12 in the inflammatory response and tissue remodel-
ing in asthma and its role in contributing to the development
of disease pathology.
Asthma is a chronic pulmonary disease thatis characterized
by airway inflammation, lung tissue remodeling, and progres-
sive airflow obstruction that is reversible. This respiratory
condition affects more than 300 million people worldwide,
and this number is expected to grow due to increased
prevalence with increasing age and environmental factors.1
Presently, there are only symptomatic therapies, and no
disease-modifying drugs are available for this disease.2-4
Chronic inflammation and the pathologic degradation of
the extracellular matrix (ECMa) of the bronchial wall
may represent important causes of airflow obstruction in
asthma. Matrix metalloproteinases (MMPs) have been sug-
gested to be the major proteolytic enzymes that induce this
airway remodeling.5,6
Macrophage metalloelastase (MMP-12) in particular, has
been demonstrated to play a significant role in allergic airway
inflammation and remodeling.7 MMP-12 is the primary
elastolytic enzyme of alveolar macrophages.8 Preclinical stu-
dies support blocking MMP-12 as a valid approach for
therapeutic intervention in asthma. Specifically, MMP-12
deficient mice display markedly reduced airway eosinophilia
*To whom correspondence should be addressed. Phone: 1-617-665-
5625. Fax: 1-617-499-1017. E-mail: weili@wyeth.com.
a Abbreviations: ECM, extracellular matrix; MMP-12, matrix metal-
loprotease 12; MMP-13, matrix metalloprotease 13; MMP-2, matrix
metalloprotease 2; COPD, chronic obstructive pulmonary disease;
mCPBA: meta-chloroperoxybenzoic acid; TFA, trifluoroacetic acid;
DBF, dibenzofuran; DBT, dibenzothiophene; DCM, dichloromethane;
HTS, high-throughput screening; IHC, immunohistochemistry; ZCG,
zinc chelating group; SAR, structure-activity relationship; PK, pharmaco-
kinetics; HLM, human liver microsomes; MLM, mouse liver microsomes;
hERG, human ether-a-go-go related gene; QD, quaque die (once a day); BID,
bis in die (twice a day); PO, per os (by mouth); ID, intradermal; rh,
recombinant human.
Human MMP-12 is a 54 kDa proenzyme containing 470
amino acids composed of three domains: the pro-domain
(9 kDa), the catalytic domain (22 kDa), and the hemopexin-
like domain (23 kDa). The pro-domain includes a highly
conserved cysteine residue that coordinates with the zinc
ion to maintain the enzyme’s latency. The catalytic domain
r
pubs.acs.org/jmc
Published on Web 08/17/2009
2009 American Chemical Society

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17 5409
Table 1. Selectivity Achieved with DBF and DBT Analogues
IC50 (nM)
selectivity over
MMP-13 (fold)
compd
MMP-12
MMP-13
Figure 1. The structures of compounds 1 and 8.
1
14
38
1.3
2500
0.1
65
(R)-2a
(S)-2b
(R)-3a
(S)-3b
(22 kDa) bears the zinc-binding motif composed of three-
conserved histidines coordinated with the zinc ion.8 This is the
domain that was used in our FRET assay for compound
screening. The hemopexin domain20 is attached to the cataly-
tic domain by a hinge region. The functions of this domain
include substrate recognition, tissue inhibitor binding, and
localization of the enzyme in the extracellular matrix com-
partment.
600
87
25000
13800
60000
42
158
80
750
Table 2. SAR of the DBT Sulfonamide Analogues
Although MMP-12 is considered to be the most active
MMP against elastin,21 its substrates have been identified to
include many other extracellular matrix components. Those
include fibronectin, fibrillin-1, laminin, entactin, type IV
collagen fragments, chondroitin sulfate, proteoglycans, and
vitronectin.22,23 In addition to inflammatory respiratory dis-
eases, MMP-12 has been considered to be a therapeutic target
for other chronic inflammatory, as well as musculoskeletal,
neurological, cardiovascular, and neoplastic diseases.24,25
Support for targeting these disease areas and MMP-12’s role
in their disease pathophysiology has been obtained largely
with animal models, including gene knockout and transgene
studies. These, in part, include in vivo studies in models
of multiple sclerosis,26,27 aortic aneurysm28 and atherosclero-
sis,29-32 and rheumatoid arthritis.33 Herein, we report our
drug discovery efforts focused on targeting MMP-12 for
asthma with the identification of a potent and orally effica-
cious compound, MMP145 (27).
IC50 (nM)
substituents A/C ring
compd
MMP-12
MMP-13
C2
C2
C3
C3
C7
C7
C8
C8
(R)-4a
(S)-4b
(R)-5a
(S)--5b
4400
2100
>25000
>25000
277
60.0
50.0
1135
87 nM vs 38 nM; 3b36 vs 2b, 750 nM vs 600 nM, respectively).
However, the DBT analogues have better selectivity over MMP-
13 than the corresponding DBF compounds (DBT 3a with 158-
fold vs DBF 2a with 65-fold). A chiral recognition trend for the
stereogenetic center of the amino acid is also observed. The (R)-
enantiomer 3a not only has better potency than the (S)-isomer
3b (IC50: 87 vs 750 nM) but also achieves better selectivity over
MMP-13. For example, the (R)-3a is 158-fold selective over
MMP-13, whereas the (S)-3b is only 80-fold selective.
Development of SAR
Development of SAR was focused on modification of
compounds composed of tricyclic cores, such as the dibenzo-
furan (DBF) or dibenzothiophene (DBT). One of the ad-
vanced DBF compounds, MMP408 (8, Figure 1), is a potent,
selective, and orally available inhibitor with therapeutic po-
tential for treatment of COPD.34 SAR for this DBF series has
been well-defined and could be used as a parallel frame of
reference for the development of SAR of the structurally
related DBT system. The tricyclic compound 8 was derived
from a biphenyl MMP-13 inhibitor 135 (Figure 1) via a
traditional medicinal chemistry approach. The tricyclic DBF
core has demonstrated the advantage of increased MMP-12
potency and selectivity over other MMPs. Therefore, the
expansion of SAR to the DBT system was warranted. SAR
developed for both DBT and DBF systems may provide more
options for selecting lead candidates.
With the preliminary favorable observations on potency,
selectivity, and chiral recognition, full SAR was developed for
the DBT system (Tables 2 and 3). New analogues from DBF
were also investigated to maximize the likelihood of success in
discovery of new drug candidates from these systems.
Derivatization on the DBT C-ring led to the preparation of
the sulfonamide analogues (Table 2). As shown by the IC50
values, potencies of these new sulfonamide analogues against
MMP-12 were reduced by comparison with the unsubstituted
counterparts (4a/b over 3a/b, respectively). Chiral recognition
appears to be weak (5a vs 5b for example). Although the C3/
C8 regioisomers (5a and 5b) have better potency over the C2/
C7 counterparts (4a and 4b), these preliminary data suggested
that derivatization for sulfonamides was not the best ap-
proach for the SAR development.
Table 3 shows the SAR of the C-ring carbamate (Y=CO,
R2=OR), and urea (Y=CO, R2=NRR0) analogues derived
from modifications on the DBT and DBF C-ring. As shown
by the IC50 values, potencies of some analogues have increased
to single digit nanomolar or even subnanomolar (7b),
with carbamates being more potent than the sulfonamides and
ureas.
Before committing efforts into full SAR development
activity, several C-ring unsubstituted DBT analogues were
synthesized to assess the feasibility of this approach (Table 1).
The SAR data provided primary information for comparison
with the corresponding DBF analogues.
As seen in Table 1, the new DBT analogues are slightly less
potent than the corresponding DBF counterparts (3a vs 2a,

5410 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17
Table 3. SAR of Carbamate and Urea Analogues
Li et al.
IC50 (nM)
substituents A/C ring
R1
R2
Y
X
compd
MMP-12
MMP-13
C2
C2
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C3
C7
C7
C8
C8
C8
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C7
C8
C8
C7
C7
C7
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
O-methyl
O-methyl
O-methyl
O-methyl
O-methyl
O-methyl
O-methyl
O-methyl
O-methyl
CO
CO
CO
CO
CO
CO
CO
CO
CO
H
S
S
(R)-6a
(S)-6b
(R)-7a
(S)-7b
(S)-8
2900
7300
1.8
>25000
>25000
1.22
65
S
S
0.4
2.0
O
S
120
(R)-9a
(R)-9b
(R)-10a
(R)-10b
(S)-11
(R)-12a
(S)-12b
(S)-13
(S)-14
(S)-15
(S)-16
(S)-17
(S)-18
(S)-19
(S)-20
(S)-21
(S)-22
(S)-23
(R)-24a
(S)-24b
(S)-25
(S)-26
(S)-27
(S)-28
(S)-29
(S)-30
29.0
9.0
1353
632
S
O
O
S
11.1
14.0
42.0
100.1
6.3
215
505
>1000
NDa
56
O-ethyl
O-ethyl
O-isopropyl
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
H
S
S
S
23.1
20.2
7.6
147
334
O-isobutyl
S
O-2-(methylsulfonyl)ethyl
O-(4)-butynyl
O-phenyl
S
40
23
S
6.1
S
25.0
36.3
28.0
260.0
>1000
187
225
235
O-p-tolyl
O-(4-fluoro)phenyl
N-ethyl
S
S
217
809
S
N-cyclepentyl
N-(thiophen-2-yl)ethyl
N-(thiophen-2-yl)ethyl
N-phenyl
S
>1000
456
187
S
O
S
18.0
1470
89.0
34.1
5.0
1286
269
N-phenyl
N-benzyl
O-CH2CH3
S
S
200
100
O
O
O
S
R1, R2 = -CH2CH2O-
R1, R2 = -CH2CH2O-
R1, R2 = -CH2CH2O-
H
1.4
9.2
106
370
44.0
17.0
140
1093
O
a ND, not determined
The SAR for the carbamate analogues is well-defined. To
withthe DBFsystem(23vs30), albeit the ureasfromDBFC3/
C7 are in general more potent than those of DBT (23 vs 22, 18
vs 187 nM, respectively). TheC3/C7 ureas appear toprefer the
S-configuration (24b vs 24a, 89 vs 1470 nM, respectively).
However, this preference did not lead to positive outcomes
compared to the parent aniline 11.
Because the carbamate analogues provided the best po-
tency and selectivity, further SAR development on the carba-
mates was warranted. The investigation of SAR led to the
preparation of cyclic carbamate derivatives (27-29). The
DBF cyclic carbamate 27 with a C3/C8 regio combination
has an IC50 value of 1.4 nM, which is a 3.5-fold increase in
potency compared to that of the corresponding open chain
ethyl carbamate 26 (5 nM). However, when the regio combi-
nation changed to C3/C7 (28), a 6.5-fold drop in potency was
observed. It is also interesting to note that the DBT cyclic
carbamate 29 (C3/C7) experienced an even greater reduction
in activity (44 nM). Expanding the five-membered ring to six
with an additional methylene also resulted in loss of potency
(not shown).
determine the best regiochemistry, methyl carbamates were
made for all regio combinations (C2/C7, C3/C8, and C3/C7).
(D)- and (L)-Valines were also used to investigate the chiral
recognition. Among the three regioisomers, the C3/C8 com-
bination is more potent than its C2/C7 and C3/C7 counter-
parts. For example, the IC50 of 7b (C3/C8) is 0.4 nM, whereas
the 6b (C2/C7) and 9b (C3/C7) are 7300 and 9 nM, respec-
tively. It is also notable that different regio combinations
prefer different chiral configuration. For C2/C7 regioisomers,
the (R)-enantiomer is more potent than the (S)-isomer (6a vs
6b). For the C3/C8, the (S)-enantiomer 7b is instead preferred
over the (R)-7a (0.4 vs 1.8 nM), albeit both enantiomers are
very potent. For the C3/C7 combination, the (S)-configura-
tion is also preferred (9b vs 9a, 12b vs 12a). It appears that the
C3/C7 combination doesprefer functionalizedO-alkyl groups
over simple alkyls (15, 16 vs 13, 14). O-Aryl carbamates (17,
18, and 19) also have reduced potency.
Efforts to improve potency through urea substituents were
not successful. None of the urea analogues resulted in a
notable increase in potency. For example, the IC50 of the
most potent urea 25 is 34 nM, which was not a significant
improvement over its parent aniline 11 (42 nM). A similar lack
of potency improvement with the urea analogues was seen
Chemistry
Preparation of the above analogues requires key nitro-DBT
sulfonyl chlorides 33, 36, and 38 (Schemes 1 and 2). Synthetic

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17 5411
Scheme 1. Preparation of the Key DBF Intermediate 33
Reagents and conditions: (a) ClSO3H, TFA, 97%; (b) SOCl2, DMF (cat.) 90-100%; (c) mCPBA, DCM 79%; (d) HNO3/TFA, 83%; (e) HOAc, conc
HBr, 89%.
Scheme 2. Preparation of the Key DBF Intermediates 36 and 38
Reagents and conditions: (a) SOCl2, DMF (cat.), 90-100%; (b) HNO3, TFA, 97%; (c) 30% oleum, 90% HNO3, 94%.
Scheme 3. Preparation of C2/C7 Methyl Sulfonamides 4a and 4b
Reagents and conditions: (a) (D/L)-valine esters, TEA, DCM, 94%; (b) Pd/C, H2, MeOH, 98%; (c) CH3SO2Cl, pyridine, DCM, 85%; (d) TFA,
DCM, 98%.
routes with high overall yields for preparation of the three key
nitro-DBT sulfonyl chlorides were developed according to
their defined combinations. Another key feature for these
developed routes is the high regioselectivity, which is crucial
for synthetic efficiency.
Preparation of the sulfonyl chloride 33 (C2/C7 combina-
tion) was straightforward and required two steps from a
known intermediate 31.37 Sulfonation of 31 with chlorosulfo-
nic acid in chloroform afforded the desired C2-sulfonic acid
32, which was treated with thionyl chloride to convert the acid
tosulfonyl chloride 33(Scheme 1) inhighyield. Preparationof
31 is a three-step process from the commercially available
dibenzothiophene. The first step involved an oxidation of the
DBT to the corresponding sulfoxide 31b using chlorine gas in
DCM. However, overoxidation to sulfone was observed. A
modified procedure using one equivalent mCPBA in DCM
provided the selective oxidation to 31b with high yield. The
electron-deficient sulfoxide directed the nitration to the de-
sired meta position to generate the isomer 31a,38 which was
reduced by followingthe knownprocedurewithHBr toafford
31.39 The overall yield was 58%, much better than the direct
nitration on DBT, where the 3-nitro DBT was obtained as a
minor isomer with only 15% yield.40
Preparation of the 8-nitro-DBT-3-sulfonyl chloride 36
(Scheme 2) would require a long route with many functional
group manipulations if starting from the 3-nitro DBT 31 via
reduction of -NO2 to -NH2, diazonium salt formation,
displacement with SO2, followed by conversion to 35. We
chose to investigate a new route based on a commercially
available compound, 5-(trifluoromethyl)-5H-dibenzo[b,
d]thiophenium-3-sulfonate (34), which has been developed
as a unique electrophilic trifluoromethylating agent.41 After

5412 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17
Li et al.
optimization of the reaction conditions, it was found that
treatment of 34 with neat thionyl chloride at reflux in the
presence of a catalytic amount of DMF generated the sulfonyl
chloride 35 in quantitative yield. To our delight, the CF3
group was removed simultaneously from the thiophene sulfur
atom under the reaction conditions. Removal of the CF3
group also set the stage for regioselective nitration (para-
orientation toS), which ledto the formation of the desired C8-
nitro compound 36 upon treatment of 35 with nitric acid in
TFA (Scheme 2, route A).
Preparation of the 7-nitrodibenzo[b,d]thiophene-3-sulfonyl
chloride (38) takes advantage of the existing strong electron-
withdrawing effect imparted by the trifluoromethylsulfonium
cation (Sþ-CF3), which should direct the nitration at the
desired C7 position (meta-orientation to S).42 It came as no
surprise that this group also substantially deactivates the C-
ring, and harsh conditions (reaction carried out in 30% oleum,
90% HNO3) had to be used to affect the nitration process to
obtain the key intermediate 37 (Scheme 2, route B). Treatment
of 37 with thionyl chloride in the presence of catalytic amount
of DMF afforded 38 in excellent yield (94%).43
As illustrated in Scheme 2, preparation of the key inter-
mediates 36 and 38 is an integral chemistry effort for max-
imizing synthetic efficiency; the same starting material 34 was
used, but the reactivity was tempered at different stages to
generate the desired regioisomers 36 and 37 from nitration.
With the three key intermediates 33, 36, and 38 in hand,
preparation of the DBT analogues for SAR development was
straightforward. Scheme 3 illustrates the synthesis of 4a and
4b. The amino acid moiety of 4a/4b was installed via coupling
of the sulfonyl chloride 33 with either (D)- or (L)-valine t-butyl
ester in the presence of base to afford 39. The nitro group on
the C ring of 39 was reduced to the corresponding aniline
analogue 40 in high yield via palladium catalyzed hydrogen-
olysis. Compound 40 was then derivatized by treatment with
methylsulfonyl chlorideinthe presence of base to generate the
penultimate t-butyl ester 41. The t-butyl was removed under
acidic conditions to generate the desired acid products 4a/4b
in good overall yield from compound 33.
The C3/C8 methyl sulfonamides analogues 5a and 5b were
prepared similarly using the intermediate 36.
Scheme 4 illustrates the synthesis of the methyl carbamate
analogues. Compound 40 was treated with methyl chloro-
formate in the presence of pyridine at0 ꢀC in DCMto produce
the t-butyl ester methyl carbamate. The t-butyl was removed
by reacting with TFA (30% in DCM) to generate the desired
carboxylic acids 6a/6b as a white powder.
Originally, the valine methyl esters were used for the
preparation of 6a/6b. However, saponification of the corre-
sponding penultimate methyl ester under basic conditions
resulted in the desired acids but with contamination arising
from the decomposition of the carbamate moiety. Thus, it was
replaced with the t-butyl ester. Chiral analysis of 6a/6b con-
firmed that there was no impurity from epimerization of the
chiral center during the synthesis. Other carbamate and urea
analogues in Table 3 were prepared similarly using different
sulfonyl chloride and N-derivatization agents to afford ana-
logues from 7a to 26.
The cyclic carbamates 27-29 were prepared by a two-step
process. For example, compound 27 was prepared by treat-
ment of 46 with 2-bromoethyl chloroformate to form the open
chain carbamate 48, which was cyclized under basic condi-
tions (KHCO3/DMF) to generate 49. Treatment of 49 with
TFA resulted in the desired 27 as a white solid (Scheme 5).
Cyclic carbamates 28 and 29 were prepared similarly using
the corresponding aniline substrates with good yields.
Profiling of the Leads. Further profiling was focused on
the carbamate analogues due to their MMP-12 potencies.
Pharmacokinetic data indicate that carbamate analogues 7a,
7b, and 27 exhibit decent exposure and moderate bioavail-
ability in C57BL/6 mice (Table 4).
It is interesting to note that the (S)-enantiomer 7b has better
PK properties than the (R)-enantiomer 7a (lower clearance,
higher Cmax and AUC). Compounds 8 and 27 have the lowest
clearance among these analogues suggesting low metabolism.
These compounds were further evaluated in the metabolic
stability studies carried out in the liver microsomal system. All
the compounds in Table 3 showed very good stability in
mouse (C57BL/6, female), rat, and human liver microsomes
(t1/2 > 30 min). The acyl glucuronides and compounds from
Scheme 4. Preparation of C2/C7 Methyl Carbamates 6a and 6b
Reagents and conditions: (a) methyl chloroformate, TEA, DCM,
90-94%; (b) TFA, DCM, 95-98%.
Scheme 5. Preparation of the Cyclic Carbamate 27
Reagents and conditions: (a) ethyl chloroformate, TEA, DCM, 92%; (b) TFA, DCM, 95-98%; (c) 2-bromoethyl chloroformate, TEA, DCM, 91%;
(c) KHCO3, DMF, 85%.

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17 5413
Table 4. Pharmacokinetic Data for Selected Compounds (C57BL/6 Mice)
compd
IV (mg/kg)
Vdss (L/kg)
CL (mL/min/kg)
PO (mg/kg)
T1/2 (h)
Cmax (ng/mL)
AUC/dose (ng h/mL)/(mg/kg)
3
F%
7a
7b
8
2
2
2
2
3.7
1.7
1.9
0.8
59.9
31.2
17.2
18.0
30
30
30
10
4.6
3.1
3.0
3.1
738
1815
3084
456
53.4
182.9
249.2
152.4
19
34
27
17
27
Scheme 6. Plausible Pathway for the in Vitro Degradation of 8 to Aniline 51
Table 5. Cross-Species Activity and Selectivity Profile of 27
Cross Species MMP-12 Activity IC50 (nM)
mouse
27
human
1.4
rat
72
sheep
2.0
Selectivity over Other Human MMPs IC50 (nM)
MMP-1
5460
-2
-3
-7
-8
-9
-12
1.4
-13
46
-14
TACE
40000
Agg-1
18000
Agg-2
22600
66
300
7830
37
318
2250
amino acid side chain oxidation were the metabolites detected
by LCMS techniques in all species at a very low level.
Further in vitro metabolic stability of 7b and 8 was also
determined in cryopreserved hepatocytes of dog, monkey,
and human. In this system, the corresponding aniline meta-
bolite from 7b and 8 were detected. We hypothesized that the
free -NH at the carbamate moiety might be responsible for
the metabolic degradation to the anilines (Scheme 6).
The cyclic carbamate 27 was thus synthesized to replace
the free N-H and tested under the same conditions as that of
7b and 8. No aniline metabolite 51 was detected. The
improved metabolic stability of 27 supports the hypothesis
that the free N-H is a liability for the biological degradation.
Compound 27 did not inhibit CYP450 isoenzymes, such as
3A4, 2D6, and 2C9. Further drug safety studies for 27 were
performed with favorable results. For example, it is negative
in the screening Ames test and has no hERG activity at 10 µM
in the IonWorks Assay.
Compound 27 was also profiled for cross-species MMP-12
activity and selectivity against other human MMPs (Table 5).
Compared with human MMP-12, compound 27 has lower
potency against rodent MMP-12 (19- and 51-fold less active
for mouse and rat, respectively). However, it does have com-
parable sheep MMP-12 activity with an IC50 value of 2.0 nM,
which is equipotent to human. The compound also main-
tains a good selectivity profile over other human MMPs.
In Vivo Pharmacology. Compound 27 was evaluated orally
in two animal models: the mouse ear inflammation model
and the sheep asthma model.
To evaluate the compounds initially in vivo, an MMP-12
dependent inflammatory response in the ear was induced in
C57BL/6 mice by a single intradermal (ID) injection of
recombinant human (rh) MMP-12.44 A 2 h postadministra-
tion time point with rhMMP-12 was selected as the optimal
period to measure the inhibitory activity of MMP-12 com-
pounds. In this model, compound 27 was able to reproducibly
Figure 2. Compound 27 reduced edema in a mouse ear-swelling
model. To induce an MMP-12 mediated edematous reaction, mice
were challenged intradermally in the left ear with rhMMP-12. As a
control, the contralateral right ear was challenged with vehicle
alone. Edema was measured as an increase in ear thickness 2 h post
challenge (mean ( SE, n = 7-8 mice/group). Compound 27 was
administered orally (PO) the evening prior to challenge and again 2
h prior to challenge. Compound 27 significantly attenuated
rhMMP-12 induced ear edema (*** p < 0.0001) by approximately
40%, 35%, and 25% when administered at 30 (red bar), 10 (green
bar), and 3 (black bar) mg/kg PO, respectively, when compared to
identically challenged vehicle treated control animals (blue bar). In
each group of animals, the contralateral right ears that were
challenged ID with vehicle alone did not mount an edematous
reaction.

5414 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17
Li et al.
Figure 3. Compound 27 blocked the LAR in a sheep asthma model. To examine the effects on EAR and LAR, compound 27 was administered
BID at 10 mg/kg PO the day prior to Ascaris suum airway challenge. Animals received a third dose of compound 1 h prior to allergen challenge.
Airway resistance was measured throughout the course of the ensuing 8 h period (N=2).
To evaluate whether or not compound 27 could attenuate
the EAR and LAR phases of the bronchoconstrictive re-
sponse, animals received three doses of compound (twice the
day before allergen challenge and then 1 h prior to challenge,
at 10 mg/kg per dose, PO). For the measurement of AHR,
the sheep received a fourth dose of compound (8 h post
allergen challenge). AHR to aerosolized carbachol was
measured the day following Ascaris suum airway challenge.
As dosed, compound 27 significantly inhibited the LAR to
allergen challenge (Figure 3) and blocked the carbachol
induced AHR (Figure 4).
Figure 4. Compound 27 inhibited the AHR provoked by inhala-
tion of the cholinergic agonist carbachol in a sheep asthma model.
AHR was assessed by determining the cumulative carbachol con-
Conclusion
centration that increased specific lung resistance by 400% over the
In summary, molecules with drug-like properties for the
MMP-12 program were obtained via SAR development of
post saline value (PC400) (N=2).
both DBT and DBF derivatives. Modification to increase the
metabolic stability of the carbamate analogues resulted in 27,
which maintains the potency, selectivity, and bioavailability
as compared to 8. The key factor that stabilizes the carbamate
group from metabolic degradation is the removal of the free -
NH on the carbamate moiety via formation of the cyclic ring.
The demonstrated ability of 27 in attenuating episodic and
reversible airway narrowing supports further development of
inhibit rhMMP-12 induced inflammation when administered
16 and 2 h prior to the rhMMP-12 challenge. Specifically,
comparative evaluation of 3, 10, and 30 mg/kg, PO, BID
doses showed significant reductions in ear swelling at all
the doses examined (p < 0.0001) when compared to vehicle
controls. Histology studies suggested that the resulting
decrease in edema with compounds appeared to be due (data
not shown), at least in part, to a reduction in rhMMP-
this compound as a potential therapeutic for asthma.
12-associated degranulation of resident mast cells present in
the ear. The results of a representative study evaluating the
efficacy of 27 in the mouse ear-swelling model are shown in
Figure 2.
The oral efficacy of compound 27 was evaluated in a
sheep asthma model. In this model, sheep that are natu-
rally sensitized to the nematode Ascaris suum are chal-
Experimental Section
Determination of IC50 against Human MMP-12. The assays
for human MMP-12 and MMP-13 activity were performed by
incubating 20 μM of the fluorogenic peptide substrate MCA-
Pro-Leu-Gly-Leu-Dpa(DNP)-Ala-Arg (Anaspec, San Jose,
CA) with 0.5 nM recombinant human MMP-12 or MMP-13
lenged via the airways with an aerosol of Ascaris suum
to induce an early phase airway bronchoconstriction
(EAR) that occurs approximately 1 h post allergen chal-
lenge, followed by a late phase bronchoconstriction that
occurs approximately 6-8 h post challenge. The airways
of the challenged animals are also hyperresponsive to the
muscarinic agonist, carbachol, resulting in airway bronch-
oconstriction at much lower concentrations of carbachol
than is observed with nonchallenged animals. The airway
hyperresponsiveness (AHR) can be assessed by determin-
ing the cumulative carbachol concentration that increases
specific lung resistance by 400% over the post saline value
(PC400).
catalytic domain along with various concentrations of com-
pound in 50 mM HEPES, pH 7.5, 100 mM NaCl, 5 mM CaCl2,
0.005% Brij-35, and 10% DMSO. The rate of increase in
fluorescent signal was measured on a Safire plate reader
(Tecan, Mannedorf, Switzerland) exciting at a wavelength of
325 nm and measuring at an emission wavelength of 395 nm.
The enzymes were expressed in Escherichia coli, refolded from
insoluble inclusion bodies, and purified.
Determination of IC50 against Mouse MMP-12. The assay to
measure potency in mouse MMP-12 catalytic domain was
identical in format to the assay used for the human MMP
enzymes with the exception that 3 nM mouse MMP-12 was
required to obtain similar catalytic rates. Cleavage of 20 μM of
the MCA-Pro-Leu-Gly-Leu-Dpa (DNP)-Ala-Arg peptide was

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17 5415
measured over time, monitoring λex 325 nm and λem 395 nm
(Tecan Safire 2, Tecan, Mannedorf, Switzerland).
12.54 (s, 1H). HRMS: calcd for C18H20N2O6S3 þ Hþ, 457.05562;
found (ESI-FTMS, [M þ H]þ), 457.0548.
Determination of IC50 against Sheep MMP-12. The assay to
measure inhibitor potency in sheep MMP-12 catalytic domain
was identical in format to the assay used for the human MMP
enzymes. The concentration of sheep MMP-12 in the assay was
0.5 nM. Cleavage of 20 μM of the MCA-Pro-Leu-Gly-Leu-Dpa
(DNP)-Ala-Arg peptide was measured over time, monitoring
(S)-3-Methyl-2-(7-(methylsulfonamido)dibenzo[b,d]thiophene-
2-sulfonamido)butanoic Acid (4b). The title compound was pre-
pared as a white solid following the procedures described for the
preparation of 4a using (S)-tert-butyl 2-amino-3-methylbuta-
noate. 1H NMR (400 MHz, DMSO-d6) δ 0.80 (d, J = 6.8 Hz,
3H), 0.84 (d, J = 6.8 Hz, 3H), 1.87-2.03 (m, 1H), 3.10 (s, 3H),
3.64 (dd, J = 5.9, 9.5 Hz, 1H), 7.39 (dd, J = 2.0, 8.6 Hz, 1H),
7.83 (dd, J = 1.8, 8.6 Hz, 1H), 7.87 (d, J = 2.0 Hz, 1H), 8.03-
8.14 (m, 1H), 8.19 (d, J = 8.3 Hz, 1H), 8.41 (d, J = 8.6 Hz, 1H),
8.61 (d, J = 1.8 Hz, 1H), 10.16 (s, 1H), 12.55 (s, 1H). HRMS:
calcd for C18H20N2O6S3 þ Hþ, 457.05562; found (ESI-FTMS,
[M þ H]þ), 457.0555.
λex 325 nm and λem 395 nm.
Evaluation of the Efficacy of a MMP-12 Inhibitor in a Mouse
Ear-Swelling Model. Female C57BL/6 mice from Taconic
(Germantown, NY) 8-10 weeks in age were received and
allowed to acclimate at least one week prior to study. The mice
were then randomly assigned to four groups. Standard mouse
chow and water were offered ad libitum. The night prior to
study, mice were pre-dosed with vehicle, 30, 10, or 3 mg/kg (PO).
The following morning, the mice were again dosed with
vehicle (2% Tween 80 and 0.5% methylcellulose) or compound.
The mice were anesthetized with isofluororane (Baxter Health-
care, Deefield, IL) until they exhibited shallow breathing. Base-
line ear measurements were taken on all of the mice, left and
right ears with a Mitutoyo Micrometer (Grainger, Boston,
MA). Mice were then challenged intradermally in the left ear
with 2.5 μg/25 μL of human MMP-12 protein with a Hamilton
syringe and 30 gauge needle. Mice were also challenged with
vehicle (MMP-12 diluent) in the right ear [20 mM Tris (pH 7.5),
200 mM NaCl, 5 mM CaCl2 buffer]. Mice were placed back in
their respective cages for recovery. The ear thickness measure-
ments (extent of swelling) were taken at 2 h post challenge. The
extent of ear swelling was expressed as the increment of the
thickness (ꢀ10-4 inch) pre- and postchallenge at each individual
time point.
Evaluation of the Efficacy of a MMP-12 Specific Inhibitor in a
Sheep Asthma Model. Compounds were dosed either intrave-
nously or per oral route twice daily, the day before challenge,
and then the following day (day of Ascaris suum challenge) 1 h
prior to challenge and 8 h post challenge. Increases in airway
resistance were measured throughout the day to capture both
the early phase asthmatic response (EAR) and late phase
asthmatic response (LAR). Airway hyper-responsiveness
(AHR) to aerosolized carbachol was measured the following
day (24 h post challenge). Following AHR measurements, lungs
were lavaged and total cell counts were quantified in the BAL
fluid.
Chemistry. All reagents and solvents were of commercial
quality and used without further purification. Column chromato-
graphy was performed using Merck silica gel 60 (230-400
mesh). Proton nuclear magnetic spectroscopy 1H NMR spectra
were obtained on Bruker spectrometers. Low-resolution mass
spectra (MS) were obtained using a micromass platform elec-
trospray ionization quadrapole mass spectrometer. High reso-
lution exact mass measurements (HRMS) were performed on a
Bruker ApexIII 7T FT/ICR/MS. All intermediates were char-
acterized by 1H NMR. All new final SAR compounds were
determined to be consistent with proposed structure by 1H
NMR, MS, and HRMS and were greater than 95% pure in
two solvent systems (HPLC method 1: H2O-CH3CN; HPLC
method 2: H2O-MeOH) as determined using an Agilent 1100
HPLC instrument on a C18 column.
(R)-3-Methyl-2-(8-(methylsulfonamido)dibenzo[b,d]thiophene-3-
sulfonamido)butanoic Acid (5a). The compound was obtained as a
white solid (see Supporting Information for detailed procedures).
1H NMR (400 MHz, DMSO-d6) δ 0.79 (d, J = 6.8 Hz, 3H), 0.83
(d, J = 6.82 Hz, 3H), 1.87-2.02 (m, 1H), 3.07 (s, 3H), 3.61 (dd,
J = 5.9, 9.5 Hz, 1H), 7.46 (dd, J = 2.0, 8.7 Hz, 1H), 7.88 (dd, J =
1.5, 8.3 Hz, 1H), 8.08 (d, J = 8.6 Hz, 1H), 8.16 (d, J = 9.4 Hz, 1H),
8.19 (d, J = 2.0 Hz, 1H), 8.43 (d, J = 8.6 Hz, 1H), 8.46 (d, J = 1.8
Hz, 1H), 9.96 (s, 1H), 12.53 (s, 1H). HRMS: calcd for
C18H20N2O6S3 þ Hþ, 457.05562; found (ESI-FTMS, [M þ H]þ),
457.0546.
(S)-3-Methyl-2-(8-(methylsulfonamido)dibenzo[b,d]thiophene-
3-sulfonamido)butanoic Acid (5b). Following procedures for the
preparation of 5a and using (S)-tert-butyl 2-amino-3-methyl-
butanoate for the coupling reaction with the sulfonyl chloride
33, compound 5b was prepared as a white solid. 1H NMR (400
MHz, DMSO-d6) δ 0.79 (d, J = 6.6 Hz, 3H), 0.83 (d, J = 6.6 Hz,
3H), 1.89-2.01 (m, 1H), 3.07 (s, 3H), 3.61 (dd, J = 5.9, 9.47 Hz,
1H), 7.46 (dd, J = 2.3, 8.6 Hz, 1H), 7.88 (dd, J = 1.8, 8.3 Hz,
1H), 8.08 (d, J = 8.6 Hz, 1H), 8.16 (d, J = 9.4 Hz, 1H), 8.19 (d,
J = 2.0 Hz, 1H), 8.43 (d, J = 8.3 Hz, 1H), 8.47 (d, J = 1.5 Hz,
1H), 9.96 (s, 1H), 12.53 (s, 1H). HRMS: calcd for C18H20N2O6-
S3 þ Hþ, 457.05562; found (ESI-FTMS, [M þ H]þ), 457.0546.
(R)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]thiophene-2-
sulfonamido)-3-methylbutanoic Acid (6a). The title compound 6a
was prepared following the scheme and synthetic procedures
described in the Supporting Information section. 1H NMR (400
MHz, DMSO-d6) δ 0.81 (d, J = 6.8 Hz, 3H), 0.84 (d, J = 6.8 Hz,
3H), 1.88-2.03 (m, 1H), 3.64 (dd, J = 5.9, 9.5 Hz, 1H), 3.72 (s,
3H), 7.56 (dd, J = 1.9, 8.7 Hz, 1H), 7.81 (dd, J = 1.8, 8.6 Hz,
1H), 8.10 (d, J = 9.6 Hz, 1H), 8.16 (d, J = 8.3 Hz, 1H), 8.22 (d,
J = 1.8 z, 1H), 8.35 (d, J = 8.6 Hz, 1H), 8.57 (d, J = 1.5 Hz, 1H),
10.07 (s, 1H), 12.54 (s, 1H). HRMS: calcd for C19H20N2O6S2 þ
Hþ, 437.08355; found (ESI-FTMS, [M þ H]þ), 437.0833.
(S)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]thiophene-2-
sulfonamido)-3-methylbutanoic Acid (6b). Following procedures
for the preparation of 6a and using the corresponding (S)-
enantiomer isomer, (S)-2-(7-(methoxycarbonylamino)dibenzo-
[b,d]thiophene-2-sulfonamido)-3-methylbutanoic acid, com-
1
pound 6b was prepared as a white solid. H NMR (400 MHz,
DMSO-d6) δ 0.80 (d, J = 6.8 Hz, 3H), 0.84 (d, J = 6.8 Hz, 3H),
1.88-2.03 (m, 1H), 3.64 (dd, J = 5.9, 9.5 Hz, 1H), 3.72 (s, 3H),
7.56 (dd, J = 1.9, 8.7 Hz, 1H), 7.81 (dd, J = 1.8, 8.3 Hz, 1H),
8.10 (d, J = 9.6 Hz, 1H), 8.16 (d, J = 8.3 Hz, 1H), 8.23 (d, J =
1.8 z, 1H), 8.35 (d, J = 8.8 Hz, 1H), 8.57 (d, J = 1.8 Hz, 1H),
10.07 (s, 1H), 12.54 (s, 1H). HRMS: calcd for C19H20N2O6S2 þ
Hþ, 437.08355; found (ESI-FTMS, [M þ H]þ), 437.0833.
(R)-2-(8-(Methoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (7a). Following procedures
for the preparation of 6a and using the intermediate (R)-
tert-butyl 2-(8-aminodibenzo[b,d]thiophene-3-sulfonamido)-3-
methylbutanoate (see preparation of 5a), compound 7a was
For detailed synthetic schemes and procedures, please see the
Supporting Information section.
(R)-3-Methyl-2-(7-(methylsulfonamido)dibenzo[b,d]thiophene-2-
sulfonamido)butanoic Acid (4a). The title compound 4a was pre-
pared from 3-nitrodibenzothiophene (see Supporting Information
1
for detailed procedures) as a white solid. H NMR (400 MHz,
DMSO-d6) δ 0.80 (d, J = 6.8 Hz, 3H), 0.84 (d, J = 6.8 Hz, 3H),
1.86-2.04 (m, 1H), 3.10 (s, 3H), 3.64 (dd, J=5.8, 9.6Hz, 1H), 7.39
(dd, J = 1.9, 8.7 Hz, 1H), 7.83 (dd, J = 1.8, 8.6 Hz, 1H), 7.87 (d,
J = 2.0 Hz, 1H), 8.11 (d, J = 9.9 Hz, 1H), 8.19 (d, J= 8.6 Hz, 1H),
8.41 (d, J = 8.6 Hz, 1H), 8.61 (d, J = 1.5 Hz, 1H), 10.17 (s, 1H),
1
prepared as a white solid. H NMR (400 MHz, DMSO-d6) δ
0.80 (d, J = 6.8 Hz, 3H), 0.83 (d, J = 6.8 Hz, 3H), 1.87-2.01 (m,
1H), 3.61 (dd, J = 5.8, 9.6 Hz, 1H), 3.73 (s, 3H), 7.61 (dd, J =
2.0, 8.8 Hz, 1H), 7.87 (dd, J=1.8, 8.3 Hz, 1H), 8.01 (d, J=8.8 Hz,

5416 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17
Li et al.
1H), 8.15 (d, J = 9.6 Hz, 1H), 8.33 (d, J = 8.3 Hz, 1H), 8.44 (d,
J = 1.5 Hz, 1H), 8.53 (d, J = 1.5 Hz, 1H), 9.95 (s, 1H), 12.54 (s,
1H). HRMS: calcd for C19H20N2O6S2 þ Hþ, 437.08355; found
(ESI-FTMS, [M þ H]þ), 437.0822.
calcd for C19H20N2O7S: C 54.28%, H 4.79%, N 6.66%; found:
C 53.95%, H 4.72%, N 6.34%.
(S)-2-(7-Aminodibenzo[b,d]thiophene-3-sulfonamido)-3-methylbu-
tanoic Acid (11). The title compound was prepared by acidic
saponification of the intermediate (S)-2-(7-amino-dibenzothio-
phene-3-sulfonylamino)-3-methyl-butyric acid tert-butyl ester
(step 4 in the preparation of compound 9b). 1H NMR (400 MHz,
MeOD) δ 1.10 (d, J = 6.8 Hz, 3H), 1.19 (d, J = 6.8 Hz, 3H), 2.16-
2.34 (m, 1H), 3.83 (d, J = 5.3 Hz, 1H), 7.10 (dd, J = 8.6, 2.02 Hz,
1H), 7.33 (d, J = 2.0 Hz, 1H), 8.02 (dd, J = 8.3, 1.77 Hz, 1H), 8.20
(d, J = 8.6 Hz, 1H), 8.30 (d, J = 8.3 Hz, 1H), 8.45 (d, J = 1.0 Hz,
1H). HRMS: calcd for C17H18N2O4S2 þ Hþ, 379.07807; found ESI-
FTMS, [M þ H]þ, 379.0779.
(S)-2-(8-(Methoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (7b). Following procedures
for the preparation of 7a and using the corresponding (S)-
enantiomer, (S)-tert-butyl 2-(8-aminodibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoate, compound 7b was obtained
as a white solid. 1H NMR (400 MHz, DMSO-d6) δ 0.80 (d, J =
6.8 Hz, 3H), 0.83 (d, J = 6.8 Hz, 3H), 1.88-2.02 (m, 1H), 3.61
(dd, J = 6.1, 9.6 Hz, 1H), 3.73 (s, 3H), 7.61 (dd, J = 2.2, 8.7 Hz,
1H), 7.87 (dd, J = 1.5, 8.3 Hz, 1H), 8.01 (d, J = 8.6 Hz, 1H), 8.15
(d, J = 9.6 Hz, 1H), 8.33 (d, J = 8.3 Hz, 1H), 8.44 (d, J = 1.5 Hz,
1H), 8.53 (d, J = 1.5 Hz, 1H), 9.95 (s, 1H), 12.54 (s, 1H). HRMS:
calcd for C19H20N2O6S2 þ Hþ, 437.08355; found (ESI-FTMS,
[M þ H]þ), 437.0833.
(R)-2-(7-(Ethoxycarbonylamino)dibenzo[b,d]thiophene-3-sulfon-
amido)-3-methylbutanoic Acid (12a). Following procedures for
the preparation of 9b and using ethyl chloroformate for the N-
derivatization step, compound 12a was prepared as a white
1
(S)-2-(8-(Methoxycarbonylamino)dibenzo[b,d]furan-3-sulfon-
amido)-3-methylbutanoic Acid (8). The title compound was
obtained as a white solid following the procedures described
for the preparation of compound 27 using methyl chloroformate
for the N-derivatization step, compound 8 was obtained as a
white solid. 1H NMR (400 MHz, MeOD) δ 0.93 (d, J = 6.8 Hz,
3H), 0.99 (d, J = 6.8 Hz, 3H), 2.01-2.13 (m, 1H), 3.75 (d, J =
5.6 Hz, 1H), 3.80 (s, 3H), 7.51-7.62 (m, 2H), 7.87 (dd, J = 8.2,
1.6 Hz, 1H), 8.07 (d, J = 1.0 Hz, 1H), 8.13 (d, J = 7.6 Hz, 1H),
8.27 (s, 1H). 13C NMR (101 MHz, DMSO-d6) δ 17.6, 18.9, 30.3,
51.7, 61.3, 110.2, 110.7, 112.1, 120.6, 121.3, 121.4, 122.5, 127.0,
135.3, 140.0, 152.4, 154.2, 154.8, 172.0. HRMS: calcd for
C19H20N2O7S þ Hþ, 421.10640; found (ESI-FTMS, [MþH]1þ),
421.1069. Anal. calcd for C19H20N2O7S, C 55.29%, H 5.10%,
N 6.45%; found C 54.70%, H 5.03%, N 6.32%.
(R)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (9a). The title compound
was prepared as a white solid following the procedures described
for the preparation of 9b and using the (R)-valine t-butyl ester.
1H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.7 Hz, 3H), 0.84
(d, J = 6.7 Hz, 3H), 1.88-2.02 (m, 1H), 3.60 (dd, J = 8.9,
6.0 Hz, 1H), 3.73 (s, 3H), 7.58 (dd, J = 8.7, 1.9 Hz, 1H), 7.84 (dd,
J = 8.5, 1.5 Hz, 1H), 8.05 (d, J = 9.4 Hz, 1H), 8.22 (d, J = 1.8
Hz, 1H), 8.35 (d, J = 8.5 Hz, 1H), 8.38 (d, J = 5.6 Hz, 1H),
8.40 (s, 1H), 10.04 (s, 1H), 12.48 (s, 1H). ESI-POS [M -H]þ
437.0.
(S)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (9b). The title compound
was prepared following the synthetic scheme and procedures
described in the Supporting Information section. 1H NMR (300
MHz, DMSO-d6) δ 0.80 (d, J = 6.9 Hz, 3H), 0.83 (d, J = 6.6 Hz,
3H), 1.95 (m, 1H), 3.61 (m, 1H), 3.72 (s, 3H), 7.81 (d, J = 8.8 Hz,
1H), 7.91 (dd, J = 8.5, 1.6 Hz, 1H), 8.10 (m, 1H), 8.42 (d, J = 8.8
Hz, 1H), 8.50 (d, J = 8.5 Hz, 1H), 8.52 (d, J = 1.3 Hz, 1H), 9.46
(s, 1H), 12.45 (s, 1H). ESI-POS [M - H]þ 437.0.
(R)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]furan-3-sulfon-
amido)-3-methylbutanoic Acid (10a). The title compound was
obtained as a white solid following the literature procedures.34
1H NMR (400 MHz, MeOD) δ 1.13 (d, J = 6.8 Hz, 3H), 1.19 (d,
J = 6.8 Hz, 3H), 2.17-2.34 (m, 1H), 3.94 (d, J = 5.6 Hz, 1H),
4.01 (s, 3H), 7.57 (dd, J = 8.5, 1.6 Hz, 1H), 8.04 (dd, J = 8.1, 1.5
Hz, 1H), 8.14-8.22 (m, 2H), 8.24 (d, J = 1.5 Hz, 1H), 8.28 (d,
J = 8.1 Hz, 1H), 9.85 (s, 1H). HRMS: calcd for C19H20N2O7S þ
Hþ, 421.10640; found (ESI-FTMS, [M þ H]þ), 421.10674.
(S)-2-(7-(Methoxycarbonylamino)dibenzo[b,d]furan-3-sulfon-
amido)-3-methylbutanoic Acid (10b). The title compound was
obtained as a white solid following the literature procedures.34
1H NMR (400 MHz, MeOD) δ 1.13 (d, J = 6.8 Hz, 3H), 1.19 (d,
J = 6.8 Hz, 3H), 2.17-2.34 (m, 1H), 3.94 (d, J = 5.6 Hz, 1H),
4.01 (s, 3H), 7.57 (dd, J = 8.5, 1.6 Hz, 1H), 8.04 (dd, J = 8.1, 1.5
Hz, 1H), 8.14-8.22 (m, 2H), 8.24 (d, J = 1.5 Hz, 1H), 8.28 (d,
J = 8.1 Hz, 1H), 9.85 (s, 1H). HRMS: calcd for C19H20N2O7S þ
Hþ, 421.10640; found (ESI-FTMS, [M þ H]þ), 421.1064. Anal.
solid. H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.6 Hz,
3H), 0.83 (d, J = 6.6 Hz, 3H), 1.28 (t, J = 7.2 Hz, 3H), 1.95 (m,
1H), 3.56 (m, 1H), 4.18 (q, J = 7.2 Hz, 2H), 7.58 (dd, J = 8.8, 1.9
Hz, 1H), 7.83 (dd, J = 8.8, 1.6 Hz, 1H), 7.99 (s, 1H), 8.22 (d, J =
1.9 Hz, 1H), 8.34 (d, J = 8.8, Hz, 1H), 8.37 (d, J = 7.9 Hz, 1H),
8.38 (d, J = 2.2 Hz, 1H), 10.00 (s, 1H), 12.49 (s, 1H). ESI-POS
[M - H]þ 451.01.
(S)-2-(7-(Ethoxycarbonylamino)dibenzo[b,d]thiophene-3-sulfon-
amido)-3-methylbutanoic Acid (12b). Following procedures for
the preparation of 9b and using ethyl chloroformate for the N-
derivatization step, compound 12b was prepared as a white
1
solid. H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.6 Hz,
3H), 0.83 (d, J = 6.6 Hz, 3H), 1.28 (t, J = 7.2 Hz, 3H), 1.95 (m,
1H), 3.56 (m, 1H), 4.18 (q, J = 7.2 Hz, 2H), 7.58 (dd, J = 8.8, 1.9
Hz, 1H), 7.83 (dd, J = 8.8, 1.6 Hz, 1H), 7.99 (s, 1H), 8.22 (d, J =
1.9 Hz, 1H), 8.34 (d, J = 8.8 Hz, 1H), 8.37 (d, J = 7.9 Hz, 1H),
8.38 (d, J = 2.2 Hz, 1H), 10.00 (s, 1H), 12.49 (s, 1H). ESI-POS
[M - H]þ 450.9.
(S)-2-(7-(Isopropoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (13). Following procedures
for the preparation of 9b and using isopropyl chloroformate for
the N-derivatization step, compound 13 was prepared as a white
1
solid. H NMR (300 MHz, DMSO-d6) δ 0.81 (d, J = 6.9 Hz,
3H), 0.84 (d, J = 6.9 Hz, 3H), 1.30 (d, J = 6.2 Hz, 6H), 1.95 (m,
1H), 3.60 (dd, J = 9.5, 6.0 Hz, 1H), 4.95 (dq, J = 6.2, 6.2 Hz,
1H), 7.58 (dd, J = 8.7, 1.9 Hz, 1H), 7.83 (dd, J = 8.3, 1.6 Hz,
1H), 8.05 (d, J = 9.6 Hz, 1H), 8.23 (d, J = 1.8 Hz, 1H), 8.33 (d,
J = 8.8 Hz, 1H), 8.38 (d, J = 7.8 Hz, 1H), 8.39 (d, J = 1.8 Hz,
1H), 9.96 (s, 1H), 12.50 (s, 1H). ESI-POS [M - H]þ 465.1.
(S)-2-(7-(Isobutoxycarbonylamino)dibenzo[b,d]thiophene-3-
sulfonamido)-3-methylbutanoic Acid (14). Following procedures
for the preparation of 9b and using isobutyl chloroformate for
the N-derivatization step, compound 14 was prepared as a white
1
solid. H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.9 Hz,
3H), 0.83 (d, J = 6.9 Hz, 3H), 0.96 (d, J = 6.6 Hz, 6H), 1.94 (m,
2H), 3.59 (m, 1H), 3.93 (d, J = 6.6 Hz, 2H), 7.58 (dd, J = 8.5, 1.9
Hz, 1H), 7.83 (dd, J = 8.5, 1.6 Hz, 1H), 8.03 (d, J = 8.5 Hz, 1H),
8.23 (d, J = 1.9 Hz, 1H), 8.34 (d, J = 8.5 Hz, 1H), 8.38 (d, J =
8.5 Hz, 1H), 8.39 (d, J = 1.6 Hz, 1H), 10.00 (s, 1H), 12.49 (s, 1H).
ESI-POS [M - H]þ 479.0.
(S)-3-Methyl-2-(7-((2-(methylsulfonyl)ethoxy)carbonylamino)-
dibenzo[b,d]thiophene-3-sulfonamido)butanoic Acid (15). Follow-
ing procedures for the preparation of 9b and using 2-methane-
sulfonyl ethyl chloroformate for the N-derivatization step,
compound 15 was prepared as a white solid. 1H NMR (300
MHz, DMSO-d6) δ 0.80 (d, J = 6.9 Hz, 3H), 0.84 (d, J = 6.9 Hz,
3H), 1.95(m, 1H), 3.10 (s, 3H), 3.58 (m, 3H), 4.51 (dd, J = 6.0, 6.0
Hz, 2H), 7.60 (dd, J = 8.4, 1.9 Hz, 1H), 7.84 (dd, J = 8.6, 1.9 Hz,
1H), 8.01(d, J = 9.1 Hz, 1H), 8.24 (d, J = 1.8 Hz, 1H), 8.42-8.34
(m, 3H), 10.16 (s, 1H), 12.52 (s, 1H). ESI-POS [M - H]þ 529.1.
(S)-2-(7-((But-3-ynyloxy)carbonylamino)dibenzo[b,d]thiophene-
3-sulfonamido)-3-methylbutanoic Acid (16). Following procedures
for the preparation of 9b and using but-3-ynyl chloroformate for

Article
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17 5417
the N-derivatization step, compound 16 was prepared as a white
solid. 1H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.9 Hz, 3H),
0.84 (d, J = 6.9 Hz, 3H), 1.95 (m, 1H), 2.60 (dt, J = 6.4, 2.6 Hz,
2H), 2.91 (t, J = 2.6 Hz, 1H), 3.60 (dd, J = 9.15.9Hz, 1H), 4.22 (t,
J = 6.4 Hz, 2H), 7.60 (dd, J = 8.7, 1.7 Hz, 1H), 7.84 (dd, J = 8.5,
1.6 Hz, 1H), 8.05 (d, J = 9.4 Hz, 1H), 8.24 (d, J = 1.7 Hz, 1H),
8.35 (d, J = 8.8 Hz, 1H), 8.39 (d, J = 8.0 Hz, 1H), 8.4 (d, J = 1.9
Hz, 1H), 10.14 (s, 1H), 12.51 (s, 1H). ESI-POS [M - H]þ 475.1.
(S)-3-Methyl-2-(7-(phenoxycarbonylamino)dibenzo[b,d]thio-
phene-3-sulfonamido)butanoic Acid (17). Following procedures
for the preparation of 9b and using phenyl chloroformate for the
N-derivatization step, compound 17 was prepared as a yellow
1H), 8.23 (d, J = 8.8 Hz, 1H), 8.30 (d, J = 8.5 Hz, 1H), 8.34 (d,
J = 1.6 Hz, 1H), 8.67 (s, 1H). ESI-POS [M - H]þ 532.1.
(S)-3-Methyl-2-(7-(3-(2-(thiophen-2-yl)ethyl)ureido)dibenzo-
[b,d]furan-3-sulfonamido)butanoic Acid2 (23). The title com-
pound was prepared as a white solid following the procedures
described for the preparation of 20 using 2-(2-isocyana-
toethyl)thiophene for the N-derivatization step. 1H NMR (400
MHz, DMSO-d6) δ 0.80 (d, J = 6.6 Hz, 3H), 0.83 (d, J = 6.8 Hz,
3H), 1.86-2.02 (m, 1H), 3.00 (t, J = 7.1 Hz, 2H), 3.40 (q, J = 6.8
Hz, 2H), 3.58 (dd, J = 9.4, 6.1 Hz, 1H), 6.39 (t, J = 5.8 Hz, 1H),
6.94 (d, J = 3.5 Hz, 1H), 6.99 (dd, J = 5.1, 3.3 Hz, 1H), 7.27 (dd,
J = 8.6, 1.8 Hz, 1H), 7.37 (dd, J = 5.2, 1.1 Hz, 1H), 7.75 (dd,
J = 8.1, 1.5 Hz, 1H), 7.97 (d, J = 1.5 Hz, 1H), 8.00-8.12 (m,
3H), 8.15 (d, J = 8.1 Hz, 1H), 9.06 (s, 1H), 12.52 (s, 1H). HRMS:
calcd for C24H25N3O6S2 þ Hþ, 516.12575; found (ESI-FTMS,
[M þ H]þ), 516.12506.
1
solid. H NMR (300 MHz, DMSO-d6) δ 0.81 (d, J = 6.9 Hz,
3H), 0.85 (d, J = 6.9 Hz, 3H), 1.96 (m, 1H), 3.58 (m, 1H), 7.28 (d,
J = 8.6 Hz, 2H), 7.29 (dd, J = 8.6, 8.6 Hz, 1H), 7.46 (dd, J =
8.6, 8.6 Hz, 2H), 7.66 (dd, J = 8.8, 2.0 Hz, 1H), 7.85 (dd, J = 8.5,
1.5 Hz, 1H), 8.02 (s, 1H), 8.26 (d, J = 1.8 Hz, 1H), 8.41 (m, 3H),
10.62 (s, 1H), 12.48 (s, 1H). ESI-POS [M - H]þ 499.0.
(S)-3-Methyl-2-(7-(p-tolyloxycarbonylamino)dibenzo[b,d]thio-
phene-3-sulfonamido)butanoic Acid (18). Following procedures
for the preparation of 9b and using 4-methyl-phenyl chlorofor-
mate for the N-derivatization step, compound 18 was prepared
as a pale-yellow solid. 1H NMR (300 MHz, DMSO-d6) δ 0.81 (d,
J = 6.9 Hz, 3H), 0.84 (d, J = 6.9 Hz, 3H), 1.96 (m, 1H), 2.33 (s,
3H), 3.57 (m, 1H), 7.14 (d, J = 8.7 Hz, 2H), 7.25 (d, J = 8.7 Hz,
2H), 7.65 (dd, J = 9.1, 2.5 Hz, 1H), 7.85 (dd, J = 8.7, 1.7 Hz,
1H), 8.04 (s, 1H), 8.25 (d, J = 1.9 Hz, 1H), 8.41 (m, 3H), 10.57 (s,
1H), 12.52 (s, 1H). ESI-POS [M - H]þ 513.1.
(R)-3-Methyl-2-(7-(3-phenylureido)dibenzo[b,d]thiophene-3-
sulfonamido)butanoic Acid (24a). The title compound was pre-
pared as a white solid following the procedures described for the
preparation of 20 using phenyl isocyanate for the N-derivatiza-
tion step. 1H NMR (300 MHz, DMSO-d6) δ 0.81 (d, J = 6.7 Hz,
3H), 0.85 (d, J = 6.7 Hz, 3H), 1.89-2.03 (m, 1H), 3.52-3.65 (m,
1H), 7.00 (t, J = 7.5 Hz, 1H), 7.31 (t, J = 8.1 Hz, 3H), 7.50 (d,
J = 7.6 Hz, 1H), 7.54 (s, 1H), 7.83 (dd, J = 8.4, 1.6 Hz, 1H),
8.25-8.41 (m, 5H), 8.84 (s, 1H), 9.08 (s, 1H), 12.47 (s, 1H). ESI-
POS [M - H]þ 498.1.
(S)-3-Methyl-2-(7-(3-phenylureido)dibenzo[b,d]thiophene-3-
sulfonamido)butanoic Acid (24b). The title compound was pre-
pared as a white solid following the procedures described for the
preparation of 20 using phenyl isocyanate for the N-derivatiza-
tion step. 1H NMR (300 MHz, DMSO-d6) δ 0.81 (d, J = 6.9 Hz,
3H), 0.84 (d, J = 6.9 Hz, 3H), 1.96 (m, 1H), 3.60 (dd, J = 9.6, 6.4
Hz, 1H), 7.00 (dd, J = 8.0, 8.0 Hz, 1H), 7.31 (dd, J = 8.0, 8.0 Hz,
2H), 7.49 (d, J = 8.0 Hz, 2H), 7.54 (m,1H), 7. 83 (dd, J = 8.5, 1.6
Hz, 1H), 8.01 (d, J = 8.5 Hz, 1H), 8.28 (d, J = 1.8 Hz, 1H), 8.33
(d, J = 8.7 Hz, 1H) 12.47 (s, 1H). ESI-POS [M - H]þ 498.1.
(S)-2-(7-(3-Benzylureido)dibenzo[b,d]thiophene-3-sulfonamido)-
3-methylbutanoic Acid (25). The title compound was prepared as
a white solid following the procedures described for the pre-
paration of 20 using benzyl isocyanate for the N-derivatization
step. 1H NMR (300 MHz, DMSO-d6) δ 0.80 (d, J = 6.9 Hz, 3H),
0.84 (d, J = 6.9 Hz, 3H), 1.95 (m, 1H), 3.59 (m, 1H), 4.34 (d, J =
5.6 Hz, 2H), 6.79 (d, J = 5.7 Hz, 1H), 7.22-7.37 (m, 5H), 7.46
(dd, J = 8.7, 2.0 Hz, 1H), 7.81 (dd, J = 8.5, 2.1 Hz, 1H), 8.0 (d,
J = 9.5 Hz, 1H), 8.25 (d, J = 1.8 Hz 1H), 8.27 (d, J = 8.2 Hz,
1H), 8.34 (d, J = 8.1 Hz, 1H), 8.35 (s, 1H), 8.96 (s, 1H), 12.49 (s,
1H). ESI-POS [M - H]þ 512.1.
(S)-2-(8-(Ethoxycarbonylamino)dibenzo[b,d]furan-3-sulfon-
amido)-3-methylbutanoic Acid (26). Following procedures for
the preparation of 27 and using ethylchloroformate for the N-
derivatization step, compound 26 was prepared as a white solid.
1H NMR (400 MHz, MeOD) δ 0.88 (d, J = 6.82 Hz, 3H), 0.95
(d, J = 6.82 Hz, 3H), 1.31 (t, J = 7.07 Hz, 3H), 1.93-2.11 (m,
1H), 3.71 (d, J = 5.56 Hz, 1H), 4.20 (q, J = 7.07 Hz, 2H), 7.44-
7.55 (m, 3H), 7.81 (dd, J = 8.34, 1.52 Hz, 1H), 8.01 (d, J = 1.01
Hz, 1H), 8.06 (d, J = 8.59 Hz, 1H), 8.20 (s, 1H). 13C NMR (101
MHz, DMSO-d6) δ 14.5, 17.7, 18.9, 30.3, 60.2, 61.3, 110.2,
110.6, 112.0, 120.5, 121.3, 122.5, 127.0, 135.4, 140.0, 152.4,
153.8, 154.8, 154.9, 172.0. HRMS: calcd for [C20H22N2O7S þ
H]þ, 435.12205; found (ESI-FTMS, [M þ H]þ), 435.1216. Anal.
calcd for C20H22N2O7S: C 55.29%, H 5.10%, N 6.45%; found:
C 55.49%, H 5.03%, N 6.32%.
(S)-2-(7-((4-Fluorophenoxy)carbonylamino)dibenzo[b,d]thio-
phene-3-sulfonamido)-3-methylbutanoic Acid (19). Following
procedures for the preparation of 9a and using 4-fluoro-phenyl
chloroformate for the N-derivatization step, compound 19 was
1
prepared as a white solid. H NMR (300 MHz, DMSO-d6) δ
0.81 (d, J = 6.9 Hz, 3H), 0.84 (d, J = 6.9 Hz, 3H), 1.95 (m, 1H),
3.6 (m, 1H), 7.37-7.23 (m, 4H), 7.65 (dd, J = 8.7, 1.8 Hz, 1H),
7.85 (dd, J = 8.5, 1.6 Hz, 1H), 8.05 (d, J = 9.5 Hz, 1H), 8.25 (d,
J = 1.9 Hz, 1H), 8.41 (m, 3H), 10.63 (s, 1H), 12.51 (s, 1H). ESI-
POS [M - H]þ 517.1.
(S)-2-(7-(3-Ethylureido)dibenzo[b,d]thiophene-3-sulfonamido)-
3-methylbutanoic Acid (20). The title compound was prepared
following the scheme and synthetic procedures described at the
Supporting Information. 1H NMR (300 MHz, DMSO-d6) δ
0.81 (d, J = 6.9 Hz, 3H), 0.84 (d, J = 6.9 Hz, 3H), 1.09 (t, J =
5.6 Hz, 3H), 1.95 (m, 1H), 3.15 (dq, J = 7.0, 5.6 Hz, 2H), 3.58
(m, 1H), 6.27 (t, J = 5.5 Hz, 1H), 7.45 (dd, J = 8.6, 2.0 Hz, 1H),
7.81 (dd, J = 8.5, 1.8 Hz, 1H), 8.00 (d, J = 9.0 Hz, 1H), 8.23 (d,
J = 1.8 Hz, 1H), 8.26 (d, J = 8.3 Hz, 1H), 8.34 (d, J = 8.3 Hz,
1H), 8.36 (d, J = 1.8 Hz, 1H), 8.82 (s, 1H), 12.51 (s, 1H). ESI-
POS [M - H]þ 450.1.
(S)-2-(7-(3-Cyclopentylureido)dibenzo[b,d]thiophene-3-sulfon-
amido)-3-methylbutanoic Acid (21). Following procedures for
the preparation of 20 and using cyclopentyl isocyanate for the
N-derivatization, compound 21 was prepared as a white solid.
1H NMR (300 MHz, CDCl3) δ 0.84 (d, J = 6.9 Hz, 3H), 0.98 (d,
J = 6.9 Hz, 3H), 1.49-1.32 (m, 2H), 1.74-1.53 (m, 4H), 2.14-
1.88 (m, 3H), 3.71 (m, 1H), 4.10 (dt, J = 13.2, 6.6 Hz, 1H), 5.33
(d, J = 10.1 Hz, 1H), 7.29 (dd, J = 8.8, 2.2 Hz, 1H), 7.83 (dd,
J = 8.2, 1.6 Hz, 1H), 7.96 (d, J = 8.8 Hz, 1H), 8.03 (d, J = 8.8
Hz, 1H), 8.19 (d, J = 2.2 Hz, 1H), 8.24 (d, J = 1.6 Hz, 1H). ESI-
POS [M - H]þ 490.1.
(S)-3-Methyl-2-(7-(3-(2-(thiophen-2-yl)ethyl)ureido)dibenzo-
[b,d]thiophene-3-sulfonamido)butanoic Acid (22). Following pro-
cedures for the preparation of 20 and using 2-(2-isocyanato-
ethyl)thiophene for the N-derivatization, compound 22 was
(S)-3-Methyl-2-(8-(2-oxooxazolidin-3-yl)dibenzo[b,d]furan-3-
sulfonamido)butanoic Acid (27, MMP145). The title compound
was prepared following the synthetic scheme and procedures
described in the Supporting Information section. 1H NMR (400
MHz, DMSO-d6) δ 0.80 (d, J = 6.8 Hz, 3H), 0.83 (d, J = 6.8 Hz,
3H), 1.88-1.98 (m, 1H), 3.61 (dd, J = 9.6, 6.1 Hz, 1H), 4.12-
4.26 (m, 2H), 4.51 (dd, J = 9.1, 6.8 Hz, 2H), 7.76-7.86 (m, 2H),
7.93 (dd, J=9.1, 2.5 Hz, 1H), 8.06 (d, J=1.3 Hz, 1H), 8.18
1
prepared as a white solid. H NMR (300 MHz, DMSO-d6) δ
0.86 (d, J = 6.9 Hz, 3H), 0.88 (d, J = 6.9 Hz, 3H), 1.99 (m, 1H),
3.04 (t, J = 6.6 Hz, 2H), 3.45 (dt, J = 6.6, 6.0 Hz, 2H), 3.63 (d,
J = 6.0 Hz, 1H), 6.22 (t, J = 6.0 Hz, 1H), 6.93 (m, 1H), 6,98 (dd,
J = 5.0, 3.5 Hz, 1H), 7.31 (dd, J = 5.0, 1.3 Hz, 1H), 7.47 (dd, J=
8.8, 1.9 Hz, 1H), 7.84 (dd, J=8.5, 1.9 Hz, 1H), 8.19 (d, J=2.2 Hz,

5418 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 17
Li et al.
(d, J=9.6 Hz, 1H), 8.30-8.39 (m, 2H). 13C NMR (400 MHz,
DMSO-d6) δ 17.8, 19.0, 30.4, 45.5, 61.3, 61.5, 110.3, 111.6,
112.1, 120.3, 121.5, 121.7, 122.7, 126.9, 134.9, 140.2, 153.0,
155.0, 155.2, 172.0. HRMS: calcd for C20H20N2O7S (M þ Hþ)
433.10640, found (ESI-FTMS, [M þ H]þ) 433.10635; CHN:
calcd for C20H20N2O7S, C 55.55%, H 4.66%, N 6.48%; found C
55.53%, H 4.67%, N 6.75%.
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(S)-3-Methyl-2-(7-(2-oxooxazolidin-3-yl)dibenzo[b,d]furan-3-
sulfonamido)butanoic Acid (28). The title compound was ob-
tained as a white solid following the procedures described for 27
using the known intermediate (S)-methyl 2-(7-aminodibenzo[b,
d]furan-3-sulfonamido)-3-methylbutanoate.34 1H NMR (400
MHz, MeOD) δ 1.13 (d, J = 6.8 Hz, 3H), 1.19 (d, J = 6.8
Hz, 3H), 2.20-2.33 (m, 1H), 3.94 (d, J = 5.7 Hz, 1H), 4.40-4.51
(m, 2H), 4.73-4.83 (m, 2H), 7.86 (dd, J = 2.0, 8.6 Hz, 1H), 8.07
(dd, J = 1.5, 8.1 Hz, 1H), 8.23 (d, J = 2.0 Hz, 1H), 8.27 (d, J =
1.5 Hz, 1H), 8.29-8.37 (m, 2H). HRMS: calcd for C20H20N2O7-
S þ Hþ, 433.10640; found (ESI-FTMS, [M þ H]þ), 433.10635.
(S)-3-Methyl-2-(7-(2-oxooxazolidin-3-yl)dibenzo[b,d]thio-
phene-3-sulfonamido)butanoic Acid (29). The product was pre-
pared as a white solid using the corresponding aniline inter-
mediate for the preparation of 9b following the procedures
1
described for 27. H NMR (300 MHz, DMSO-d6) δ 0.81 (d,
J = 6.7 Hz, 3H), 0.84 (d, J = 6.7 Hz, 3H), 1.90-2.01 (m, 1H),
3.61 (dd, J = 9.4, 5.9 Hz, 1H), 4.19 (t, J = 8.1 Hz, 2H), 4.51 (t,
J = 8.1 Hz, 2H), 7.86 (dd, J = 8.5, 1.8 Hz, 1H), 7.90 (dd, J =
8.8, 2.1 Hz, 1H), 8.08 (d, J = 9.4 Hz, 1H), 8.23 (d, J = 2.1 Hz,
1H), 8.41-8.49 (m, 3H), 12.52 (s, 1H). ESI-POS [M - H]þ
449.05.
(S)-2-(7-Aminodibenzo[b,d]furan-3-sulfonamido)-3-methylbu-
tanoic Acid (30). The title compound was prepared by saponi-
fication of the known compound, (S)-methyl 2-(7-aminodi-
benzo[b,d]furan-3-sulfonamido)-3-methylbutanoate2 under ba-
sic conditions (THF/water/LiOH). 1H NMR (400 MHz,
DMSO-d6) δ 0.74 (d, J = 7.1 Hz, 3H). 0.86 (d, J = 7.1 Hz,
3H), 1.93-2.05 (m, 1H), 2.92 (s, 1H), 5.80 (s, 2H), 6.67 (dd, J =
1.8, 8.3 Hz, 1H), 6.76 (d, J = 1.5 Hz, 1H), 6.80 (s, 1H), 7.62 (dd,
J = 1.5, 8.1 Hz, 1H), 7.77 (d, J = 8.3 Hz, 1H), 7.81 (d, J = 1.0
Hz, 1H), 7.92 (d, J=8.1 Hz, 1H). HRMS: calcd for C17H18-
N2O5S þ Hþ, 363.10092.
Acknowledgment. We thank Thiru Singanallore and Jean
Schmid for synthetic support, Jiayao Wang and Louis Leung
for support on drug metabolism studies, and Nelson Huang,
Walter Massefski, Peter Tate, and Ning Pan for analytical
support.
Supporting Information Available: Details of syntheses and
assays and characterization of all compounds. This material is
available free of charge via the Internet at http://pubs.acs.org.
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