Structure-based design and synthesis of potent, ethylenediamine-based, mammalian farnesyltransferase inhibitors as anticancer agents

Article abstract of DOI:10.1021/jm1001748

A potent class of anticancer, human farnesyltransferase (hFTase) inhibitors has been identified by "piggy-backing" on potent, antimalarial inhibitors of Plasmodium falciparum farnesyltransferase (PfFTase). On the basis of a 4-fold substituted ethylenediam

Full text of DOI:10.1021/jm1001748

J. Med. Chem. 2010, 53, 6867–6888 6867
DOI: 10.1021/jm1001748
Structure-Based Design and Synthesis of Potent, Ethylenediamine-Based,
Mammalian Farnesyltransferase Inhibitors as Anticancer Agents
Steven Fletcher,#,† Erin Pusateri Keaney,#,† Christopher G. Cummings,† Michelle A. Blaskovich,‡ Michael A. Hast,§
Matthew P. Glenn,† Sung-Youn Chang,† Cynthia J. Bucher,‡ Ryan J. Floyd,‡ William P. Katt,† Michael H. Gelb,
Wesley C. Van Voorhis,^ Lorena S. Beese,§ Said M. Sebti,‡ and Andrew D. Hamilton*,†
†Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, ‡Department of Drug Discovery,
H. Lee Moffitt Cancer Center and Research Institute and Department of Molecular Medicine, University of South Florida,
Tampa, Florida 33612, §Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, North Carolina 27710,
Department of Chemistry and Biochemistry, and ^Department of Medicine, University of Washington, Seattle, Washington 98195.
#These authors contributed equally to this paper.
Received February 9, 2010
A potent class of anticancer, human farnesyltransferase (hFTase) inhibitors has been identified by
“piggy-backing” on potent, antimalarial inhibitors of Plasmodium falciparum farnesyltransferase
(PfFTase). On the basis of a 4-fold substituted ethylenediamine scaffold, the inhibitors are structurally
simple and readily derivatized, facilitating the extensive structure-activity relationship (SAR) study
reported herein. Our most potent inhibitor is compound 1f, which exhibited an in vitro hFTase IC50
value of 25 nM and a whole cell H-Ras processing IC50 value of 90 nM. Moreover, it is noteworthy that
several of our inhibitors proved highly selective for hFTase (up to 333-fold) over the related
prenyltransferase enzyme geranylgeranyltransferase-I (GGTase-I). A crystal structure of inhibitor 1a
co-crystallized with farnesyl pyrophosphate (FPP) in the active site of rat FTase illustrates that the para-
benzonitrile moiety of 1a is stabilized by a π-π stacking interaction with the Y361β residue, suggesting a
structural explanation for the observed importance of this component of our inhibitors.
Introduction
the results are mixed. For example, a lack of activity was
reported when Tipifarnib13 (R115777) was used against ad-
vanced colorectal and pancreatic cancers.14,15 In contrast,
extremely encouraging results were observed when Tipifarnib
was used against breast cancer in combination with cytotoxic
agents.16,17 In recent years, it has become clear that aberrant
Ras activity is not the only target for FTIs, and it is likely that
other FTase substrates, such as Rheb, are also involved in
oncogenesis.18-21 Nonetheless, despite the now-apparent com-
plexity of this system and the unclear molecular mechanisms by
which FTIs operate, the past decade has seen many FTIs
established as antiproliferative agents of high efficacy and
low toxicity, validating the continued research into more
drug-like FTIs as alternative chemotherapeutics for cancer.1-3
The prenyltransferases are a family of zinc metalloenzymes
that catalyze the prenylation (addition of a prenyl group
through a thioether linkage) of a particular set of proteins,
many of which are crucial to signal transduction pathways,
causing their localization to the plasma membrane and other
cellular compartments and so rendering them biologically
active.22 There are three members of the prenyltransferase
family: farnesyltransferase (FTase), geranygeranyltransferase-
I (GGTase-I), and geranygeranyltransferase-II (GGTase-II).
FTase catalyzes the transfer of a farnesyl (C15 isoprenoid)
group from the cosubstrate farnesyl pyrophosphate (FPP)
to the cysteine residue within the C-terminus Ca1a2X tetra-
peptide sequence of the target protein (including Ras and
Rheb), where C = cysteine, a = an aliphatic amino acid, and
X = methionine (M), serine (S), alanine (A), or glutamine
As the successful treatment of cancer remains a challenging
goal, research into novel, selective, and less toxic chemothera-
peutic agents is gathering pace.1-3 Indeed, increasing under-
standing of the cellular processes that lead to cancer has
identified additional targets for the design of such chemother-
apeutics. Ras, the protein product of the ras oncogene, is a
small GTPase that is important in signal transduction, cell
growth, and cell proliferation.4 Mutations in Ras, which cause
the protein to persistently bind GTP and thus become con-
stitutively active, can lead to unregulated cell division; such
Ras mutants are found in approximately 30% of human
tumors.5,6 In the 1980s, it was reported that Ras required
farnesylation to enhance its hydrophobicity and thereby
facilitate its anchorage to the plasma membrane, a process
necessary for its signaling function.7,8 Accordingly, it was
envisioned that inhibition of the enzyme that performs this post-
translational modification, protein farnesyltransferase (FTasea),
would offer an indirect method of blocking the function of Ras
oncoproteins. Indeed, in addition to inhibiting FTase in vitro,9-12
farnesyltransferase inhibitors (FTIs) have demonstrated anti-
tumor activity in several animal models.2,9 Clinically, however,
*To whom correspondence should be addressed. Phone: (203) 432
5570. Fax: (203) 432-3221. E-mail: andrew.hamilton@yale.edu.
aAbbreviations: FTase, farnesyltransferase; hFTase, human FTase;
rFTase, rat FTase; PfFTase, Plasmodium falciparum FTase; FTI,
farnesyltransferase inhibitor; FPP, farnesyl pyrophosphate; GGTase-I,
geranylgeranyltransferase-I; IC50, inhibitor concentration that inhibits
50% of enzyme activity; rt, room temperature.
r
2010 American Chemical Society
Published on Web 09/07/2010
pubs.acs.org/jmc

6868 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
Figure 1. One high scoring active site conformation of inhibitor 1a (green) as identified by flexible ligand GOLD32 docking experiments
(A) using a Connoly analytical surface graphical representation developed in PyMOL,37 red hydrophobic to blue hydrophilic, and (B) using a
“cartoon” graphical representation developed in PyMOL37 and overlaid with the peptide inhibitor CVFM (orange) from the rFTase crystal
structure. Binding surface of rat FTase (PDB ID: 1JCR35), values in parentheses refer to corresponding residues in PfFTase;31 small molecules
colored by atom type: FPP colored red (farnesyl) and blue (pyrophosphate); blue spheres = water molecules; purple sphere = zinc ion.
(Q).23 Likewise, GGTase-I catalyzes the corresponding
S-geranylgeranylation by accelerating the transfer of the
geranylgeranyl group (C20 isoprenoid) from geranylgeranyl
pyrophosphate (GGPP) to the cysteine within the C-terminus
Ca1a2X sequence of the substrate protein (including Rho,
Rap, and Ral),24 where this time X is usually leucine (L),
isoleucine (I), or phenylalanine (F).23 It is the identity of the
X residue that dictates if a target protein is farnesylated or
geranylgeranylated, and is so-called the specificity residue.
Finally, in a similar fashion, GGTase-II transfers two geranyl-
geranyl groups to protein trafficking Rab proteins that contain
Cys-Cys or Cys-Ala-Cys sequences at the C-terminus.23
Previous research within our laboratories has focused on the
design of peptidomimetic inhibitors of FTase based on the
Ca1a2X tetrapeptide substrate.25-28 Herein we describe a novel
series of ethylenediamine-based, mammalian FTase inhibitors
as anticancer compounds that were discovered by a “piggy-
back” approach after the success of the core scaffold in a series
of antimalarial plasmodial FTase inhibitors.29 We present an
extensive structure-activity relationship (SAR) study of these
inhibitors with both in vitro and whole cell data, including
relative activities against FTase and GGTase-I. Additionally,
we discuss our efforts to improve inhibitor potency against
mammalian FTase, and we present crystallographic data that
reveals the actual binding mode of our inhibitors within the
active site of the enzyme.
Results and Discussion
Design. We have previously reported on the design and
synthesis of inhibitors of Plasmodium falciparum farnesyl-
transferase (PfFTase).29,30 An homology model of the active
site of PfFTase suggests the presence of four sub-pockets.31
By employing the computational modeling program
GOLD,32 we identified that an ethylenediamine scaffold
with both nitrogens doubly substituted in order to gain
simultaneous access to these four subpockets might furnish
inhibitors of PfFTase. Indeed, compounds based on this
scaffold, including 1a (Figure 1), in which the choice of
the four substituents (para-benzonitrile, imidazolylmethyl,
arylmethyl, and heterocycle-substituted sulfonyl) was influ-
enced by the BMS series of tetrahydrobenzodiazepine-
based33 and tetrahydroquinoline (THQ)-based34 FTase inhi-
bitors, proved particularly potent inhibitors of PfFTase, both
in vitro and in infected erythrocytes.29,30 Although PfFTase
is significantly larger than rat FTase (rFTase) in both the
R- (472 vs 379 residues) and β-subunits (923 vs 437 residues),

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6869
Table 1. Enzyme Inhibition and Whole Cell Data of a Focused Set of Ethylenediamine-Based PfFTase Inhibitors
compd
IC50 (nM)a
processing IC50 (μM)c
H-Ras Rap1A
>10
no.
X
R1
hFTase
GGTase-l
selectivityb
3 (FTI-2581)
4 (FTI-2584)
5 (FTI-2586)
1a (FTI-2585)
H
Br
H
6300 ( 360
730 ( 20
79 ( 30
>10000
4400
1.6
6.0
6.7
48
>10
>10
>10
>10
H
5.7 ( 1.2
1.6 ( 1.3
1.9 ( 1.2
Br
CN
Me
Me
530 ( 170
2700 ( 2200
56 ( 29
a IC50 = inhibitor concentration requiredto achieve 50% inhibition of hFTase or GGTase-I in vitro. b Ratio of GGTase-I to FTase IC50s. c Processing
IC50 = inhibitor concentration required to achieve 50% inhibition of farnesylation of H-Ras or geranylgeranylation of Rap1A in whole cells. In all
cases, IC50 data represents the average of three independent assays (n = 3), unless otherwise stated, and errors are given as standard deviations.
the differences are mainly due to insertions in the PfFTase
protein sequence, and overall there is minimal difference in the
residues that form the active site.29,31 Of the sequence segments
in the model of PfFTase, there is 23% identity (53% similarity)
for the R-subunit between PfFTase and rFTase isoforms and
37% (56%) for the β-subunit. Therefore, we anticipated that
our PfFTase inhibitors may also inhibit mammalian FTase,
binding in the same sub-domains but, in certain instances, to
differing active site residues (i.e., PfFTase31 f rFTase (PDB
ID: 1JCR35): S150 f N165R, F151 f Y166R, N317 f H201R),
providing a route to inhibitor selectivity for the mammalian
isoform of the enzyme.
Specifically, as with an almost identical analogue of 1a in
the homology model of the active site of PfFTase (Figure 2 in
ref 29b), we hypothesized that the more basic of the two
imidazoles, the 1-methyl-1H-imidazol-5-ylmethyl substi-
tuent of 1a, would bind the zinc ion (itself held in place by
D297β (D659), C661β (C299), and H362β (H838), where the
labels in parentheses represent the corresponding residues in
PfFTase31). In addition, we envisioned that the para-benzo-
nitrile moiety would bind in the mostly hydrophobic pocket
constructed from the tetramethylene portion of the side
chain of K164R (K149) and Y166R (F151) and whose
deepest point forms a hydrophilic domain (H201R (N317)
and N165R (S150)). We considered that the benzyl moiety
would bind in the hydrophobic pocket comprising W102β
(W452), W106β (W456), and Y361β (Y837), and finally that
the sulfonylimidazole would bind in the hydrophilic domain
formed by R202β (R564) and three water molecules partici-
pating in a hydrogen-bonded network between S99β (S449)
and Q167R (Q152).
To maintain consistency with the GOLD docking experi-
ments of our ethylenediamine-based inhibitors in the homol-
ogy model of the active site of PfFTase,29,30 the only
constraint imposed in the flexible ligand GOLD docking
with compound 1a in the active site of rFTase (PDB ID:
1JCR) was that the more basic, non-sulfonylated imidazole
should again bind the Zn2þ ion. Due to the flexible nature
of the ethylenediamine scaffold in 1a, we did not want to
bias the docking results any further and used no addi-
tional constraints. Moreover, despite the similarities of
the pendant groups in 1a and the former clinical candidate
(R)-7-cyano-2,3,4,5-tetrahydro-1-(1H-imidazol-4-ylmethyl)-
3-(phenylmethyl)-4-(2-thienylsulfonyl)-1H-1,4-benzodiazepine
(BMS-214662, 233), we elected not to use the knowledge of the
crystal structure of 236 given its more rigid tetrahydrobenzo-
diazepine scaffold. As was anticipated owing to the similarities
in the active sites of PfFTase and rFTase, several low energy
GOLD docked poses of compound 1a in rFTase demonstrated
an almost identical binding mode to that observed with a very
close analogue of 1a in PfFTase, with the biggest difference
being that the benzyl group, rather than binding in the W102β,
W106β, Y361β sub-pocket, is engaged in a π-π stacking
interaction with Y361β (compare Figure 2 in ref 29b with
Figure 1A above). Figure 1A illustrates one such high scoring
(low energy) docked pose of compound 1a in green and colored
by atom type, using the graphical representation (Connolly
analytical surface, PyMOL37) and orientation employed in
previous publications.29,30 The binding surface of rFTase
shown incorporates the cosubstrate farnesyl pyrophosphate
(FPP: farnesyl, red; pyrophosphate, blue). This binding mode
of 1a overlays well with the tetrapeptide inhibitor CVFM
from the rFTase crystal structure as shown in Figure 1B, in
which we have used an alternative graphical representation
(“cartoon”, PyMOL37) and orientation that have also been
presented by us recently.38 For simplicity, the latter graphical
representation shall be used throughout the remainder of this
manuscript. Given the highly flexible nature of the ligand,
coupled with the fact that the other high scoring poses from
our studies (data not shown) were generally those in which the
scaffold projected functionalities to positions similar to those
seen in Figure 1, we feel that it is likely that the molecule, in
solution, would occupy pockets as previously predicted as
part of an ensemble of binding motifs.
Initially, we selected a focused set of our PfFTase inhibi-
tors and analyzed their abilities to inhibit human FTase
(hFTase), as well as GGTase-I, both in vitro and in whole
cells (Table 1). The amino acid sequences of rat and human
FTase are 95% identical with complete sequence and struc-
tural conservation around the active site,35 so it is reasonable
to analyze inhibition of hFTase with respect to docking
studies in rFTase. Briefly, in vitro inhibition assays for
hFTase and GGTase-I were carried out by measuring the
incorporation of [3H]FPP and [3H]GGPP into recombinant
H-Ras-CVLS and H-Ras-CVLL, respectively, as described
previously.39 Whole cell inhibition of farnesylation and
geranylgeranylation were determined based on the level of
inhibition by synthetic compounds of H-Ras and Rap1A
processing, respectively.40 In all cases, IC50 data represent
the average of three independent assays (n = 3), unless

6870 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
Figure 2. (A) Co-crystal structure of inhibitor 1a (yellow, and colored by atom type) and FPP bound to rFTase (PDB ID: 3E32),38 and (B) co-
crystal structure of FPP and inhibitor 1a overlaid with the tetrapeptide inhibitor CVFM (orange, and colored by atom type) from PDB ID: 1JCR.35
otherwise stated, and errors are given as standard deviations.
The importance of both the para-substitution of the aniline
component and Nπ-methylation (R1 = Me) of the imidazole
that we observed in the inhibition of PfFTase29 was reflected
in the mammalian isoform of the enzyme. Unsubstituted
aniline 3 exhibited little activity toward the inhibition of
hFTase. Incorporation of bromine into the para position of
the aniline ring, however, led to an order of magnitude
increase in potency with in vitro IC50s for hFTase improving
from 6300 ( 360 nM for 3 to 730 ( 20 nM for 4. Addition-
ally, H-Ras processing IC50s of the FTIs were enhanced from
>1 0 μM to 5.7 ( 1.2 μM. A further order of magnitude
increase in FTase inhibition in vitro was achieved upon
Nπ-methylation of the imidazole, with 5 exhibiting an IC50
Figure 3. Overlay of the crystal structures of the ternary complexes
of 1a38 (yellow, colored by atom type) and 236 (cyan, colored by
atom type) with FPP in rFTase.
of 79 ( 30 nM, and an associated increase in whole cell
activity (H-Ras processing IC50 = 1.6 ( 1.3 μM) was also
observed. Even greater hFTase inhibitory activity was
achieved by the replacement of bromine with cyano in the
para position of the aniline ring (1a: IC50 = 56 ( 29 nM). It is
interesting to note that a considerable improvement in
selectivity for hFTase over GGTase-I was also observed;
1a was approximately 7-fold more selective for hFTase than
was 5. In addition, the trends observed here in the inhibition
of the mammalian isoform of FTase are mirrored by those
observed in the disruption of the plasmodial isoform.29
Given these very encouraging data, we embarked on an
SAR study of our ethylenediamine-based inhibitors in order
to optimize the inhibitory activity of 1a against hFTase.
Crystal Structure. We recently reported the crystal struc-
ture of the 1a:FPP:rFTase ternary complex (Figure 2A; PDB
ID: 3E32).38 As a comparison, in Figure 2B we have super-
imposed the crystal structure of 1a with that of the tetrapep-
tide substrate CVFM (PDB ID: 1JCR). Interestingly, the
crystal structure shows that the ethylenediamine-based FTIs
actually adopt a different binding mode to that predicted
(Figure 1B). Figure 2A illustrates that the para-benzonitrile
substituent of 1a is oriented toward the product exit groove
and is partially stabilized by a stacking interaction with
Y361β. The rings are approximately 30ꢀ offset from parallel,
˚
first isoprene of FPP (4.1 A distance). The non-methylated
τ-nitrogen of the 1-methyl-1H-imidazole-4-sulfonyl group
˚
also makes a single, weak polar contact (3.7 A distance) to
the side chain hydroxyl of Y361β. The phenyl substituent of
1a binds in a pocket formed by W106β, W102β, and L96β,
essentially the a2 residue binding site of the Ca1a2X substrate,
and occupying almost exactly the same space as the phenyl-
alanine side chain of CVFM (Figure 2B).
Several similarities exist between the chemical substituents
and binding mode of the ethylenediamine inhibitor 1a with
tetrahydrobenzodiazepine 2; their crystal structures are
overlaid in Figure 3. The binding modes of the para-benzo-
nitrile group and the non-sulfonylated N-methylimidazole
group of the ethylenediamine inhibitor 1a are nearly indis-
tinguishable from the similar substituents in 2, with the
imidazole of 2 coordinating the catalytic zinc ion like the
non-sulfonylated N-methylimidazole in 1a. The scaffold
nitrogen atoms bearing these substituents in both 1a and 2
occupy similar locations. The para-benzonitrile groups ex-
tend into the exit groove, with the positions of the cyano
group nitrogen atoms from the two molecules differing by
˚
only ∼0.4 A, a value close to the estimated error in crystallo-
˚
with the distance between them ranging from 3.8 to 4.9 A.
graphic coordinates. Finally, the phenyl substituents of
both compounds take advantage of the aromatic character
of the Ca1a2X a2 residue site, interacting with tryptophan
residues 102β and 106β. The sulfonamide positions of
both compounds exhibit the greatest differences in binding
modes. As a consequence, the scaffold nitrogen bearing
this group in the tetrahydrobenzodiazepine ring of 2 is
not oriented in a spatially similar location to the nitrogen
bearing the sulfonylated N-methylimidazole of 1a, which is
The binding pocket also consists of F360β (not shown
in Figure), Y93β, L96β, and W106β, creating a generally
hydrophobic environment for this moiety. Inhibitor 1a
possesses two N-methylimidazole groups: one coordinates
˚
the catalytic zinc ion (2.0 A distance) through its nonmethy-
lated τ-nitrogen in place of the Ca1a2X box cysteine residue,
while the second (at the sulfonamide position) is stacked
˚
between the first N-methylimidazole (3.7 A distance) and the

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6871
sandwiched between the first isoprene of the lipid sub-
strate and the zinc-coordinating N-methylimidazole moiety.
By contrast, the thienyl group of 2 is largely solvent-exposed
and binds in a manner resembling the a1 residue of the
Ca1a2X motif. This ring is primarily stabilized by stacking
on the tetrahydrobenzodiazepine ring scaffold itself, as
opposed to interacting with the enzyme active site or lipid
substrate.
Scheme 1a
The crystal structure of the ternary complex of 1a:FPP:
rFTase was solved toward the end of this research; the
medicinal chemistry research program reported herein was
actually driven by piggy-backing on our inhibitors of
PfFTase and, to a lesser extent, the GOLD docking result
presented in Figure 1. At the end of the SAR discussion, the
FTase inhibition data will be evaluated in the context of both
this crystal structure and the GOLD docking models.
Chemistry. “Piggy-back” mammalian FTase inhibitors
(FTIs) were prepared as described previously,29 with new
FTIs furnished by synthetic routes depicted in Schemes 1-3.
Inhibitors incorporating the para-benzonitrile moiety were
accessed by the route in Scheme 1. Briefly, mono-N-Boc-
ethylenediamine (6) was arylated withpara-fluorobenzonitrile
at 120 ꢀC for 48 h in DMSO, affording secondary aniline 7.29b
Installation of the imidazole was achieved by double depro-
tonation of 7 with LDA at -78 ꢀC and subsequent chemo-
selective alkylation with 5-chloromethyl-1-methyl-1H-imi-
a (a) para-Fluorobenzonitrile, DIPEA, DMSO, 120 ꢀC, 48 h, 89%;
(b) (1) LDA, THF, -78 ꢀC, 30 min, (2) 5-chloromethyl-1-methyl-1H-
imidazole HCl,29b NaH, -78 ꢀC, 1 h, 52% (98% brsm); (c) TFA-CH2-
3
Cl2, 1:1, rt, 30min, 99%;(d) (1) R CHO, AcOH, 4 A MS, MeOH, rt, 30min,
2
˚
(2) NaCNBH3, rt, 16 h, 72-84%; (e) R2SO2Cl, DIPEA, CH3CN, 0 ꢀC f rt,
dazole HCl,29b affording 829b in a moderate yield. After Boc
16 h, 82-93%; ((f) R3Br, Cs2CO3, DMF, rt, 16 h, 79-82%.
3
Scheme 2a
a (a) tert-Butyl para-fluorobenzoate, DMSO, 120 ꢀC, 24 h, 96%; (b) 1-methyl-1H-imidazole-4-sulfonyl chloride, DIPEA, CH3CN, 0 ꢀC f rt, 12 h,
90%; (c) BnBr, Cs2CO3, DMF, rt, 16 h, 92%; (d) (1) NaH, DMF, 0 ꢀC, 30 min, (2) 5-chloromethyl-1-methyl-1H-imidazole HCl,29b 0 ꢀC f rt, 3 h, 76%;
(e) TFA-CH2Cl2, 1:1, 3 h, rt, 96%; (f) NH4Cl, HBTU, DIPEA, DMF, rt, 16 h, 89%.
3
Scheme 3a
a (a) 1-Methyl-1H-imidazole-4-sulfonyl chloride, DIPEA, CH3CN, 0 ꢀC f rt, 16 h, 95%; (b) 4-bromomethyl-N-(2-pyrimidinyl)-piperidine, Cs2CO3,
DMF, rt, 4 d, 94%; (c) TFA-CH2Cl2-TIPS-H2O, 47.5:47.5:2.5:2.5, rt, 1 h, 100%; (d) R4F, DIPEA, DMSO, 120 ꢀC, 24-48 h, 48-97%; (e) (1) NaH, 0 ꢀC,
30 min, (2) 5-chloromethyl-1-methyl-1H-imidazole HCl,29b 0 ꢀC f rt, 2-3 h, 63-96%.
3

6872 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
Table 2. Enzyme Inhibition and Whole Cell Data of Ethylenediamine-Based FTIs Exhibiting a Range of R2 Sulfonyl Groups
a ND = not determined.
deprotection, completion of the syntheses of FTase inhibi-
tors 1 was conducted in one of two ways: either sulfonylation
of 9,29b followed by alkylation of the resultant sulfonamide,
or reductive amination of 9, and then sulfonylation of the
resultant secondary amine. Finally, purification of the FTIs
was achieved by silica gel flash column chromatography,
followed by rpHPLC. Full details can be found in the
Experimental Section.
the poorest H-Ras processing IC50 (1.9 ( 1.2 μM). This
might be a consequence of the basicity of imidazole, and its
protonation could hinder cellular entry. Regardless of this,
the potent in vitro activity of 1a against hFTase, coupled
with the fact that we already had several inhibitors func-
tionalized with the 1-methyl-1H-imidazole-4-sulfonyl group
in-house from the related Pf FTase project,29 led us to retain
this particular sulfonyl group as a benchmark while varying
other parts of the molecule. Selectivity of these FTIs for the
hFTase isoform over the PfFTase isoform might then later
be achieved by taking advantage of the previously mentioned
three amino acid differences in the subpocket that is pre-
dicted to bind the para-benzonitrile ring.
Sulfonyl R2 SAR. With R1 constrained as methyl and R3 as
benzyl, a series of eight R2 sulfonyl groups was surveyed
(Table 2), all of which proved potent inhibitors of hFTase.
The largest and most basic 5-dimethylamino-naphthalene-
1-sulfonyl derivative 1h was the least active inhibitor
(hFTase IC50 = 160 ( 110 nM) of this series, with the most
potent being the pyridine-2-sulfonyl compound 1f (hFTase
IC50 = 25 ( 20 nM). Additionally, these inhibitors were
more selective for hFTase over GGTase-I, with selectivi-
ties ranging from around 8-fold to 333-fold. Many of these
compounds also demonstrated very good whole cell activity,
with pyridine-2-sulfonyl derivative 1f proving one of the
most effective inhibitors (H-Ras processing IC50 = 0.09 (
0.06 μM). Despite its potency in vitro (hFTase: IC50 = 56 (
29 nM), 1-methyl-1H-imidazole-4-sulfonyl derivative 1a had
Sulfonamide R3 SAR. Thus, constraining R2 as 1-methy-
1H-imidazole-4-sulfonyl, the R3 group was next investigated
with a broad series of derivatives, which included previously
reported29 and novel inhibitors (Table 3). Replacement of
benzyl in the parent inhibitor 1a with a propargyl group
(1aa) led to a reduction in both in vitro activity (IC50 = 720 (
200 nM cf. 56 ( 29 nM) and whole cell activity, as well as in
GGTase-I/FTase selectivity. However, the unsubstituted allyl
derivative (1ab) was tolerated in vitro (IC50 = 54 ( 30 nM),
although not in whole cells (H-Ras processing IC50 >10 μM).

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Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6873
Table 3. Enzyme Inhibition and Whole Cell Data of Ethylenediamine-Based FTIs Exhibiting a Range of R3 Sulfonamides
Substitution of the allyl moiety with a methyl group
at position-2 (1ac) led to a reduction in hFTase in vitro
activity and, at the same time, afforded an improvement in
GGTase-I, resulting in a reduced GGTase-I/FTase selec-
tivity of about 5-fold. Again, whole cell activity was poor but
this was recovered somewhat by replacement of the methyl in
1ac with a bromine atom, giving an H-Ras processing IC50 of
5.7 ( 1.5 μM for inhibitor 1ad. Extension of this sp2-
hybridized series to the bulky tert-butylacetamido derivative
1ae was not tolerated, neither in vitro nor in whole cells.
Incorporation of nitrogen into the para position of benzyl
to give pyridine derivative 1af maintained activity in vitro
(IC50 = 72 ( 20 nM), although it showed little activity in
whole cells. Nonetheless, 1af exhibited substantially im-
proved selectivity toward hFTase, with a GGTase-I/FTase
selectivity of >139-fold.
value of 30 ( 33 nM. Conversely, the series of furans
and thiophenes typically proved much poorer inhibitors,
although interestingly FTase inhibitory activity was found
to be sensitive to heteroatom position. Furan 1ah was more
than twice as potent as isomeric 1aj, and thiophene 1ai was
more than 34 times as potent as isomeric 1ak and approxi-
mately as active as 1a. Despite these moderate to poor in
vitro data for hFTase (except for 1ai) all members of this
series exhibited reasonable H-Ras processing whole cell data
and in all cases the IC50 values were more potent than 1a. The
remaining heteroaromatics (1al-1an) containing two het-
eroatoms were poor inhibitors of hFTase.
Introduction of a methyl group on the benzyl ring of 1a
was tolerated in the ortho (1ao) and meta (1ap) positions
(in vitro hFTase IC50s of 51 ( 26 nM and 54 ( 30 nM,
respectively) but not in the para (1aq) position (IC50 = 370 (
210 nM). A similar trend was observed in whole cell activity,
with meta-derivative 1ap the most potent (H-Ras processing
IC50 = 0.3(0.2 μM). Themembersofthisseriesdemonstrated
We next examined a focused set of five-membered hetero-
aromatics 1ag-1an. Pyrrole 1ag was around twice as active
as the parent inhibitor 1a, disrupting hFTase with an IC50

6874 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
Table 4. Enzyme Inhibition and Whole Cell Data of Ethylenediamine-Based FTIs Exhibiting a Range of para-Substituted Anilines
compd
IC50 (nM)
processing IC50 (nM)
no.
X
hFTase
79 ( 30
56 ( 29
5400 (n = 2)
GGTase-I
selectivity
H-Ras
Rap1A
>10
4 (FTI-2586)
Br
CN
530 ( 170
2700 ( 2200
4900 (n = 2)
>10000
6.7
48
1.6 ( 1.3
1.9 ( 1.2
ND
1a (FTI-2585)
11 (FTI-2720)
12 (FTI-2721)
13 (FTI-2728)
14 (FTI-2727)
>10
ND
ND
ND
ND
CO2tBu
COOH
CONH2
Ph
0.9
-
>10000
5300 (n = 2)
6850 (n = 2)
ND
ND
>10000
5000 ( 2600
>2
0.7
ND
GGTase-I IC50 values between 580 and 780 nM, considerably
reducing the GGTase-I/hFTase selectivities, relative to that of
the parent benzyl inhibitor 1a. The greater potency of meta-
substituted benzyl groups over their para counterparts was also
observed for the cyano derivatives 1ar and 1as and for the
phenyl derivatives 1at and 1au, a finding that was reflected in
their corresponding H-Ras processing whole cell activities.
Additionally, the same trend was noticed in the in vitro data
of GGTase-I inhibition. The poor in vitro inhibition of hFTase
by para-phenyl derivative 1au (IC50 = 1700 ( 900 nM) was
improved by approximately 4-fold by replacement of the
terminal phenyl group with the smaller pyrrole heterocycle
(1av; IC50 = 390 ( 210 nM), which was also reflected in the
whole cell assays (IC50 = 5 ( 1 μM (1au) vs 4 (1 μM (1av)).
The small cyclopropylmethyl derivative 1aw was less
active than the parent benzyl inhibitor 1a, but the larger
cyclohexylmethyl derivative 1ax, a closer match to benzyl,
proved a potent inhibitor in vitro (hFTase IC50 = 60 (
10 nM) and was one of our most potent inhibitors in whole
cells (H-Ras processing IC50 = 0.1 ( 0.07 μM)). However,
able to participate in additional hydrogen-bonding interac-
tions and so furnish more potent hFTase inhibitors. We also
investigated nonpolar substituents in the para position, such
as Br, Ph and CO2t-Bu, which, provided the aniline group
binds as predicted, would be expected to inhibit hFTase
less well. Accordingly, para-(tert-butyl ester) derivative 11
was prepared in a similar manner to the synthetic route in
Scheme 1 but employing tert-butyl para-fluorobenzoate in
place of para-fluorobenzonitrile (see Experimental Section
for full details). As shown in Scheme 2, treatment of 11 with
TFA furnished the para-carboxylic acid 12, which was then
converted to para-carboxamide 13 using HBTU and ammo-
nium chloride. para-Phenyl derivative 14 was prepared from the
previously reported intermediate 1-tert-butoxycarbonylamino-
2-[biphenyl-4-yl-(3-methyl-3H-imidazol-4-ylmethyl)amino]-
ethane (compound 9a in ref 29b; see Experimental Section
for full details). As illustrated in Table 4, all replacements
for the cyano group afforded compounds that were poorer
inhibitors of hFTase in vitro. Interestingly, FTIs with bulky X
groups (11: X = CO2t-Bu; 14: X = Ph) exhibited a reversed
selectivity for GGTase-I over hFTase, suggesting the aniline-
binding domain may be larger in GGTase-I than in hFTase.
Aniline R4 SAR: The Aromatic Ring. In addition to the
para-substituent of the aniline affecting inhibitor activity,
GOLD docking studies suggested that two of the polar
amino acids within the para-benzonitrile-binding pocket
might influence binding of the aniline ring itself. Specifically,
Y166R could make contact with hydrogen bonding acceptor
or donor groups in the ortho and meta positions of the aniline
to improve inhibitor binding in mammalian FTase, and
likewise, H201R might be exploited with an appropriate
group in the meta position. Accordingly, a series of FTase
inhibitors was preparedinwhich thepara-benzonitrileportion
was modified in an attempt to target these two amino acids;
the synthetic route that was pursued is shown in Scheme 3. We
selected compound 1az bearing the N-(2-pyrimidinyl)-piper-
idin-4-ylmethyl R3 group as the benchmark, anticipating that
its moderate activity would better highlight the effects of
modifying the para-benzonitrile component. Again, with the
only constraint being that the non-methylated τ-nitrogen
of the 1-methyl-1H-imidazol-5-ylmethyl group should bind
the active site Zn2þ ion, several GOLD docking experiments
of compound 1az were peformed. While the R3 = N-(2-pyri-
midinyl)-piperidin-4-ylmethyl and the 1-methyl-1H-imida-
zole-4-sulfonyl groups in 1az bound differently to the corres-
ponding groupsin 1a, the R4 = para-benzonitrile group under
inhibitor 1ax was also quite active toward GGTase-I (IC50
=
530 ( 120 nM), giving a much-reduced hFTase/GGTase-I
selectivity of about 9-fold. We envisaged probing deeper
into the binding pocket that was predicted to bind the R3
group by modifying the cyclohexylmethyl substituent to a
4-piperidinylmethyl group; the piperidine nitrogen provided
a handle from which to achieve further functionalization.
Accordingly, N-Boc-piperidin-4-ylmethyl derivative 1ay and
N-(2-pyrimidinyl)-4-ylmethyl derivative 1az were synthe-
sized. Introduction of the N-Boc group at the 4 position of
the cyclohexyl group (1ay) caused more than a 60-fold drop
in hFTase inhibition relative to 1ax. Activity was recovered
by more than 7-fold through replacement of the bulky tert-
butoxycarbonyl group with the planar 2-pyrimidinyl group
(1az: IC50 = 510 ( 62 nM; cf. 1ay: IC50 = 3700 ( 790 nM)
although both piperidinylmethyl derivatives exhibited poor
whole cell activities.
Aniline R4 SAR: The para-Position (X). At the deepest
point of the predominantly hydrophobic pocket of rFTase in
which GOLD docking studies consistently predicted the
para-benzonitrile moiety (the aniline “R4 group”) of our
inhibitors would bind, there is a hydrophilic domain formed
by N165R, Y166R, and H201R. To probe this site further, we
replaced the cyano group (X) of the para-benzonitrile moiety
with alternative polar groups, such as a carboxylic acid or a
carboxamide, in the anticipation that such groups might be

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6875
Figure 4. Onehighscoring rFTase activesite conformation ofinhibitor 1az (purple, colored byatomtype) as identified by flexible ligandGOLD32
docking experiments (A) in isolation and (B) overlaid with the high scoring active site conformation of inhibitor 1a (green, colored by atom type)
that was presented in Figure 1B. The co-substrate FPP was included in the docking experiments as this forms part of the binding surface.
investigation bound in the same subpocket (tetra-
methylene side chain of K164R and side chain of Y166R) as
the corresponding motif in 1a in four out of the five highest
scoring (lowest energy) docking solutions (for example, Fig-
ure 4A). Furthermore, in most of those cases, the para-
benzonitrile moieties of 1a and 1az overlaid excellently, as
illustrated in Figure 4B. Thus, we were confident the SAR
data that would be acquired by varying the R4 aniline
component of 1az would be directly translatable to 1a and
related inhibitors.
19d (pyrimidine), respectively. Replacement of all four ring
hydrogens in 19h offered no benefit to hFTase inhibition,
relative to parent 1az. Finally, it is noteworthy that all
derivatives based on the parent compound 1az generally
exhibited very good to excellent selectivity for inhibition of
hFTase over GGTase-I, particularly for ortho-pyridine 19c
and ortho-fluoride 19f.
Scaffold Optimization. After optimizing the R1, R2, R3,
R4, and X groups, we next investigated modifying the
ethylenediamine core with a variety of alternative diamino-
based scaffolds, whose structures are depicted in Table 6
and whose syntheses have been described elsewhere.30
1,3-Diaminopropane-based inhibitor 20a has increased con-
formational flexibility relative to the corresponding ethyle-
nediamine-based inhibitor 1a. The data in Table 6 suggest
that increasing the flexibility in this way caused more than
a 7-fold drop in hFTase inhibitory activity. Likewise, redu-
cing the conformational flexibility of the scaffold with the
1,2- and 1,3-diaminocyclopentyl derivatives 20b-20e also
led to a decrease in hFTase inhibitor potency, with the cis-
configurations exhibiting half the potencies of their trans-
counterparts. Similar trends were observed in PfFTase.30 Of
all the different scaffolds examined, the ethylenediamine unit
was found to be optimal at delivering the four substituents
into the proposed subpockets as well as furnishing the
greatest GGTase-I/hFTase selectivity.
As depicted in Scheme 3, mono-N-Boc-ethylenediamine
(6) was sulfonylated with 1-methyl-1H-imidazole-4-sulfonyl
chloride to give 15 in 95% yield. Chemoselective alkylation
of the more acidic and less hindered sulfonamide NH was
then readily accomplished by treatment of 15 with N-(2-
pyrimidinyl)-piperidin-4-ylmethyl bromide in the presence
of cesium carbonate in DMF. After TFA-mediated Boc
deprotection of 16, arylation of the resultant primary amine
was achieved by heating 17 at 120 ꢀC in DMSO with a series
of aryl fluorides, giving the secondary anilines 18 in a range
of yields from 48 to 97%. Finally, these secondary anilines
were then smoothly alkylated in good to excellent yields by
deprotonation with NaH in DMF, followed by reaction with
5-chloromethyl-1-methyl-1H-imidazole HCl29b to furnish
3
the FTase inhibitors 19a-19h (Table 5).
Positioning a chlorine (19a) at the ortho position had little
effect relative to the parent compound 1az on the inhibition
of hFTase. Conversely, replacement of an ortho-CH unit
with nitrogen to give pyridine 19c conferred approximately
4-fold improvement in hFTase enzymatic inhibitory activity
(19c 110 ( 26 nM vs 1az 510 ( 320 nM), while meta-
substituted pyridine 19b offered no enhancement in activity,
suggesting an important role for a hydrogen-bonding accep-
tor group in the ortho position. However, incorporation of
nitrogens at both ortho positions, as in pyrimidine 19d,
caused a reduction in the IC50 value back to approximately
the same as that exhibited by the parent compound 1az.
Inhibitor 19e with a fluorine at one of the meta positions was
around twice as potent as 1az, while a fluorine at the ortho
position led to an especially potent inhibitor (19f) with
an hFTase IC50 of 64 ( 8.6 nM, approximately 8-fold as
active as 1az and twice as potent as the ortho-pyridine 19c.
Introduction of a second fluorine atom at the other ortho
position (inhibitor 19g) caused a reduction in inhibition
potency relative to the singly ortho-substituted inhibitor
19f, as was observed with the pyridine derivatives 19c and
Optimization of FTIs. Finally, we designed three ethyle-
nediamine-based inhibitors incorporating optimized R1, R2,
R3, R4, and X substituents that were identified from our SAR
studies, as illustrated by compounds 21a-21c in Table 7.
Primary data considered in the selection of moieties that we
hoped would furnish optimized inhibitors were in vitro
FTase inhibition, whole cell H-Ras processing data, and to
a lesser extent, GGTase-I/hFTase selectivity. The R1 group
selected was methyl (Table 1), R2 was 2-pyridinesulfonyl
(Table 2), R3 was cyclohexylmethyl (Table 3), R4 was para-
benzonitrile (Table 4) substituted at the ortho position
(Table 5), and the core scaffold incorporated was the simple
ethylenediamine unit (Table 6), leading to inhibitors 21a,
21b, and 21c in Table 7. As a comparison, we have also
included in Table 7 three of our most potent “unoptimized”
FTIs: 1a, 1ax, and 1f. The trend observed in Table 5 upon
varying the ortho-CH unit to CF and to N was reproduced
with these optimized inhibitors, however none of com-
pounds 21a-21c exhibited improved activity over the leads
1a, 1ax, and 1f, possibly due to the adoption of different

6876 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
Table 5. Enzyme Inhibition and Whole Cell Data of Ethylenediamine-
Based FTIs Exhibiting a Range of R4 Anilines
Table 6. Enzyme Inhibition Data of FTIs Exhibiting a Range of
Ethylenediamine-Analogue Scaffolds
as Figure 5 illustrates, the para-benzonitrile and the sulfo-
nylimidazole substituents were found to bind in different
manners to those predicted. Specifically, the para-benzonitrile
moiety was predicted to bind in the subpocket created by
K164R, N165R, H201R, Y166R, but was actually found
engaged in a weak π-π interaction with Y361β in the product
exit groove, F360β, Y93β, L96β, W106β, while the sulfo-
nylimidazole group was predicted to bind the Arg202β, yet
was found stacked between the Zn-binding imidazole and the
first isoprene of FPP.
Despite the GOLD prediction of a very different binding
mode for the para-benzonitrile moiety, several potent inhi-
bitors (e.g., 19f, Table 5) were serendipitously identified as a
consequence of the para-benzonitrile making alternative but
still significant contacts. The observed π-π stacking of the
para-benzonitrile moiety against the Y361β residue suggests
an explanation for the observed in vitro SAR data for the
modifications made to the para-benzonitrile ring of 1a
(Tables 1 and Table 4) and 1az (Table 5). π-π Stacking
interactions are known to be energetically more favorable
between an electron-rich arene, here Y361β, and an electron-
poor arene, here the para-benzonitrile of inhibitor 1a. For
the series of inhibitors in Table 4, substitution of the para
position of the aniline with a strongly electron-withdrawing
cyano group led to the most potent inhibitor (1a) while
eliminating all substitution from the aniline ring of 1a and
with R1 = H essentially abolished activity (compound 2,
Table 1). Additionally, the product exit groove where the
para-benzonitrile binds is of limited size and mostly hydro-
phobic, suggesting that substituents larger than the linear
binding geometries. Much reduced selectivities for hFTase
over GGTase-I were also observed. Nonetheless, 21b was
equipotent with 1ax in whole cells, whereby both inhibitors
disrupted H-Ras processing with IC50 values of about 90 nM.
Discussion of SAR Data in the Context of the Crystal
Structure of 1a and the GOLD Docking of 1a. Figure 5 shows
the crystal structure of 1a (yellow; taken from Figure 2A)
overlaid with the flexible ligand GOLD docking of 1a (green;
taken from Figure 1B). We correctly predicted that the more
basic imidazole 1-methyl-1H-imidazol-5-ylmethyl would bind
the zinc ion (which was the only constraint implemented in the
GOLD docking experiments), and GOLD subsequently cor-
rectly placed the benzyl moiety of 1a in very close proximity to the
sub-pocket formed by W102β, W106β, and Y361β. However,

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6877
Table 7. Enzyme Inhibition and Whole Cell Data of Optimized, Ethylenediamine-Based FTIs
(with respect to the aniline nitrogen) CH (1az) with either N
(19c) or CF (19f) led to an approximate 5-fold or 8-fold
improvement in inhibitor activity, respectively. This may be
due to the introduced electron-withdrawing groups that
render the aniline even more electron-poor, thereby enhan-
cing its interaction with Y361β. On the other hand, repla-
cement of the meta-CH (1az) with N (19b) resulted in no
improvement in activity, while substitution of the meta-CH
with a CF group (19e) led to only a 2-fold increase in
inhibitor potency, as opposed to the 8-fold enhancement
achieved by ortho-fluoride 19f. The crystal structure of 1a
suggests that the incorporation of electronegative groups in
the meta position might be poorly tolerated due to a clash
with the anionic side chain of D359β, explaining the reduced
enhancement in potency of inhibitors 19b and 19e (as a
means of avoiding this unfavorable interaction, 180ꢀ rota-
tion about the N-C aniline bond would direct the intro-
duced N or CF group into a hydrophobic domain
comprising L96β, W102β and W106β and would therefore
also be unfavorable). Replacement of both ortho-CH groups
with either two nitrogens (19d) or two CF groups (19g) was
not tolerated relative to the mono-ortho-substituted inhibi-
tors (19b and 19e, respectively). This observation may be a
Figure 5. Overlay of the co-crystal structure of 1a (yellow, colored
by atom type; PDB ID: 3E3238) and FPP with a high scoring (low
energy) GOLD docked pose of 1a (green, colored by atom type) in
the active site of rFTase.
cyano unit, such as the bulky tert-butyl ester in 11 or the
phenyl ring in 14, and more polar than the cyano group, such
as the acid in 12 and the carboxamide in 13, would be poorly
tolerated. This was confirmed experimentally (Table 4). For
the series of inhibitors in Table 5, replacement of the ortho

6878 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
consequence of one of the electronegative groups being forced
into the hydrophobic L96β, W102β and W106β region in
order that the energetically favorable π-π stacking between
the aniline ring of the inhibitor and Y361β is maintained.
Generally, there was little variation in activity among the
R2 sulfonyl derivatives shown in Table 2, which may be a
consequence of this moiety exhibiting insignificant interac-
tions with the protein itself, being found stacked between the
zinc-binding imidazole and FPP. However, there were clear
trends in the hFTase inhibition data for the R3 series of
sulfonamide analogues (Table 3). The crystal structure of 1a
illustrates that the R3 phenyl ring can access the a2 residue
binding site (L96β, W102β and W106β) of the Ca1a2X
substrate. For the most part, small, hydrophobic R3 groups
afforded potent hFTase inhibitors, likely due to the R3 group
making van der Waals contacts with L96β, W102β and/or
W106β. Within a particular series of R3 substituents, for
example the ortho-, meta-, and para-tolyl derivatives 1ao,
1ap, and 1aq, respectively, ortho- and meta-functionalized
compounds were tolerated, whereas para-functionalization
was not. This may be a consequence of the para derivative
being too large to access the a2 residue binding site. Indeed,
the crystal structure of 1ay shows that the large N-Boc-
piperidin-4-ylmethyl group traverses, rather than binds in,
the a2 residue binding site and instead reaches into the X
residue binding site.38 We have previously reported on the
relative selectivities of our ethylenediamine-based inhibitors
for the Plasmodium isoform of FTase over the mammalian
isoform.29,30 With this crystal structure data in hand, along
with several others,38 it should now be possible to tailor these
compounds to become more selective for one enzyme iso-
form over the other.
site metal ion. Each ligand was used to seed the genetic algo-
rithm 10 times.
Chemistry: General Methods. Solvents CH2Cl2, CH3CN, and
DMF were dried on an Innovative Techonology SPS-400 dry
solvent system. Anhydrous MeOH and DMSO were purchased
from Sigma-Aldrich and used directly from their Sure-Seal
bottles. Molecular sieves were activated by heating to 300 ꢀC
under vacuum overnight. All reactions were performed under an
atmosphere of dry nitrogen in oven-dried glassware and were
monitored for completeness by thin-layer chromatography
(TLC) using silica gel (visualized by UV light, or developed by
treatment with KMnO4 stain or Hanessian’s stain). 1H and 13
C
NMR spectra were recorded on Bruker AM 400 MHz and
Bruker AM 500 MHz spectrometers in either CDCl3, MeOH-d4,
or DMSO-d6. Chemical shifts (δ) are reported in parts per
million after calibration to residual isotopic solvent. Coupling
constants (J) are reported in Hz. Mass spectrometry was per-
formed using electrospray ionization on either a Varian MAT-
CH-5 (HRMS) or Waters Micromass ZQ (LRMS). Before
biological testing, all new target molecules (1b, 1c, 1ah-1an,
1aw, 11-14, 19a-19h, 21a-21c) were subjected to further
purification by reversed-phase HPLC (rpHPLC). Analysis
and purification by rpHPLC were performed using either a
Phenonenex Luna 5 μm C18 (2) 250 mm ꢀ 21 mm column
run at 15 mL/min (preparative) or a Microsorb-MV 300 A C18
250 mm ꢀ 4.6 mm column run at 1 mL/min (analytical), using
gradient mixtures of (A) water with 0.1% TFA and (B) 10:1
acetonitrile/water with 0.1% TFA. Appropriate product frac-
tions were pooled and lyophilized to dryness, affording the
inhibitors as fluffy, white powders as their TFA salts. Inhibitor
purity was confirmed by analytical rpHPLC using linear gra-
dients from 100% A to 100% B, with changing solvent compo-
sition of either (I) 4.5% or (II) 1.5% per min after an initial 2 min
of 100% A. For reporting HPLC data, percentage purity is given
in parentheses after the retention time for each condition. FTase
inhibitors 1a, 1d-1h, 1aa-1ag, 1ao-1av, 1ax-1az, 3-5, and
20a-20e have been previously reported in ref 29b.
Conclusions
General Procedure A (Reaction of Amines with Sulfonyl
Chlorides). The appropriate sulfonyl chloride (1.2 equiv) was
added to a solution of the amine (1 equiv) and DIPEA (2 equiv)
in anhydrous CH3CN (0.1 M) at 0 ꢀC. The reaction was warmed
to room temperature and stirred for 16 h, at which time the
solvent was evaporated. The residue was redissolved in CH2Cl2,
washed with 5% NaHCO3, water, brine, dried (Na2SO4), filtered,
and concentrated.
General Procedure B (Alkylation of Sulfonamides). To a solu-
tion of the sulfonamide (1 equiv) and Cs2CO3 (2 equiv) in DMF
(0.1 M) at 0 ꢀC was added the appropriate alkyl bromide or
chloride (1.1 equiv). The resulting mixture was stirred at room
temperature overnight. The reaction was diluted with water, then
extracted into EtOAc (ꢀ3). The combined EtOAc extractions
were washed with 5% NaHCO3 (ꢀ3), brine, dried (Na2SO4),
filtered, and concentrated.
In summary, we have developed a potent series of mamma-
lian farnesyltransferase inhibitors (FTIs) based on an ethyle-
nediamine scaffold. This class of compounds was identified by
a “piggy-back” approach on our potent antimalarial inhibi-
tors of plasmodium FTase. The simple and cost-effective
ethylenediamine core allowed facile access to a diverse array
of inhibitors, greatly facilitating lead inhibitor optimization.
We have identified several inhibitors with double-digit nano-
molar inhibition of hFTase in vitro, the most potent com-
pound being 1f (IC50 = 25 nM). In most cases, potent
inhibition of hFTase in vitro was accompanied by potent
whole cell data (inhibition of H-Ras processing); for example,
inhibitor 1f displayed a whole cell IC50 of 90 nM, one of the
most active of the entire series. Moreover, in all but two cases
inhibitors were selective for hFTase over GGTase-I, with the
greatest selectivity (333-fold) exhibited by inhibitor 1g. Final-
ly, we have solved the crystal structure of one of our ethyle-
nediamine-based FTIs (1a) in the active site of rFTase, and
this will assist in the future design of more potent and isoform-
selective mammalian farnesyltransferase inhibitors.
General Procedure C (Reductive Amination of Primary
Amines). To a solution of 9 (1 equiv) in dry methanol (0.2 M)
ꢀ
˚
with 4 A molecular sieves was added the appropriate aldehyde
(1.1 equiv) and acetic acid (1.3 equiv). The reaction was stirred
under nitrogen at room temperature for 30 min. Sodium cya-
noborohydride (1.5 equiv) was added, and the resulting suspen-
sion was stirred at room temperature overnight. The reaction
mixture was decanted, washing thoroughly with further MeOH,
and then dry-loaded onto silica gel.
Experimental Section
Ligand Docking Studies. Ligand energy minimization was
peformed with the CVFF force field in InsightII on an SGI O2.
Flexible ligand docking studies were subsequently performed
with GOLD, version 3.0,32 on a Linux PC. Default GOLD
parameters were utilized with the following exceptions: (i)
maximal ligand flexibility was allowed; (ii) the affinity of nitro-
gen for zinc ion was increased in the GOLD parameters file to
better reflect the ability of an imidazole ring to bind to the active
General Procedure D (Arylation of Primary Amines). To a
stirring solution of the primary amine (1 equiv) in DMSO
(0.2 M) were added the aryl fluoride (1.2 equiv) and DIPEA
(3 equiv). The reaction mixture was heated to 120 ꢀC for 48 h.
After allowing the reaction to cool, H2O was added, and the
crude product was extracted with EtOAc (ꢀ3). The EtOAc
extractions were combined, washed with water (ꢀ3), brine, dried
(Na2SO4), filtered, and concentrated.

Article
General Procedure E (Alkylation of Secondary Anilines). The
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6879
N-Benzyl, N-{2-[(4-Cyanophenyl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl} Cyclopropanesulfonamide (1c). First,
amine 9 was reacted with cyclopropanesulfonyl chloride, ac-
cording to general procedure A, on a 0.15 mmol scale. After
workup and flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 92:7:1), N-{2-[(4-cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl} cyclopropanesulfonamide
was yielded as a colorless film (44 mg, 82%): δH (500 MHz,
MeOH-d4) 0.98 (m, 4H, 2 CH2 (cyclopropyl)), 2.51 (m, 1H, CH
(cyclopropyl)), 3.33 (t, J = 5.8 Hz, 2H, NHCH2CH2N), 3.67 (t,
J = 5.8 Hz, 2H, NHCH2CH2N), 3.88 (s, 3H, CH3 (Im)), 4.76 (s,
2H, CH2Im), 6.95 (d, J = 8.83 Hz, 2H, 2 CH (Ar)), 7.25 (s, 1H,
CH (Im)), 7.53 (d, J = 8.84 Hz, 2H, 2 CH (Ar)), 8.86 (s, 1H, CH
(Im)); δC (125 MHz, MeOH-d4) 4.1, 29.0, 32.8, 39.9, 44.5, 50.5,
99.1, 112.7, 117.8, 119.4, 131.6, 133.4, 136.3, 150.4; LRMS (ESI)
m/z 382.1 [C17H21N5O2S þ Na]. Subsequently, the sulfonamide
(36 mg, 0.1 mmol) was treated with benzyl bromide, according
to general procedure B. The crude material was dry-loaded onto
silica gel and purified by flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 192:7:1) to give 1c as a white foam
(40 mg, 89%): δH (500 MHz, MeOH-d4) 0.95 (m, 4H, 2 CH2
(cyclopropyl)), 2.55 (m, 1H, CH (cyclopropyl)), 3.31 (m, 4H,
NCH2CH2N), 3.71 (s, 3H, CH3 (Im)), 4.32 (s, 2H, CH2Ph), 4.43
(s, 2H, CH2Im), 6.51 (d, J = 8.89 Hz, 2H, 2 CH (Ar)), 7.02 (s,
1H, CH (Im)), 7.26-7.33 (m, 7H, 5 CH (Ph), 2 CH (Ar)), 8.76 (s,
1H, CH (Im)); δC (125 MHz, MeOH-d4) 5.3, 28.1, 34.3, 45.1,
46.3, 51.1, 54.9, 100.3, 113.7, 119.1, 120.8, 129.4, 129.9, 130.3,
132.7, 134.7, 137.8, 138.2, 151.5; HRMS (ESI) m/z calcd for
secondary aniline (1 equiv) was dissolved in DMF (0.07 M), and
then the reaction was cooled to 0 ꢀC. After 15 min, NaH (3 equiv)
was added in oneportion. After a further 15min, 5-chloromethyl-
1-methyl-1H-imidazole HCl31 (1.1 equiv) was added. The reac-
3
tion was allowed to stir at 0 ꢀC from 2-3 h, when TLC indicated
the reaction was complete or had stalled. Upon quenching the
reaction with brine (approximately 1 mL for 1 mmol scale), the
reaction was diluted with water and extracted with EtOAc (ꢀ3).
The EtOAc extractions were combined, and washed with 5%
NaHCO3 (ꢀ3), brine, dried (Na2SO4), filtered, and concentrated.
General Procedure F (Cyanation of Aryl Bromides). A stirring
solution of the aryl bromide (1 equiv) in DMF (0.1 M) was
degassed, and then Zn(CN)2 (0.6 equiv), Pd(PPh3)4 (0.1 equiv),
Zn dust (0.05 equiv), and Zn(OAc)2 (0.05 equiv) were added. The
mixture was heated to 120 ꢀC for 2 h, after which time the reaction
was allowed to cool, diluted with water, and extracted into EtOAc
(ꢀ3). The EtOAc extractions were combined and washed with 5%
NaHCO3 (ꢀ3), brine, dried (Na2SO4), filtered, and concentrated.
4-[(2-Aminoethyl)-(3-methyl-3H-imidazol-4-ylmethyl)-amino]-
benzonitrile (9). To a solution of 4-[(2-{N-tert-butoxycarbonyl}-
aminoethyl)-(3-methyl-3H-imidazol-4-ylmethyl)-amino]-benzo-
nitrile (compound 9c in ref 29b) (8.0 g, 30.6 mmol) in CH2Cl2
(75 mL) cooled to 0 ꢀC was added TFA (75 mL). The reaction was
warmed to room temperature and stirred for 30 min, after which
time the solvent was concentrated in vacuo, and then the crude
material was repeatedly re-dissolved in CHCl3 and re-evaporated
until a constant weight was achieved, to afford the ditrifluoro-
acetic acid salt of 9 as a light-brown solid (14.8 g, 100%): δH
(500 MHz, MeOH-d4) 3.20 (t, J = 7.1 Hz, 2H, CH2CH2NH2), 3.81
(t, J = 7.1 Hz, 2H, CH2CH2NH2), 3.87 (s, 3H, CH3 (Im)), 4.82 (s,
2H, CH2Im), 6.96 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 7.19 (s, 1H, CH
(Im)), 7.56 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 8.88 (s, 1H, CH (Im));
δC (125 MHz, MeOH-d4) 33.9, 37.1, 45.3, 48.2, 100.8, 114.0, 118.4,
120.4, 132.3, 134.6, 137.5, 151.0; HRMS (ESI) m/z calcd for
[C14H17N5 þ H] 256.1562, obsd 256.1559. Subsequently, the free
base form of 9, which is the form used for all subsequent reactions,
was furnished by passing the di-TFA salt through a short pad of
silica gel (eluent CH2Cl2/MeOH/NH4OH, 92:7:1).
[C24H27N5O2S þ H] 450.1964, obsd 450.1985; HPLC (I) tR
=
12.70 min (100%), (II) tR = 18.99 min (100%).
[N-(Furan-3-ylmethyl), N-{2-[(4-Cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-imidazole-4-
sulfonamide (1ah, 4.38). Furan-3-carbaldehyde was reductively
aminated with amine 9 according to general procedure C, on a
0.15 mmol scale. Purification by flash column chromatography
(eluent CH2Cl2/MeOH/NH4OH, 92:7:1) then gave 4-[{2-
[(furan-3-ylmethyl)-amino]-ethyl}-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-benzonitrile as a film (39 mg, 78%): δH (400
MHz, MeOH-d4) 3.24 (obscured t, 2H, NHCH2CH2N), 3.78
(m, 5H, NHCH2CH2N, CH3 (Im)), 4.07 (s, 2H, CH2-furan),
4.75 (s, 2H, CH2Im), 6.50 (s, 1H, CH (furan)), 6.88 (d, J = 9.0
Hz, 2H, 2 CH (benzonitrile)), 7.11 (s, 1H, CH (furan)),
7.42-7.53 (m, 3H, 2 CH (benzonitrile), CH (Im)), 7.62 (s,
1H, CH (furan)), 8.82 (s, 1H, CH (Im)); δC (100 MHz, MeOH-
d4) 34.5, 43.5, 44.7, 45.9, 47.7, 101.7, 111.9, 114.5, 117.3,
119.0, 120.8, 132.9, 135.2, 138.2, 145.1, 146.0, 151.5; LRMS
(ESI) m/z 358.2 [C19H21N5O þ Na]. This secondary amine (34
mg, 0.1 mmol) was reacted with 1-methyl-1H-imidazole-4-
sulfonyl chloride according to general procedure A to yield
the title compound 1ah as a white foam (43 mg, 90%): δH (500
MHz, MeOH-d4) 3.38 (obscured t, 2H, ((furan-3-ylmethyl)-
NHCH2CH2N)), 3.56 (t, J = 7.0 Hz, 2H, ((furan-3-ylmethyl)-
NHCH2CH2N)), 3.81 (s, 3H, CH3 (Im)), 3.89 (s, 3H, CH3
(Im)), 4.19 (s, 2H, CH2-furan), 4.70 (s, 2H, CH2Im), 6.57 (s,
1H, CH (furan)), 6.77 (d, J = 8.94 Hz, 2H, 2 CH (benzo-
nitrile)), 7.25 (s, 1H, CH (furan)), 7.46-7.52 (m, 4H, 2 CH
(benzonitrile), 2 CH (Im)), 7.78 (s, 1H, CH (furan)), 7.81 (s,
1H, CH (Im)), 8.91 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4)
34.3, 34.4, 45.3, 45.5, 45.9, 51.0, 100.4, 111.9, 113.8, 119.3,
120.8, 122.0, 126.8, 132.9, 134.8, 137.9, 139.1, 141.5, 143.2,
145.3, 151.7; HRMS (ESI) m/z calcd for [C23H25N7O3S þ H]
480.1818, obsd 480.1809; HPLC (I) tR = 12.62 min (100%).
[N-(Thiophen-3-ylmethyl), N-{2-[(4-Cyanophenyl)-(3-methyl-
3H-imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-imidazole-4-
sulfonamide (1ai, 4.39). Thiophene-3-carbaldehyde was reductively
aminated with amine 9 (38 mg, 0.15 mmol) according to general
procedure C to give, after flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 92:7:1), 4-((3-methyl-3H-imidazol-
4-ylmethyl)-{2-[(thiophen-3-ylmethyl)-amino]-ethyl}-amino)-
benzonitrile as a glassy film (40 mg, 76%): δH (400 MHz,
N-Benzyl, N-{2-[(4-Cyanophenyl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl} Propane-1-sulfonamide (1b). Compound 9
was treated with propane-1-sulfonyl chloride, according to general
procedure A, on a 0.15 mmol scale. The crude material was purified
by silica gel flash column chromatography (eluent CH2Cl2/MeOH/
NH4OH, 92:7:1) to give N-{2-[(4-cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl} propane-1-sulfonamide as a
colorless film (46 mg, 85%): δH (500 MHz, MeOH-d4) 0.98 (t,
J = 7.5 Hz, 3H, CH2CH2CH3), 1.71 (sextet, J = 7.5 Hz, 2H,
CH2CH2CH3), 2.96 (m, 2H, NHCH2CH2N), 3.21-3.26 (m, 2H,
CH2CH2CH3), 3.61 (t, J = 6.5 Hz, 2H, NHCH2CH2N), 3.84 (s,
3H, CH3 (Im)), 4.79 (s, 2H, CH2Im), 6.91 (d, J = 9.1 Hz, 2H, 2 CH
(Ar)), 7.20 (s, 1H, CH (Im)), 7.47 (d, J = 9.1 Hz, 2H, 2 CH (Ar)),
8.82 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4) 11.7, 16.9, 32.8,
39.7, 44.4, 50.6, 53.2, 98.9, 112.6, 117.7, 119.4, 131.5, 133.3, 136.2,
150.4; LRMS (ESI) m/z 384.2 [C17H23N5O2S þ Na]. Subsequently,
the sulfonamide (36 mg, 0.1 mmol) was treated with benzyl bromide
according to general procedure B. After the usual workup and flash
chromatography over silica gel (eluent CH2Cl2/MeOH/NH4OH,
192:7:1), the title compound 1b was furnished as a glassy film
(37 mg, 82%): δH (400 MHz, MeOH-d4) 1.20 (t, J = 7.4 Hz, 3H,
CH2CH2CH3), 1.99 (m, 2H, CH2CH2CH3), 3.24 (t, J = 7.8 Hz,
2H, N(Bn)CH2CH2N), 3.40 (obscured, 4H, NHCH2CH2N, CH2-
CH2CH3), 3.94 (s, 3H, CH3 (Im)), 4.52 (s, 2H, CH2Ph), 4.65 (s, 2H,
CH2Im), 6.75 (d, J = 8.9 Hz, 2H, 2 CH (Ar)), 7.25 (s, 1H, CH
(Im)), 7.55 (m, 7H, 5 CH (Ph), 2 CH (Ar)), 9.00 (s, 1H, CH (Im));
δC (125 MHz, MeOH-d4) 13.7, 18.6, 34.6, 45.4, 46.8, 51.6, 53.4,
55.1, 100.3, 114.1, 119.6, 121.2, 129.8, 130.7, 133.1, 135.1, 138.2,
138.7, 151.9, 152.9; HRMS (ESI) m/z calcd for [C24H29N5O2Sþ H]
452.2120, obsd 452.2108; HPLC (I) tR = 13.45 min (100%),
(II) tR = 19.72 min (100%).

6880 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
MeOH-d4) 3.20 (obscured t, 2H, NHCH2CH2N), 3.70-
3.75 (m, 5H, NHCH2CH2N, CH3 (Im)), 4.16 (s, 2H, CH2-
thiophene), 4.69 (s, 2H, CH2Im), 6.74 (d, J = 9.0 Hz, 2H, 2 CH
(benzonitrile)), 7.06 (s, 1H, CH (Im)), 7.09 (d, J = 3.9 Hz, 1H,
CH (thiophene)), 7.41-7.48 (m, 4H, 2 CH (benoznitrile), 2 CH
(thiophene)), 8.77 (s, 1H, CH (Im)); δC (100 MHz, MeOH-d4)
34.7, 45.0, 46.1, 47.4, 47.9, 102.0, 114.7, 119.2, 120.9, 129.0,
129.1, 129.5, 133.1, 133.2, 135.4, 138.4, 151.6; LRMS (ESI) m/z
374.2 [C19H21N5S þ Na]. This secondary amine (35 mg, 0.1
mmol) was then reacted with 1-methyl-1H-imidazole-4-sulfo-
nyl chloride according to general procedure A to give, after
purification by silica gel flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 192:7:1), compound 1ai as a white
foam (46 mg, 93%): δH (400 MHz, MeOH-d4) 3.29 (obscured t,
2H, ((thiophen-3-ylmethyl)NCH2CH2N)), 3.39 (t, J = 6.9 Hz,
2H, ((thiophen-3-ylmethyl)NCH2CH2N)), 3.69 (s, 3H, CH3
(Im)), 3.75 (s, 3H, CH3 (Im)), 4.20 (s, 2H, 2 CH (CH2-
thiophene)), 4.50 (s, 2H, CH2Im), 6.57 (d, J = 9.1 Hz, 2H, 2
CH (benoznitrile)), 6.95 (d, J = 3.8 Hz, 1H, CH (thiophene)),
7.09 (s, 1H, CH (thiophene)), 7.22 (s, 1H, CH (Im)), 7.31 (m,
1H, CH (thiophene)), 7.36 (d, J = 9.1 Hz, 2H, 2 CH (benzo-
nitrile)), 7.65 (s, 1H, CH (Im)), 7.70 (s, 1H, CH (Im)), 8.79 (s, 1H,
CH (Im)); δC (125 MHz, MeOH-d4) 34.7, 34.8, 45.5, 46.7, 50.3,
51.5, 100.7, 114.1, 119.6, 121.2, 126.2, 127.2, 128.3, 129.7, 133.2,
135.2, 138.2, 139.0, 139.5, 141.9, 152.0; HRMS (ESI) m/z calcd for
(obscured t, 2H, NHCH2CH2N), 3.88-3.92 (m, 5H, NHCH2-
CH2N, CH3 (Im)), 4.54 (s, 2H, CH2-thiophene), 4.86, (s, 2H,
CH2Im), 6.87 (m, 1H, CH (thiophene)), 7.00 (d, J = 8.8 Hz, 2H, 2
CH (benzonitrile)), 7.13 (m, 1H, CH (thiophene)), 7.23 (s, 1H, CH
(Im)), 7.34(m, 1H, CH(thiophene)), 7.59(d, J = 8.8 Hz, 2H, 2 CH
(benzonitrile)), 8.93 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4)
32.8, 42.9, 44.2, 45.0, 45.9, 100.2, 113.0, 117.4, 119.0, 127.3, 128.2,
130.6, 131.2, 131.5, 133.5, 136.6, 149.7; LRMS (ESI) m/z 374.2
[C19H21N5S þ Na]. This secondary amine (35 mg, 0.1 mmol) was
reacted with 1-methyl-1H-imidazole-4-sulfonyl chloride according
to general procedure A. The usual workup and purification by
flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) gave 1ak as a glassy film (44 mg, 89%): δH (400 MHz,
MeOH-d4) 3.31 (t, J = 7.1 Hz, 2H, ((thiophen-2-yl)NCH2-
CH2N)), 3.47 (t, J = 7.1 Hz, 2H, ((thiophen-2-yl)NCH2CH2N)),
3.69 (s, 3H, CH3 (Im)), 3.75 (s, 3H, CH3 (Im)), 4.41 (s, 2H, CH2-
thiophene), 4.55 (s, 2H, CH2Im), 6.61, (d, J = 9.0 Hz, 2H, 2 CH
(benzonitrile)), 6.85 (m, 1H, CH (thiophene)), 6.89 (d, J = 2.70
Hz, 1H), 7.11 (s, 1H, CH (Im)), 7.29 (m, 1H, CH (thiophene)), 7.37
(d, J = 9.0 Hz, 2H, 2 CH (benzonitrile)), 7.67 (s, 1H, CH (Im)),
7.69 (s, 1H, CH (Im)), 8.78 (s, 1H, CH (Im)); δC (100 MHz,
MeOH-d4) 34.7, 34.8, 45.7, 46.6, 50.3 (obscured), 51.0, 100.9,
114.2, 119.6, 121.2, 126.5, 127.2, 128.5, 130.0, 133.2, 135.2,
138.2, 139.5, 140.7, 141.9, 152.0; HRMS (ESI) m/z calcd for
[C23H25N7O2S2 þ H] 496.1589, obsd 496.1585; HPLC (I) tR
=
[C23H25N7O2S2 þ H] 496.1589, obsd 496.1576; HPLC (I) tR
=
12.90 min (100%).
12.64 min (99.0%), (II) tR = 18.84 min (98.2%).
[N-(3,5-Dimethyl-isoxazol-4-ylmethyl), N-{2-[(4-Cyanophenyl)-
(3-methyl-3H-imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-
imidazole-4-sulfonamide (1al, 4.36). Amine 9 was reacted with
1-methyl-1H-imidazole-4-sulfonyl chloride according to general
procedure A, on a 0.15 mmol scale. Flash column chromatogra-
phy of the crude material over silica gel (eluent CH2Cl2/MeOH/
NH4OH, 92:7:1) afforded 1-methyl-1H-imidazole-4-sulfonic acid
{2-[(4-cyano-phenyl)-(3-methyl-3H-imidazol-4-ylmethyl)-amino]-
ethyl}-amide as a white powder (55 mg, 92%): δH (400 MHz,
MeOH-d4) 3.19 (t, J = 6.3 Hz, 2H, NHCH2CH2N), 3.64 (t, J =
6.3 Hz, 2H, NHCH2CH2N), 3.72 (s, 3H, CH3 (Im)), 3.88 (s, 3H,
CH3 (Im)), 4.81 (s, 2H, CH2Im), 6.89 (d, J = 9.0 Hz, 2H, 2 CH
(benzonitrile)), 7.22 (s, 1H, CH (Im)), 7.50 (d, J = 9.0 Hz, 2H, 2
CH (benzonitrile)), 7.62 (s, 1H, CH (Im)), 7.71 (s, 1H, CH (Im)),
8.87 (s, 1H, CH (Im)); δC (100 MHz, MeOH-d4) 33.8, 33.9, 40.7,
45.4, 50.9, 99.5, 113.5, 118.5, 120.5, 125.3, 132.3, 134.2, 137.2,
139.9, 140.7, 151.2; HRMS (ESI) m/z calcd for [C18H21N7O2S þ
H] 400.1556, obsd 400.1545. This secondary sulfonamide was then
alkylated with 4-chloromethyl-3,5-dimethyl-isoxazole according
to general procedure B, on a 0.1 mmol scale. After workup,
purification was accomplished by silica gel flash column chroma-
tography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1) to furnish the
title compound 1al as a white foam (40 mg, 79%): δH (500 MHz,
MeOH-d4) 2.15 (s, 3H, CH3 (isoxazole)), 2.20 (s, 3H, CH3
(isoxazole)), 3.23 (t, J = 6.7 Hz, 2H, ((isoxazol-4-ylmethyl)NCH2-
CH2N)), 3.53 (t, J = 6.7 Hz, 2H, ((isoxazol-4-ylmethyl)NCH2-
CH2N)), 3.77 (s, 3H, CH3 (Im)), 3.82 (s, 3H, CH3 (Im)), 4.02 (s,
2H, CH2-isoxazole), 4.56 (s, 2H, CH2Im), 6.66 (d, J = 8.7 Hz, 2H,
2 CH (benzonitrile)), 7.17 (s, 1H, CH (Im)), 7.45 (d, J = 8.7 Hz,
2H, 2 CH (benzonitrile)), 7.74 (s, 1H, CH (Im)), 7.78 (s, 1H, CH
(Im)), 8.85 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4) 10.2, 10.9,
34.3, 34.4, 44.4, 45.0, 47.0, 51.2, 100.6, 110.7, 113.7, 119.3, 120.8,
127.1, 132.6, 134.9, 137.9, 138.2, 141.7, 151.4, 161.6, 169.6; HRMS
(ESI) m/z calcd for [C24H28N8O3S þ H] 509.2083, obsd 509.2072;
HPLC (I) tR = 12.27 min (100%), (II) tR = 17.76 min (100%).
[N-(2,4-Dimethyl-thiazol-5-ylmethyl), N-{2-[(4-Cyanophenyl)-
(3-methyl-3H-imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-
imidazole-4-sulfonamide (1am, 4.40). 2,4-Dimethyl-thiazole-5-car-
baldehyde was reductively aminated with amine 9 (38 mg, 0.15
mmol) according to general procedure C to give, after flash column
chromatography (eluent CH2Cl2/MeOH/NH4OH, 92:7:1), 4-[{2-
[(2,4-dimethyl-thiazol-5-ylmethyl)-amino]-ethyl}-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-benzonitrile as a glassy film (42 mg,
74%): δH (500 MHz, MeOH-d4) 2.34 (s, 3H, CH3 (thiazole)), 2.60
[N-(Furan-2-ylmethyl), N-{2-[(4-Cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-imidazole-4-
sulfonamide (1aj, 4.41). Furan-2-carbaldehyde was reductively
aminated with amine 9 according to general procedure C, on a
0.15 mmol scale. Purification by silica gel flash column chro-
matography (eluent CH2Cl2/MeOH/NH4OH, 92:7:1) afforded
4-[{2-[(furan-2-ylmethyl)-amino]-ethyl}-(3-methyl-3H-imidazol-
4-ylmethyl)-amino]-benzonitrile as a film (39 mg, 78%): δH (500
MHz, MeOH-d4) 3.31 (obscured t, 2H, NHCH2CH2N), 3.84 (t,
J = 7.4 Hz, 2H, NHCH2CH2N), 3.87 (s, 3H, CH3 (Im)), 4.33 (s,
2H, CH2-furan), 4.81 (s, 2H, CH2Im), 6.48 (m, 1H, CH (furan)),
6.61 (d, J = 3.19 Hz, 1H, CH (furan)), 6.95 (d, J = 8.9 Hz, 2H,
2 CH (benzonitrile)), 7.18, (s, 1H, CH (Im)), 7.54 (d, J = 8.9 Hz,
2H, 2 CH (benzonitrile)), 7.60 (m, 1H, CH (furan)), 8.88 (s, 1H,
CH (Im)); δC (125 MHz, MeOH-d4) 32.8, 43.0, 43.1, 44.2, 46.0,
100.1, 110.7, 112.4, 113.0, 117.4, 119.0, 131.2, 133.5, 136.5, 144.5,
144.8, 149.7; LRMS (ESI) m/z 358.2 [C19H21N5O þ Na]. This
secondary amine was reacted with 1-methyl-1H-imidazole-4-
sulfonyl chloride according to general procedure A, on a 0.1
mmol scale. After workup, the crude material was purified by
silica gel flash column chromatography (eluent CH2Cl2/MeOH/
NH4OH, 192:7:1) to furnish the title compound 1aj as a white
foam (43 mg, 90% 47.91818): δH (500 MHz, MeOH-d4) 3.34 (t,
J = 6.9 Hz, 2H, ((furan-3-ylmethyl)NCH2CH2N)), 3.46 (t, J =
6.9 Hz, 2H, ((furan-3-ylmethyl)NCH2CH2N)), 3.67 (s, 3H, CH3
(Im)), 3.79 (s, 3H, CH3 (Im)), 4.23 (s, 2H, CH2-furan), 4.63 (s,
2H, CH2Im), 6.18 (m, 1H, CH (furan)), 6.23(m, 1H, CH (furan)),
6.73 (d, J = 9.1 Hz, 2H, 2 CH (benzonitrile)), 7.15 (s, 1H, CH
(Im)), 7.29 (s, 1H, CH (furan)), 7.41 (d, J = 9.1 Hz, 2H, 2 CH
(benzonitrile)), 7.59 (s, 1H, CH (Im)), 7.64 (s, 1H, CH (Im)), 8.79
(s, 1H, CH (Im)); δC (125 MHz, MeOH-d4) 34.3, 45.4, 46.5, 47.1,
49.6 (obscured), 50.8, 100.4, 111.3, 111.7, 113.9, 119.3, 120.9,
126.8, 132.9, 134.8, 137.8, 139.1, 141.4, 144.4, 150.9, 151.8;
HRMS (ESI) m/z calcd for [C23H25N7O3S þ H] 480.1818, obsd
480.1833; HPLC (I) tR = 12.51 min (100%).
[N-(Thiophen-2-ylmethyl), N-{2-[(4-Cyanophenyl)-(3-methyl-
3H-imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-imidazole-
4-sulfonamide (1ak, 4.42). Thiophene-2-carbaldehyde was reduc-
tively aminated with amine 9 (38 mg, 0.15 mmol) according to
general procedure C, giving, after flash column chromatography
(eluentCH2Cl2/MeOH/NH4OH, 92:7:1), 4-((3-methyl-3H-imidazol-
4-ylmethyl)-{2-[(thiophen-2-ylmethyl)-amino]-ethyl}-amino)-benzo-
nitrile as a colorless film (38 mg, 72%): δH (500 MHz, MeOH-d4) 3.37

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6881
(s, 3H, CH3 (thiazole)), 3.32 (t, J = 7.06 Hz, 2H, NHCH2CH2N),
3.83 (m, 5H, NHCH2CH2N, CH3 (Im)), 4.39 (s, 2H, CH2-
thiazole), 4.78 (s, 2H, CH2Im), 6.92 (d, J = 9.0 Hz, 2H, 2 CH
(benzonitrile)), 7.14 (s, 1H, CH (Im)), 7.51 (d, J = 9.0 Hz, 2H, 2
CH (benzonitrile)), 8.85 (s, 1H, CH (Im)); LRMS (ESI) m/z 403.2
[C20H24N6S þ Na]. The secondary amine (38 mg, 0.1 mmol)
was then treated with 1-methyl-1H-imidazole-4-sulfonyl chloride
according to general procedure A. Workup and purification
(flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1)) as usual yielded 1am as a white foam (47 mg, 90%): δH
(500 MHz, MeOH-d4) 2.21 (s, 3H, CH3 (thiazole)), 2.55 (s, 3H,
CH3 (thiazole)), 3.39 (t, J = 6.5 Hz, 2H, ((thiazol-5-ylmethyl)-
NCH2CH2N)), 3.64 (t, J = 6.5 Hz, 2H, ((thiazol-5-ylmethyl)-
NCH2CH2N)), 3.77(s, 3H, CH3 (Im)), 3.86 (s, 3H, CH3 (Im)), 4.38
(s, 2H, CH2-thiazole), 4.73 (s, 2H, CH2Im), 6.71 (d, J = 9.1 Hz,
2H, 2 CH (benzonitrile)), 7.20 (s, 1H, CH (Im)), 7.46 (d, J = 9.1
Hz, 2H, 2 CH (benzonitrile)), 7.76 (s, 1H, CH (Im)), 7.79 (s, 1H,
CH (Im)), 8.87 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4)
14.8, 18.9, 34.7, 34.8, 45.9, 47.3, 47.6, 51.3, 100.8, 114.0, 119.6,
121.1, 127.5, 128.6, 133.2, 135.2, 138.3, 138.8, 142.0, 142.1, 150.9,
151.8; HRMS (ESI) m/z calcd for [C24H28N8O2S2 þ H] 525.1855,
obsd 525.1828; HPLC (I) tR = 12.14 min (96.61%), (II) tR = 17.00
min (96.03%).
(s, 2H, NHCH2CH2N), 3.50 (m, 2H, NHCH2CH2N), 3.55
(s, 3H, CH3 (Im)), 4.88 (s, 2H, CH2Im), 6.68 (d, J = 8.8 Hz,
2H, 2 CH (benzonitrile)), 6.86 (s, 1H, CH (Im)), 7.26 (s, 1H,
CH (Im)), 7.46 (d, J = 8.8 Hz, 2H, 2 CH (benzonitrile); LRMS
(ESI) m/z 332.2 [C18H23N5 þ Na]. This secondary amine was
then reacted with 1-methyl-1H-imidazole-4-sulfonyl chloride
according to general procedure A, on a 0.1 mmol scale. After
workup, the crude material was purified by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to furnish 1aw as a white powder (39 mg, 86%): δH
(500 MHz, MeOH-d4) 0.14 (m, 2H, 2 CH (cyclopropyl)), 0.43
(m, 2H, 2 CH (cyclopropyl)), 0.84 (m, 1H, CHCH2NCH2-
CH2N), 2.50 (d, J = 6.9, 2H, CH2-cyclopropyl), 2.99 (t, J =
6.9 Hz, 2H, ((cyclopropylmethyl)NCH2CH2N)), 3.73 (s, 3H,
CH3 (Im)), 3.81 (t, J = 6.9 Hz, 2H, ((cyclopropylmethyl)-
NCH2CH2N)), 3.88 (s, 3H, CH3 (Im)), 4.85 (s, 2H, CH2Im),
6.97 (d, J = 9.1 Hz, 2H, 2 CH (benzonitrile)), 7.28 (s, 1H, CH
(Im)), 7.62 (d, J = 9.1 Hz, 2H, 2 CH (benzonitrile)), 7.67 (s,
1H, CH (Im)), 7.71 (s, 1H, CH (Im)), 8.87 (s, 1H, CH (Im)); δC
(125 MHz, MeOH-d4) 4.6, 11.0, 34.3, 34.4, 45.8, 46.8, 51.6,
55.9, 100.4, 114.1, 119.3, 120.9, 126.5, 133.1, 134.9, 137.9,
139.5, 141.4, 151.9; HRMS (ESI) m/z calcd for [C22H27N7-
O2S þ H] 454.2025, obsd 454.2009; HPLC (I) tR = 12.55 min
(99.05%), (II) tR = 18.46 min (98.47%).
[N-(1,3,5-Trimethyl-1H-pyrazol-4-ylmethyl), N-{2-[(4-Cyano-
phenyl)-(3-methyl-3H-imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-
1H-imidazole-4-sulfonamide (1an, 4.49). Trimethyl-1H-pyrazole-4-
carbaldehyde was reductively aminated with amine 9, according to
general procedure C, on a 0.15 mmol scale. The crude material was
chromatographed over silica gel (eluent CH2Cl2/MeOH/NH4OH,
92:7:1) to give 4-((3-methyl-3H-imidazol-4-ylmethyl)-{2-[(1,3,5-tri-
methyl-1H-pyrazol-4-ylmethyl)-amino]-ethyl}-amino)-benzonitrile
as a film (46 mg, 81%): δH (400 MHz, MeOH-d4) 2.28 (s, 3H, CH3
(pyrazole)), 2.34 (s, 3H, CH3 (pyrazole)), 3.39 (t, J = 7.5 Hz, 2H,
NHCH2CH2N), 3.75 (s, 3H, N-CH3 (pyrazole)), 3.88-3.95 (m,
5H, NHCH2CH2N, CH3 (Im)), 4.15 (s, 2H, CH2-pyrazole), 4.88
(s, 2H, CH2Im), 7.01 (d, J = 8.9 Hz, 2H, 2 CH (benzonitrile)), 7.22
(s, 1H, CH (Im)), 7.59 (d, J = 8.9 Hz, 2H, 2 CH (benzonitrile)), 8.94
(s, 1H,CH(Im));δC (125 MHz, MeOH-d4) 9.8, 11.4, 34.3, 36.1, 42.3,
44.7, 45.6, 47.5, 99.9, 108.3, 114.3, 118.8, 120.6, 132.8, 135.0, 138.0,
142.6, 148.5, 151.3; LRMS (ESI) m/z 400.2 [C21H27N7 þ Na]. This
secondary amine (38 mg, 0.1 mmol) was then reacted with 1-methyl-
1H-imidazole-4-sulfonyl chloride according to general procedure A.
Workup then the usual purification (silica gel flash column chroma-
tography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1)) furnished the
title compound 1an as a white foam (44 mg, 84%): δH (500 MHz,
MeOH-d4) 2.00 (s, 3H, CH3 (pyrazole)), 2.06 (s, 3H, CH3
(pyrazole)), 3.15 (t, J = 6.5 Hz, 2H, ((pyrazole-4-ylmethyl)-
NCH2CH2N)), 3.44 (t, J = 6.5 Hz, 2H, ((pyrazole-4-ylmethyl)-
NCH2CH2N)), 3.51 (s, 3H, N-CH3 (pyrazole)), 3.73 (s, 3H,
CH3 (Im)), 3.78 (s, 3H, CH3 (Im)), 3.92 (s, 2H, CH2-pyrazole),
4.48 (s, 2H, CH2Im), 6.50 (d, J = 8.9 Hz, 2H, 2 CH (ben-
zonitrile)), 7.11 (s, 1H, CH (Im)), 7.39 (d, J = 8.9 Hz, 2H,
2 CH (benzonitrile)), 7.72 (s, 1H, CH (Im)), 7.75 (s, 1H, CH
(Im)), 8.80 (s, 1H, CH (Im)); δC (125 MHz, MeOH-d4) 9.5,
11.7, 34.3, 34.4, 36.0, 45.1, 45.4, 46.5, 51.2, 100.2, 111.8,
113.4, 119.2, 120.8, 127.1, 132.7, 134.8, 137.9, 138.1, 141.2,
tert-Butyl 4-[{2-[benzyl-(1-methyl-1H-imidazole-4-sulfonyl)-
amino]-ethyl}-(3-methyl-3H-imidazol-4-ylmethyl)-amino]-benzoate
(10). tert-Butyl p-fluorobenzoate (750 mg, 3.93 mmol, 1 equiv) was
dissolved in ethylenediamine (9; 4 mL, 59.8 mmol, 15.2 equiv) and
heated to 120 ꢀC for 24 h. All solvent was evaporated, and then the
residue was dry-loaded onto silica gel and purified by flash column
chromatography (eluent CH2Cl2/MeOH/NH4OH, 92:7:1) to fur-
nish tert-butyl 4-(2-amino-ethylamino)-benzoate as a white pow-
der (891 mg, 96%): δH (400 MHz, CD2Cl2) 1.59 (s, 9H, CO2-
(CH3)3), 2.98 (t, J = 5.8 Hz, 2H, H2NCH2CH2NH), 3.23 (q, J =
5.8 Hz, 2H, H2NCH2CH2NH), 4.67 (br, 1H, H2NCH2CH2NH),
6.62 (d, J = 8.6 Hz, 2H, 2 CH (Ar)), 7.81 (d, J = 8.6 Hz, 2H, 2 CH
(Ar)); δC (125 MHz, CD2Cl2) 28.9, 41.7, 46.6, 80.3, 112.1, 120.9,
131.9, 152.9, 166.7; HRMS (EIþ) m/z calcd for [C13H20N2O2]
236.1525, obsd 236.1527. tert-Butyl 4-(2-amino-ethylamino)-
benzoate (700 mg, 3.03 mmol, 1 equiv) was then sulfonylated with
1-methyl-1H-imidazole-4-sulfonyl chloride according to general
procedure A. The crude material was dry-loaded onto silica gel,
and then purified by flash column chromatography (eluent CH2-
Cl2/MeOH/NH4OH, 192:7:1) to give tert-butyl 4-[2-(1-methyl-
1H-imidazole-4-sulfonylamino)-ethylamino]-benzoate as a white
powder (1.04 g, 90%): δH (500 MHz, CDCl3) 1.56 (s, 9H, CO2-
(CH3)3), 3.17 (m, 2H, SO2NHCH2CH2NH), 3.28 (m, 2H,
SO2NHCH2CH2NH), 3.67 (s, 3H, CH3 (Im)), 6.51 (d, J = 8.5
Hz, 2H, 2 CH (Ar)), 7.46 (s, 1H, CH (Im)), 7.51 (s, 1H, CH (Im)),
7.75 (d, J = 8.5 Hz, 2H, 2 CH (Ar)); δC (125 MHz, MeOH-d4)
28.7, 34.6, 42.4, 43.1, 80.8, 111.9, 120.5, 125.2, 131.8, 140.1, 140.3,
152.4, 167.4; HRMS (ESIþ) m/z calcd for [C17H24N4O4S þ H]
381.1597, obsd 381.1573. tert-Butyl 4-[2-(1-methyl-1H-imidazole-
4-sulfonylamino)-ethylamino]-benzoate (610 mg, 1.63 mmol,
1 equiv) was then chemoselectively benzylated on the sulfonamide
NH with benzyl bromide according to general procedure B.
The crude material was then flash chromatographed over silica
gel to furnish tert-butyl 4-{2-[benzyl-(1-methyl-1H-imidazole-4-
sulfonyl)-amino]-ethylamino}-benzoate as a white solid (703 mg,
92%): δH (400 MHz, CDCl3) 1.52 (s, 9H, CO2(CH3)3), 3.13 (t, J =
6.2 Hz, 2H, (Bn)NCH2CH2NH), 3.43 (t, J = 6.2 Hz, 2H,
(Bn)NCH2CH2NH), 3.68 (s, 3H, CH3 (Im)), 4.32 (s, 2H, CH2Ph),
6.30 (d, J = 8.8 Hz, 2H, 2 CH (Ar)), 7.23-7.30 (m, 5H, 5 CH
(Ph)), 7.42 (s, 1H, CH(Im)), 7.49(s, 1H, CH(Im)), 7.70(d, J =8.8
Hz, 2H, 2 CH (Ar)); δC (500 MHz, CDCl3) 28.1, 33.9, 41.6,
46.6, 52.6, 79.6, 111.1, 119.9, 124.4, 127.9, 128.3, 128.6, 131.1,
136.0, 139.0, 139.8, 151.1, 166.1; HRMS (ESIþ) m/z calcd
for [C24H30N4O4S þ H] 471.2066, obsd 471.2053. tert-Butyl
4-{2-[benzyl-(1-methyl-1H-imidazole-4-sulfonyl)-amino]-ethyl-
amino}-benzoate (220 mg, 0.473 mmol, 1 equiv) was alkylated
141.7, 147.9, 151.4; HRMS (ESI) m/z calcd for [C25H31
-
N9O2S þ H] 522.2400, obsd 522.2377; HPLC (I) tR = 12.49
min (95.83%), (II) tR = 17.78 min (96.33%).
[N-(Cyclopropylmethyl), N-{2-[(4-Cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl}] 1-Methyl-1H-imidazole-4-sulfo-
namide (1aw, 4.34). First, cyclopropanecarbaldehyde was re-
ductively aminated with amine 9 (38 mg, 0.15 mmol), accord-
ing to general procedure C. Flash column chromatography
(eluent CH2Cl2/MeOH/NH4OH, 92:7:1) purified the material
to give 4-[[2-(cyclopropylmethyl-amino)-ethyl]-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-benzonitrile as a colorless film
(39 mg, 84%): δH (400 MHz, CDCl3) 0.07 (m, 2H, 2 CH
(cyclopropyl)), 0.46 (m, 2H, 2 CH (cyclopropyl)), 0.78 (m, 1H,
CHCH2NHCH2CH2N), 2.41 (m, 2H, CH2-cyclopropyl), 2.75

6882 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
on the aniline NH with 5-chloromethyl-1-methyl-1H-imidazole
Fletcher et al.
benzyl-[2-(biphenyl-4-ylamino)-ethyl]-amide as a colorless film
(30 mg, 91%) Next, the secondary aniline of 1-methyl-1H-imida-
zole-4-sulfonic acid benzyl-[2-(biphenyl-4-ylamino)-ethyl]-amide
(30 mg, 0.067 mmol, 1 equiv) was alkylated with the HCl salt of
5-chloromethyl-1-methyl-1H-imidazole31 according to general pro-
cedure E. After the usual workup, the crude material was dry-
loaded onto silica gel and purified by flash column chromatography
(eluent CH2Cl2/MeOH/NH4OH, 92:7:1) to give 14 as a glassy film
(24 mg, 65%): δH (500 MHz, CDCl3) 3.16 (m, 2H, (Bn)NCH2-
CH2N), 3.33 (m, 2H, (Bn)NCH2CH2N), 3.44 (s, 3H, CH3 (Im)),
3.75 (s, 3H, CH3 (Im)), 4.27 (s, 2H, CH2Ph), 4.38 (s, 2H, CH2Im),
6.56 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 6.79 (s, 1H, CH (Im)), 7.34 -
7.51 (m, 15 H, 10 CH (Ph), 3 CH (Im), 2 CH (Ar)); δC (125 MHz,
CDCl3) 31.9, 34.2, 44.9, 45.4, 50.0, 54.5, 113.5, 124.6, 126.4, 126.5,
128.1, 128.3 (2), 128.9, 129.0, 129.2, 129.4, 130.5, 136.8, 138.8,
139.3, 139.9, 141.1, 147.2; HRMS (ESIþ) m/z calcd for [C30H32N6-
O2S þ H] 541.2380, obsd 541.2386; HPLC (I) tR = 13.01 min
(100%), (II) tR = 20.24 min (100%).
N-(2-tert-Butoxycarbonylaminoethyl) 1-Methyl-1H-imidazole-
4-sulfonamide (15). Mono-N-Boc-ethylenediamine (6; 5 g, 31.2
mmol, 1 equiv) was sulfonylated with 1-methyl-1H-imidazole-4-
sulfonyl chloride (6.76 g, 37.4 mmol, 1.2 equiv), according to
general procedure A. After 16 h, the solvent was reduced and
then the reaction mixture was dry-loaded onto silica gel and
purified by flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 1092:7:1) to give the title compound as a white
powder (9 g, 95%): δH (500 MHz, CD2Cl2) 1.37 (s, 9H, C(CH3)3),
2.99 (t, J = 5.8 Hz, 2H, CH2NHSO2), 3.11 (q, J = 5.8 Hz, 2H,
CH2NHBoc), 3.71 (s,3H, CH3), 5.53 (s,1H, NHSO2), 5.68(s, 1H,
NHBoc), 7.48 (s, 1H, Im), 7.56 (s, 1H, Im); δC (125 MHz,
CD2Cl2) 27.6, 33.5, 39.8, 42.6, 78.9, 124.0, 127.2, 139.2, 156.1;
HRMS (ESIþ) m/z calcd for [C11H20N4O4S þ H] 305.1284, obsd
305.1294.
[N-(2-tert-Butoxycarbonylaminoethyl), N-{N-(2-Pyrimidinyl)-
piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (16).
N-(2-tert-Butoxycarbonylaminoethyl) 1-methyl-1H-imidazole-4-
sulfonamide (5.94 g, 19.5 mmol, 1 equiv) was chemoselectively
alkylated on the sulfonamide NH with N-(2-pyrimidinyl)-piperi-
din-4-ylmethyl bromide (6 g, 23.4 mmol, 1.2 equiv), according to
general procedure B, but the reaction was stirred for 4 d
at room temperature. [N-(2-Pyrimidinyl)-piperidin-4-ylmethyl bro-
mide was made from the reaction of N-(2-pyrimidinyl)-piperidin-4-
ylmethyl alcohol (5 g, 25.9 mmol, 1 equiv) with PPh3Br2 (14.2 g, 33.7
mmol, 1.3 equiv) in CH2Cl2 (130 mL) at 0 ꢀC to room temperature
over 6 h. At this point, the reaction was complete. Water (100 mL)
was added to quench, and then the CH2Cl2 layer was diluted further
(500 mL total volume). The organic layer was collected, and the
aqueous layer was extracted twice further (2 ꢀ 50 mL). The organic
layers were collected, dried (Na2SO4), filtered, and concentrated.
The residue was redissolved in CH2Cl2, dry-loaded onto silica gel,
then purified by flash column chromatography (eluent Hex/EtOAc,
7:1) to furnish N-(2-pyrimidinyl)-piperidin-4-ylmethyl bromide as a
white powder (6.04 g, 91%).] After workup, the crude material was
dry-loaded onto silica gel and purified by silica gel flash column
chromatography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1), afford-
ing the title compound as a white solid (8.81 g, 94%): δH (500 MHz,
CDCl3) 1.09 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)),
1.36 (s, 9H, C(CH3)3), 1.69-1.78 (m, 2H, 2 CH (piperidinyl-
methyl)), 1.84-1.92 (m, 1H, CH (piperidinylmethyl)), 2.77-2.83
(m, 2H, 2CH(piperidinylmethyl)), 2.97(brd,J=8.0Hz, 2H, 2CH
(piperidinylmethyl)), 3.25-3.34 (m, 4H, CH2CH2NHBoc), 3.67 (s,
3H, CH3), 4.64-4.69 (m, 2H, 2 CH (piperidinylmethyl)), 5.53 (m,
1H, NHBoc), 6.34(t, J= 4.9 Hz, 1H, CH (pyrimidine)), 7.36 (s, 1H,
CH (Im)), 7.40 (s, 1H, CH (Im)), 8.20 (t, J = 4.9 Hz, 2H, 2 CH
(pyrimidine)); δC (125 MHz, CDCl3) 28.3, 29.4, 34.8, 35.4, 39.6,
43.4, 49.1, 55.2, 79.0, 109.2, 124.2, 138.9, 140.6, 155.9, 157.5, 161.4;
HRMS (ESIþ) m/z calcd for [C21H33N7O4S þ H] 480.2393, obsd
480.2409.
3
HCl31 according to general procedure E. The crude material was
flash chromatographed over silica gel (eluent CH2Cl2/MeOH/
NH4OH, 192:7:1) to afford the title compound 11 as a colorless
foam (200 mg, 76%): δH (500 MHz, CDCl3) 1.53 (s, 9H, C(CH3)3),
3.09-3.15 (m, 2H, CH2CH2NSO2), 3.29-3.34 (m, 2H, CH2CH2-
NSO2), 3.43 (s, 3H, CH3), 3.73 (s, 3H, CH3), 4.26 (s, 2H, CH2Ph),
4.30 (s, 2H, CH2Im), 6.35 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 6.69 (s,
1H, CH (Im)), 7.31-7.37 (m, 5H, 5 CH (Ph)), 7.39 (s, 1H, CH
(Im)), 7.42 (s, 1H, CH (Im)), 7.46 (s, 1H, CH (Im)), 7.68 (d, J = 9.0
Hz, 2H, 2 CH (Ar)); δC (125 MHz, CDCl3) 28.2, 31.6, 33.9, 44.1,
45.0, 49.7, 54.3, 79.8, 111.0, 120.0, 124.4, 127.5, 128.1, 128.6, 128.7,
128.9, 131.1, 136.2, 138.5, 139.0, 139.1, 150.3, 165.8; HRMS (ESIþ)
m/z calcd for [C29H36N6O4S þ H] 565.2597, obsd 565.2576; HPLC
(I) tR = 12.53 min (100%),(II) tR = 18.77 min (100%).
4-[{2-[Benzyl-(1-methyl-1H-imidazole-4-sulfonyl)-amino]-ethyl}-
(3-methyl-3H-imidazol-4-ylmethyl)-amino]-benzoic Acid (12). TFA
(1.5 mL) was added to a solution of 11 (150 mg, 0.268 mmol,
1 equiv) in CH2Cl2 (1.5 mL), and the resulting mixture was stirred
for 3 h at room temperature, after which time all solvents were
evaporated. Residual TFA was removed by repeated coevapora-
tion with a 2:1 mixture of CHCl3/MeOH, then the residue was
purified by silica gel flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 25:7:1) to afford the title compound as a sticky
foam (131 mg, 96%): δH (500 MHz, MeOH-d4) 3.34-3.39 (m, 2H,
CH2CH2NSO2), 3.42-3.46 (m, 2H, CH2CH2NSO2), 3.81 (s, 3H,
CH3), 3.84 (s, 3H, CH3), 4.30 (s, 2H, CH2Ph), 4.55 (s, 2H, CH2Im),
6.53 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 7.15 (s, 1H, CH (Im)),
7.34-7.38 (m, 5H, 5 CH (Ph)), 7.76-7.79 (m, 3H, 2 CH (Ar), CH
(Im)), 7.82 (s, 1H, CH (Im)), 8.87 (s, 1H, CH (Im)); δC (125 MHz,
MeOH-d4) 34.3, 34.4, 45.0, 46.5, 51.2, 55.2, 112.8, 119.3, 120.3,
126.8, 129.3, 129.9 (2 CH), 132.7, 133.1, 137.7, 137.9, 139.1, 141.5,
152.0, 170.1; HRMS (ESIþ) m/z calcd for [C25H28N6O4S þ H]
509.1971, obsd 509.1953; HPLC (I) tR = 11.24 min (100%), (II)
tR = 15.21 min (100%).
4-[{2-[Benzyl-(1-methyl-1H-imidazole-4-sulfonyl)-amino]-ethyl}-
(1-methyl-1H-imidazol-4-ylmethyl)-amino]-benzamide (13). To a
solution of acid 12 (50 mg, 0.0984 mmol, 1 equiv), NH4Cl (10.5
mg, 0.197 mmol, 2 equiv), and DIPEA (34 μL) in DMF (1 mL) was
added HBTU (48.5 mg, 0.128 mmol, 1.3 equiv). The reaction
mixture was stirred for 1 h, after which time TLC indicated the
reaction was complete. Water (25 mL) was added, and then the
crude product was extracted into EtOAc (5 ꢀ 5 mL). The EtOAc
extractions were combined, washed with water (3 ꢀ 5 mL), brine
(5 mL), dried (Na2SO4), filtered, and concentrated. The residue
was dry-loaded onto silica gel, then flash chromatographed (eluent
CH2Cl2/MeOH/NH4OH, 92:7:1) to furnish primary amide 13 as a
white powder (44 mg, 89%): δH (500 MHz, CDCl3) 3.15 (m, 2H,
(Bn)NCH2CH2N), 3.31 (m, 2H, (Bn)NCH2CH2N), 3.41 (s, 3H,
CH3 (Im)), 3.71(s, 3H, CH3 (Im)), 4.23(s, 2H,CH2Ph), 4.29 (s, 2H,
CH2Im), 6.02 (br, 2H, NH2), 6.42 (d, J = 9.0 Hz, 2H, 2 CH (Ar)),
6.66 (s, 1H, CH (Im)), 7.29-7.34 (m, 6H, 5 CH (Ph), CH (Im)),
7.41 (s, 1H, CH (Im)), 7.45 (s, 1H, CH (Im)), 7.56 (d, J = 9.0 Hz,
2H, 2 CH (Ar)); δC (125 MHz, CDCl3) 31.3, 33.7, 43.9, 44.8, 49.4,
50.2, 54.0, 111.1, 121.0, 124.2, 127.2, 127.9, 128.4, 128.6, 128.9,
136.0, 138.4, 138.8, 138.9, 149.8, 168.9; HRMS (ESIþ) m/z calcd
for [C25H29N7O3S þ H] 508.2137, obsd 508.2131; HPLC (I) tR =
11.72 min (100%), (II) tR = 16.29 min (100%).
[N-Benzyl, N-{2-[(biphenyl-4-yl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl}] 1-methyl-1H-imidazole-4-sulfonamide
(14). Previously reported 1-tert-butoxycarbonylamino-{2-
[biphenyl-4-yl-(3-methyl-3H-imidazol-4-ylmethyl)-amino]}-ethane
(compound 9a in ref 31) (30 mg, 0.0739 mmol) was deprotected
by stirring in a 1:1 mixture of TFA-CH2Cl2 (1 mL) for 30 min.
After removal of all solvent in vacuo, the residue (23 mg, 0.0739
mmol) was sulfonylated with 1-methyl-1H-imidazole-4-sulfonyl
chloride according to general procedure A, but with 5 equiv of
DIPEA. After the usual workup, the residue was purified by silica
gel flash column chromatography (eluent CH2Cl2/MeOH/
NH4OH, 92:7:1) to afford 1-methyl-1H-imidazole-4-sulfonic acid
[N-(2-Aminoethyl), N-{N-(2-Pyrimidinyl)-piperidin-4-ylmethyl}]
1-Methyl-1H-imidazole-4-sulfonamide (17). To a cooled (0 ꢀC),

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6883
stirring solution of 16 (8.67 g, 18.1 mmol) in CH2Cl2 (47.5 mL) was
added triisopropylsilane (TIPS; 2.5 mL), H2O (2.5 mL) and
TFA (47.5 mL). After 5 min, the reaction was removed from the
ice bath and allowed to stir for 1 h at room temperature, and then
all solvents were evaporated. The residue was redissolved in CH2Cl2
and the minimal required volume of MeOH, then dry-loaded
onto silica gel and purified by flash column chromatography
(eluent CH2Cl2/MeOH/NH4OH, 92:7:1) to give 17 as a white,
sticky foam (7.2 g, 100%): δH (500 MHz, CDCl3) 1.10 (qd, J =
12.2, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.73-1.78 (m, 2H, 2
CH (piperidinylmethyl)), 1.87-1.95 (m, 1H, CH (piperidinyl)),
2.77-2.83 (m, 2H, 2 CH (piperidinylmethyl)), 2.92 (t, J = 6.5 Hz,
2H, CH2NH2) 3.00 (br d, J = 7.5 Hz, 2H, 2 CH (piperidinyl-
methyl)), 3.32 (t, J = 6.4 Hz, 2H, CH2CH2NH2), 3.46-3.51 (br s,
NH2), 3.69 (s, 3H, CH3 (Im)), 4.66-4.72 (m, 2 H, 2 CH (piperi-
dinylmethyl)), 6.38 (t, J = 4.7 Hz, 1H, CH (pyrimidine)), 7.40 (s,
1H, CH (Im)), 7.47 (s, 1H, CH (Im)), 8.22 (t, J = 4.7 Hz, 2H, 2 CH
(pyrimidine)); δC (125 MHz, CDCl3) 29.5, 33.8, 35.5, 40.1, 43.4,
52.5, 54.9, 109.2, 124.2, 139.0, 139.4, 158.5, 161.5; HRMS (ESIþ)
m/z calcd for [C16H25N7O2S þ H] 380.1869, obsd 380.1886.
[N-{2-(2-Chloro-4-cyanophenyl)-aminoethyl}, N-{N-(2-Pyrimi-
dinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide
(18a). Compound 17 was reacted with 2-chloro-4-fluorobenzonitrile
on a 0.338 mmol scale, according to general procedure D. After the
usual workup, the crude material was purified by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1)
to give the title compound as a colorless, viscous oil (158 mg, 91%):
δH (500 MHz, CDCl3) 1.08 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH
(piperidinylmethyl)), 1.68-1.74 (m, 2H, 2 CH (piperidinylmethyl)),
1.77-1.86 (m, 1H, CH (piperidinylmethyl)), 2.72 (td, J = 12.5, 2.5
Hz, 2H, 2 CH (piperidinylmethyl)), 3.00 (br d, J=7.5Hz, 2H, 2CH
(piperidinylmethyl)), 3.48-3.55 (m, 4H, CH2CH2NHAr), 3.71 (m,
3H, CH3 (Im)), 4.63-4.69 (m, 2 H, 2 CH (piperidinylmethyl)), 5.77
(t, J = 5.3 Hz, 1H, CH2NHAr), 6.40 (t, J = 4.7 Hz, 1H, CH
(pyrimidine)), 6.66 (d, J = 8.5 Hz, 1H, CH (Ar)), 7.37 (dd, J = 8.5,
2.0 Hz, 1H, CH (Ar)), 7.43 (s, 1H, CH (Im)), 7.45 (d, J = 2.0 Hz,
1H, CH (Ar)), 7.46 (s, 1H, CH (Im)), 8.22 (t, J = 4.7 Hz, 2H,
2 CH (pyrimidine)); δC (125 MHz, CDCl3) 29.6, 33.9, 36.0, 42.2,
43.4, 48.7, 56.1, 98.7, 109.4, 110.0, 118.6, 119.0, 124.4, 132.4, 132.5,
139.1, 139.5, 147.0, 157.5, 161.4; HRMS (ESIþ) m/z calcd for
[C23H27N8O2SCl þ H] 515.1744, obsd 515.1754.
δH (500 MHz, CDCl3) 1.11 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH
(piperidinylmethyl)), 1.72-1.78 (m, 2H, 2 CH (piperidinyl-
methyl)), 1.87-1.97 (m, 1H, CH (piperidinylmethyl)), 2.78 (td,
J = 12.8, 2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.03 (br d, J = 8.0
Hz, 2H, 2 CH (piperidinylmethyl)), 3.49-3.57 (m, 4H, CH2CH2-
NHAr), 3.72 (m, 3H, CH3 (Im)), 4.67-4.73 (m, 2 H, 2 CH
(piperidinylmethyl)), 5.62 (t, J = 5.3 Hz, 1H, CH2NHAr), 6.34
(dd, J = 9.0 Hz, 1H, CH (Ar)), 6.41 (t, J = 4.9 Hz, 1H, CH
(pyrimidine)), 7.40 (dd, J = 9.0, 2.5 Hz, 1H, CH (Ar)), 7.42 (s, 1H,
CH(Im)), 7.47(s, 1H, CH(Im)), 8.05(d,J=2.5Hz, 1H, CH(Ar)),
8.25 (t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)); δC (125 MHz, CDCl3)
29.7, 33.9, 35.6, 40.5, 43.6, 48.5, 55.0, 106.8, 109.3, 109.7, 124.4,
138.9, 139.3, 140.0, 148.4, 156.9, 157.6, 161.5; HRMS (ESIþ) m/z
calcd for [C21H27N8O2SBr þ H] 535.1239, obsd 535.1259.
[N-{2-(5-Bromopyrimidin-2-yl)-aminoethyl}, N-{N-(2-Pyrimi-
dinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide
(18d). Compound 17 was reacted with 5-bromo-2-fluoropyrimidine
on a 0.528 mmol scale, according to general procedure D. After
the usual workup, the crude material was purified by silica gel
flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to give the title compound as a white foam (255 mg, 90%):
δH (500 MHz, CDCl3) 1.08(qd, J= 12.3, 4.0 Hz, 2H, 2 CH (piperi-
dinylmethyl)), 1.70-1.77 (m, 2H, 2 CH (piperidinylmethyl)),
1.83-1.92 (m, 1H, CH (piperidinylmethyl)), 2.78 (td, J = 12.8,
2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.03 (br d, J=8.0Hz, 2H, 2
CH (piperidinylmethyl)), 3.43 (t, J = 6.3 Hz, 2H, CH2CH2NHAr),
3.57 (t, J = 6.3 Hz, 2H, CH2CH2NHAr), 3.68 (m, 3H, CH3 (Im)),
4.60-4.66 (m, 2 H, 2 CH (piperidinylmethyl)), 6.39 (t, J = 4.6 Hz,
1H, CH(pyrimidine)), 7.40(s, 1H, CH(Im)), 7.47(s, 1H, CH(Im)),
8.19(s, 2H, 2CH(Ar)), 8.21(t,J= 4.6 Hz, 2H, 2 CH (pyrimidine));
δC (125 MHz, CDCl3) 29.5, 33.8, 35.5, 40.4, 43.6, 48.3, 55.0, 106.1,
109.3, 124.3, 139.1, 139.6, 157.6, 158.1, 160.3, 161.3; HRMS (ESIþ)
m/z calcd for [C20H26N9O2SBr þ H] 536.1192, obsd 536.1213.
[N-{2-(3-Fluoro-4-cyanophenyl)-aminoethyl}, N-{N-(2-Pyrimi-
dinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide
(18e). Compound 17 was reacted with 2,4-difluorobenzonitrile on a
0.417 mmol scale, according to general procedure D, to give a
separable mixture of the two expected isomers. After the usual
workup, the crude material was purified by prepTLC (eluent
CH2Cl2/MeOH/NH4OH, 92:7:1) to give the title compound as a
white foam (99 mg, 48%): δH (500 MHz, CDCl3) 1.15(qd,J=12.5,
4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.73-1.79 (m, 2H, 2 CH
(piperidinylmethyl)), 1.87-1.95 (m, 1H, CH (piperidinylmethyl)),
2.80 (td, J= 12.8, 2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.03 (br d,
J = 7.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.36 (q, J = 5.5 Hz, 2H,
CH2CH2NHAr),3.65(t, J= 5.8 Hz, 2H, CH2CH2NHAr), 3.77(m,
3H, CH3 (Im)), 4.70-4.75 (m, 2 H, 2 CH (piperidinylmethyl)),
6.10-6.13 (m, 1H, CH2NHAr), 6.30 (dd, J = 12.0, 2.0 Hz, 1H, CH
(Ar)), 6.39 (dd, J = 8.8, 2.0 Hz, 1H, CH (Ar)), 6.44 (t, J = 4.9 Hz,
1H, CH (pyrimidine)), 7.32 (dd, J =8.8, 7.3 Hz, 1H, CH (Ar)), 7.47
(s, 1H, CH(Im)), 7.52(s, 1H, CH(Im)), 8.27(t, J= 4.9 Hz, 2H, CH
(pyrimidine)); δC (125 MHz, CDCl3) 29.5, 34.0, 35.5, 41.5, 43.5,
47.7, 54.4, 87.0 (d, JCF = 15.5 Hz), 98.1 (d, JCF = 22.8 Hz), 108.8
(br), 109.4, 115.7, 124.6, 133.9 (d, JCF = 2.75 Hz), 139.0, 139.6,
153.4 (d, JCF = 10.9 Hz), 157.6, 161.5, 165.0 (d, JCF = 252 Hz);
HRMS (ESIþ) m/z calcd for [C23H27N8O2FS þ H] 499.2040, obsd
499.2057.
N-(2-(2-Cyanopyridin-5-ylamino)ethyl)-1-methyl-N-((1-(pyri-
midin-2-yl)piperidin-4-yl)methyl)-1H-imidazole-4-sulfonamide
(18b). Compound 17 was reacted with 2-cyano-5-fluoropyri-
dine on a 0.791 mmol scale, according to general procedure D.
After the usual workup, the crude material was purified by
silica gel flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 192:7:1) to give the title compound as a
colorless, viscous oil (320 mg, 84%): δH (500 MHz, CDCl3)
0.95 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)),
1.63-1.71 (m, 2H, 2 CH (piperidinylmethyl)), 1.74-1.83 (m,
1H, CH (piperidinylmethyl)), 2.72 (td, J = 12.5, 2.5 Hz, 2H,
2 CH (piperidinylmethyl)), 2.93 (br d, J = 7.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 3.23-3.27 (m, 2H, CH2CH2NHAr),
3.34-3.36 (m, 2H, CH2CH2NHAr), 3.65 (m, 3H, CH3 (Im)),
4.55-4.59 (m, 2 H, 2 CH (piperidinylmethyl)), 6.54 (m, 1H,
CH2NHAr), 6.96 (t, J = 4.9 Hz, 1H, CH (pyrimidine)), 7.04 (m,
1H, CH (Ar)), 7.62 (s, 1H, CH (Im)), 7.77-7.78 (m, 2H, CH (Im),
CH (Ar)), 8.02 (m, 1H, CH (Ar)), 8.28 (t, J = 4.9 Hz, 2H, 2 CH
(pyrimidine)); δC (125 MHz, DMSO-d6) 28.96, 33.34, 34.88, 40.33,
41.20, 43.03, 47.87, 54.82, 109.46, 117.39, 118.92, 124.99, 129.69,
136.90, 137.56, 139.75, 146.98, 157.72, 161.02; HRMS (ESIþ) m/z
calcd for [C22H27N9O2S þ H] 482.2087, obsd 482.2086.
[N-{2-(2-Fluoro-4-cyanophenyl)-aminoethyl}, N-{N-(2-pyrimi-
dinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide
(18f). Compound 17 was reacted with 3,4-difluorobenzonitrile on
a 0.343 mmol scale, according to general procedure D. After the
usual workup, the crude material was purified by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1)
to give the title compound as a white foam (138 mg, 82%): δH (500
MHz, CDCl3) 1.13 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH (piperidinyl-
methyl)), 1.73-1.78 (m, 2H, 2 CH (piperidinylmethyl)), 1.83-1.91
(m, 1H, CH (piperidinylmethyl)), 2.78 (td, J = 12.8, 2.5 Hz, 2H, 2
CH (piperidinylmethyl)), 3.04 (br d, J = 7.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 3.51 (q, J = 5.7 Hz, 2H, CH2CH2NHAr),
3.59 (t, J = 6.0 Hz, 2H, CH2CH2NHAr), 3.75 (m, 3H, CH3 (Im)),
[N-{2-(5-Bromopyridin-2-yl)-aminoethyl}, N-{N-(2-pyrimidinyl)-
piperidin-4-ylmethyl}] 1-methyl-1H-imidazole-4-sulfonamide (18c).
Compound 17 was reacted with 5-bromo-2-fluoropyridine on a
0.512 mmol scale, according to general procedure D. After the usual
workup, the crude material was purified by silica gel flash column
chromatography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1) to give
the title compound as a colorless, viscous oil (200 mg, 73%):

6884 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
4.69-4.75 (m, 2 H, 2 CH (piperidinylmethyl)), 5.74-5.78 (m, 1H,
CH2NHAr), 6.43 (t, J = 4.7 Hz, 1H, CH (pyrimidine)), 6.68 (t, J =
8.5Hz, 1H, CH(Ar)), 7.19(dd,J= 11.5, 1.5 Hz, 1H, CH (Ar)), 7.31
(br dd, J = 8.5, 1.5 Hz, 1H, CH (Ar)), 7.44 (s, 1H, CH (Im)), 7.49
(s, 1H, CH (Im)), 8.27 (t, J = 4.7 Hz, 2H, 2 CH (pyrimidine)); δC
(125 MHz, CDCl3) 29.5, 33.9, 35.7, 41.6, 43.4, 48.3, 55.1, 97.4 (d,
CH (Im)), 7.23 (d, J = 8.5 Hz, 1H, CH (Ar)), 7.36 (s, 1H, CH
(Im)), 7.41 (s, 1H, CH (Im)), 7.43 (s, 1H, CH (Im)), 7.48 (dd, J =
8.5, 2.0 Hz, 1H, CH (Ar)), 7.63 (d, J = 2.0 Hz, 1H, CH (Ar)), 8.26
(t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)); δC (125 MHz, CDCl3)
29.6, 31.7, 33.9, 36.0, 43.5, 45.7, 47.1, 50.7, 55.6, 107.1, 109.4,
117.6, 123.7, 124.1, 126.6, 129.0, 129.9, 131.4, 134.3, 138.9, 139.0,
139.7, 151.0, 157.6, 161.5; HRMS (ESIþ) m/z calcd for [C28H33-
N10O2SCl þ H] 609.2275, obsd 609.2296; HPLC (I) tR = 12.90
min (99.13%), (II) tR = 19.65 min (98.61%).
N-(2-((2-Cyanopyridin-5-yl)((1-methyl-1H-imidazol-5-yl)methyl)-
amino)ethyl)-1-methyl-N-((1-(pyrimidin-2-yl)piperidin-4-yl)methyl)-
1H-imidazole-4-sulfonamide (19b). As per general procedure E with
18b on a 0.415 mmol scale. After the usual workup, the crude
material was purified by silica gel flash column chromatography
(eluent CH2Cl2/MeOH/NH4OH, 192:7:1) to afford the title com-
pound as a white foam (186 mg, 78%): δH (500 MHz, DMSO-d6)
1.05-1.13 (m, 4H, 4 CH (piperidinylmethyl)), 1.69-1.74 (m,
1H, CH (piperidinylmethyl)), 2.79 (td, J = 12.5, 2.5 Hz, 2H, 2
CH (piperidinylmethyl)), 2.95 (br d, J = 7.0 Hz, 2H, 2 CH (piperi-
dinylmethyl)), 3.28 (s, 3H, CH3 (Im)), 3.34-3.39 (m, 2H,
SO2NCH2CH2N), 3.41-3.42 (m, 2H, SO2NCH2CH2N), 3.68 (s,
3H, CH3 (Im)), 4.38 (s, 2H, CH2Im), 4.60-4.64 (m, 2 H, 2 CH
(piperidinylmethyl)), 6.41 (t, J = 4.8 Hz, 1H, CH (pyrimidine)),
6.86(s, 1H, CH(Ar)), 7.02(s, 1H, CH(Im)), 7.20(m, 1H,CH(Ar)),
7.41-7.50 (m, 2H, CH (Im), CH (Ar)), 7.65 (s, 1H, CH (Im)), 7.80
(s, 1H, CH (Im)), 8.26 (t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)); δC
(125 MHz, DMSO-d6) 29.5, 32.0, 32.8, 34.0, 35.9, 43.5, 44.2, 48.9,
49.2, 49.4, 49.7, 53.2, 56.2, 109.5, 118.1, 120.8, 122.3, 124.6, 129.4,
135.8, 139.3, 145.5, 157.7, 161.4; HRMS (ESIþ) m/z calcd for
[C27H33N11O2S þ H] 576.2618, obsd 576.2617.
JCF = 9.13 Hz), 109.4, 110.8 (d, JCF =4.5Hz), 117.5(d, JCF =21.9
Hz), 119.2 (d, JCF = 2.75 Hz), 124.3, 130.1 (d, JCF = 2.75 Hz),
139.1, 139.6, 140.5 (d, JCF = 11.9 Hz), 149.8 (d, JCF = 241 Hz),
157.6, 161.4; HRMS (ESIþ) m/z calcd for [C23H27N8O2FS þ H]
499.2040, obsd 499.2055.
[N-{2-(2,6-Difluoro-4-cyanophenyl)-aminoethyl}, N-{N-(2-
Pyrimidinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-
sulfonamide (18g). Compound 17 was reacted with 3,4,5-tri-
fluorobenzonitrile on a 0.359 mmol scale, according to general
procedure D. After the usual workup, the crude material was
purified by silica gel flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 192:7:1) to give the title compound
as a white foam (179 mg, 97%): δH (500 MHz, CDCl3) 1.09 (qd,
J = 12.3, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.68-1.75 (m,
2H, 2 CH (piperidinylmethyl)), 1.81-1.90 (m, 1H, CH (piperi-
dinylmethyl)), 2.75 (td, J = 12.5, 2.5 Hz, 2H, 2 CH (piperidinyl-
methyl)), 2.98 (br d, J = 7.0 Hz, 2H, 2 CH (piperidinylmethyl)),
3.51 (t, J = 5.8 Hz, 2H, CH2CH2NHAr), 3.72 (m, 5H, CH2CH2-
NHAr, CH3 (Im)), 4.65-4.73 (m, 2H, 2 CH (piperidinylmethyl)),
5.67 (m, 1H, CH2NHAr), 6.40 (t, J = 4.9 Hz, 1H, CH
(pyrimidine)), 7.05 (dd, J = 7.5, 2.5 Hz, 2H, CH (Ar)), 7.43 (s,
1H, CH (Im)), 7.47 (s, 1H, CH (Im)), 8.23 (t, J = 4.9 Hz, 2H, 2 CH
(pyrimidine)); δC (125 MHz, CDCl3) 29.6, 33.9, 35.7, 43.5, 43.7,
50.2, 55.4, 96.7 (t, JCF = 11.4 Hz), 109.3, 115.8 (dd, JCF = 18.3, 8.13
Hz),117.9(t, JCF = 3.19 Hz), 124.4, 130.8 (t, JCF = 12.3 Hz), 139.0,
139.7, 150.8 (dd, JCF = 241, 10.0 Hz), 157.5, 161.4; HRMS (ESIþ)
m/z calcd for [C23H26N8O2F2S þ H] 517.1946, obsd 517.1953.
[N-{2-(2,3,5,6-Tetrafluoro-4-cyanophenyl)-aminoethyl}, N-{N-(2-
Pyrimidinyl)-piperidin-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfo-
namide (18h). Compound 17 was reacted with 2-chloro-4-fluorobe-
noznitrile on a 0.338 mmol scale, according to general procedure D,
although the reaction was complete within 12 h at room tempera-
ture. After the usual workup, the crude material was purified by
silica gel flash column chromatography (eluent CH2Cl2/MeOH/
NH4OH, 192:7:1) to give the title compound as a white foam (158
mg, 85%): δH (500 MHz, CDCl3) 1.13 (qd, J = 12.2, 4.0 Hz, 2H,
2 CH (piperidinylmethyl)), 1.72-1.79 (m, 2H, 2 CH (piperidinyl-
methyl)), 1.88-1.97 (m, 1H, CH (piperidinylmethyl)), 2.81 (td,
J = 12.8, 2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 2.97 (br d, J =
7.0 Hz, 2H, 2 CH (piperidinylmethyl)), 3.63 (t, J = 5.0 Hz, 2H,
CH2CH2NHAr), 3.77 (s, 3H, CH3 (Im)), 3.78-3.84 (m, 2H, CH2-
CH2NHAr), 4.71-4.77 (m, 2 H, 2 CH (piperidinylmethyl)), 6.44 (t,
J = 4.8 Hz, 1H, CH (pyrimidine)), 6.81-6.86 (m, 1H, CH2NHAr),
7.47(s,1H,CH(Im)),7.51(s,1H, CH(Im)), 8.27(t,J=4.8Hz,2H,
CH (pyrimidine)); δC (125 MHz, CDCl3) 29.7, 34.1, 35.9, 43.4, 43.5,
50.2, 55.0, 78.4 (t, JCF =18.3 Hz), 109.0 (m), 109.5, 124.7, 133.5 (m),
135.9 (dm), 139.0, 140.1, 148.1 (dm), 157.7, 161.6; HRMS (ESIþ)
m/z calcd for [C23H24N8O2F4S þ H] 553.1757, obsd 553.1774.
[N-{2-[(2-Chloro-4-cyanophenyl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-
ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (19a). As
per general procedure E with 18a on a 0.068 mmol scale.
After the usual workup, the crude material was purified by
silica gel flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 192:7:1) to afford the title compound as a
white foam (37 mg, 90%): δH (500 MHz, CDCl3) 1.04 (qd, J =
12.2, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.63-1.68 (m,
2H, 2 CH (piperidinylmethyl)), 1.70-1.76 (m, 1H, CH (piperi-
dinylmethyl)), 2.76 (td, J = 12.5, 2.5 Hz, 2H, 2 CH (piperidinyl-
methyl)), 2.94 (br d, J = 7.0 Hz, 2H, 2 CH (piperidinylmethyl)),
3.31-3.36 (m, 2H, SO2NCH2CH2N), 3.39-3.44 (m, 2H, SO2-
NCH2CH2N), 3.51 (s, 3H, CH3 (Im)), 3.73 (m, 3H, CH3 (Im)),
4.41 (s, 2H, CH2Im), 4.65-4.71 (m, 2 H, 2 CH (piperidinyl-
methyl)), 6.42 (t, J = 4.9 Hz, 1H, CH (pyrimidine)), 6.97 (s, 1H,
[N-{2-[(5-Cyanopyridin-2-yl)-(3-methyl-3H-imidazol-4-ylmethyl)-
amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-ylmethyl}]
1-Methyl-1H-imidazole-4-sulfonamide (19c). As per general
procedure E with 18c on a 0.178 mmol scale. After the usual
workup, the crude material was purified by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to furnish [N-{2-[(5-bromopyridin-2-yl)-(3-methyl-
3H-imidazol-4-ylmethyl)amino]ethyl},N-{N-(2-pyrimidinyl)-
piperidin-4-ylmethyl}] 1-methyl-1H-imidazole-4-sulfonamide as
a white foam (107 mg, 96%): δH (500 MHz, CDCl3) 1.12 (qd, J =
12.5, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.72-1.80 (m, 3H,
3 CH (piperidinylmethyl)), 2.84 (td, J = 13.0, 2.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 2.98 (br d, J = 7.0 Hz, 2H, 2 CH (piperi-
dinylmethyl)), 3.14-3.18 (m, 2H, NSO2CH2CH2N), 3.55 (s, 3H,
CH3 (Im)), 3.62-3.67 (m, 2H, NSO2CH2CH2N), 3.73 (m, 3H,
CH3 (Im)), 4.69-4.78 (m, 2H, 2 CH (piperidinylmethyl)), 4.80 (s,
2H, CH2Im), 6.43 (t, J = 4.9 Hz, 1H, CH (pyrimidine)), 6.69 (d,
J = 9.5 Hz, 1H, CH (Ar)), 6.96 (s, 1H, CH (Im)), 7.38 (s, 1H, CH
(Im)), 7.43 (s, 1H, CH (Im)), 7.46 (s, 1H, CH (Im)), 7.55 (dd, J =
9.0, 2.5 Hz, 1H, CH (Ar)), 8.15 (d, J = 2.5 Hz, 1H, CH (Ar)), 8.27
(t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)); δC (125 MHz, CDCl3)
29.6, 31.8, 33.9, 35.6, 41.0, 43.5, 46.2, 47.0, 55.9, 107.1, 107.6,
109.3, 124.2, 128.2, 129.1, 138.8, 138.9, 139.3, 140.1, 148.2, 155.9,
157.6, 161.5; HRMS (ESIþ) m/z calcd for [C26H33N10O2SBr þ
H] 629.1770, obsd 629.1780; HPLC (I) tR = 12.78 min (100%),
(II) tR = 18.88 min (100%). The aryl bromide was then converted
to the corresponding aryl nitrile on a 0.115 mmol scale, according
to general procedure F. After workup, the crude material was
dry-loaded onto silica gel, and purified by flash column chroma-
tography (eluent CH2Cl2/MeOH/NH4OH, 192:7:1) to give 19c as
a white foam (51 mg, 77%): δH (500 MHz, CDCl3) 1.11 (qd, J =
12.5, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.67-1.77 (m, 3H,
3 CH (piperidinylmethyl)), 2.78-2.87 (m, 2H, 2 CH (piperidinyl-
methyl)), 2.93 (br d, J = 7.0 Hz, 2H, 2 CH (piperidinylmethyl)),
3.15-3.22 (m, 2H, SO2NCH2CH2N), 3.54 (s, 3H, CH3 (Im)),
3.69-3.78 (m, 5H, SO2NCH2CH2N, CH3 (Im)), 4.68-4.76 (m,
2H, 2 CH (piperidinylmethyl)), 4.91 (s, 2H, CH2Im), 6.43 (t, J =
4.9 Hz, 1H, CH (pyrimidine)), 6.85 (d, J = 9.5 Hz, 1H, CH (Ar)),
6.97 (s, 1H, CH (Im)), 7.39 (s, 1H, CH (Im)), 7.42 (s, 1H, CH (Im)),
7.43 (s, 1H, CH (Im)), 7.66 (dd, J = 9.0, 2.5 Hz, 1H, CH (Ar)),

Article
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6885
139.1, 139.2, 152.7 (d, JCF = 10.9 Hz), 157.6, 161.5, 164.9 (d, JCF
252 Hz); HRMS (ESIþ) m/z calcd for [C28H33N10O2SF þ H]
593.2571, obsd 593.2588; HPLC (I) tR = 12.54 min (98.51%),
(II) tR = 18.51 min (98.09%).
8.27 (t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)), 8.41 (d, J = 2.5 Hz,
1H, CH (Ar)); δC (125 MHz, CDCl3) 29.7, 31.9, 34.0, 35.7, 41.0
(br), 43.6, 46.3, 47.1, 56.0, 97.1, 106.1, 109.4, 118.3, 124.3, 127.3,
129.7, 139.0, 139.2, 139.4, 140.3, 152.4, 157.6, 158.5, 161.6;
HRMS (ESIþ) m/z calcd for [C27H33N11O2S þ H] 576.2618,
obsd 576.2628; HPLC (I) tR = 12.43 min (100%), (II) tR = 17.87
min (100%).
=
[N-{2-[(2-Fluoro-4-cyanophenyl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-
ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (19f). As
per general procedure E with 18f on a 0.060 mmol scale. After
the usual workup, the crude material was purified by silica gel
flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to afford 19f as a white foam (33 mg, 93%): δH (500
MHz, CDCl3) 1.09 (qd, J = 12.3, 4.0 Hz, 2H, 2 CH (piperi-
dinylmethyl)), 1.70-1.78 (m, 3H, 3 CH (piperidinylmethyl)),
2.76-2.83 (m, 2H, 2 CH (piperidinylmethyl)), 2.95 (br d, J =
7.0 Hz, 2H, 2 CH (piperidinylmethyl)), 3.31 (br t, J = 7.5 Hz, 2H,
SO2NCH2CH2N), 3.53 (br t, J = 7.5 Hz, 2H, SO2NCH2CH2N),
3.58 (m, 3H, CH3 (Im)), 3.73 (m, 3H, CH3 (Im)), 4.50 (s, 2H,
CH2Im), 4.67-4.73 (m, 2H, 2 CH (piperidinylmethyl)), 6.43 (t,
J = 4.7 Hz, 1H, CH (pyrimidine)), 6.93 (s, 1H, CH (Im)), 7.06 (t,
J = 8.8 Hz, 1H, CH (Ar)), 7.28 (dd, J = 13.0, 1.8 Hz, 1H, CH
(Ar)), 7.31 (br dd, J = 8.5, 1.8 Hz, 1H, CH (Ar)), 7.37 (s, 1H, CH
(Im)), 7.41 (s, 1H, CH (Im)), 7.48 (s, 1H, CH (Im)), 8.26 (t, J =
4.7 Hz, 2H, 2 CH (pyrimidine)); δC (125 MHz, CDCl3) 29.6, 31.8,
34.0, 35.9, 43.5, 45.9, 47.5, 50.5, 55.8, 103.0 (d, JCF = 10 Hz),
109.4, 118.2 (d, JCF = 1.8 Hz), 119.5 (d, JCF = 4.6 Hz), 120.2 (d,
JCF = 25.5 Hz), 124.2, 126.9, 129.3, 129.5 (d, JCF = 2.8 Hz),
138.9, 139.0, 139.6, 141.5 (d, JCF = 8.1 Hz), 152.9 (d, JCF = 244
Hz), 157.6, 161.5; HRMS (ESIþ) m/z calcd for [C28H33N10O2-
FS þ H] 593.2571, obsd 593.2568; HPLC (I) tR = 12.75 min
(100%), (II), tR = 19.09 (99.22%).
[N-{2-[(2,6-Difluoro-4-cyanophenyl)-(3-methyl-3H-imidazol-
4-ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-
ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (19g). As
per general procedure E with 18g on a 0.068 mmol scale.
After the usual workup, the crude material was purified by
silica gel flash column chromatography (eluent CH2Cl2/
MeOH/NH4OH, 192:7:1) to yield 19g as a white foam (40
mg, 97%): δH (500 MHz, CDCl3) 1.06 (qd, J = 12.3, 4.0 Hz,
2H, 2 CH (piperidinylmethyl)), 1.67-1.77 (m, 3H, 3 CH
(piperidinylmethyl)), 2.78 (td, J = 12.8, 2.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 2.96 (br d, J = 6.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 3.26-3.30 (m, 2H, SO2NCH2CH2N),
3.39-3.43 (m, 2H, SO2NCH2CH2N), 3.57 (s, 3H, CH3 (Im)),
3.73 (s, 3H, CH3 (Im)), 4.38 (s, 2H, CH2Im), 4.66-4.73 (m,
2H, 2 CH (piperidinylmethyl)), 6.42 (t, J = 4.9 Hz, 1H, CH
(pyrimidine)), 6.92 (s, 1H, CH (Im)), 7.12-7.17 (m, 2H, 2 CH
(Ar)), 7.35 (s, 1H, CH (Im)), 7.40 (s, 1H, CH (Im)), 7.42 (s, 1H,
CH (Im)), 8.26 (t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)); δC (125
MHz, CDCl3) 29.6, 31.4, 33.9, 36.0, 43.5, 46.3 (t, JCF = 4.5
Hz), 47.8, 51.9 (t, JCF = 2.6 Hz), 55.6, 106.9 (t, JCF = 11.9
Hz), 109.4, 116.6 (m), 116.6 (t, JCF = 2.8 Hz), 124.1, 126.9,
129.9, 131.1 (t, J = 13.3 Hz), 138.9, 139.2, 139.7, 157.6, 158.3
(dd, JCF = 249, 8.3 Hz), 161.5; HRMS (ESIþ) m/z calcd for
[C28H32N10O2F2S þ H] 611.2477, obsd 611.2494; HPLC (I)
tR = 12.93 min (100%), (II) tR = 19.59 min (100%).
[N-{2-[(5-Cyanopyrimidin-2-yl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-
ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (19d). As
per general procedure E with 18d on a 0.187 mmol scale
to afford [N-{2-[(5-bromopyrimidin-2-yl)-(3-methyl-3H-
imidazol-4-ylmethyl)amino]ethyl},N-{N-(2-pyrimidinyl)-piperidin-
4-ylmethyl}] 1-methyl-1H-imidazole-4-sulfonamide as a white foam
(109 mg, 93%): δH (500 MHz, CDCl3) 1.17 (qd, J = 12.2, 4.0 Hz,
2H, 2 CH (piperidinylmethyl)), 1.78-1.84 (m, 2H, 2 CH (piperi-
dinylmethyl)), 1.92-1.99(m, 1H, CH(piperidinylmethyl)), 2.82(td,
J = 12.8, 2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.10 (br d, J = 7.5
Hz, 2H, 2 CH (piperidinylmethyl)), 3.19-3.23 (m, 2H, SO2NCH2-
CH2N), 3.58 (s, 3H, CH3 (Im)), 3.71-3.75 (m, 5H, SO2NCH2-
CH2N, CH3 (Im)), 4.71-4.77 (m, 2 H, 2 CH (piperidinylmethyl)),
4.89 (s, 2H, CH2Im),6.43(t,J= 4.9 Hz, 1H, CH (pyrimidine)), 7.05
(s, 1H, CH (Im)), 7.42 (s, 1H, CH (Im)), 7.43 (s, 1H, CH (Im)), 7.46
(s, 1H, CH (Im)), 8.28 (t, J = 4.9 Hz, 2H, 2 CH (pyrimidine)) 8.30
(s,2H,2CH(Ar));δC (125 MHz, CDCl3) 29.7, 31.9, 33.9, 35.6, 40.7,
43.7, 46.0, 46.2, 55.8, 106.4, 109.3, 124.4, 128.1, 129.5, 138.5, 138.9,
139.3, 157.6, 158.0, 159.3, 161.6; HRMS (ESIþ) m/z calcd for
[C25H32N11O2SBr þ H] 630.1723, obsd 630.1748; HPLC (I) tR
=
13.05 min (100%), (II) tR = 19.52 min (100%). The aryl bromide
was then converted to the corresponding aryl nitrile on a 0.127
mmol scale, according to general procedure F. After workup,
the crude material was dry-loaded onto silica gel and purified by
flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to give 19d as a white foam (50 mg, 69%): δH (500 MHz,
CDCl3) 1.16 (qd, J = 12.2, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)),
1.75-1.82 (m, 2H, 2 CH (piperidinylmethyl)), 1.86-1.94 (m, 1H,
CH (piperidinylmethyl)), 2.80 (td, J = 12.8, 2.5 Hz, 2H, 2 CH
(piperidinylmethyl)), 3.07 (br d, J = 7.5 Hz, 2H, 2 CH (piperi-
dinylmethyl)), 3.26-3.30 (m, 2H, SO2NCH2CH2N), 3.58 (s, 3H,
CH3 (Im)), 3.74 (s, 3H, CH3 (Im)), 3.83-3.87 (m, 2H, SO2NCH2-
CH2N), 4.70-4.76 (m, 2 H, 2 CH (piperidinylmethyl)), 4.99 (s, 2H,
CH2Im), 6.44 (t, J = 4.8 Hz, 1H, pyrimidine), 7.07 (s, 1H, CH
(Im)), 7.39-7.44, (s, 3H, 3 CH (Im)), 8.28 (t, J = 4.9 Hz, 2H, 2 CH
(pyrimidine)), 8.54 (br s, 2H, 2 CH (Ar)); δC (125 MHz, CDCl3)
29.7, 32.0, 34.0, 35.8, 40.9, 43.7, 46.3, 46.5, 55.9, 96.8, 109.5, 116.2,
124.5, 127.2, 129.8, 138.8, 139.0, 139.3, 157.7, 160.6, 161.0, 161.6;
HRMS (ESIþ) m/z calcd for [C26H32N12O2S þ H] 577.2570, obsd
577.2569; HPLC (I) tR = 12.45 min (100%), (II) tR = 17.94 min
(100%).
[N-{2-[(3-Fluoro-4-cyanophenyl)-(3-methyl-3H-imidazol-4-
ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperidin-4-ylmethyl}]
1-Methyl-1H-imidazole-4-sulfonamide (19e). As per general proce-
dure E with 18e on a 0.0683 mmol scale. After the usual workup, the
crude material was purified by silica gel flash column chromatogra-
phy (eluent CH2Cl2/MeOH/NH4OH, 192:7:1) to furnish 19e as a
white foam (36 mg, 89%): δH (500 MHz, CDCl3) 1.10 (qd, J = 12.2,
4.0 Hz, 2H, 2 CH (piperidinylmethyl)), 1.60-1.67 (m, 1H, CH
(piperidinylmethyl)), 1.69-1.75 (m, 2H, 2 CH (piperidinylmethyl)),
2.80 (td, J = 12.8, 2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 2.95 (br d,
J = 7.5 Hz, 2H, 2 CH (piperidinylmethyl)), 3.20-3.24 (m, 2H,
SO2NCH2CH2N), 3.56 (s, 3H, CH3 (Im)), 3.62-3.66 (m, 2H,
SO2NCH2CH2N), 3.72 (m, 3H, CH3 (Im)), 4.52 (s, 2H, CH2Im),
4.67-4.73 (m, 2H, 2 CH (piperidinylmethyl)), 6.43 (t, J = 4.7 Hz,
1H, CH (pyrimidine)), 6.60 (dd, J= 13.0, 2.5 Hz, 1H, CH (Ar)), 6.67
(dd, J=9.0, 2.5Hz, 1H, CH(Ar)), 6.87(s, 1H, CH(Im)), 7.37-7.40
(m, 2H, CH (Im), CH (Ar)), 7.43 (s, 1H, CH (Im)), 7.48 (s, 1H, CH
(Im)), 8.26 (t, J = 4.7 Hz, 2H, 2 CH (pyrimidine)); δC (125 MHz,
CDCl3) 29.5, 31.7, 34.0, 35.9, 43.5, 44.5, 46.5, 49.3, 56.3, 88.1 (d,
[N-{2-[(2,3,5,6-Tetrafluoro-4-cyanophenyl)-(3-methyl-3H-
imidazol-4-ylmethyl)-amino]-ethyl}, N-{N-(2-Pyrimidinyl)-piperi-
din-4-ylmethyl}] 1-Methyl-1H-imidazole-4-sulfonamide (19h). As
per general procedure E with 18h on a 0.0688 mmol scale. After
the usual workup, the crude material was purified by silica gel
flash column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1) to afford 19h as a white foam (28 mg, 63%): δH (500 MHz,
CDCl3) 1.08 (qd, J = 12.2, 4.0 Hz, 2H, 2 CH (piperidinylmethyl)),
1.69-1.81 (m, 3H, 3 CH (piperidinylmethyl)), 2.80 (td, J = 12.8,
2.5 Hz, 2H, 2 CH (piperidinylmethyl)), 2.96 (br d, J = 7.5 Hz, 2H,
2 CH (piperidinylmethyl)), 3.34-3.40 (m, 2H, SO2NCH2CH2N),
3.51-3.56 (m, 2H, SO2NCH2CH2N), 3.57 (s, 3H, CH3 (Im)), 3.74
(s, 3H, CH3 (Im)), 4.53 (s, 2H, CH2Im), 4.68-4.74 (m, 2 H, 2 CH
(piperidinylmethyl)), 6.43 (t, J = 4.7 Hz, 1H, CH (pyrimidine)),
6.98 (s, 1H, CH (Im)), 7.38 (s, 1H, CH (Im)), 7.41-7.46 (m, 2H,
JCF = 15.5 Hz), 99.3 (d, JCF = 24.6 Hz), 108.4 (d, JCF = 1.9 Hz),
109.5, 115.2, 124.4, 126.3, 129.1, 134.3 (d, JCF = 2.75 Hz), 139.0,

6886 Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19
Fletcher et al.
2 CH (Im)), 8.27 (t, J = 4.7 Hz, 2H, CH (pyrimidine)); δC (125
MHz, CDCl3) 29.6, 31.5, 33.9, 36.0, 43.5, 46.2, 47.9, 51.9 (m), 55.7,
86.9 (t, JCF = 17.4 Hz), 107.8 (m), 109.5, 124.2, 126.2, 130.2, 133.9
(m), 139.0, 139.4, 139.6, 142.1 (dm), 147.8 (dm), 157.6, 161.5;
HRMS (ESIþ) m/z calcd for [C28H30N10O2F4S þ H] 647.2288,
obsd 647.2314; HPLC (I) tR = 12.74 min (98.92%), (II) tR = 19.07
min (98.14%).
(cyclohexylmethyl)), 3.28-3.38 (m, 4H, SO2NCH2CH2NHAr),
6.61 (d, J = 8.5 Hz, 2H, 2 CH (Ar)), 6.70 (t, J = 6.4 Hz, 1H,
NH), 7.45 (d, J = 8.5 Hz, 2H, 2 CH (Ar)), 7.66 (m, 1H, CH (Py)),
7.94 (m, 1H, CH (Py)), 8.07 (m, 1H, CH (Py)), 8.73 (m, 1H, CH
(Py)); δC (125 MHz, DMSO) 25.1, 25.8, 29.9, 35.8, 41.5, 47.7, 55.6,
95.9, 111.6, 120.3, 122.2, 127.1, 133.3, 138.6, 150.1, 151.6, 157.0;
HRMS (ESIþ) m/z calcd for [C21H26N4O2S þ H] 399.1855, obsd
399.1857. N-(2-(4-Cyanophenylamino)ethyl)-N-(cyclohexyl-
methyl)pyridine-2-sulfonamide was then alkylated with
N-(2-Aminoethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide
(21). Mono-N-Boc-ethylenediamine (6; 860 mg, 5.37 mmol, 1 equiv)
was reacted with pyridine-2-sulfonyl chloride according to general
procedure A. After workup, the crude material was dry-loaded onto
silica gel and purified by flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 92:7:1) to afford tert-butyl 2-(pyridine-2-
sulfonamido)ethylcarbamate as a white powder (1.26 g, 80%): δH
(400 MHz, DMSO-d6) 0.89 (s, 9H, C(CH3)3), 2.04 (m, 2H,
SO2NHCH2CH2NHBoc), 2.86 (m, 2H, SO2NHCH2CH2NHBoc),
6.30 (br, 1H, NHSO2), 7.21 (m, 1H, CH (Py)), 7.414 (m, 1H,
NHBoc), 7.47 (m, 1H, CH (Py)), 7.63, (m, 1H, CH (Py)), 8.27 (m,
1H,CH(Py));δC (125MHz,DMSO-d6) 28.0, 39.9, 42.5, 77.6, 121.4,
126.8, 138.5, 149.8, 155.3, 157.7; HRMS (ESIþ) m/z calcd for
[C12H19N3O4S þ H] 302.1175, obsd 302.1174. The sulfonamide
NH of tert-butyl 2-(pyridine-2-sulfonamido)ethylcarbamate (1.1 g,
3.65 mmol, 1 equiv) was then chemoselectively alkylated with
cyclohexylmethyl bromide (840 mg, 4.75 mmol, 1.3 equiv) according
to general procedure B, but the reaction was stirred for 4 days at
room temperature. After workup, the crude material was dry-loaded
onto silica gel and purified by flash column chromatography (eluent
CH2Cl2/MeOH/NH4OH, 92:7:1) to furnish tert-butyl 2-(N-(cyclo-
hexylmethyl)pyridine-2-sulfonamido)ethylcarbamate in quantita-
tive yield (1.53 g) as a white solid: δH (500 MHz, DMSO-d6)
0.77-0.83 (m, 2H, 2 CH (cyclohexylmethyl)), 1.09-1.19 (m, 3H,
3 CH (cyclohexylmethyl)), 1.36 (s, 9H, C(CH3)3), 1.54-1.65 (m,
6H, 6 CH (cyclohexylmethyl)), 3.03-3.07 (m, 4H, SO2NCH2CH2-
NHBoc, NCH2CH (cyclohexylmethyl)), 3.24 (t, J = 7.0 Hz, 2H,
SO2NCH2CH2NHBoc), 6.79 (br, 1H, NHBoc)), 7.67 (m, 1H, CH
(Py)), 7.92 (m, 1H, CH (Py)), 8.09 (m, 1H, CH (Py)), 8.72 (m, 1H,
CH(Py));δC (125MHz, DMSO-d6) 25.1, 25.8, 28.0, 29.9, 35.6, 39.9,
48.4, 55.4, 77.6, 122.1, 127.0, 138.6, 150.0, 155.3, 157.1; HRMS
(ESIþ) m/z calcd for [C19H31N3O4S þ H] 398.2114, obsd 398.2113.
tert-Butyl 2-(N-(cyclohexylmethyl)pyridine-2-sulfonamido)ethyl-
carbamate (1.28 g, 3.22 mmol, 1 equiv) was dissolved in propan-
2-ol (15 mL). Upon complete dissolution of the solid, 4 M HCl
(15 mL) was added, and the reaction was stirred for one hour. All
solvents were then evaporated. The residue was redissolved in
CH2Cl2 (250 mL) and carefully washed with saturated NaHCO3
(25 mL ꢀ 3), dried (Na2SO4), filtered, and concentrated to afford
N-(2-aminoethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide
(21) as a viscous oil (945 mg, 97%): δH (500 MHz, DMSO-d6)
0.78-0.84 (m, 2H, 2 CH (cyclohexylmethyl)), 1.09-1.17 (m, 3H,
3 CH (cyclohexylmethyl)), 1.57-1.68 (m, 6H, 6 CH (cyclohexyl-
methyl)), 2.75 (t, J = 7.0 Hz, 2H, NCH2CH (cyclohexyl-
methyl)), 3.04 (t, J = 7.4 Hz, 2H, SO2NCH2CH2NH2), 3.34 (t,
J = 7.4 Hz, 2H, SO2NCH2CH2NH2), 5.15 (br, 2H, NH2), 7.68
(m, 1H, CH (Py)), 7.93 (m, 1H, CH (Py)), 8.10 (m, 1H, CH (Py)),
8.73 (m, 1H, CH (Py)); δC (125 MHz, DMSO) 25.1, 25.8, 29.9,
35.7, 49.4, 55.5, 66.2, 122.2, 127.1, 138.7, 150.0, 157.1; HRMS
(ESIþ) m/z calcd for [C14H23N3O2S þ H] 298.1589, obsd
298.1589.
5-chloromethyl-1H-imidazole HCl according to general pro-
3
cedure E on a 0.117 mmol scale. After workup and chroma-
tography over silica gel (eluent CH2Cl2/MeOH/NH4OH,
192:7:1), the title compound N-(2-((4-cyanophenyl)((1-methyl-
1H-imidazol-5-yl)methyl)amino)ethyl)-N-(cyclohexylmethyl)-
pyridine-2-sulfonamide (21a) was furnished as a glassy film (46
mg, 80%): δH (500 MHz, CDCl3) 0.84-0.78 (m, 2H, 2 CH (cyclo-
hexylmethyl)), 1.06-1.14 (m, 3H, 3 CH (cyclohexylmethyl)),
1.35-1.27 (m, 1H, CH (cyclohexylmethyl)), 1.66-1.59 (m, 5H, 5
CH (cyclohexylmethyl)), 2.95 (d, J = 7.0 Hz, 2H, NCH2CH
(cyclohexyl)), 3.36 (t, J = 7.9 Hz, 2H, SO2NCH2CH2N), 3.61 (s,
3H, CH3 (Im)), 3.65 (t, J = 7.9 Hz, 2H, SO2NCH2CH2N), 4.55 (s,
2H, CH2Im), 6.85 (d, J = 9.0 Hz, 2H, 2 CH (Ar)), 6.88 (s, 1H, CH
(Im)), 7.47-7.44 (m, 3H, 2 CH (Ar), CH (Im)), 7.71 (s, 1H, CH
(Py)), 7.91-7.86 (m, 2H, 2 CH (Py)), 8.61 (m, 1H, CH (Py)); δC
(125MHz, CDCl3) 25.6, 26.2, 30.6, 32.0, 36.9, 44.3, 46.8, 49.4, 57.1,
99.5, 112.3, 119.9, 122.5, 126.6, 127.2, 127.7, 133.8, 137.9, 138.7,
149.9, 150.4, 157.5; HRMS (ESIþ) m/z calcd for [C26H32N6O2S þ
H] 493.2386, obsd 493.2364.
N-(2-((4-Cyano-2-fluorophenyl)((1-methyl-1H-imidazol-5-yl)-
methyl)amino)ethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide
(21b). The primary amine of N-(2-aminoethyl)-N-(cyclohexyl-
methyl)pyridine-2-sulfonamide (21) was arylated with 3,4-di-
fluorobenzonitrile on a 0.337 mmol scale, according to general
procedure D. After workup and purification by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1), N-(2-(4-cyano-2-fluorophenylamino)ethyl)-N-(cyclo-
hexylmethyl)pyridine-2-sulfonamide was obtained as a white
foam (111 mg, 79%): δH (500 MHz, DMSO-d6) 0.83-0.77 (m,
2H, 2 CH (cyclohexylmethyl)), 1.09 (br, 3H, 3 CH (cyclohexyl-
methyl)), 1.62-1.51 (m, 6H, 6 CH (cyclohexylmethyl)), 3.06 (d,
J = 7.5 Hz, 2H, NCH2CH (cyclohexyl)), 3.42-3.34 (m, 4H,
SO2NCH2CH2N), 6.54 (br, 1H, NHAr), 6.80 (t, J = 8.5 Hz, 1H,
CH (Ar)), 7.45 (dd, J = 11.5, 1.5 Hz, 1H, CH (Ar)), 7.53 (dd, J =
8.5, 1.5 Hz, 1H, CH (Ar)), 7.66 (m, 1H, CH (Py)), 7.93 (m, 1H,
CH (Py)), 8.07 (m, 1H, CH (Py)), 8.71 (m, 1H, CH (Py)); δC (125
MHz, DMSO-d6) 25.1, 25.9, 30.0, 35.7, 37.1, 41.3, 47.5, 55.5, 61.8,
94.4, 122.2, 127.1, 130.4, 138.7, 140.7, 142.5, 150.1, 156.9, 179.7;
HRMS (ESIþ) m/z calcd for [C21H25FN4O2S þ H] 417.1760,
obsd 417.1749. N-(2-(4-Cyano-2-fluorophenylamino)ethyl)-N-
(cyclohexylmethyl)pyridine-2-sulfonamide was then alkylated
with 5-chloromethyl-1H-imidazole HCl according to general
3
procedure E on a 0.216 mmol scale. After workup and chromato-
graphy over silica gel (eluent CH2Cl2/MeOH/NH4OH, 192:7:1),
the title compound N-(2-((4-cyano-2-fluorophenyl)((1-methyl-
1H-imidazol-5-yl)methyl)amino)ethyl)-N-(cyclohexylmethyl)-
pyridine-2-sulfonamide was afforded as a white foam (90 mg,
81%): δH (500 MHz, CDCl3) 0.68-0.75 (m, 2H, 2 CH (cyclo-
hexylmethyl)), 1.03 (br, 3H, 3 CH (cyclohexylmethyl)), 1.23-
1.32 (m, 1H, CH (cyclohexylmethyl)), 1.50-1.60 (m, 5H, 5 CH
(cyclohexylmethyl)), 2.80 (s, 2H, NCH2CH (cyclohexyl-
methyl)), 3.34-3.47 (m, 4H, SO2NCH2CH2N), 3.54 (s, 3H,
CH3 (Im)), 4.46 (s, 2H, CH2Im), 6.61 (br, 1H, CH (Ar)), 6.95 (s,
1H, CH (Im)), 7.11 (m, 1H, CH (Ar)), 7.26 (br, 1H, CH (Ar)),
7.53 (m, 2H, CH (Py), CH (Im)) 7.65 (br, 1H, CH (Py)), 8.26 (m,
1H, CH (Py)), 8.69 (m, 1H, CH (Py)); δC (125 MHz, CDCl3)
25.5, 26.1, 30.5, 31.3, 31.8, 36.6, 45.7, 47.3, 50.4, 56.4, 102.9,
118.1, 119.5, 120.2, 122.4, 126.5, 128.7, 129.3, 138.8, 141.3,
149.8, 153.9, 157.6, 162.4; HRMS (ESIþ) m/z calcd for
[C26H31FN6O2S þ H] 511.2291, obsd 511.2265; HPLC (I)
tR = 18.69 min (99.3%), (II) tR = 36.03 min (99.7%).
(2-((4-Cyanophenyl)((1-methyl-1H-imidazol-5-yl)methyl)amino)-
ethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide (21a). The
primary amine of N-(2-aminoethyl)-N-(cyclohexylmethyl)-
pyridine-2-sulfonamide (21) was arylated with p-fluoroben-
zonitrile on a 0.336 mmol scale, according to general proce-
dure D. After workup and purification by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1), N-(2-(4-cyanophenylamino)ethyl)-N-(cyclohexylmethyl)-
pyridine-2-sulfonamide was obtained as a colorless gum (119 mg,
89%): δH (500 MHz, DMSO-d6) 0.77-0.83 (m, 2H, 2 CH (cyclo-
hexylmethyl)), 1.09 (br, 3H, 3 CH (cyclohexyl)), 1.48 1.63 (m, 6H, 6
CH (cyclohexylmethyl)), 3.06 (d, J = 6.4 Hz, 2H, NCH2CH

Article
N-(2-((5-Cyanopyridin-2-yl)((1-methyl-1H-imidazol-5-yl)-
Journal of Medicinal Chemistry, 2010, Vol. 53, No. 19 6887
(2) Bell, I. Inhibitors of farnesyltransferase: a rational approach to
cancer chemotherapy? J. Med. Chem. 2004, 47, 1869–1878.
(3) Doll, R. J.; Kirschmeier, P.; Bishop, W. R. Farnesyltransferase
inhibitors as anticancer agents: critical crossroads. Curr. Opin.
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methyl)amino)ethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide
(21c). The primary amine of N-(2-aminoethyl)-N-(cyclohexyl-
methyl)pyridine-2-sulfonamide (21) was arylated with 5-cyano-2-
fluoropyridine on a 0.350 mmol scale, according to general
procedure D. After workup and purification by silica gel flash
column chromatography (eluent CH2Cl2/MeOH/NH4OH,
192:7:1), N-(2-(5-cyanopyridin-2-ylamino)ethyl)-N-(cyclohexyl-
methyl)pyridine-2-sulfonamide was obtained as a colorless gum
(115 mg, 82%): δH (500 MHz, DMSO-d6) 0.78-0.82 (m, 2H, 2
CH (cyclohexylmethyl)), 1.09 (br, 3H, 3 CH (cyclohexylmethyl)),
1.57-1.63 (m, 6H, 6 CH(cyclohexylmethyl)), 3.06(d, J = 7.5 Hz,
2H, NCH2CH (cyclohexylmethyl)), 3.37-3.47 (m, 4H, SO2-
NCH2CH2N), 6.50 (t, J = 8.5 Hz, NH), 6.87 (d, J = 9.0 Hz,
1H, CH (Ar)), 7.61-7.66 (m, 3H, 2 CH (Ar), CH (Py)), 7.92 (d,
J = 7.5 Hz, 1H, CH (Py)), 8.06 (m, 1H, CH (Py)), 8.36 (m, 1H,
CH (Ar)), 8.71 (m, 1H, CH (Py)); δC (125 MHz, DMSO-d6) 25.1,
25.8, 30.0, 35.6, 47.7, 54.7, 55.5, 69.3, 94.7, 108.7, 118.7, 122.1,
126.9, 138.5, 150.0, 152.8, 157.0, 159.6; HRMS (ESIþ) m/z
calcd for [C20H25N5O2S þ H] 400.1807, obsd 400.1795. N-(2-(5-
Cyanopyridin-2-ylamino)ethyl)-N-(cyclohexylmethyl)pyridine-
2-sulfonamide was then alkylated with 5-chloromethyl-1H-
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imidazole HCl according to general procedure E on a 0.240
3
mmol scale. After workup and chromatography over silica gel
(eluent CH2Cl2/MeOH/NH4OH, 192:7:1), the title compound
N-(2-((5-cyanopyridin-2-yl)((1-methyl-1H-imidazol-5-yl)methyl)-
amino)ethyl)-N-(cyclohexylmethyl)pyridine-2-sulfonamide was
afforded as a white foam (110 mg, 93%): δH (500 MHz, CDCl3)
0.75-0.83 (m, 2H, 2 CH (cyclohexylmethyl)), 1.07-1.16 (m, 3H, 3
CH (cyclohexylmethyl)), 1.33-1.43 (m, 1H, CH (cyclohexyl-
methyl)), 1.59-1.65 (m, 5H, 5 CH (cyclohexylmethyl)), 2.94
(d, J = 7.0 Hz, 2H, NCH2CH (cyclohexylmethyl)), 3.28 (t, J =
8.1 Hz, 2H, SO2NCH2CH2N), 3.55 (s, 3H, CH3 (Im)), 3.70 (t,
J = 8.1 Hz, 2H, SO2NCH2CH2N), 4.89 (s, 2H, CH2Im), 6.81 (d,
J = 9.0 Hz, 1H, CH (Ar)), 6.97 (s, 1H, CH (Im)), 7.45 (m, 1H, CH
(Im)), 7.57 (s, 1H, CH (Ar)), 7.64 (m, 1H, CH (Ar)), 7.89-7.85 (m,
2H, 2 CH (Py)), 8.39-8.38 (m, 1H, CH (Ar)), 8.60 (m, 1H, CH
(Py)); δC (125 MHz, CDCl3) 25.6, 26.2, 30.5, 32.0, 36.6, 40.9, 47.2,
56.8, 97.1, 105.9, 118.2, 122.5, 126.6, 127.4, 128.8, 137.9, 138.9,
140.2, 149.9, 152.3, 157.5, 158.4, 162.4; HRMS (ESIþ) m/z calcd
for [C25H31N7O2S þ H] 494.2338, obsd 494.2313; HPLC (I) tR =
18.15 min (99.5%), (II) tR = 34.66 min (97.4%).
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In Vitro and Whole Cell Inhibition Assays of Protein Prenylation.
In vitro inhibition assays for FTase and GGTase-I were conducted
by measuring the incorporation of [3H]FPP and [3H]GGPP into
recombinant H-Ras-CVLS and H-Ras-CVLL, respectively, as
previously described.36 The in vivo inhibition of farnesylation and
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tion by synthetic compounds of H-Ras and Rap1A processing,
respectively.37 Briefly, oncogenic H-Ras-transformed NIH3T3 cells
were treated with various concentrations of inhibitors, and the cell
lysates were isolated and proteins separated on a 12.5% SDS-
PAGE gel. The separated proteins were transferred to nitrocellulose
and immunoblotted using an anti-Ras antibody (Y13-258) or
an anti-Rap1A antibody (SantaCruz Biotechnology, Santa Cruz,
CA), respectively. Antibody reactions were visualized using either
peroxidase-conjugated goat antirat IgG or goat antirabbit IgG
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Acknowledgment. Financial support for this work was
provided by the National Institutes of Health (CA67771 &
GM52382) and the Medicines for Malaria Venture (MMV).
We also thank Vijay M. Shahani for additional assistance in
the flexible ligand GOLD docking experiments.
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