Cyclic sulfones as novel P3-caps for hepatitis C virus NS3/4A (HCV NS3/4A) protease inhibitors: Synthesis and evaluation of inhibitors with improved potency and pharmacokinetic profiles

Article abstract of DOI:10.1021/jm9016027

HCV infection affects more than 170 million people worldwide and many of those patients will reach the end stage complications of the disease which include hepatocarcinoma and liver failure. The success rate for treatment of patients infected with genotype-1 is about 40%. Therefore, novel treatments are needed to combat the infection. The HCV NS3 protease inhibitor Boceprevir (1) was reported by our research group and efforts continue for the discovery of more potent compounds with improved pharmacokinetic profiles. A new series of HCV NS3 protease inhibitors having a cyclic sulfone P3-cap have been discovered. Compounds 43 and 44 showed K_i* values in the single-digit nM range and their cellular potency was improved by 10-fold compared to 1. The pharmacokinetic profiles of 43 and 44 in rats and monkeys were also improved to achieve higher plasma levels after oral administration.

Full text of DOI:10.1021/jm9016027

J. Med. Chem. 2010, 53, 3075–3085 3075
DOI: 10.1021/jm9016027
Cyclic Sulfones as Novel P3-Caps for Hepatitis C Virus NS3/4A (HCV NS3/4A) Protease Inhibitors:
Synthesis and Evaluation of Inhibitors with Improved Potency and Pharmacokinetic Profiles
ꢀ
ꢀ
Francisco Velazquez,* Mousumi Sannigrahi, Frank Bennett, Raymond G. Lovey, Ashok Arasappan, Stephane Bogen,
Latha Nair, Srikanth Venkatraman, Melissa Blackman, Siska Hendrata, Yuhua Huang, Regina Huelgas, Patrick Pinto,
Kuo-Chi Cheng, Xiao Tong, Andrew T. McPhail,‡ and F. George Njoroge
Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033-1300. ‡Affiliation: Department of Chemistry,
Duke University, Durham, North Carolina 27708.
Received October 29, 2009
HCV infection affects more than 170 million people worldwide and many of those patients will reach the
end stage complications of the disease which include hepatocarcinoma and liver failure. The success rate
for treatment of patients infected with genotype-1 is about 40%. Therefore, novel treatments are needed
to combat the infection. The HCV NS3 protease inhibitor Boceprevir (1) was reported by our research
group and efforts continue for the discovery of more potent compounds with improved pharmacoki-
netic profiles. A new series of HCV NS3 protease inhibitors having a cyclic sulfone P3-cap have been
discovered. Compounds 43 and 44 showed Ki* values in the single-digit nM range and their cellular
potency was improved by 10-fold compared to 1. The pharmacokinetic profiles of 43 and 44 in rats and
monkeys were also improved to achieve higher plasma levels after oral administration.
Introduction
NS5B junctions to deliver proteins essential for replication.4
Because of the pivotal role that HCV NS3/4A plays in viral
replication, numerous groups have engaged in research activ-
ities directed toward finding potent and selective inhibitors
that could provide patients with alternative treatments. To
date, several compounds have undergone clinical trials in-
cluding our first generation HCV NS3 protease inhibitor
boceprevir (1),5 which is currently in phase III. Other HCV
NS3/4A inhibitors include telaprevir (VX-950),6 also in phase
III, ciluprevir (BILN 2061),7 and more recently danoprevir
(ITMN-191) and vaniprevir (MK-7009).8
Our research group has actively pursued the identification
of a second generation HCV NS3 protease inhibitor. On the
basis of our experience in the development of 1, the following
criteria were established for the new compound: (a) improved
cellular potency compared to that of 1 (EC90 = 350 nM) to
potentially reduce the dose needed for effectively reducing
viral load in humans; therefore, a 5-fold or higher increase in
the cellular potency was set as a requirement for the second
generation compound; (b) improved pharmacokinetic profile
to attain higher exposure in primates and target once a day
dosing for humans.
Hepatitis C virus (HCVa) infection remains a public health
burdenby afflicting morethan170 million people worldwide.1
Chronic HCV infection is the leading cause for liver failure
and liver cancer. The health care costs associated with HCV
are expected to increase substantially as the majority of
patients reach the end stage complications of the disease.
The current standard of care for HCV infection is a combina-
tion of peginterferon and ribavirin.2 This treatment is effective
and can successfully deliver sustained virologic response
(SVR) in >75% of patients infected with genotype-2 and -3.
However, patients infected with genotype-1, which include
most of the patients in U.S., Europe, and Japan, achieve only
40% SVR. Therefore, tremendous efforts have been directed
to develop new and more effective therapeutic agents for the
treatment of HCV infection.
The HCV genome is a (þ)-RNA strand that encodes a
polyprotein that contains both structural and nonstructural
proteins.3 The C-terminus of the HCV NS3 enzyme is a serine
protease that plays an important role in viral replication
because it is responsible for the cis-cleavage of the NS3-NS4
junction and the trans-cleavage of the NS4B, NS5A, and
Herein, we report the results obtained for a new class of
HCV NS3/4A inhibitors containing a cyclic sulfone moiety at
the P4-site while maintaining the ketoamide moiety that had
proven to be an effective serine trap for the enzyme. We
describe the rationale that led us to design inhibitors that
extend beyond the tert-butylurea P3-cap and a diastereose-
lective method for the synthesis of the chiral cyclic sulfones
that were evaluated in this study.
*To whom correspondence should be addressed. Phone: 908-740-
6654. Fax: 908-740-7152. E-mail: francisco.velazquez@spcorp.com.
Current address: Merck Research Laboratories, 2015 Galloping Hill
Road, K-15-3 3545, Kenilworth, NJ 07033-1300.
a Abbreviations: HCV, hepatitis C virus; PK, pharmacokinetic;
AUC, area under the curve; SAR, structure-activity relationship;
THF, tetrahydrofuran; PhMe, toluene; DCM, dichloromethane;
HATU, 2-(1H-7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexa-
fluorophosphate; DIPEA, diisopropylethylamine; DMF, dimethylforma-
mide; DMSO, dimethyl sulfoxide; TFA, trifluoroacetic acid; TLC, thin
layer chromatography; NMR, nuclear magnetic resonance; LC-MS,
liquid chromatography-mass spectrometry; LRMS, low resolution mass
spectrometry; HRMS, high resolution mass spectrometry.
Design of P4 Cyclic Sulfone Cap
The structure and partial profile of 1 are shown in Figure 1.
Structural features of 1 include the ketoamide moiety, which
r
2010 American Chemical Society
Published on Web 03/19/2010
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3076 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8
Velaꢀzquez et al.
Figure 3. Modification of P3-cap. From cyclohexylmethylurea to
ethylsulfone and cyclization strategy.
among others.11 More recently, several inhibitors containing
alkyl- and arylsulfones were also investigated.12 Thus, the
ethylsulfone analogue 3 is a representative example from the
sulfone series (Figure 3). Compound 3 showed improved
cellular potency (Ki*=5 nM and EC90=90 nM). This cellular
potency represented a 2-fold improvement compared to 2 and
almost 4-fold compared to 1. Unfortunately, plasma levels of 3
after oral administration in rats could not be attained
Figure 1. Modification of P3-cap. From tert-butylurea (compound 1)
to cyclohexylmethylurea (compound 2).
(AUC(0-6h)=0 μM h at 10 mpk).13 It is important to mention
3
the synergy existing between the sulfone moiety and the
spirocyclohexyl group; sulfone analogues having a gem-
dimethyl moiety instead of the spirocyclohexyl group showed
poor cellular potency with EC90 values in the micromolar
range. Therefore, the spirocyclohexyl group was maintained
in our targets to further expand the SAR studies in the sulfone
series.
Modifications of compound 3 to further improve its po-
tency and PK profiles were based on SAR developed in our
group. As indicated above, compound 3 did not attain
detectable levels in plasma after oral administration in rats,
and similar PK profiles were observed for other sulfone
analogues with primary ketoamides. Therefore, we antici-
pated improvement of oral exposure in rats and other species
by capping the P10 moiety.5 Also, we envisioned a novel class
of cyclic sulfone inhibitors based on the ethylsulfone moiety
in 3. The tethering of the ethyl group onto the methylene
spacer between the sulfone and the spirocyclohexyl groups
was deemed appropriate (as indicated by the arrow in
Figure 3). This modification would lead to a more rigid
structure that could potentially have improved potency and
PK profiles. Molecular modeling suggested that inhibitors
having either R- or S-stereochemistry in the cyclic sulfone
moiety would have appropriate binding. Thus, we initiated
the diastereoselective synthesis of compounds having four-,
five-, and six-membered cyclic sulfone P3-caps to evaluate
their potency and PK profiles. Details for the diastereoselec-
tive synthesis of the proposed targets are described below.
Figure 2. Molecular modeling of compound 2 bound to HCV NS3/
4A active site.
serves as trap for Ser-139, and the tert-butylurea which serves
as P3-capping. Also, a unique characteristic of compound 1 is
the fused gem-dimethylcyclopropane proline group at the P2-
site. We previously established that this proline derived amino
acid provided inhibitors with better potency and PK profiles.9
To continue the structure-activity relationship (SAR)
studies in 1, we synthesized the cyclohexylmethylurea analo-
gue 2 and had its potency measured. The binding affinity and
cellular potency of 2 and all other inhibitors synthesized for
this study were determined following previously reported
procedures.10 Compound 2 had improved binding and cellu-
lar potencies, Ki* = 9 nM and EC90 = 200 nM. Molecular
modeling of compound 2 bound to HCV NS3 protease active
site showed that 2 had a hydrophobic interaction between its
cyclohexyl ring and the S4-pocket (Figure 2). Furthermore, it
was determined that the methyl group in the cyclohexylmethyl
urea P3-cap could be used as a point of attachment for other
groups to extend into the S4-pocket. Toward this end, we used
the aforementioned methyl group to append different struc-
tural moieties such as sulfonamides and carbonyl groups,
Chemistry
The retrosynthetic analysis for synthesis of targets of type 4
is shown in Figure 4. The key disconnections include the urea
linkage between the P3-P4 groups and the amide bond
between P1-P2 groups. These disconnections gave the cyclic
sulfone P3-cap 5, P2-P3 dipeptide 6, and hydroxyamide 7 as
synthons for preparation of target compounds. Syntheses of
fragments 6 and 7 have been described in previous commu-
nications from our research group.5 Synthesis of the P4-cyclic
sulfone 5 required an approach that allowed the stereocon-
trolled installation of the chiral center at the R-position to the

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8 3077
Scheme 1. Stereoselective Synthesis of Cyclic Sulfones via
Addition of Sulfonyl Anions to Chiral Sulfinyliminesa
Figure 4. Retrosynthetic analysis of proposed targets.
a Reagents and conditions: (i) (S)-t-butanesulfinamide, Ti(OEt)4,
THF, 65 °C; (ii) sulfone, n-BuLi, THF, -78 °C; (iii) 4 M HCl, MeOH,
0-25 °C; (iv) C(O)Cl2, PhMe/DCM, aq NaHCO3, 0 °C.
sulfone moiety. We have previously reported the synthesis of
β-substituted β-aminosulfones via addition of sulfonyl anions
to chiral sulfinylimines derived from aldehydes.14 We consid-
ered using a similar approach to investigate the addition of
sulfonyl anions to sulfinylimines derived from cyclohexanone
(Scheme 1). Two important issues were expected to be ad-
dressed following this approach: (a) efficiency of the addition
(competition between addition and deprotonation of the
imine could lead to undesired side reactions); (b) level of
stereocontrol in the addition reaction (effectiveness of the
chiral sulfoxide to control the stereochemical outcome of the
reaction).
Scheme 2. Synthesis of Urea 19 for Assignment of Stereochem-
istry via Single Crystal X-ray Analysisa
Synthesis of chiral sulfinylimine 9 from cyclohexanone and
(S)-tert-butanesulfinamide was accomplished in 70% yield
following standard procedures (Scheme 1).15 The next crucial
step was to install the required stereogenic center in the
R-position relative to the sulfone. This reaction was carried
out by deprotonation of four-, five-, and six-membered cyclic
sulfones followed by reaction with the sulfinylimine 9. The
reactions proceeded in good yields albeit the level of stereo-
control was modest. Nevertheless, the diastereomeric pro-
ducts 10-12 in all cases were easily separated by silica gel
chromatography.
After separation of the diastereomeric productsS,S-10 toS,
S-12 from the S,R-10 to S,R-12, the amines were unmasked
by cleavage of the sulfinamide group under acidic conditions
to deliver the corresponding optically pure amines 13-15
in quantitative yields with S-stereochemistry in addition to
their corresponding enantiomers R-13 to R-15 (not shown).
The stereochemical assignment was secured by single-crystal
X-ray analysis of the urea 19 derived from amine hydrochlor-
ide R-14 (Scheme 2).16 The stereochemical assignment for the
rest of the amines was established by NMR analysis using
11 as reference compound. The amines were converted to
the corresponding isocyanates 16-18 using standard proce-
dures.
Synthesis of target 25 is shown in Scheme 3. Isocyanate
R-17 was coupled to the P2-P3 dipeptide 20 following
previously described procedures to give 21. Then the methyl
ester in 21 was hydrolyzed with lithium hydroxide and the
resulting acid 22 was coupled with the P1-P10 amine 23 using
HATU to deliver hydroxyamide 24. Oxidation of 24 to yield
ketoamide 25 was accomplished using Dess-Martin reagent.
All target compounds presented in this study were synthesized
using this general protocol.
a ORTEP diagram for urea 19 is shown at the bottom. Reagents and
conditions: (i) (R)-(1-isocyanatoethyl)benzene, aq NaHCO3, 25 °C.
Results and Discussion
The first set of target compounds synthesized were expected
to provide information about the optimum ring size for
binding and the required configuration at the chiral center
in the R-position relative to the sulfone moiety. As mentioned
above, an improvement in PK profile of target compounds
was expected by capping the primary ketoamide with small
alkyl groups. Therefore, target compounds were synthesized
containing allyl and cyclopropyl groups to evaluate their
potency and PK profiles. In addition, SAR studies had
demonstrated that branched P1 groups were less tolerated
when the primary ketoamides were capped.5 Consequently,
we decided to start our studies with analogues having the
nonbranched amino acid norleucine at the P1 site and cyclo-
propyl at the P10.17 Table 1 shows binding and cellular

3078 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8
Velaꢀzquez et al.
Scheme 3. Synthesis of Targets Containing Cyclic Sulfones as
Table 1. Cyclic Sulfone Derived P3-Caps: SAR for Ring Size and
Absolute Configuration
P3-Capsa
compd
n
absolute config
Ki* (nM)
EC90 (nM)
25
26
27
28
29
30
1
1
0
0
2
2
R
S
R
S
R
S
4
4
20
30
10
5
60
120
50
10
11
60
Table 2. Five- and Six-Membered Cyclic Sulfone Inhibitors: Evaluation
of P10-Allyl Groupa
a Reagents and conditions: (i) 20, DIPEA, DMF; (ii) LiOH, THF/
H2O; (iii) 23, HATU, N-methylmorpholine, DMF/DCM; (iv) Dess-
Martin periodinane, DCM.
potencies for compounds 25-30. This set of compounds in-
cluded targets with the proposed four-, five-, and six-membered
cyclic sulfone P3-caps and had either S- or R-configuration in
the chiral center present in the cyclic sulfone moiety. Remark-
ably, all the compounds had excellent binding potency with Ki*
values in the low nanomolar range. Moreover, the results
indicated that there was not an apparent preference for absolute
configuration of the chiral center in the cyclic sulfone moiety
which suggested that both R- and S-isomers were appropriately
predisposed to bind tightly to the HCV NS3/4A active site. This
result could be explained based on the fact that the sulfone
moiety could adopt different conformations when the inhibitors
are bound to the enzyme. However, we observed a slight
preference for the R-isomer when measuring cellular potency.
This effect was more evident for the four-membered sulfone
analogues. The R-isomer 27 had EC90 = 60 nM, whereas the
S-isomers 28 had EC90 = 120 nM. In contrast, the difference in
EC90 values between R- and S-isomers in both five- and six-
membered analogues was negligible. For example, in the five-
membered series the EC90 values for the R- and S-isomers were
20 and 30 nM, respectively.
a (§) Epimeric mixture at P1 site.
small number of compounds having the five-membered cyclic
sulfone moiety and primary ketoamides were prepared
(compounds not shown). However, the cellular potency for
all those compounds were significantly higher (EC90
g
400 nM) compared to the compounds presented in Table 1.
The evaluation of compounds with P10 allyl group and tert-
butylglycine at P3 was carried out. Norleucine, norvaline, and
homocyclopropylalanine amino acids were chosen for the P1
site SAR investigations. These three amino acids have been
extensively used in SAR development for HCV NS3 protease
inhibitors.5,9 The potency data for allyl containing analogues
are shown in Table 2. The data clearly showed that both five-
and six-membered series were potent with Ki* values in the
single-digit nanomolar rangeand nosignificant difference was
observed between the two series. Also, cellular potency was
very similar for compounds in both series with EC90 values
From this study, it was determined that five- and six-
membered sulfone analogues were slightly more potent than
the corresponding four-membered counterparts, and further
investigations were continued preferentially on the R-isomers
of five- and six-membered sulfone analogues.18 It is important
to mention that to pursue a thorough SAR investigation, a

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8 3079
Table 3. Five- and Six-Membered Cyclic Sulfone Inhibitors: P10-Cy-
clopropyl Analoguesa
Figure 5. Potency and pharmacokinetic profile for compound 34.
that ranged from 30 to 60 nM for the six-membered com-
pounds 31-33 and from 30 to 35 nM for the five-membered
analogues 34-36. A trend showing slightly better cellular
potency for five-membered analogues as a group could be
observed, and further investigation of pharmacokinetic pro-
file was started for compounds in the five-membered series.
The norleucine compound 34 in the five-membered series
was further examined in the rapid rat experiment to determine
its plasma levels after oral administration19 (Figure 5). Com-
pound 34 achieved high plasma levels with AUC(0-6h) = 4.6
μM h at 10 mpk. Encouraged by the positive results obtained
3
in the PK experiments, compound 34 was orally dosed in
monkeys at 3 mpk. Once again, compound 34 achieved good
plasma levels with an AUC(0-24h) = 2.2 μM h. Comparison
3
between plasma levels in monkeys of compound 34 and that
of 1 (AUC = 0.12 μM h) showed a >18-fold improvement in
3
AUC. It is important to mention that analogues of 1 having a
P10-allyl group showed poor binding and cellular potencies
(Ki* g 100 nM). Therefore, the potency andPKdata of34and
the other five- and six-membered cyclic sulfone analogues
demonstrated that a new P3-cap that delivered inhibitors with
improved potency and pharmacokinetic profiles had been
discovered.
In spite of the positive results obtained for compound 34 in
potency and pharmacokinetic experiments, the allyl group at
the P10 site remained a concern because of its potential to
undergo metabolic activation to form a reactive species via
epoxidation. To assess this potential liability, compound 34
was subjected to incubation with microsomes in the presence
of glutathione. Unfortunately, under this conditions the
oxidation of the allyl group was observed and the correspond-
ing glutathione adducts arising from the reactive intermediate
were detected. This unfavorable result prompted us to aban-
don the P10 allyl series and focus instead on profiling the P10
cyclopropyl analogues.
a (§) Determined in rats at 10 mpk in 0.4% MC. (†) Not available.
the six-membered analogues had EC90 values between 40 and
50 nM (compounds 29, 37, 38). The pharmacokinetic profiles
for P10 cyclopropyl analogues were also investigated in rats
(determined at 10 mpk in 0.4% MC).13,19 Unfortunately, all
compounds showed suboptimal AUC values in the range of
0.2-0.9 μM h. Norleucine compound 25 in the five-mem-
3
bered series gave the highest exposure after oral administra-
The cyclopropyl group had been employed in the P10 site in
our earlier SAR studies to determine optimum ring size and
stereochemistry of the newly synthesized cyclic sulfone P3
caps. To further evaluate the five- and six-membered cyclic
sulfone series with P10 cyclopropyl, we prepared targets
having similar amino acids in the P1 (norleucine, norvaline,
homocyclopropylalanine) and P3 (tert-butylglycine) sites.
The data for these targets are shown in Table 3. The Ki* and
EC90 values for the P10 cyclopropyl analogues 25, 29, 37-40
were similar to their P10 allyl counterparts, and only slight
improvements were observed in a few cases. Once again, most
of the compounds in both five- and six-membered series had
Ki* values in the single-digit nanomolar range. However, in
the P10 cyclopropyl series, the five-membered compounds
showed a trend for slightly better cellular potency with EC90
values between 20and40nM (compounds25, 39, 40), whereas
tion (AUC(0-6h) = 0.9 μM h). A comparison of the plasma
3
levels achieved by compound 34 (P10 allyl) with its direct
analogue 25 (P10 cyclopropyl) revealed a significant drop for
the latter. Furthermore, all other compounds in the P10
cyclopropyl series, including five- and six-membered analo-
gues, showed lower plasma levels than 25. The data clearly
showed that replacement of the P10 allyl group with a cyclo-
propyl group was effective to retain binding and cellular
potencies but resulted in lower plasma levels after oral admin-
istration in rats. In order to correct this issue, we decided to
introduce the β-methylcyclohexylglycine amino acid at the P3
site. This unnatural amino acid was previously reported by
our group, and it has proved to be a useful P3 replacement for
a number of inhibitors.20 Moreover, the use of β-methylcy-
clohexylglycine amino acid has resulted in inhibitors with
improved pharmacokinetic profiles. The binding potency for

3080 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8
Velaꢀzquez et al.
Table 4. Plasma Levels for Selected Compounds after Oral Adminis-
tration in Monkeys
44 to determine their viability as potential second generation
HCV NS3 inhibitors.
compd
AUC(0-24h) (μM h)a
[ccmpd]8h (nM)
[8 h]/EC90
3
Conclusions
25
43
44
45
0.4
9.0
20.8
3.5
10
0.5
37
47
8
742
934
303
A novel class of HCV NS3 protease inhibitors has been
discovered and provide potential second generation com-
pounds for development. An approach based on SAR devel-
opment in the S4 region of the HCV NS3/4A enzyme was
employed for the identification of a cyclic sulfone P3-cap for
compounds with improved potency and PK profiles com-
pared to 1. The cyclic sulfone moiety fitted well in the S4
pocket, and systematic modifications allowed determination
of the appropriate ring size and absolute configuration for
optimum potency. Initial experiments showed that five- and
six-membered sulfones were the most active and that having
the R-configuration atthe chiral centerR tothe sulfone moiety
was preferred. Further evaluation of target compounds deter-
mined that inhibitors in the five-membered series had better
PK profiles. Finally, introduction of the β-methylcyclohex-
ylglycine at the P3 site provided compounds with high plasma
levels in rats and monkeys. The five-membered sulfone ana-
logues 43 and 44 stood out for their potency and PK profiles.
Binding and cellular potencies for these two compounds were
improved by more than 10-fold compared to 1. Moreover,
modifications using unnatural amino acids developed in our
group resulted in significant improvements for 43 and 44 in
terms of plasma levels attained after oral administration in
monkeys. The substantial improvement in PK profile for 43
and 44 compared to 1 was an important step toward identi-
fication of a viable second generation candidate for clinical
development.
a Determined at 3 mpk dose in 0.4% MC.
compounds having β-methylcyclohexylglycine at P3 was
again in the single-digit nanomolar range for compounds in
both five- and six-membered series (41-45). The previous
observation regarding better cellular potencies for five-
membered sulfone analogues was again confirmed from these
targets. Thus, five-membered compounds 43-45 had EC90
values between 20 and 40 nM and were slightly more potent
than their six-membered counterparts 41 and 42 (EC90 values
between 50 and 100 nM). The pharmacokinetic profile
of β-methylcyclohexylglycine analogues was subsequently
evaluated in rats.13,19 In the five-membered series, the
β-methylcyclohexylglycine compounds 43-45 showed higher
plasma levels compared to their tert-butylglycine counter-
parts 25, 39, 40. Thus, the norleucine analogue 43 attained
the highest plasma levels (AUC(0-6h) = 2.7 μM h) whereas
3
the norvaline and homocyclopropylalanine compounds 50
and 51 showed AUC values of 1.2 and 1.5 μM h, respectively.
3
These results clearly demonstrated that introduction of
the unnatural amino acid β-methylcyclohexylglycine at the
P3-site had a positive effect in the pharmacokinetic profile of
our compounds without being detrimental to their cellular
potency.
On the basis of potency and exposure in rats, key com-
pounds were selected for PK studies in monkeys (at 3 mpk
dose in 0.4% MC). The data shown in Table 4 include the
exposure after oral administration, concentration of the
compounds in plasma after 8 h, and the ratio between their
concentrations at 8 h over EC90.
The PK data in Table 4 clearly demonstrated that com-
pounds with β-methylcyclohexylglycine P3 in the five-mem-
bered series could achieve high plasma levels after oral
administration. A direct comparison between the tert-butyl-
Experimental Section
Dry solvents were purchased from Aldrich or Acros and used
without further purification. Other solvents or reagents were used
as obtained except when otherwise noted. Analytical thin layer
chromatography (TLC) was performed on precoated silica gel
plates available from Analtech. Visualization was accomplished
with UV light or by staining with basic KMnO4 solution,
methanolic H2SO4, or Vaughn’s reagent. Column chromatogra-
phy was performed using Merck silica gel 60 (particle size
0.040-0.055 mm, 230-400 mesh) or using Biotage or Isco
chromatographic systems. NMR spectra were recorded in CDCl3
or DMSO-d6 in 400 or 500 MHz (1H NMR) and in 100 or 125
MHz (13C NMR). Low and high resolution mass spectra were
obtained using electron spray or FAB ionization methods. Purity
of compounds was determined by LC-MS analysis using Agilent
chromatographic systems under the following conditions: sample
concentration, 1 mg/mL in methanol; column, Agilent SBC
(3.0 mm ꢀ 50 mm, 1.8 μm); flow rate, 1.0 mL/min; solvent A,
H2O-0.1% TFA; solvent B, acetonitrile-0.1% TFA; gradient
table, 0 min at 10% B, 0.3 min at 10% B, 1.5 min at 95% B,
2.7 min at 95% B; UV detector, 254 nM. Compounds presented
in this manuscript showed g95% purity.
(S)-N-Cyclohexylidene-2-methylpropane-2-sulfinamide (9). 9
was prepared in 70% yield according to the procedure described
in ref 15. 1H NMR (CDCl3, 500 MHz): δ 2.86 (1H, ddd, J =5.12,
8.05, 13.18 Hz), 2.70 (1H, ddd, 5.12, 8.05, 13.91 Hz), 2.41 (2H, t,
J = 6.59 Hz), 1.70-1.86 (4H, m), 1.66 (2H, dd, J = 5.12, 10.98
Hz), 1.21 (9H, s).
General Procedure for Addition of Sulfonyl Anions to N-
Sulfinylimine 9. n-Butyllithium (1.3 equiv, 8.1 mL of a 1.6 M
solution in hexanes) was added over 10 min to a cooled (-78 °C)
solution of sulfone (1.35 equiv, 1.8 g, 13.41 mmol) in 50 mL of
dry THF under anhydrous atmosphere. The mixture was stirred
for 30 min at that temperature and then transferred via cannula
glycine analogue 25 (AUC(0-24h) = 0.4 μM h) and the
3
β-methylcyclohexylglycine analogue 43 (AUC(0-24h) = 9.0
μM h) demonstrated an improvement in exposure of more
3
than 20 times. Furthermore, the plasma concentration of 25 at
8 h was only 10 nM which was lower than the compound’s
EC90. In contrast, 43 had a high plasma concentration at 8 h
(742 nM) which was equivalent to 37 times its EC90. The
norvaline analogue 44 had the highest AUC value (20.8
μM h) in the β-methylcyclohexylglycine series. Moreover,
3
the compound’s concentration in plasma at 8 h and the ratio
between concentration over EC90 were also the highest for
these two analogues, 934 nM and 47, respectively. The
homocyclopropylalanine analogue 45 had moderate exposure
(AUC(0-24h) =3.5 μM h) and plasma concentration at 8 h
3
(303 nM). In summary, compounds 43 and 44 achieved high
plasma levels after oral administration and their concentra-
tion in plasma after 8 h was still a lot higher than their EC90
values. All the cyclic sulfone analogues tested in the monkey
PK assay in this study demonstrated higher exposures than
our clinical candidate 1. Compounds 43 and 44 (in the five-
membered series with β-methylcyclohexylglycine P3 and
cyclopropyl P10) stood out in terms of potency and plasma
levels achieved. We are currently profiling compounds 43 and

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8 3081
to a solution of sulfinylimine 9 (2.0 g, 9.93 mmol) in 50 mL of dry
THF at -78 °C. After addition was completed, the reaction
mixture was stirred for 3 h. The reaction was quenched at
-78 °C by addition of 5 mL of aqueous saturated ammonium
chloride solution. The mixture was allowed to reach room
temperature and then partitioned between dichloromethane
(100 mL) and aqueous saturated sodium bicarbonate solution
(50 mL). The aqueous layer was back-extracted with dichlor-
omethane (2 ꢀ 50 mL). The combined organic layers were dried
over magnesium sulfate, filtered, and concentrated. The residue
was chromatographed on silica gel to afford the corresponding
diastereomeric S,S- and S,R-products.
N-[1-(1,1-Dioxido-2(S)-thietanyl)cyclohexyl]-2-methyl-2-pro-
pane-(S)-sulfinamide (S,S-10). S,S-10 was obtained in 48% yield
according to the general procedure. 1H NMR (CDCl3, 400
MHz): δ 4.82 (1H, dd, J = 8.78, 9.52 Hz), 4.33 (1H, s), 3.95
(1H, dt, J = 9.52, 13.18 Hz), 3.82 (1H, dt, J = 7.32, 13.18 Hz),
2.18 (1H, d, J = 8.78 Hz), 2.15 (1H, m), 2.01 (3H, m), 1.34-1.74
(7H, m), 1.22 (9H, s). LRMS (ESI) calcd for C13H26NO3S2 [M þ
H]þ, 308.14; found, 308.03
N-[1-(1,1-Dioxido-2(R)-thietanyl)cyclohexyl]-2-methyl-2-pro-
pane-(S)-sulfinamide (S,R-10). S,R-10 was obtained in 48%
yield according to the general procedure. 1H NMR (CDCl3,
400 MHz): δ 4.97 (1H, s), 4.44 (1H, t, J=9.52 Hz), 4.02 (1H, ddt,
J = 1.46, 5.12, 13.18 Hz), 3.93 (1H, ddd, J = 8.05, 10.25, 13.18
Hz), 2.85 (1H, ddt, J = 8.05, 8.78, 10.98 Hz), 2.06 (2H, m), 1.83
(1H, m), 1.76 (1H, ddd, J=3.66, 9.52, 13.18 Hz), 1.29-1.66 (7H,
m), 1.26 (9H, s). LRMS (ESI) calcd for C13H25NO3S2Na [M þ
Na]þ, 330.12; found, 330.02.
N-[1-(Tetrahydro-1,1-dioxido-2(S)-thienyl)cyclohexyl]-2-meth-
yl-2-propane-(S)-sulfinamide (S,S-11). S,S-11 was obtained in
75% yield according to the general procedure. 1H NMR
(CDCl3, 500 MHz): δ 5.16 (1H, s), 3.10 (1H, dd, J=7.88, 11.35
Hz), 3.08 (1H, m), 3.06 (1H, d, J = 5.04 Hz), 2.78 (1H, ddt, J =
5.99, 7.25, 11.98 Hz), 2.21 (2H, m), 2.07 (2H, m), 1.97 (1H, m),
1.88 (1H, m), 1.49-1.66 (5H, m), 1.46 (1H, m), 1.37 (1H, m), 1.26
(9H, s). 13C NMR (CDCl3, 125 MHz): δ 69.0, 58.7, 56.6, 52.8,
38.0, 33.1, 25.1, 24.5, 23.0, 21.3, 21.1, 20.0 ppm. LRMS (ESI) calcd
for C14H28NO3S2 [M þ H]þ, 322.15; found, 322.05. LRMS (ESI)
calcd for C14H27NO3S2Na [M þ Na]þ, 344.13; found, 344.00.
N-[1-(Tetrahydro-1,1-dioxido-2(R)-thienyl)cyclohexyl]-2-meth-
yl-2-propane-(S)-sulfinamide (S,R-11). S,R-11 was obtained in
75% yield according to the general procedure. 1H NMR
(CDCl3, 500 MHz): δ 4.85 (1H, s), 3.59 (1H, dd, J=7.88, 10.40
Hz), 3.16 (1H, m), 2.90 (1H, ddd, J = 7.25, 10.71, 13.24 Hz), 2.35
(1H, 13.87 Hz), 1.97-2.23 (6H, m), 1.64-1.80 (3H, m), 1.57 (2H,
m), 1.37 (2H, m), 1.24 (9H, s). 13C NMR (CDCl3, 125 MHz): δ
65.0, 58.9, 56.2, 52.9, 36.7, 33.5, 24.8, 24.2, 23.0, 22.2, 21.6, 19.4
ppm. LRMS (ESI) calcd for C14H28NO3S2 [M þ H]þ: 322.15;
found, 322.02. LRMS (ESI) calcd for C14H27NO3S2Na [M þ
Na]þ: 344.13; found, 344.00.
dissolved in 50 mL of methanol and treated with 20 mL of 4 M HCl
solution in dioxane. The mixture was stirred for about 1 h at which
point all the starting material had been consumed as determined by
TLC (acetone/hexanes, 35:65). The solvents were evaporated to
dryness. Dichloromethane was added (10 mL) to make a cloudy
solution. Upon addition of 100 mL of ether, a white precipitated
formed. The precipitate was recovered by filtration (Whatman
no. 1) to yield the amine hydrochloride R-14 (1.22 g, 98%) as a
white powder. 1H NMR (CDCl3, 500 MHz): δ 8.61 (3H, broad s),
3.47 (1H, dd, J = 7.32, 12.44 Hz), 3.24 (1H, m), 3.18 (1H, ddt, J =
4.39, 7.32, 13.18 Hz), 2.75 (1H, ddt, J = 5.12, 8.05, 13.18 Hz), 2.35
(3H, m), 2.17 (2H, m), 2.04 (2H, m), 1.92 (1H, dd, J = 5.12, 9.52
Hz), 1.84 (1H, m), 1.61 (2H, m), 1.51 (1H, m), 1.39 (1H, m). 13
C
NMR (CDCl3, 100 MHz): δ 62.4, 57.7, 52.9, 34.1, 32.2, 24.1, 24.0,
21.1, 20.7, 19.7 ppm. LRMS (ESI) calcd for C10H20NO2S [M þ
H]þ, 218.12; found, 218.32.
N-(1(R)-Phenylethyl)-N0-[1-(tetrahydro-1,1-dioxido-2(R)-thie-
nyl)cyclohexyl]urea (19). A solution of amine hydrochloride R-14
(100 mg, 0.394 mmol) in 10 mL of dichloromethane was treated
with aqueous saturated sodium bicarbonate solution (0.5 mL)
at 0 °C. (R)-(1-Isocyanatoethyl)benzene (1.2 equiv, 69 mg) was
added, and the resulting mixture was allowed to reach room
temperature and stirred for 2 h. Some amine starting material
was still unreacted, and more isocyanate was added (69 mg).
After 2 h the mixture was diluted with dichloromethane (50 mL)
and dried over magnesium sulfate. The mixture was filtered and
concentrated under reduced pressure. The residue was chroma-
tographed on silica gel (gradient, acetone/hexanes, 1:9 to 1:1) to
afford the product 19 (100 mg, 70%) as a white solid. 1H NMR
(CDCl3, 400 MHz): δ 7.36 (4H, m), 7.24 (1H, t, J=7.32 Hz), 4.93
(1H, broads), 4.70 (2H, m), 3.73 (1H, dd, J=7.32, 11.71Hz), 3.08
(1H, m), 2.82 (1H, ddd, J = 7.32, 10.25, 12.44 Hz), 2.51 (1H, d,
J = 11.71 Hz), 2.40 (1H, m), 1.87-2.20 (4H, m), 1.24-1.53 (6H,
m), 1.43 (3H, d, J = 6.59 Hz), 1.11 (1H, m), 1.00 (1H, m). LRMS
(ESI) calcd for C19H29N2O3S [M þ H]þ, 365.19; found, 365.29.
Calcd for C19H28N2O3SNa [M þ Na]þ, 387.17; found, 387.20.
Methyl (1R,5S)-3-[3,3-Dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-
1,1-dioxido-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-
6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2(S)-carboxylate (21). A
solution of amine hydrochloride R-14 (2.0 g, 7.88 mmol) in 40 mL
of dichloromethanewas treatedwith 20 mL of aqueoussaturated
sodium bicarbonate solution and stirred vigorously for 10 min
at 0 °C. Stirring was stopped, and layers were allowed to sepa-
rate. Phosgene (10 mL of 20% solution in toluene) was added
through a needle to the organic layer in one portion. The mixture
was vigorously stirred immediately after addition for 10 min at
0 °C and further stirred at room temp for 3 h. The mixture was
diluted with 150 mL of dichloromethane, and layers were
separated. The organic layer was washed with 50 mL of cold
aqueous saturated sodium bicarbonate solution and dried over
magnesium sulfate. The organic layer was filtered and diluted
with 15 mL of toluene. The resulting solution was concentrated
to almost dryness and adjusted with toluene to give a 0.525 M
solution of R-17 in toluene.
N-[1-(Tetrahydro-1,1-dioxido-2H-thiopyran-2(S)-yl)cyclohexyl]-
2-methyl-2-propane-(S)-sulfinamide (S,S-12). S,S-12 was obtained
in 80% yield according to the general procedure. 1H NMR(CDCl3,
500 MHz): δ 5.15 (1H, s), 3.76 (1H, dd, J = 2.52, 12.92 Hz), 3.00
(1H, dt, J = 4.72, 13.87 Hz), 2.98 (1H, m), 2.91 (1H, ddd, J = 2.52,
3.46, 13.87 Hz), 2.19 (2H, m), 2.01-2.15 (4H, m), 1.93 (2H, m), 1.83
(1H, m), 1.72 (1H, dt, J = 3.78, 11.35 Hz), 1.39-1.68 (5H, m), 1.27
(9H, s). 13C NMR (CDCl3, 125 MHz): δ 69.8, 61.1, 56.3, 54.5, 52.1,
34.1, 31.9, 26.1, 25.2, 24.2, 22.9, 21.1, 21.0 ppm.
N-[1-(Tetrahydro-1,1-dioxido-2H-thiopyran-2(R)-yl)cyclohexyl]-
2-methyl-2-propane-(S)-sulfinamide (S,R-12). S,R-12 was obtained
in 80% yield according to the general procedure. 1H NMR(CDCl3,
500 MHz): δ 4.18 (1H, s), 3.25 (1H, dd, J = 2.83, 12.61 Hz), 2.98
(2H, m), 2.26 (3H, m), 2.18 (1H, m), 1.94-2.13 (4H, m), 1.73 (1H,
d, J = 13.87 Hz), 1.56 (4H, m), 1.45 (3H, m), 1.27 (9H, s). 13C
NMR (CDCl3, 125 MHz): δ 69.0, 60.9, 56.5, 55.3, 36.3, 33.5, 25.2,
25.1, 24.7, 24.0, 22.9, 21.6, 21.3 ppm.
In a separate flask, a solution of amine hydrochloride 20 (1.25
equiv, 1.99 g) in 50 mL of dichloromethane was treated with
N-methylmorpholine (4.0 equiv, 2.2 mL, d 0.920) at 0 °C. After
5 min, 9.5 mL of the isocyanate R-17 solution (0.525 M solution
in toluene) was added. The mixture was stirred overnight
(temperature from 0 to 25 °C). The reaction was quenched by
addition of aqueous 1 M HCl (80 mL). The mixture was
extracted with ethyl acetate (3 ꢀ 100 mL). The combined
organic layers were washed with brine (50 mL), dried over
magnesium sulfate, filtered, and concentrated. The residue
was chromatographed on silica gel (gradient, acetone/hexanes,
1:9 to 1:1) to afford the product 21 (2.06 g, 78%) as a white solid.
1H NMR (CDCl3, 400 MHz): δ 5.08 (1H, broad s), 4.79 (1H, s),
4.45 (1H, s), 4.33 (1H, broad s), 4.05 (1H, d, J = 10.25 Hz), 3.85
(1H, dd, J = 3.66, 10.25 Hz), 3.73 (3H, s), 3.68 (1H, dd, J =
7.32, 11.71 Hz), 3.09 (1H, m), 2.92 (1H, ddd, J = 7.32, 10.98,
1-(Tetrahydro-1,1-dioxido-2(R)-thienyl)cyclohexanamine, Hydro-
chloride (R-14). The sulfinamide S,R-11 (1.55 g, 4.82 mmol) was

3082 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8
Velaꢀzquez et al.
13.18 Hz), 2.58 (1H, d, J = 10.25 Hz), 2.38 (1H, m), 1.87-2.19
(4H, m), 1.34-1.67 (9H, m), 1.18 (1H, m), 1.01 (12H, s), 0.89
(3H, s). LRMS (ESI) calcd for C26H44N3O6S [M þ H]þ, 526.30;
found, 526.35.
9.77 Hz), 3.72 (1H, dd, J = 5.35, 10.08 Hz), 3.12 (1H, m), 2.89
(1H, ddd, J = 7.56, 10.08, 12.92 Hz), 2.74 (1H, m), 1.99 (3H,
m), 1.70-1.85 (4H, m), 1.21-1.57 (14H, m), 1.09 (1H, m), 1.00
(3H, s), 0.89 (9H, s), 0.86 (3H, t = 7.25 Hz), 0.82 (3H, s), 0.65
(2H, m), 0.57 (2H, m). 13C NMR (DMSO-d6, 125 MHz): δ
197.0, 171.0, 170.2, 161.9, 156.6, 66.3, 58.9, 56.3, 55.1, 53.5,
52.3, 47.3, 34.2, 30.6, 29.9, 29.2, 27.4, 26.7, 26.3, 26.2, 26.0,
25.0, 23.8, 22.4, 21.6, 20.5, 20.3, 18.5, 18.4, 13.6, 12.4, 5.4,
5.3 ppm. HRMS (FAB) calcd for C35H58N5O7S [M þ H]þ,
692.4057; found, 692.4037.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxido-2(R)-
thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-dimethyl-
3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (25). A solution
of methyl ester 21 (2.03 g, 3.86 mmol) in 120 mL of a 2:1
mixture of THF/water was cooled to 0 °C and treated with
lithium hydroxide monohydrate (2.5 equiv, 404 mg). The
mixture was stirred for 10 min, and the cooling bath was
removed. The mixture was stirred at room temperature until
all starting material had been consumed as determined by
TLC (acetone/hexanes, 3:7). After 3 h, the mixture was
treated with aqueous 1 M HCl (∼100 mL) to make the mixture
acidic (pH 2). The mixture was extracted with dichloro-
methane (3 ꢀ 100 mL). The combined organic layers were
dried over magnesium sulfate, filtered, and concentrated
under reduced pressure to afford the carboxylic acid 22
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[2(S)-[[[[1-(1,1-dioxido-2(R)-thietanyl)cyclohexyl]amino]carbonyl]-
amino]-3,3-dimethyl-1-oxobutyl]-6,6-dimethyl-3-azabicyclo[3.1.0]-
1
hexane-2(S)-carboxamide (27). H NMR (CDCl3, 400 MHz): δ
7.71 (1H, d, J = 7.81 Hz), 7.32 (1H, d, J = 3.90 Hz), 5.78 (1H, d,
J = 10.16 Hz), 5.49 (1H, dt, J = 3.12, 8.59 Hz), 5.15 (1H, s), 4.60
(1H, s), 4.57 (1H, t, J = 9.37 Hz), 4.50 (1H, d, J = 10.16 Hz), 4.00
(1H, d, J = 10.16 Hz), 3.77-3.96 (4H, m), 2.81 (2H, m), 2.53 (1H,
ddd, J =8.59, 10.94, 19.53 Hz), 2.17 (1H, ddt, J=4.68, 7.03, 10.16
Hz), 1.95 (2H, m), 1.46-1.59 (7H, m), 1.16-1.45 (9H, m), 1.00
(3H, s), 0.95 (9H, s), 0.87 (3H, m), 0.86 (3H, s), 0.64 (2H, m). 13
C
(1.93 g, 98%) as a white solid. LRMS (ESI) calcd for C25H42
-
N3O6S [M þ H]þ, 512.28; found, 512.28.
NMR (CDCl3, 125 MHz): δ 197.9, 172.2, 170.6, 160.3, 157.2,
87.8, 62.6, 59.6, 57.6, 56.4, 53.7, 48.5, 35.3, 32.2, 30.9, 29.6, 27.8,
27.3, 26.4, 25.3, 22.6, 21.8, 21.0, 18.6, 13.7, 12.6, 10.1, 6.3, 6.2, 1.0
ppm. LRMS (ESI) calcd for C34H56N5O7S [M þ H]þ, 678.39;
found, 678.52.
A solution of carboxylic acid 22 (130 mg, 0.254 mmol) in 3 mL
of dry dichloromethane and 3 mL of dry DMF was stirred at
0 °C and treated with HATU (1.4 equiv, 135 mg). The amine
hydrochloride 23 (1.2 equiv, 72 mg) was added followed by
N-methylmorpholine (4.0 equiv, 0.11 mL, d 0.920). The reaction
mixture was stirred overnight (temperature from 0 to 25 °C). All
the volatiles were removed under vacuum, and the residue was
dissolved in 60 mL of ethyl acetate. The organic layer was
washed with water (10 mL), aqueous 1 M HCl (10 mL), aqueous
saturated sodium bicarbonate solution (10 mL), and brine
(10 mL). The organic layer was dried over magnesium sulfate,
filtered, and concentrated under reduced pressure to afford the
crude product 24 (∼99%, 175 mg) which was used without
further purification. The hydroxyamide 24 (175 mg, 0.251
mmol) was dissolved in 10 mL of dry dichloromethane and
treated with Dess-Martin periodinane (2.0 equiv, 215 mg). The
reaction mixture was stirred at room temperature for 30 min.
The mixture was treated with aqueous 1 M sodium thiosulfate
solution (10 mL) and stirred for 5 min. Aqueous saturated
sodium bicarbonate solution (10 mL) was also added, and
stirring was continued for a further 10 min. The mixture was
extracted with dichloromethane (3 ꢀ 30 mL). The combined
organic layers were dried over magnesium sulfate, filtered, and
concentrated. The residue was chromatographed on silica gel
(gradient, acetone/hexanes, 1:9 to 4:6) to afford the product 25
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[2(S)-[[[[1-(1,1-dioxido-2(S)-thietanyl)cyclohexyl]amino]carbonyl]-
amino]-3,3-dimethyl-1-oxobutyl]-6,6-dimethyl-3-azabicyclo[3.1.0]-
1
hexane-2(S)-carboxamide (28). H NMR (CDCl3, 500 MHz): δ
7.55 (1H, d, J = 6.93 Hz), 7.09 (1H, s), 5.51 (1H, s), 5.36 (1H, ddd,
J = 4.41, 7.88, 8.82 Hz), 5.09 (1H, dd, J = 9.45, 9.77 Hz), 4.93
(1H, s), 4.51 (1H, s), 4.48 (1H, d, J = 9.77 Hz), 4.01 (1H, d, J =
10.40 Hz), 3.75-3.92 (3H, m), 2.80 (1H, m), 2.51 (1H, d, J = 9.45
Hz), 2.31 (1H, d, J = 10.71 Hz), 2.19 (1H, m), 2.06 (1H, ddt, J =
4.41, 10.08, 11.03 Hz), 1.95 (1H, ddd, J = 4.41, 8.82, 12.92 Hz),
1.17-1.63 (14H, m), 1.00 (3H, s), 0.96 (9H, s), 0.84-0.89 (6H, m),
0.83 (3H, s), 0.62 (2H, m). 13C NMR (CDCl3, 125 MHz): δ 196.9,
172.6, 170.6, 160.4, 156.8, 85.5, 62.0, 59.8, 57.7, 55.9, 53.8, 48.6,
35.0, 32.3, 31.7, 31.5, 31.1, 29.6, 27.5, 27.4, 26.5, 26.3, 25.3, 22.6,
22.4, 21.8, 21.0, 20.8, 18.8, 14.0, 13.6, 12.7, 10.3, 6.4, 6.3 ppm.
HRMS (FAB) calcd for C34H56N5O7S [M þ H]þ, 678.3900;
found, 678.3883.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxido-2(H)-
thiopyran-2(R)-yl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-
dimethyl-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (29). 1H
NMR (CDCl3, 500 MHz): δ 7.51 (1H, d, J = 7.2 Hz), 7.06
(1H, d, J = 3.4 Hz), 5.51 (1H, d, J = 10.0 Hz), 5.30-5.36 (1H,
m), 4.79 (1H, s), 4.50 (1H, s), 4.47 (1H, d, J = 10.0 Hz), 4.02 (1H,
d, J=10.7), 3.87 (1H, d, J = 12.5 Hz), 3.83 (1H, dd, J = 10.7 and
5.3 Hz), 2.86-2.92 (2H, m), 2.76-2.83 (1H, m), 2.32-2.38 (1H,
m), 2.24-2.30 (1H, m), 2.10-2.16 (1H, m), 1.08-2.06 (22H, m),
1.00 (3H, s), 0.98 (9H, s), 0.84-0.90 (5H, m), 0.83 (3H, s),
0.59-0.64 (2H, m). 13C NMR (CDCl3, 125 MHz): δ 196.7,
172.8, 170.1, 160.5, 156.7, 67.0, 60.0, 58.0, 57.5, 54.8, 53.9, 48.5,
35.1, 32.7, 31.8, 31.1, 29.5, 27.7, 27.4, 26.4 (3C), 26.3, 26.2, 25.4,
25.3, 24.4, 22.5, 22.0, 21.2, 20.8, 18.8, 13.7, 12.6, 6.5, 6.4 ppm.
HRMS (FAB) calcd for C36H60N5O7S [M þ H]þ, 706.421 34;
found, 706.420 70.
1
(130 mg, 75%) as a white powder. H NMR (DMSO-d6, 500
MHz): δ 8.74 (1H, d, J = 5.04 Hz), 8.36 (1H, d, J = 6.62 Hz),
6.21 (1H, d, J = 9.77 Hz), 6.08 (1H, s), 4.94 (1H, ddd, J = 3.78,
6.62, 9.45 Hz), 4.30 (1H, s), 4.13 (1H, d, J = 10.08 Hz), 3.93 (1H,
d, J = 10.40 Hz), 3.83 (1H, dd, J = 7.88, 11.35 Hz), 3.72 (1H, dd,
J = 5.35, 10.08 Hz), 3.12 (1H, m), 2.88 (1H, ddd, J = 7.56, 10.40,
12.92 Hz), 2.74 (1H, m), 2.46 (1H, d, J=11.66 Hz), 1.86-2.05 (4H,
m), 1.75 (2H, m), 1.64 (1H, dt, J = 4.41, 12.92 Hz), 1.21-1.58
(13H, m), 1.08 (1H, m), 1.00 (3H, s), 0.90 (9H, s), 0.86 (3H, t, J =
7.25 Hz), 0.83 (3H, s), 0.65 (2H, m), 0.57 (2H, m). 13C NMR
(DMSO-d6, 125 MHz): δ 197.0, 171.0, 170.5, 161.9, 156.8, 66.3,
58.9, 56.6, 55.0, 53.5, 52.4, 47.3, 34.0, 30.6, 30.2, 29.2, 27.4, 26.8,
26.2, 26.0, 25.0, 23.9, 22.4, 21.6, 20.6, 20.3, 18.5, 18.3, 13.6, 12.2,
5.4, 5.3 ppm. HRMS (FAB) calcd for C35H58N5O7S [M þ H]þ,
692.4057; found, 692.4043.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxido-2(S)-
thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-dimethyl-
3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (26). 1H NMR
(DMSO-d6, 500 MHz): δ 8.74 (1H, d, J = 5.35 Hz), 8.37
(1H, d, J = 6.93 Hz), 6.26 (1H, d, J = 10.08 Hz), 6.01 (1H, s),
4.94 (1H, ddd, J = 3.78, 6.93, 9.45 Hz), 4.30 (1H, s), 4.17 (1H,
d, J= 10.08 Hz), 3.90 (1H, d, J= 10.40 Hz), 3.83 (1H, dd, J=9.14,
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxido-2H-thio-
pyran-2(S)-yl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-di-
methyl-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (30). 1H
NMR (CDCl3, 500 MHz): δ 7.37 (1H, d, J=6.9 Hz), 7.01 (1H,
d, J = 3.0 Hz), 5.35 (1H, d, J = 10.0 Hz), 5.28-5.35 (1H, m),
4.58 (1H, s), 4.49 (1H, s), 4.42 (1H, d, J = 9.9 Hz), 4.04 (1H, d,
J = 10.4 Hz), 3.80 (1H, dd, J=10.4, 5.2 Hz), 3.69 (1H, d, J =
12.5 Hz), 2.82-2.93 (2H, m), 2.75-2.81 (1H, m), 2.56 (1H, d,
J = 13.3 Hz), 2.21 (1H, d, J=13.6 Hz), 1.16-2.08 (21H, m),

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Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8 3083
1.01 (3H, s), 0.97 (9H, s), 0.87 (3H, t, J = 6.3 Hz), 0.86 (3H, s),
0.83 (2H, m), 0.55-0.64 (2H, m). 13C NMR (CDCl3, 125
MHz): δ 196.6, 172.6, 170.6, 160.5, 156.7, 68.0, 59.9, 58.2,
57.7, 55.0, 54.1, 48.5, 35.1, 33.2, 33.0, 31.1, 29.2, 27.8, 27.4,
26.4 (4C), 26.1, 25.3, 25.2, 24.4, 22.4, 22.1, 21.5, 21.2, 18.8,
13.7, 12.8, 6.5, 6.4 ppm. HRMS (ESI) calcd for C36H60N5O7S
[M þ H]þ: 706.421 34; found, 706.418 81.
172.6, 170.9, 160.5, 156.7, 67.1, 59.9, 57.9, 57.3, 54.7, 53.7, 48.6,
35.2, 32.7, 31.7, 31.6, 30.5, 30.0, 27.4, 26.5 (3C), 26.3, 26.2, 25.4,
25.3, 24.4, 22.5, 21.3, 20.8, 18.9, 12.8, 10.1, 6.4, 6.4, 4.7, 4.2 ppm.
HRMS (FAB) calcd for C37H60N5O7S [M þ H]þ, 718.421 34;
found, 718.421 84.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]butyl]-
3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxido-2(R)-
thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-dimethyl-
3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (39). 1H NMR
(CDCl3, 400 MHz): δ 7.75 (1H, d, J = 8.59 Hz), 7.20 (1H, d,
J = 3.12 Hz), 5.74 (1H, d, J = 9.37 Hz), 5.44 (1H, dt, J = 3.12,
8.59 Hz), 5.11 (1H, s), 4.55 (1H, m), 4.54 (1H, s), 4.03 (1H, d,
J = 10.94 Hz), 3.95 (1H, dd, J = 7.81, 11.72 Hz), 3.87 (1H, dd, J =
4.68, 10.16 Hz), 3.11 (1H, m), 2.91 (1H, ddd, J = 7.81, 10.94, 13.28
Hz), 2.81 (1H, ddt, J = 3.90, 7.03, 10.94 Hz), 2.54 (1H, d, J = 7.03
Hz), 2.46 (1H, d, J = 7.03 Hz), 1.31-2.19 (17H, m), 1.15 (1H, m),
0.99 (3H, s), 0.97 (9H, s), 0.91 (3H, t, J = 7.03 Hz), 0.85 (2H, m),
0.83 (3H, s), 0.63 (2H, m). 13C NMR (CDCl3, 100 MHz): δ 197.4,
172.6, 170.8, 160.3, 156.7, 67.4, 59.7, 57.3, 56.3, 53.4, 52.8, 48.6, 35.1,
33.3, 33.0, 30.9, 29.9, 27.3, 26.5, 26.3, 25.5, 25.0, 22.5, 21.0, 20.9, 19.4,
18.8, 18.7, 13.2, 12.8, 6.4, 6.3 ppm. LRMS (ESI) calcd for
C34H56N5O7S [M þ H]þ: 678.39; found, 678.25.
(1R,5S)-3-[3,3-Dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxi-
do-2H-thiopyran-2(R)-yl)cyclohexyl]amino]carbonyl]amino]butyl]-
N-[1(S)-[1,2-dioxo-2-(2-propenylamino)ethyl]butyl]-6,6-dimethyl-
3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (32). 1H NMR
(CDCl3, 500 MHz): δ 7.72 (1H, d, J = 8.0 Hz), 7.27 (1H, t,
J = 5.9 Hz), 5.90 (1H, d, J = 9.9 Hz), 5.77-5.86 (1H, m),
5.38-5.46 (1H, m), 5.20 (1H, dq, J = 17.1, 1.3 Hz), 5.16 (1H, dq,
J = 17.1, 1.3 Hz), 5.04 (1H, s), 4.54 (1H, d, J = 10.0 Hz), 4.52
(1H, s), 3.97 (1H, d, J = 9.9 Hz), 3.84-3.94 (5H, m), 2.83-2.92
(2H, m), 2.25-2.37 (2H, m), 2.08-2.16 (1H, m) 1.96-2.16 (2H,
m), 1.81-1.92 (3H, m), 1.64-1.77 (1H, m), 1.33-1.52 (12H, m),
0.99 (3H, s), 0.97 (9H, s), 0.90 (3H, t, J = 7.3Hz), 0.82 (3H, s). 13
C
NMR (CDCl3, 125 MHz): δ 196.3, 172.5, 171.0, 159.1, 156.8,
132.8, 117.3, 67.1, 60.0, 57.9, 57.3, 54.7, 53.5, 48.7, 41.7 35.3, 33.4,
32.7, 31.8, 30.2, 27.4, 26.6 (3C), 26.3, 26.2, 25.4, 25.3, 24.4, 21.2,
20.8, 18.9, 18.7, 13.3, 12.9 ppm. HRMS (FAB) calcd for
C35H58N5O7S [M þ H]þ: 692.405 69; found, 692.40555.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]pentyl]-
6,6-dimethyl-3-[2(S)-(1-methylcyclohexyl)-2-[[[[1-(tetrahydro-1,1-
dioxido-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]acetyl]-3-
azabicyclo[3.1.0]hexane-2(S)-carboxamide (43). 1H NMR (DMSO-
d6, 500 MHz): δ 8.74 (1H, d, J = 5.04 Hz), 8.34 (1H, d, J = 6.93
Hz), 6.24 (1H, d, J = 10.08 Hz), 6.06 (1H, s), 4.94 (1H, ddd, J =
4.09, 6.93, 9.45 Hz), 4.29 (1H, s), 4.17 (1H, d, J = 10.08 Hz), 3.95
(1H, d, J = 10.40 Hz), 3.83 (1H, dd, J = 7.88, 11.35 Hz), 3.74 (1H,
dd, J = 5.35, 10.08 Hz), 3.13 (1H, m), 2.87 (1H, ddd, J = 7.88,
10.40, 12.92 Hz), 2.74 (1H, m), 2.46 (1H, d, J=11.35 Hz), 1.86-2.05
(4H, m), 1.75 (2H, m), 1.64 (1H, dt, J = 4.41, 12.61 Hz), 1.18-1.58
(22H, m), 1.09 (2H, m), 1.00 (3H, s), 0.92 (3H, s), 0.86 (3H, t, J =
6.93 Hz), 0.82 (3H, s), 0.65 (2H, m), 0.57 (2H, m). 13C NMR
(DMSO-d6,125MHz):δ197.0, 171.0, 170.4, 161.9, 156.8, 66.3, 58.9,
57.2, 55.0, 53.5, 52.4, 47.3, 36.7, 33.4, 33.0, 30.6, 30.5, 30.2, 29.2, 27.4,
26.8, 26.0, 25.8, 25.0, 23.9, 22.3, 21.6, 21.2, 21.0, 20.6, 20.3, 19.0, 18.5,
18.3, 13.6, 12.2, 5.3, 5.2 ppm. HRMS (ESI) calcd for C38H62N5O7S
[M þ H]þ, 732.437 00; found, 732.440 36.
(1R,5S)-3-[3,3-Dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-diox-
ido-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-N-[1(S)-
[1,2-dioxo-2-(2-propenylamino)ethyl]pentyl]-6,6-dimethyl-3-azabi-
cyclo[3.1.0]hexane-2(S)-carboxamide (34). 1H NMR (CDCl3, 400
MHz): δ 8.84 (1H, t, J = 5.47 Hz), 8.33 (1H, d, J = 7.03 Hz), 6.21
(1H, d, J = 10.16 Hz), 6.07 (1H, s), 5.79 (1H, m), 5.09 (1H, d, J =
17.19 Hz), 5.06 (1H, d, J = 10.16 Hz), 4.96 (1H, m), 4.31 (1H, s),
4.14 (1H, d, J = 10.16 Hz), 3.93 (1H, d, J = 10.16 Hz), 3.82 (1H,
dd, J = 8.59, 10.94 Hz), 3.74 (3H, m), 3.11 (1H, m), 2.87 (1H, m),
2.45 (1H, m), 1.86-2.07 (4H, m), 1.75 (2H, m), 1.65 (1H, dt, J =
4.68, 12.50 Hz), 1.19-1.59 (13H, m), 1.10 (1H, m), 1.01 (3H, s),
0.90 (9H, s), 0.86 (3H, t, J=7.03 Hz), 0.84 (3H, s). 13C NMR
(CDCl3, 100 MHz): δ 197.1, 170.9, 170.5, 160.6, 156.8, 133.9,
115.4, 66.3, 58.8, 56.6, 55.0, 53.5, 52.3, 47.2, 40.7, 33.9, 30.6, 30.5,
30.2, 29.2, 27.3, 26.8, 26.2, 26.0, 24.9, 23.8, 21.5, 20.6, 20.3, 18.5,
18.3, 13.5, 12.2 ppm. LRMS (ESI) calcd for C35H58N5O7S [M þ
H]þ, 692.41; found, 692.24.
(1R,5S)-N-[1(S)-[2-(Cyclopropylamino)-1,2-dioxoethyl]butyl]-
6,6-dimethyl-3-[2(S)-(1-methylcyclohexyl)-2-[[[[1-(tetrahydro-1,1-
dioxido-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]acetyl]-
3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (44). 1H NMR
(CDCl3, 400 MHz): δ 7.65 (1H, d, J = 7.81 Hz), 7.16 (1H, d,
J = 3.90 Hz), 5.54 (1H, d, J = 9.37 Hz), 5.41 (1H, dt, J = 4.68,
9.37 Hz), 5.06 (1H, s), 4.54 (1H, s), 4.51 (1H, d, J = 10.16 Hz),
4.06 (1H, d, J = 10.16 Hz), 3.87 (1H, d, J = 10.16 Hz), 3.86 (1H,
m), 3.11 (1H, m), 2.90 (1H, ddd, J = 7.81, 10.16, 13.28 Hz), 2.80
(1H, ddt, J = 3.90, 7.81, 10.94 Hz), 2.55 (1H, d, J = 9.37 Hz),
2.46 (1H, d, J = 9.37 Hz), 1.67-2.20 (8H, m), 1.08-1.62 (19H,
m), 1.00 (3H, s), 0.97 (3H, s), 0.91 (3H, t, J = 7.03 Hz), 0.83 (6H,
s), 0.62 (2H, m). 13C NMR (CDCl3, 100 MHz): δ 197.3, 172.6,
170.6, 160.3, 156.8, 67.6, 59.6, 58.6, 56.4, 53.6, 52.7, 48.6, 38.0,
34.2, 33.6, 33.3, 33.2, 31.1, 29.6, 29.3, 27.3, 26.3, 26.1, 25.5, 25.0,
22.5, 21.6, 21.5, 20.9, 19.4, 19.0, 18.6, 13.4, 12.7, 6.4, 6.3 ppm.
LRMS (ESI) calcd for C37H60N5O7S [M þ H]þ, 718.42; found,
718.28
(1R,5S)-N-[3-(Cyclopropylamino)-1(S)-(2-cyclopropylethyl)-2,3-
dioxopropyl]-6,6-dimethyl-3-[2(S)-(1-methylcyclohexyl)-2-[[[[1-(tetra-
hydro-1,1-dioxido-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]-
acetyl]-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (45). 1H NMR
(CDCl3, 400 MHz): δ 7.58 (1H, d, J = 7.03 Hz), 7.15 (1H, d, J =
3.90 Hz), 5.44 (2H, m), 5.01 (1H, s), 4.53 (1H, s), 4.49 (1H, d, J =
9.37 Hz), 4.08 (1H, d, J = 10.94 Hz), 3.86 (1H, d, J = 10.94 Hz),
3.85 (1H, m), 3.11 (1H, m), 2.89 (1H, ddd, J = 7.81, 10.94, 13.28
Hz), 2.80 (1H, ddt, J = 3.90, 7.03, 10.94 Hz), 2.54 (1H, d, J = 8.59
Hz),2.47(1H, d, J=9.37Hz), 1.90-2.21 (5H, m), 1.06-1.76 (22H,
m), 1.00 (3H, s), 0.98 (3H, s), 0.84 (6H, s), 0.67 (1H, m), 0.62 (2H,
m), 0.41 (2H, dd, J = 1.56, 7.89 Hz), 0.01 (1H, dd, J = 4.68, 18.75
(1R,5S)-N-[1-(2-Cyclopropylethyl)-2,3-dioxo-3-(2-propenyla-
mino)propyl]-3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxi-
do-2(R)-thienyl)cyclohexyl]amino]carbonyl]amino]butyl]-6,6-dimeth-
yl-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (36). 1H NMR
(CDCl3, 400 MHz): δ 7.36 (1H, d, J = 6.25 Hz), 7.04 (1H, t, J =
5.47 Hz), 5.84 (1H, ddt, J = 5.47, 10.94, 17.19 Hz), 5.36 (1H, m),
5.22 (1H, d, J = 17.19 Hz), 5.19 (1H, d, J = 10.94 Hz), 4.81 (1H,
broad s), 4.47 (1H, s), 4.44 (1H, s), 4.09 (1H, d, J = 10.16 Hz), 3.94
(2H, m), 3.79 (2H, m), 3.10 (1H, m), 2.91 (1H, ddd, J = 7.03, 10.16,
12.50 Hz), 2.54 (1H, d, J = 8.59 Hz), 2.47 (1H, d, J = 8.59 Hz),
1.89-2.22 (6H, m), 1.13-1.80 (13H, m), 1.02 (3H, s), 1.00 (9H, s),
0.85 (3H, s), 0.66 (1H, m), 0.42 (2H, dd, J = 1.56, 7.81 Hz), 0.04
(1H, m), 0.01 (1H, dd, J = 1.56, 4.68 Hz). 13C NMR (CDCl3, 125
MHz): δ 196.4, 172.9, 170.5, 159.0, 156.8, 132.7, 117.4, 67.8, 59.9,
57.9, 56.6, 54.2, 52.7, 48.5, 41.6, 34.9, 33.6, 31.5, 31.4, 30.7, 29.2, 27.5,
26.4, 26.3, 25.4, 24.9, 21.1, 21.0, 19.4, 18.7, 12.6, 10.3, 4.6, 4.3 ppm.
LRMS (ESI) calcd for C36H58N5O7S [M þ H]þ, 704.41; found,
704.32.
(1R,5S)-N-[3-(Cyclopropylamino)-1(S)-(2-cyclopropylethyl)-2,3-
dioxopropyl]-3-[3,3-dimethyl-1-oxo-2(S)-[[[[1-(tetrahydro-1,1-dioxi-
do-2H-thiopyran-2(R)-yl)cyclohexyl]amino]carbonyl]amino]butyl]-
6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2(S)-carboxamide (38). 1H
NMR (CDCl3, 500 MHz): δ 7.62 (1H, d, J = 7.7 Hz), 7.17 (1H, d,
J = 3.7 Hz), 5.75 (1H, d, J = 9.8 Hz), 5.41-5.48 (1H, m), 4.98
(1H, s), 4.52 (1H, d, J = 9.8Hz), 4.51 (1H, s), 3.99 (1H, d, J = 10.4
Hz), 3.82-3.91 (2H, m), 2.84-2.92 (2H, m), 2.76-2.82 (1H, m),
2.25-2.38 (2H, m), 1.08-2.16 (20H, m), 0.97 (12H, s), 0.80-0.88
(2H, m), 0.82 (3H, s), 0.60-0.70 (3H, m), 0.36-0.44 (2H, m),
-0.08--0.06 (2H, m). 13C NMR (CDCl3, 125 MHz): δ 197.2,

3084 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 8
Velaꢀzquez et al.
Hz), 0.00 (1H, m). 13C NMR (CDCl3, 100 MHz): δ 197.3, 172.6,
170.6, 160.3, 156.8, 67.6, 59.6, 58.6, 56.4, 53.8, 52.7, 48.5, 37.9, 34.2,
33.7, 33.4, 31.3, 31.2, 30.7, 29.2, 27.3, 26.4, 26.1, 25.4, 25.0, 22.5, 21.6,
21.5, 21.0, 20.9, 19.4, 19.0, 18.5, 12.6, 10.2, 6.3, 6.3, 4.7, 4.2 ppm.
LRMS (ESI) calcd for C39H62N5O7S [M þ H]þ, 744.44; found,
744.33.
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Acknowledgment. We thank John Pichardo, Sony Agrawal,
Andrea Hart, and Robert Budich, Schering-Plough Research
Institute, for their support in this project.
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