Potent, highly selective, and non-thiol inhibitors of protein geranylgeranyltransferase-I

Article abstract of DOI:10.1021/jm9900873

The design, synthesis, and biological evaluation of a family of peptidomimetic inhibitors of protein geranylgeranyltransferase-I (PGGTase-I) are reported. The inhibitors are based on the C-terminal CAAL sequence of many geranylgeranylated proteins. Using

Full text of DOI:10.1021/jm9900873

J . Med. Chem. 1999, 42, 1333-1340
1333
Expedited Articles
P oten t, High ly Selective, a n d Non -Th iol In h ibitor s of P r otein
Ger a n ylger a n yltr a n sfer a se-I
Anil Vasudevan,† Yimin Qian,† Andreas Vogt,‡ Michelle A. Blaskovich,| J unko Ohkanda,§ Said M. Sebti,*,| and
Andrew D. Hamilton*,§
Department of Chemistry, Yale University, New Haven, Connecticut 06511, Drug Discovery Program, H. Lee Moffitt Cancer
Center, Department of Biochemistry and Molecular Biology, University of South Florida, Tampa, Florida, and Departments of
Chemistry and Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
Received August 3, 1998
The design, synthesis, and biological evaluation of a family of peptidomimetic inhibitors of
protein geranylgeranyltransferase-I (PGGTase-I) are reported. The inhibitors are based on the
C-terminal CAAL sequence of many geranylgeranylated proteins. Using 2-aryl-4-aminobenzoic
acid derivatives as mimetics for the central dipeptide (AA), we have attached a series of
imidazole and pyridine derivatives to the N-terminus as cysteine replacements. These non-
thiol-containing peptidomimetics show exceptional selectivity for PGGTase-I over the closely
related enzyme protein farnesyltransferase (PFTase). This selectivity is retained in whole cells
where the inhibitors were shown to block the geranylgeranylation of Rap-1A without affecting
the farnesylation of small GTP-binding proteins such as Ras.
In tr od u ction
binding proteins such as Rho A, Rho B, Rho C, and
CDC42. We have recently shown that inhibitors of
PGGTase-I can block cells in their G1 phase6 and inhibit
the growth of human tumors in nude mouse xenografts.7
Furthermore, PGGTase-I inhibitors suppress the growth
of and induce apoptosis in smooth muscle cells8 and also
cause a superinduction of nitric oxide synthase-2 after
IL-1â treatment.9 As a result there is a growing recogni-
tion of the potential application of PGGTase-I inhibitors
in several clinical areas, including novel therapies for
cancer and cardiovascular diseases. However, the few
PGGTase-I inhibitors available are not particularly
selective for GGTase-I.10 This has spurred us to search
for highly active PGGTase-I inhibitors that show much
greater selectivity over other prenyltransferase enzymes
(particularly PFTase) and that can act as probes of the
effect of protein geranylgeranylation in normal and
oncogenic cell growth.11
Protein geranylgeranyltransferase-I (PGGTase-I) is
an enzyme that plays a critical role in a range of cellular
processes.1 It is a member of the protein prenyltrans-
ferase family that catalyzes the transfer of prenyl
groups from prenylpyrophosphates to cysteine residues
at the C-termini of a specific set of proteins in eukaryotic
cells. Several small G-proteins require this prenylation
for proper cellular localization and regulation of signal
transduction. PGGTase-I attaches a C20 geranylgeranyl
group to the cysteine residue of proteins that contain
the C-terminal motif CAAX, where C is cysteine, A is
an aliphatic amino acid, and X is leucine or phenyl-
alanine. A separate enzyme, protein farnesyltransferase
(PFTase), attaches a farnesyl (C15) group to proteins
terminating in the CAAX sequence, where X is me-
thionine, serine, glutamine, alanine, cysteine, or pos-
sibly other residues.2 The third prenyltransferase is
protein geranylgeranyltransferase-II (PGGTase-II) which
attaches two C20 geranylgeranyl groups to newly syn-
thesized Rab proteins.3 The enzymological characteriza-
tion of these three enzymes has demonstrated that, in
principle, it should be possible to selectively inhibit one
with little or no effect on the others.
Ch em istr y
Since PGGTase-I is a bisubstrate enzyme, the design
of inhibitors can be approached by mimicking either the
isoprenyl substrate geranylgeranylpyrophosphate (GGPP)
or the C-terminal sequence CAAL. Recently, GGPP
analogues have been shown to inhibit the geranyl-
geranylation of Rap in cell cultures.12 A more attractive
and potentially selective strategy is the peptidomimetic
approach, in which the central aliphatic dipeptide unit
in CAAL is replaced by a hydrophobic spacer, such as a
substituted 4-aminobenzoyl group. We had earlier used
a related approach to prepare highly potent peptido-
mimetic inhibitors of PFTase (e.g., FTI-276) which also
have excellent antitumor properties.13 Extrapolation of
this strategy to PGGTase-I afforded potent but weakly
selective inhibitors (e.g., 1, GGTI-286; 3, GGTI-297; only
In the past several years major emphasis has been
placed on the design of inhibitors of PFTase as potential
antitumor agents.4 However, geranylgeranylated pro-
teins have recently been shown to be required for cells
to proceed from G1 to S phase in the cell cycle.5 Known
substrates of PGGTase-I include the γ subunits of brain
heterotrimeric G-proteins and Ras-related small GTP-
† Department of Chemistry, University of Pittsburgh.
‡ Department of Pharmacology, University of Pittsburgh.
| University of South Florida.
§ Yale University.
10.1021/jm9900873 CCC: $18.00 © 1999 American Chemical Society
Published on Web 04/08/1999

1334 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8
Vasudevan et al.
Sch em e 1a
a
Reagents: (a) Pd(PPh3)4, arylboronic acid, K2CO3, reflux, 24 h, 75%; (b) NaOH, MeOH, reflux, 85%; (c) L-leucine methyl ester
hydrochloride, EDCI, HOBT; (d) SnCl2; (e) tritylimidazole-4-carboxaldehyde, NaCNBH3, rt; (f) LiOH, THF/H2O; (g) TFA/triethylsilane.
2-4-fold for PGGTase-I over PFTase).7,14 These pepti-
domimetics were further hampered by the presence of
a free and metabolically unstable thiol functionality. We
have investigated a series of N-terminal groups to
replace the cysteine thiol and potentially coordinate to
the putative Zn2+ ion in the active site of PGGTase-I.15
In this paper we report the synthesis of a series of highly
potent, non-thiol-containing inhibitors that show re-
markable selectivity for PGGTase-I over PFTase.
Replacement of the mercaptan functional group by an
imidazole has been successfully employed in the design
of inhibitors for several zinc-containing enzymes, in-
cluding angiotensin-converting enzyme (ACE)16 and
PFTase.17 Since Zn2+ has been implicated in the mech-
anism of action of PGGTase-I,15 a similar modification
to our PGGTase-I inhibitors would be expected to confer
increased metabolic stability as well as probe the
importance of having a metal-coordinating ligand at the
N-terminal. Using 2-aryl-4-aminobenzoic acid deriva-
tives as mimetics for the central dipeptide in the CAAX
sequence, we have attached a series of imidazole and
pyridine derivatives to the N-terminus. The syntheses
of these compounds followed the general route outlined
in Scheme 1.18
ation and farnesylation was determined based on the
level of inhibition of Rap1A and H-Ras processing,
respectively.7 Briefly, oncogenic H-Ras-transformed NIH
3T3 cells were treated with various concentrations of
peptidomimetics, and the cell lysates were separated on
12.5% SDS-PAGE. The separated proteins were trans-
ferred to nitrocellulose and immunoblotted using an
anti-Ras antibody (Y13-258) or an anti-Rap1A antibody
(SC-65; Santa Cruz Biotechnology). Antibody reactions
were visualized using either peroxidase-conjugated goat
Suzuki coupling of the arylboronic acid with ethyl
2-bromo-4-nitrobenzoate followed by ester hydrolysis
afforded the appropriately substituted nitrobenzoic acid.
An alternative route involved aryl-aryl coupling of
2-bromo-4-nitrotoluene with the arylboronic acid fol-
lowed by oxidation of the methyl group. Coupling of the
benzoic acid with L-leucine methyl ester hydrochloride
using 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide
hydrochloride (EDCI)/1-hydroxybenzotriazole (HOBT),
followed by reduction of the nitro group, afforded the
corresponding aniline derivative. Reductive amination
with the heterocyclic aldehyde (with trityl protection for
imidazole derivatives) afforded the fully protected pep-
tidomimetic. Saponification of the methyl ester (fol-
lowed, when necessary, by TFA removal of the trityl
group) afforded the unprotected inhibitors. The com-
pounds prepared in this study are listed in Chart 1.
Resu lts a n d Discu ssion
F igu r e 1. In vitro inhibition of PGGTase-I and PFTase by
non-thiol-containing CAAL peptidomimetics. Human FTase
and GGTase-I were incubated in the presence of various
concentrations of peptidomimetics, and the ability of the
compounds to inhibit the transfer of (A) geranylgeranyl from
[3H]GGPP to recombinant Ras-CVLL or (B) farnesyl from [3H]-
FPP to recombinant Ras-CVLS was determined: GGTI-297
(b), GGTI-2132 (1), GGTI-2133 (2).
The in vitro inhibition assays of PGGTase-I and
PFTase were carried out by measuring the [3H]GGPP
and [3H]FPP incorporated into H-Ras-CVLL and H-Ras-
CVLS, respectively, using the same procedure described
before.6 Representative dose-respose curves are shown
in Figure 1. The in vivo inhibition of geranylgeranyl-

Non-Thiol Inhibitors of PGGTase-I
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8 1335
Ch a r t 1
anti-rat IgG or goat anti-rabbit IgG and an enhanced
chemiluminescence detection system. An example of this
Western blot analysis for several key compounds is
shown in Figure 2.
of H-Ras (Figure 2). Modification to the 2-imidazole-
methylene derivative 15 (GGTI-2159) gave less in vitro
selectivity (Table 1), but the corresponding methyl ester
16 (GGTI-2160) showed similarly high potency (0.5 µM)
and selectivity (>60-fold) for inhibition of Rap1A ger-
anylgeranylation in whole cells (Figure 2).
Highest selectivity was seen with the aminomethyl
homologue 11 (GGTI-2151), but the corresponding
methyl ester was much less active. The basic imidazole
N appears more important than the hydrogen-bonding
NH center since N-alkylated 13 (GGTI-2157) retained
potent in vitro activity. However, replacement of the
imidazole by differently substituted pyridine groups led
to loss of inhibition activity (cf. 10, 17, 20). Similarly,
in a probe of the shape demands of the PGGTase-I active
site, the 4-substituted aminobenzoate spacer was found
to be much more effective than the related 2- or
3-substituted derivatives (19 and 20).
In most cases replacement of the cysteine residue in
1 (GGTI-287) and 3 (GGTI-297) led to diminished
inhibition of both PFTase and PGGTase-I (Table 1).
However, the effect was much more pronounced for
PFTase leading to a family of highly selective inhibitors
of PGGTase-I. For example, Figure 1 shows that 4-imid-
azolemethylene derivative 7 (GGTI-2133) has an IC50
for PGGTase-I of 38 nM and a 140-fold selectivity over
FTase (Table 1). The corresponding methyl ester 8
(GGTI-2147) retained this selectivity in whole cells,
blocking Rap1A processing at concentrations as low as
1 µM with no effect on Ras processing at 30 µM (Figure
2). Compound 8 (GGTI-2147) inhibited the geranylgeran-
ylation of Rap1A with an IC50 value more than 60-fold
lower than that required to disrupt the farnesylation
In summary, we have developed a highly potent series

1336 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8
Vasudevan et al.
F igu r e 2. Effect of non-thiol-containing peptidomimetics on processing of H-Ras and Rap1A in NIH 3T3 cells (H-Ras 61L). Cells
were treated on each of two successive days with peptidomimetics, then harvested, and subjected to Western blot analysis to
demonstrate the inhibition of geranylgeranylated Rap1A or farnesylated H-Ras as seen in the band shift from processed (P)
protein to unprocessed (U) protein: lane 1, vehicle control; lane 2, 5 µM FTI-277; lane 3, 15 µM GGTI-298; lanes 4-5, 1 and 10
µM GGTI-2132; lanes 6-8, 0.1, 1, and 10 µM GGTI-2146; lanes 9-10, 1 and 10 µM GGTI-2133; lanes 11-13, 0.1, 1, and 10 µM
GGTI-2147; lanes 14-15, 1 and 10 µM GGTI-2159; lanes 16-18, 0.1, 1, and 10 µM GGTI-2160.
Ta ble 1. IC50 Values for Enzyme Inhibition, Rap1A or H-Ras Processing, and Relative Selectivity for PGGTase and PFTase
Inhibitors 1-20
IC50 (nM)
IC50 (µM)
inhibitor
PGGTase
PFTase
PFTase/PGGTase
RapIA
H-Ras
H-Ras/RapIA
1 (GGTI-286)14b
2 (GGTI-287)14b
3 (GGTI-297)14b
4 (GGTI-298)14b
5 (GGTI-2132)
6 (GGTI-2146)
7 (GGTI-2133)
8 (GGTI-2147)
9 (GGTI-2144)
10 (GGTI-2145)
11 (GGTI-2151)
12 (GGTI-2152)
13 (GGTI-2157)
14 (GGTI-2158)
15 (GGTI-2159)
16 (GGTI-2160)
17 (GGTI-2164)
18 (GGTI-2165)
19 (GGTI-2163)
20 (GGTI-2139)
240 ( 65
7.3 ( 2.6
55 ( 19
nd
90
nd
38 ( 9
nd
150
4000
44 ( 10
nd
32 ( 11
nd
210
nd
1600
nd
6100
400
183 ( 104
17 ( 13
203 ( 17
nd
1300
nd
5400 ( 750
nd
900
100000
10000
nd
303 ( 57
nd
8000
nd
58000
nd
46000
50000
0.76
2.3
3.7
10
nd
10
5
>10
10
10
0.5
>30
nd
>3
>30
>20
>10
>30
>30
>30
>100
nd
>100
>10
>10
>10
>30
>30
>30
>30
>100
>100
>3
>4
14.4
140
>3
>3
>60
6
25
230
>100
nd
>100
10
>10
>10
20
0.5
>30
20
>1
9.5
38
36
>1.5
>60
>1.5
7.5
125
>100
>100
followed by 1 mL of glacial acetic acid, and the reaction was
stirred for 30 min. This was followed by the addition of
NaCNBH3 (0.046 g, 0.74 mmol), and the reaction was stirred
at room temperature for 2 h. The solvent was evaporated, and
the residue was dissolved in ethyl acetate (∼3 mL) and
chromatographed on a silica gel column (1.05” × 23”) to afford
a white solid (0.30 g, 61%): 1H NMR (300 MHz, CDCl3) 0.79
(dd, 6 H), 1.10-1.35 (m, 3 H), 3.64 (s, 3 H), 4.28 (d, 2 H), 4.51
(m, 1 H), 4,66 (br s, 1 H), 5.45 (d, 1 H), 6.49 (s, 1 H), 6.64 (dd,
1 H), 6.74 (s, 1 H), 7.12 (m, 6 H), 7.09-7.27 (m, 15 H), 7.48 (s,
1 H), 7.69 (d, 1 H).
The above compound (0.30 g, 0.45 mmol) was dissolved in
15 mL of THF/H2O (3:2), and LiOH (0.035 g, 0.91 mmol) was
added. The reaction was stirred at room temperature for 2 h.
The THF was evaporated, the residue was dissolved in 15 mL
of water, and 1 N HCl was added to lower the pH to 2. The
compound was then extracted with ethyl acetate (3 × 25 mL)
and dried, and the solvents were evaporated to afford the free
carboxylic acid as a white solid (0.25 g, 84%).
The above compound (0.25 g, 0.38 mmol) was dissolved in
10 mL of dichloromethane and 3 mL of trifluoroacetic acid
followed by the addition of 1.5 mL of triethylsilane, and the
reaction was stirred at room temperature for 2 h. The solvents
were evaporated, and ether was added followed by the addition
of 6 N HCl in ether to precipitate the desired compound (GGTI-
2132) which was collected by rapid filtration (0.12 g, 77%): 1H
NMR (300 MHz, DMSO-d6) 0.76 (dd, 6 H), 1.38 (m, 2 H), 1.55
(m, 1 H), 4.19 (m, 1 H), 4.42 (d, 2 H), 6.63 (s, 1 H), 6.73 (d, 1
H), 7.31-7.36 (m, 6 H), 7.63 (s, 1 H), 8.23 (d, 1 H), 9.09 (s, 1
H); HRMS (FAB) m/z calcd for C23H26N4O3‚H+ 407.2083, found
407.2083.
of inhibitors for PGGTase-I that shows unprecedented
selectivity over the closely related prenyltransferase,
PFTase. Importantly, these compounds do not contain
thiol groups and are able to selectively block the
processing of a known geranylgeranylated protein,
Rap1A, at submicromolar concentrations in whole cells.
We are at present investigating the antitumor activity
of these compounds in a range of animal models.
Exp er im en ta l Section
Nuclear magnetic resonance spectra were acquired using
1
Bruker AM-300 series spectrometers (300 MHz for H, 75 MHz
for 13C) and are reported in δ units. All synthesized final
compounds (amine hydrochloride or amine trifluoroacetate
salts) were checked for purity by analytical high-pressure
liquid chromatography which was performed using a Rainin
HP controller and a Rainin UV-C detector with a Rainin 250-
× 4.6-mm, 5-µm Microsorb C18 column. Preparative HPLC
was performed on a Waters 600E controller and a Waters 490E
multiwavelength UV detector with a 25- × 10-cm Delta-Pak
C-18 300-Å cartridge column inside a Waters 25- × 10-cm
Radial compression module. Solvents consisting of 20-80%
acetonitrile and 0.1% TFA in water were used with a flow rate
of 15 mL/min in 40 min.
Syn th esis of GGTI-2132 (5). 4-[[N-(1-Tr itylim id a zol-4-
yl)m eth ylen eam in o]-2-ph en ylben zoyl]leu cin e Meth yl Es-
ter . To a solution of 2-phenyl-4-aminobenzoylleucine methyl
ester hydrochloride14b (0.25 g, 0.74 mmol) in methanol was
added tritylimidazole-4-carboxaldehyde (0.25 g, 0.74 mmol)

Non-Thiol Inhibitors of PGGTase-I
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8 1337
Syn th esis of GGTI-2133 (7). 4-[[N-(Im id a zol-4-yl)m eth -
ylen ea m in o]-2-(1-n a p h th yl)ben zoyl]leu cin e. The synthe-
sis followed a similar procedure to that for GGTI-2132, using
2-(1-naphthyl)-4-aminobenzoylleucine methyl ester hydrochlo-
ride (0.59 g, 1.5 mmol), tritylimidazole-4-carboxaldehyde (0.61
g, 1.80 mmol), and NaCNBH3 (0.34 g, 5.4 mmol) to afford a
white solid (0.72 g, 67%): 1H NMR (300 MHz, CDCl3) 0.13 (m,
0.8 H), 0.44 (m, 5.2 H), 0.57 (m, 2 H), 0.93 (m, 1 H), 3.40 (s, 1
H), 3.57 (s, 2 H), 4.24 (m, 1 H), 5.37-5.47 (dd, 1 H), 6.49 (s, 1
H), 7.08 (m, 2 H), 7.09-7.11 (m, 6 H), 7.30-7.32 (m, 11 H),
7.49-7.57 (m, 5 H), 7.80 (m, 2 H), 8.08 (d, 1 H).
ylen eam in o]-2-ph en ylben zoyl]leu cin e Meth yl Ester . 4-[[N-
(1-Tritylimidazol-4-yl)methyleneamino]-2-phenylbenzoyl]leu-
cine methyl ester (0.45 g, 0.68 mmol) was dissolved in 10 mL
of dichloromethane, and 3 mL of TFA was added, followed by
the addition of 1.5 mL of triethylsilane. The colorless solution
was stirred at room temperature for 2 h, following which the
solvent was evaporated and the residue was dissolved in ethyl
acetate and washed with saturated NaHCO3 (25 mL). The
organic layer was dried and evaporated to afford GGTI-2146
as a white solid (0.24 g, 84%): 1H NMR (300 MHz, DMSO-d6)
0.76 (d, 3 H), 0.81 (d, 3 H), 1.38 (m, 2 H), 1.52 (m, 1 H), 3.60
(s, 3 H), 4.19 (m, 1 H), 4.42 (d, 2 H), 6.61 (s, 1 H), 6.67 (dd, 1
H), 7.22-7.35 (m, 6 H), 7.55 (s, 1 H), 8.18 (d, 1 H), 9.04 (s, 1
H); HRMS (FAB) m/z calcd for C24H28N4O3‚H+ 421.2239, found
421.2240.
The above compound (0.24 g, 0.34 mmol) was dissolved in
10 mL of THF/H2O (2:1), and LiOH (0.029 g, 0.68 mmol) was
added. The reaction was stirred at room temperature for 2 h
and following a similar workup gave a white solid (0.20 g,
84%). This compound (0.20 g, 0.29 mmol) was dissolved in 10
mL of dichloromethane and 3 mL of trifluoroacetic acid
followed by the addition of 1.5 mL of triethylsilane, and the
reaction was stirred at room temperature for 2 h. The solvents
were evaporated, and ether was added followed by the addition
of 6 N HCl in ether to precipitate the desired compound (GGTI-
2133) which was collected by rapid filtration (0.096 g, 74%):
1H NMR (300 MHz, DMSO-d6) 0.37 (m, 3 H), 0.65 (m, 3 H),
1.08 (m, 2 H), 1.25 (m, 1 H), 3.89 (m, 1 H), 4.37 (d, 2 H), 6.53
(s, 1 H), 6.79 (m, 1 H), 7.01 (m, 1 H), 7.42-7.62 (m, 8 H), 7.86-
7.94 (m, 2 H), 8.86 (s, 1 H); HRMS (FAB) m/z calcd for
Syn th esis of GGTI-2147 (8). 4-[[N-(Im id a zol-4-yl)m eth -
ylen ea m in o]-2-(1-n a p h th yl)ben zoyl]leu cin e Meth yl Es-
ter . This was prepared by a similar route to GGTI-2146, using
4-[[N-(1-tritylimidazol-4-yl)methyleneamino]-2-(1-naphthyl)-
benzoyl]leucine methyl ester (0.40 g, 0.56 mmol), 3 mL of TFA
added, and 1.5 mL of triethylsilane to afford GGTI-2147 as a
white solid (0.21 g, 81%): 1H NMR (300 MHz, DMSO-d6) 0.38-
0.74 (m, 6 H), 0.91 (m, 2 H), 1.11 (m, 1 H), 3.46 (s, 3 H), 3.94
(m, 1 H), 4.41 (d, 2 H), 6.55 (s, 1 H), 6.79 (m, 1 H), 7.34-7.57
(m, 8 H), 7.83-7.94 (m, 3 H), 9.05 (s, 1 H); HRMS (FAB) m/z
calcd for C28H30N4O3‚H+ 471.2396, found 471.2400.
C
27H28N4O3‚H+ 457.2240, found 457.2245.
Syn th esis of GGTI-2163 (19). 6-[[N-(1-Tr itylim id a zol-
4-yl)m eth ylen ea m in o]-2-p h en ylben zoyl]leu cin e Meth yl
Ester . To a mixture of 35 mL of acetone and 43 mL of water
were added 2-bromo-6-nitrotoluene (3.42 g, 15 mmol), phenyl-
boronic acid (1.92 g, 15.7 mmol), K2CO3 (5.17 g, 37 mmol), and
palladium acetate (168 mg, 0.75 mmol), and the mixture was
refluxed for 20 h. The solution was cooled to room temperature,
then acidified to pH 3 with 1 N HCl, and extracted with ethyl
ether. Drying with MgSO4, followed by evaporation of the
solvent, afforded a white solid (2.37 g, 74%): 1H NMR (CDCl3)
7.43 (d, J ) 6.8 Hz, 1 H), 7.12-6.91 (m, 7 H), 1.99 (s, 3 H,
CH3); 13C NMR (CDCl3) 151.41, 145.03, 140.11, 133.83, 130.07,
129.23, 128.49, 127.82, 126.17, 123.05, 16.84.
Syn th esis of GGTI-2139 (20). 5-[[N-(4-P yr id yl)m eth yl-
en ea m in o]-2-p h en ylben zoyl]leu cin e Meth yl Ester . This
was prepared by a similar route to GGTI-2132, using 2-phenyl-
5-aminobenzoylleucine methyl ester hydrochloride (0.50 g, 1.47
mmol), pyridine-4-carboxaldehyde (0.164 g, 1.53 mmol), and
NaCNBH3 (0.16 g, 2.56 mmol) to afford a yellowish solid (0.40
g, 63%): 1H NMR (300 MHz, CDCl3) 0.76 (m, 6 H), 1.10-1.17
(m, 2 H), 1.27-1.32 (m, 1 H), 3.62 (s, 3 H), 4.43-4.53
(overlapping m & s, 3 H), 5.60 (d, 1 H), 6.61-6.65 (dd, 1 H),
6.97 (d, 1 H), 7.13 (d, 1 H), 7.25-7.35 (m, 8 H), 8.55 (m, 2 H).
The above compound (0.22 g, 0.51 mmol) was dissolved in
10 mL of THF/H2O (2:1) and cooled to 0 °C, and LiOH (0.04 g,
1.02 mmol) was added. The reaction was stirred at 0 °C for 1
h, followed by stirring at room temperature for 2 h. The
solvents were evaporated, and the residue was passed through
a bed of silica gel and eluted with CH2Cl2:CH3OH (9:1) to afford
the desired GGTI-2139 as a white solid (0.19 g, 90%): 1H NMR
(300 MHz, DMSO-d6) 0.79 (t, 6 H), 1.19 (m, 2 H), 1.42 (m, 1
H), 4.06 (m, 1 H), 4.36 (d, 2 H), 6.53 (dd, 1 H), 6.81 (m, 2 H),
7.04 (d, 1 H), 7.17-7.31 (m, 6 H), 7.59 (d, 1 H), 8.46 (d, 2 H);
HRMS (FAB) m/z calcd for C25H27N3O3‚H+ 418.2131, found
418.2128.
Syn th esis of GGTI-2145 (10). 4-[[N-(2-P yr id yl)m eth yl-
en ea m in o]-2-(1-n a p h th yl)ben zoyl]leu cin e Meth yl Ester .
This was prepared by a similar route to GGTI-2132, using 2-(1-
naphthyl)-4-aminobenzoylleucine methyl ester hydrochloride
(0.20 g, 0.51 mmol), pyridine-2-carboxaldehyde (0.06 g, 0.51
mmol), and NaCNBH3 (0.05 g, 0.77 mmol) to give the protected
derivative as a yellow solid (0.15 g, 61%): 1H NMR (300 MHz,
CDCl3) 0.13 (m, 0.8 H), 0.48 (m, 5.2 H), 0.57-0.64 (m, 2 H),
0.96-1.1 (m, 1 H), 3.4 (s, 1 H), 3.61 (s, 2 H), 4.21 (m, 1 H),
4.50 (m, 2 H), 5.40 (m, 1 H), 5.48 (br t, 1 H), 6.57 (d, 1 H), 6.82
(dd, 1 H), 7.23-7.52 (m, 7 H), 7.85 (m, 1 H), 7.92-8.04 (m, 3
H), 8.57 (d, 1 H).
The above compound (2.23 g, 11.5 mmol) was suspended in
11.5 mL of pyridine and 21 mL of water, and the mixture was
heated to boiling, at which time KMnO4 (9.9 g, 63 mmol) was
added gradually and the mixture heated at reflux for 72 h. At
that time, additional amounts of KMnO4 (3.3 g, 21 mmol) were
added, and the mixture was refluxed for 96 h. The mixture
was cooled and filtered through Celite, following which the
filtrate was acidified with 6 N HCl and the product was
extracted with ethyl acetate to afford a yellow solid (1.28 g,
51%): 1H NMR (300 MHz, CDCl3) 8.02 (d, J ) 6.27 Hz, 1 H,
H-5), 7.61-7.53 (m, 2 H, H-3, H-4), 7.37-7.32 (m, 5 H, phenyl).
The nitro compound (1.22 g, 5 mmol) was suspended in
anhydrous dichloromethane (20 mL). To this solution were
added L-leucine methyl ester hydrochloride (0.90 g, 5 mmol),
triethylamine (0.69 mL, 5 mmol), 1-[3-(dimethylamino)propyl]-
3-ethylcarbodiimide (1.00 g, 5.2 mmol), and 1-hydroxybenzo-
triazole (0.67 g, 5 mmol) at 0 °C, and the mixture stirred at 0
°C for 1 h and then at room temperature for 12 h. The mixture
was then washed with 1 N HCl, and the organic layer was
dried and evaporated to affford 2-phenyl-6-nitrobenzoylleucine
methyl ester (1.38 g, 75%).
The above compound was obtained as a 2:3 mixture of
diastereomers. No attempt was made to separate the indi-
vidual rotational isomers: 1H NMR (minor isomer) (CDCl3)
8.30 (m, 1 H), 8.04 (d, 2 H), 7.79 (m, 3 H), 7.21 (m, 2 H), 6.65
(d, 1 H), 4.81 (m, 1 H), 3.73 (s, 3 H), 1.33-1.29 (m, 2 H), 1.27
The above compound (0.15 g, 0.31 mmol) was dissolved in
10 mL of THF/H2O (2:1) and cooled to 0 °C, and LiOH (0.03 g,
0.62 mmol) was added. The reaction was stirred at 0 °C for 1
h, followed by stirring at room temperature for 2 h. The
solvents were evaporated, and the residue was passed through
a bed of silica gel and eluted with CHCl3:CH3OH (9:1) to afford
the desired GGTI-2145 as a white solid (0.13 g, 86%): 1H NMR
(300 MHz, DMSO-d6) 0.45 (m, 7 H), 0.81 (m, 1 H), 1.08 (m, 1
H), 3.77 (m, 1 H), 4.39 (s, 2 H), 6.22 (d, 1 H), 6.50 (m, 1 H),
6.72 (d, 1 H), 7.15 (br s, 1 H), 7.18-7.51 (m, 8 H), 7.81 (m, 1
H), 7.88 (m, 2 H), 8.48 (m, 1 H); HRMS (FAB) m/z calcd for
1
(m, 1 H), 0.93 (m, 6 H); H NMR (major isomer) (CDCl3) 7.39
(m, 5 H), 7.66 (m, 3 H), 6.13 (d, 1 H), 4.57 (m, 1 H), 3.60 (s, 3
H), 1.73 (m, 2 H), 0.91 (m, 1 H), 0.77 (t, 6 H).
The above compound (1.25 g, 3.24 mmol) was suspended in
ethyl acetate (50 mL), SnCl2 (3.67 g, 16.2 mmol) was added,
and the mixture was heated to reflux for 3 h. The mixture
was cooled and washed with saturated NaHCO3; the combined
organic extracts were dried and evaporated to afford the amino
C
29H29N3O3‚H+ 468.2287, found 468.2282.
Syn th esis of GGTI-2146 (6). 4-[[N-(Im id a zol-4-yl)m eth -

1338 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8
Vasudevan et al.
compound as a yellow solid (0.99 g, 90%). The 1H NMR
indicated the presence of two diastereomers.
7.35 (m, 8 H), 8.55 (m, 2 H); HRMS (FAB) m/z calcd for
C30H31N3O3‚H+ 482.2444, found 482.2446.
The amine (0.5 g, 1.47 mmol) was suspended in 15 mL of
methanol, and tritylimidazole-4-carboxaldehyde (0.49 g, 1.47
mmol) was added. After stirring for 0.5 h, glacial acetic acid
(1 mL) was added followed by NaCNBH3 (0.18 g, 2.94 mmol).
The mixture was stirred for 1 h, then an additional amount of
tritylimidazole (0.25 g, 0.74 mmol) was added, and the mixture
was stirred for another 1 h. The solvents were evaporated, and
the mixture was purified by column chromatography on silica
gel using ethyl acetate:hexanes:NH4OH (1:1:0.1) as the eluant
to afford 6-[[N-(1-triphenylmethylimidazol-4-yl)methylene-
amino]-2-phenylbenzoyl]leucine methyl ester as a white solid
(0.48 g, 50%): 1H NMR (CDCl3) 7.38 (m, 4 H), 7.29 (m, 12 H),
7.12 (m, 6 H), 6.76 (s, 1 H), 6.70 (d, 1 H), 6.65 (d, 1 H), 6.07 (t,
1 H), 5.75 (d, 1 H), 4.36 (overlapping m and d, 3 H), 3.55 (s, 3
H), 1.24 (m, 2 H), 0.92 (m, 1 H), 0.71 (m, 6 H).
Saponification of the methyl ester afforded the desired
GGTI-2164 as a white solid (82%): 1H NMR (DMSO-d6) 8.46
(d, 2 H), 7.55 (d, J ) 8.3 Hz, 1 H), 7.31-7.21 (m, 7 H), 7.01
(m, 1 H), 6.83-6.79 (m, 2 H), 6.72 (d, J ) 6.6 Hz, 1 H), 4.22
(d, J ) 5.7 Hz, 2 H), 4.01 (m, 1 H, leu R-CH), 1.47-1.32 (m, 3
H, leu CH2, CH), 0.77 (d, J ) 5.5 Hz, 6 H, leu CH3); HRMS
(FAB) m/z calcd for C29H29N3O3‚H+ 468.2287, found 468.2287.
Syn t h esis of GGTI-2151 (11) a n d GGTI-2152 (12).
Meth yl 4-Nitr o-2-(1-n a p h th yl)ben zoa te. Methyl 2-bromo-
4-nitrobenzoate (3.86 g, 14.85 mmol) was coupled with 1-naph-
thylboronic acid (3.06 g, 17.79 mmol) in DMF in the presence
of K2CO3 (3.0 equiv) and Pd(PPh3)4 (0.03 equiv) at 110 °C for
15 h. After flash column chromotography purification, methyl
4-nitro-2-(1-naphthyl)benzoate was obtained as a pale yellow
oil (3.86 g, 85%): 1H NMR (CDCl3) 8.34 (d, J ) 8.5 Hz, 1 H),
8.28 (s, 1 H), 8.14 (d, J ) 8.5 Hz, 1 H), 7.92 (m, 2 H), 7.47-
7.56 (m, 2 H), 7.41 (d, J ) 3.8 Hz, 2 H), 7.34 (d, J ) 6.8 Hz, 1
H), 3.40 (s, 3 H); 13C NMR (CDCl3) 166.4, 149.2, 142.7, 137.2,
136.8, 133.2, 131.3, 131.0, 128.6, 128.4, 126.6, 126.2, 126.0,
125.0, 124.7, 122.3, 52.3.
The coupled product (0.40 g, 0.60 mmol) was dissolved in
10 mL of a 3:2 mixture of THF/water, and LiOH was added.
The mixture was stirred at 0 °C for 1 h and then at room
temperature for 4 h. The mixture was acidifed with 1 N HCl
and the solvents were evaporated and extracted with ethyl
acetate to afford a white solid (0.31 g, 81%).
Meth yl 4-Iod o-2-(1-n a p h th yl)ben zoa te. This compound
was prepared from the nitro derivative. A catalytic amount of
Pd/C was added, and the mixture was hydrogenated at 40 psi
for 1 h. After removal of the catalyst, the reduced product was
obtained. This amine was dissolved in 7 mL of concentrated
hydrochloric acid (12 N), 1 mL of water, and 3 mL of acetic
acid. To this clear solution was added sodium nitrite in 4 mL
of water at 0 °C. The mixture was stirred at 0 °C for 25 min.
Then a solution of KI (1.5 equiv) in 4 mL of 2 N HCl was added.
The mixture was warmed to 60 °C and then extracted with
ethyl acetate. The ethyl acetate solution was washed with
sodium bicarbonate. After evaporation of solvents, the residue
was purified by flash column chromatography to give a pale
yellow oil (54%): 1H NMR (CDCl3) 7.85-7.90 (m, 3 H), 7.73-
7.80 (m, 2 H), 7.31-7.53 (m, 4 H), 7.28 (t, J ) 6.8 Hz, 1 H),
3.37 (s, 3 H); 13C NMR (CDCl3) 166.7, 142.8, 140.3, 137.7,
136.5, 132.8, 131.4, 131.2, 130.5, 128.0, 127.7, 125.9, 125.6,
125.5, 124.9, 124.8, 98.8, 51.6.
Met h yl 4-Cya n o-2-(1-n a p h t h yl)b en zoa t e. This com-
pound was prepared by dissolving the above iodo derivative
in 10 mL of THF. Then Pd(PPh3)4 (2.2% equiv) and powdered
KCN (1.5 equiv) were added. The mixture was refluxed for 12
h. GC/MS showed all the starting material was converted to
the product. The mixture was extracted with ethyl acetate and
water. After evaporation of solvents, the residue was purified
by flash column chromatography (10:1 hexane/ethyl acetate)
to give an oily product (50%): 1H NMR (CDCl3) 8.10 (d, J )
8.1 Hz, 1 H), 7.92 (d, J ) 8.2 Hz, 2 H), 7.81 (d, J ) 8.1 Hz, 1
H), 7.75 (s, 1 H), 7.46-7.56 (m, 2 H), 7.38 (d, J ) 3.7 Hz, 2 H),
7.32 (d, J ) 7.0 Hz, 1 H), 3.40 (s, 3 H); 13C NMR (CDCl3) 165.9,
141.5, 136.5, 135.2, 134.7, 132.7, 131.0, 130.7, 130.1, 128.0,
126.1, 125.8, 125.5, 124.7, 124.3, 117.3, 114.7, 51.7.
4-Cya n o-2-(1-n a p h th yl)ben zoylleu cin e Meth yl Ester .
The above ester (780 mg, 2.72 mmol) was dissolved in 8.0 mL
of THF. To this solution were added 0.5 N LiOH (6.5 mL, 1.2
equiv) and 4.0 mL of methanol. The mixture was refluxed for
2 h. TLC showed the disappearance of the starting material.
Solvents were evaporated, and the residue was first acidified
with 1 N HCl and then extracted with ethyl acetate. After the
evaporation of solvents, a white solid was obtained (752 mg,
100%). This acid (741 mg, 2.71 mmol) was coupled with
L-leucine methyl ester hydrochloride (542 mg, 1.10 equiv) using
EDCI and HOBT. After purification by flash column chroma-
tography (2:1 hexane/ethyl acetate), 4-cyano-2-(1-naphthyl)-
benzoylleucine methyl ester was obtained (775 mg, 72%): 1H
NMR (CDCl3) 8.10 (d, J ) 8.0 Hz, 0.6 H), 7.89-7.97 (m, 2.4
H), 7.80 (m, 1 H), 7.67 (s, 1 H), 7.36-7.59 (m, 5 H), 5.68 (d, J
) 7.9 Hz, 0.5 H), 5.60 (d, J ) 7.9 Hz, 0.5 H), 4.25 (m, 1 H),
3.55 (s, 1.5 H), 3.50 (s, 1.5 H), 1.02-1.05 (m, 0.5 H), 0.87-
0.95 (m, 0.5 H), 0.73-0.76 (m, 0.5 H), 0.40-0.58 (m, 6.5 H),
0.18-0.25 (m, 1 H); 13C NMR (CDCl3) 172.2, 172.0, 166.3,
165.6, 140.0, 139.0, 138.7, 135.6, 135.0, 134.6, 134.5, 133.3,
This solid was dissolved in 10 mL of dichloromethane, and
2 mL of TFA was added, followed by the dropwise adddition
of triethylsilane until the yellow coloration disappeared. The
solvents were evaporated, and anhydrous ether was added to
precipitate a white solid. This solid was sonicated in 15 mL of
ether for 1 h, following which the supernatant was decanted.
This procedure was repeated two times, and after the third
wash, the solid was dried to afford pure GGTI-2163 (0.17 g,
1
72%): mp 168-170 °C; H NMR (DMSO-d6) 8.59-8.54 (m, 2
H), 7.36-7.21 (m, 7 H), 6.73 (d, 1 H, J ) 8.3 Hz), 6.60 (d, 1 H,
J ) 7.53 Hz), 5.85 (br s, 1 H), 4.34 (s, 2 H), 4.08 (m, 1 H),
1.49-1.29 (m, 1.7 H), 1.10-1.06 (m, 1.3 H), 0.73 (d, 3 H, J )
6.42 Hz), 0.63 (d, 3 H, J ) 6.33 Hz); HRMS (FAB) m/z calcd
for C23H26N4O3‚H+ 407.2083, found 407.2083.
Syn th esis of GGTI-2160 (16). 4-[[N-(1H-Im id a zol-2-yl)-
m eth ylen ea m in o]-2-(1-n a p h th yl)ben zoyl]leu cin e Meth yl
Ester . This compound was obtained via the reductive amina-
tion of 2-(1-naphthyl)-4-aminobenzoyl-L-leucine methyl ester
hydrochloride and imidazole-2-carboxaldehyde, following simi-
lar procedures to those described for GGTI-2132, to afford after
purification a pale yellow solid (46%): mp 167-169 °C; 1H
NMR (CDCl3) 9.10 (br s, 1 H, imidazole-NH), 7.89-7.80 (m, 3
H, aryl), 7.55-7.45 (m, 3 H, aryl), 7.35-7.28 (m, 2 H), 6.90 (s,
2 H), 6.58 (d, 1 H, J ) 8.7 Hz), 6.51 (d, 1 H, J ) 2 Hz), 5.62
(m, 1 H, NH), 4.43 (d, 2 H, CH2), 4.14 (m, 1 H, leu R-CH), 3.50
(s, 2 H, COOCH3), 3.36 (s, 1 H, COOCH3), 1.25-1.18 (m, 1 H),
1.03 (m, 2 H), 0.56 (d, 2 H), 0.40 (m, 4 H); HRMS (FAB) m/z
calcd for C28H30N4O2‚H+ 471.2396, found 471.2391.
Syn th esis of GGTI-2159 (15). 4-[[N-(1H-Im id a zol-2-yl)-
m eth ylen eam in o]-2-(1-n aph th yl)ben zoyl]leu cin e. This com-
pound was obtained via the deprotection of the above methyl
ester using LiOH in a 3:2 mixture of THF/H2O, following
procedures described for the synthesis of GGTI-2146, to afford
a white solid, after lyophilization (88%): mp 110-114 °C
(softens); 1H NMR (DMSO-d6) 7.92-7.77 (m, 3 H, aryl), 7.57-
7.13 (m, 9 H, aryl), 6.84 (m, 1 H), 6.56 (s, 1 H), 4.73 (d, 2 H,
CH2), 3.86 (m, 1 H, leu R-CH), 1.32-1.02 (m, 3 H), 0.65 (d, J
) 6.2 Hz, 1.5 H), 0.56 (d, J ) 6.2 Hz, 1.5 H), 0.45 (d, J ) 6.09
Hz, 1.5 H), 0.36 (d, J ) 6.2 Hz, 1.5 H); HRMS (FAB) m/z calcd
for C27H28N4O3‚H+ 457.2240, found 457.2241.
Syn th esis of GGTI-2164 (17) a n d GGTI-2165 (18). 4-[[N-
(4-P yr id yl)m eth ylen ea m in o]-2-(1-n a p h th yl)ben zoyl]leu -
cin e. This compound was synthesized in a manner similar to
that described for the synthesis of GGTI-2145, via the reduc-
tive amination of 2-(1-naphthyl)-4-aminobenzoylleucine methyl
ester and pyridine-4-carboxaldehyde in methanol to afford,
after purification, GGTI-2165 as a white solid (64%): 1H NMR
(DMSO-d6) 0.71 (d, J ) 5.45 Hz, 3 H), 0.82 (d, J ) 5.13 Hz, 3
H), 1.20-1.27 (m, 2 H), 1.29-1.32 (m, 1 H), 3.72 (s, 2 H), 3.79
(s, 1 H), 4.15 (m, 1 H, leu R-CH), 4.41 (d, 2 H, CH2), 5.52 (d, 1
H, NH), 6.67-6.75 (dd, 1 H), 6.89 (d, 1 H), 7.23 (m, 2 H), 7.25-

Non-Thiol Inhibitors of PGGTase-I
J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8 1339
131.3, 131.2, 131.1, 130.1, 129.5, 129.0, 128.8, 128.3, 128.2,
127.0, 126.9, 126.6, 126.4, 126.1, 125.1, 124.6, 124.4, 117.6,
117.5, 114.2, 113.4, 51.8, 50.4, 40.3, 23.6, 23.5, 22.2, 20.9, 20.8.
purified by reverse-phase preparative HPLC (20%, three
steps): 1H NMR (CD3OD) 8.54 (s, 1 H), 7.91 (br d, J ) 5.2 Hz,
2 H), 7.69-7.79 (m, 2 H), 7.38-7.58 (m, 7 H), 4.40 (br s, 4 H),
4.03-4.14 (m, 1 H), 3.59 (s, 1.3 H), 3.54 (s, 1.7 H), 1.11-1.21
(m, 2 H), 0.60 (m, 1.7 H), 0.52 (br s, 2.3 H), 0.31-0.33 (m, 3
H); HRMS (FAB) m/z calcd for C29H32N4O3‚H+ 485.2553, found
485.2551.
Syn t h esis of GGTI-2157 (13) a n d GGTI-2158 (14).
Meth yl 4-Meth oxy-2-p h en ylben zoa te. Methyl 2-hydroxy-
4-methoxybenzoate (11.0 g, 60.4 mmol) was dissolved in 30
mL of pyridine. To this solution was slowly added trifluoro-
methanesulfonic anhydride (20 g, 70.8 mmol) at 0 °C. The
mixture was stirred at room temperature for 20 h. After
evaporation of pyridine, the residue was extracted with ether
and water. The ether solution was washed with 1 N HCl. After
evaporation of solvent, the residue was purified by flash
column chromatography to give the desired triflate (16.5 g,
87%). GC/MS showed this compound was pure (m/ z ) 314):
1H NMR (CDCl3) 8.06 (d, J ) 8.8 Hz, 1 H), 6.94 (d, J ) 8.8 Hz,
1 H), 6.77 (s, 1 H), 3.93 (s, 3 H), 3.88 (s, 3 H).
This aryltriflate (5.02 g, 16.0 mmol) was reacted with
phenylboronic acid in DMF in the presence of Pd(PPh3)4 (0.03
equiv) and potassium carbonate (6.62 g, 3.0 equiv). After
stirring at 100 °C for 7 h, the mixture was worked up and
purified by flash column chromatography to give methyl
4-methoxy-2-phenylbenzoate (3.53 g, 91%). GC/MS showed the
compound was pure (m/ z ) 242): 1H NMR (CDCl3) 7.90 (d, J
) 8.7 Hz, 1 H), 7.30-7.43 (m, 5 H), 6.92 (d, J ) 8.7 Hz, 1 H),
6.86 (s, 1 H), 3.86 (s, 3 H), 3.63 (s, 3 H); 13C NMR (CDCl3)
167.4, 161.2, 144.7, 141.1, 131.8, 127.8, 127.3, 126.6, 122.0,
115.8, 111.8, 54.6, 50.8.
Meth yl 4-(2-Br om oeth oxy)-2-p h en ylben zoa te. AlCl3 (4.0
g, 30 mmol) was dissolved in 6 mL of methylene chloride and
9.5 mL of EtSH at 0 °C. To this solution was added methyl
4-methoxy-2-phenylbenzoate (2.42 g, 10 mmol) in 10 mL of
methylene chloride. The mixture was stirred at 0 °C for 2 h
and at room temperature for 30 min. This mixture was poured
into ice water and neutralized with 3 N aqueous HCl. The
mixture was extracted with ethyl acetate. After evaporation
of solvents, a pale pink oil was obtained (2.20 g). This material
was pure as shown by TLC. The oily compound (2.20 g, 10
mmol) was dissolved in 60 mL of acetone. To this solution were
added 1,2-dibromoethane (7.52 g, 40 mmol) and potassium
carbonate (5.52 g, 40 mmol). The mixture was refluxed for 2
days. After workup, the crude material was purified by flash
column chromatography (12% ethyl acetate in hexane) to give
methyl 4-(2-bromoethoxy)-2-phenylbenzoate as a pale yellow
oil (1.69 g, 52%): 1H NMR (CDCl3) 7.89 (d, J ) 8.7 Hz, 1 H),
7.36-7.40 (m, 3 H), 7.26-7.30 (m, 2 H), 6.92 (d, J ) 8.7 Hz, 1
H), 6.86 (s, 1 H), 4.35 (t, J ) 6.2 Hz, 2 H), 3.66 (t, J ) 6.2 Hz,
2 H), 3.62 (s, 3 H); 13C NMR (CDCl3) 167.9, 160.1, 145.3, 141.3,
132.3, 128.1, 127.8, 127.2, 123.2, 116.8, 113.0, 67.8, 51.6, 28.6.
Meth yl 4-[2-(Im id a zol-1-yl)eth oxy]-2-p h en ylben zoa te.
The above bromoethyl derivative (1.62 g, 4.83 mmol) was
dissolved in 20 mL of THF. To this solution were added
imidazole (656 mg, 9.64 mmol) and triethylamine (1.38 mL,
10 mmol). The mixture was refluxed overnight. After evapora-
tion of solvents, the crude material was purified by flash
column chromatography (7% methanol in methylene chloride)
to give unreacted starting material (530 mg) and the desired
compound as a colorless oil (748 mg, 71%): 1H NMR (CDCl3)
7.87 (d, J ) 8.6 Hz, 1 H), 7.59 (s, 1 H), 7.35-7.42 (m, 3 H),
7.26-7.28 (m, 2 H), 7.05 (d, J ) 12 Hz, 2 H), 6.87 (d, J ) 8.6
Hz, 1 H), 6.81 (s, 1 H), 4.36 (t, J ) 5.0 Hz, 2 H), 4.27 (t, J )
4.9 Hz, 2 H), 3.61 (s, 3 H); 13C NMR (CDCl3) 167.4, 159.6, 144.8,
140.7, 137.0, 131.9, 128.9, 127.7, 127.4, 126.8, 122.8, 118.9,
116.3, 112.4, 66.8, 51.2, 45.6.
4-[2-(Im id a zol-1-yl)et h oxy]-2-p h en ylb en zoylleu cin e
Meth yl Ester (GGTI-2158). The above ester (2.29 mmol)
was dissolved in 5 mL of methanol. To this solution was added
4.5 mL of 1 N NaOH solution, and the mixture was refluxed
for 5 h. The solution was filtered, and the filtrate was acidified
with 1 N aqueous HCl to pH 4.2. After cooling in an ice bath,
the carboxylic acid was collected and coupled with L-leucine
4-(N -Boc-a m in om e t h yl)-2-(1-n a p h t h yl)b e n zoylle u -
cin e Meth yl Ester . The above nitrile (700 mg, 1.75 mmol)
was dissolved in 1 mL of THF and 12 mL of methanol. To this
solution was added CoCl2‚6H2O (835 mg, 3.5 mmol). The
mixture was vigorously stirred, and then NaBH4 (670 mg, 17.5
mmol) was added in several portions (H2 gas evolved and color
turned to black). The black mixture was stirred at room
temperature for 3 h. The solvents were evaporated, and the
residue was extracted with ethyl acetate. After evaporation
of solvents, the residue (550 mg) was dissolved in 10 mL of
methylene chloride. To this solution was added di-tert-butyl
dicarbonate (445 mg, 1.5 equiv), and the mixture was stirred
for 10 h. After evaporation of solvents, the residue was purified
by flash column chromatography (1.3:1 hexane/ethyl acetate)
to give a colorless oil (300 mg, 34% for two steps): 1H NMR
(CDCl3) 8.00 (d, J ) 8.0 Hz, 0.6 H), 7.84-7.92 (m, 2.4 H), 7.55
(d, J ) 8.0 Hz, 1 H), 7.35-7.50 (m, 5 H), 7.23 (s, 1 H), 5.63 (d,
J ) 7.9 Hz, 0.6 H), 5.55 (d, J ) 7.9 Hz, 0.4 H), 5.07 (br s, 1 H),
4.38 (br s, 2 H), 4.21-4.29 (m, 1 H), 3.52 (s, 1.8 H), 3.44 (s, 1.2
H), 1.42 (s, 9 H), 1.01-1.10 (m, 0.4 H), 0.84-0.93 (m, 0.6 H),
0.71-0.77 (m, 0.5 H), 0.46-0.55 (m, 3.3 H), 0.39-0.45 (m, 3.7
H), 0.14-0.19 (m, 0.6 H).
4-[N-(1H-Im idazol-4-yl)m eth ylam in om eth yl]-2-(1-n aph -
th yl)ben zoylleu cin e Tr iflu or oa ceta te (GGTI-2151). The
above Boc-protected derivative was dissolved in 7 mL of
methylene chloride. To this solution was added 4 mL of 4 N
HCl in ether. The mixture was stirred at room temperature
for 15 min. TLC showed all starting material had disappeared.
The solvents were evaporated, and the amine hydrochloride
salt was obtained in quantitative yield: 1H NMR (CDCl3) 8.30
(br s, 3 H), 7.80 (m, 1 H), 7.57 (d, J ) 8.0 Hz, 1 H), 7.24 (m,
4.5 H), 7.07 (d, J ) 7.4 Hz, 0.5 H), 6.26 (d, J ) 6.9 Hz, 1 H),
4.55 (m, 1 H), 4.04 (br s, 2 H), 3.60 (s, 3 H), 2.13 (s, 1.5 H),
2.00 (s, 1.5 H), 1.99 (m, 5 H), 1.80-1.88 (m, 1 H), 1.57-1.64
(m, 1 H).
The above hydrochloride salt was extracted with ethyl
acetate and 5% aqueous ammonium hydroxide. After evapora-
tion of solvents, a corresponding amine was obtained. This
amine was dissolved in 4 mL of THF. To this solution were
added N-tritylimidazol-4-ylaldehyde (1.25 equiv) and titanium
isopropoxide (1.25 equiv). The mixture was stirred at room
temperature for 1 h. This reaction mixture was diluted with 6
mL of anhydrous methanol, and then 2.0 mL of 0.43 N
NaBCNH3 (0.67 equiv) in THF was added dropwise. The
mixture was stirred at room temperature for 4 h, and then
solvents were evaporated. The residue was extracted with
ethyl acetate and 5% ammonium hydroxide. The ethyl acetate
layer was filtered to remove the white precipitate. The solvents
were evaporated, and the residue was dissolved in 3 mL of
methylene chloride. To this solution was added TFA (2 mL),
and then triethylsilane was added dropwise until the deep
brown color disappeared. The mixture was stirred at room
temperature for 1 h. The solvents were evaporated, and the
residue was dried under vacuum. The white residue was
washed with ether. The white precipitate was filtered, dried,
and dissolved in 1 mL of methanol and then 2 mL of 1 N NaOH
was added. The mixture was stirred at room temperature for
30 min. The solvents were evaporated, and the residue was
lyophilized. The crude mixture was purified by reverse-phase
preparative HPLC (20% for four steps): 1H NMR (CD3OD) 8.66
(s, 1 H), 7.88-7.93 (m, 2 H), 7.80 (d, J ) 7.9 Hz, 0.5 H), 7.68-
7.75 (m, 1.5 H), 7.66 (s, 1 H), 7.46-7.62 (m, 4.5 H), 7.34-7.42
(m, 1.5 H), 4.45 (s, 2 H), 4.39 (s, 2 H), 4.00-4.11 (m, 1 H),
1.04-1.26 (m, 2 H), 0.59 (d, J ) 6.3 Hz, 1.5 H), 0.51 (br s, 2
H), 0.43-0.50 (m, 0.5 H), 0.29-0.34 (m, 3 H); HRMS (FAB)
m/z calcd for C28H30N4O3‚H+ 471.2396, found 471.2400.
4-[N-(1H-Im idazol-4-yl)m eth ylam in om eth yl]-2-(1-n aph -
th yl)ben zoylleu cin e Meth yl Ester Tr iflu or oacetate (GGTI-
2152). This compound was prepared by the same method as
described in the preparation of GGTI-2151 except that the
methyl ester was not hydrolyzed. The final product was

1340 J ournal of Medicinal Chemistry, 1999, Vol. 42, No. 8
Vasudevan et al.
(7) Sun, J .; Qian, Y.; Hamilton, A. D.; Sebti, S. M. Both farnesyl-
transferase and geranylgeranyltransferase are required for
inhibition of oncogenic K-Ras prenylation but each alone is
sufficient to supress human tumor growth in nude mouse
xenografts. Oncogene 1998, 16, 1467-1473.
(8) Stark, W. W.; Blaskovich, M. A.; J ohnson, B. A.; Vasudevan, A.;
Hamilton, A. D.; Sebti, S. M.; Davies, P. Inhibition of geranyl-
geranylation, but not farnesylation, promotes apoptosis in
vascular smooth muscle cells. Am. J . Physiol. Lung Cell. Mol.
Physiol. 1998, 275, L55-L63.
(9) Finder, J . D.; Litz, J . L.; Blaskovich, M. A.; McGuire, T. F.; Qian,
Y.; Hamilton, A. D.; Davies, P.; Sebti, S. M. Inhibition of protein
geranylgeranylation causes a superinduction of nitric oxide
synthase by IL-1â in artery smooth muscle cells. J . Biol. Chem.
1997, 272, 13484-13488.
(10) Qian, Y.; Sebti, S. M.; Hamilton, A. D. Peptidomimetic inhibitors
of farnesyltransferase: An approach to new antitumor agents.
In Advances in Peptidomimetic Chemistry; Abell, A., Ed.; J ai
Press: Greenwich, CT, 1997; Vol. 1, pp 165-192.
methyl ester in methylene chloride using EDCI and HOBT.
After workup with sodium bicarbonate solution, the residue
was purified by flash column chromatography (6% methanol
in methylene chloride) to give GGTI-2158 as a white foam
(93%): 1H NMR (CDCl3) 7.72 (d, J ) 8.6 Hz, 1 H), 7.57 (br s,
1 H), 7.33-7.43 (m, 5 H), 7.02 (br s, 2 H), 6.86 (d, J ) 8.6 Hz,
1 H), 6.75 (s, 1 H), 5.64 (d, J ) 7.7 Hz, 1 H), 4.47 (ddd, J )
3.1, 5.1, and 7.7 Hz, 1 H), 4.32 (t, J ) 4.9 Hz, 2 H), 4.23 (t, J
) 4.8 Hz, 2 H), 3.61 (s, 3 H), 1.28-1.38 (m, 1 H), 1.07-1.18
(m, 2 H), 0.76 (t, J ) 6.4 Hz, 6 H); 13C NMR (CDCl3) 172.7,
168.1, 158.6, 141.5, 139.7, 137.1, 130.5, 128.9, 128.2, 127.9,
127.5, 119.1, 115.8, 112.7, 67.0, 51.7, 50.7, 45.9, 40.5, 24.0, 22.4,
21.4; HRMS (FAB) m/z calcd for C25H29N3O4‚H+ 436.2236,
found 436.2230.
4-[2-(Im idazol-1-yl)eth oxy]-2-ph en ylben zoylleu cin e Tr i-
flu or oa ceta te (GGTI-2157). This compound was prepared
from the hydrolysis of GGTI-2158. The final product was
purified by preparative HPLC (85%): 1H NMR (CD3OD) 9.07
(s, 1 H), 7.75 (s, 1 H), 7.58 (s, 1 H), 7.48 (d, J ) 8.4 Hz, 1 H),
7.34-7.39 (m, 5 H), 6.99 (d, J ) 8.5 Hz, 1 H), 6.94 (s, 1 H),
4.69 (t, J ) 4.6 Hz, 2 H), 4.45 (t, J ) 4.6 Hz, 2 H), 4.33 (t, J )
7.4 Hz, 1 H), 1.46 (t, J ) 7.1 Hz, 2 H), 1.15-1.24 (m, 1 H),
0.80 (dd, J ) 6.5 Hz, 6 H); HRMS (FAB) m/z calcd for C24
H27N3O4‚ H+ 422.2080, found 422.2082.
(11) Lerner, E. C.; Zhang, T. T.; Knowles, D.; Qian, Y.; Hamilton, A.
D.; Sebti, S. M. Inhibition of the prenylation of K-Ras, but not
H- or N-Ras, is highly resisitant to CAAX peptidomimetics and
requires both
a farnesyltransferase and a geranylgeranyl-
tranferase I inhibitor in human cell lines. Oncogene 1997, 15,
1283-1288.
(12) Ratemi, E. S.; Dolence, J . M.; Poulter, C. D.; Veders, J . C.
Synthesis of protein farnesyltransferase and protein geranyl-
geranyltransferase inhibitors: rapid access to chaetomellic acid
A and its analogues. J . Org. Chem. 1996, 61, 6296-6301.
Macchia, M.; J annitti, N.; Gervasi, G.; Danesi, R. Geranylgeranyl
diphosphate-based inhibitors of post-translational geranyl-
geranylation of cellular proteins. J . Med. Chem. 1996, 39, 1352-
1356.
Ack n ow led gm en t. We thank the National Insti-
tutes of Health (Grant CA67771) for financial support
of this work.
Refer en ces
(13) Lerner, E. C.; Qian, Y.; Blaskovitch, M.; Fossum, R.; Vogt, A.;
Sun, J .; Cox, A. D.; Der, C. J .; Hamilton, A. D.; Sebti, S. M. Ras
CAAX peptidomimetic FTI277 selectively blocks oncogenic Ras
signaling by inducing cytoplasmic accumulation of inactive Ras/
Raf complexes. J . Biol. Chem. 1995, 270, 26802-26806. Qian,
Y.; Vogt, A.; Sebti, S. M.; Hamilton, A. D. Design and synthesis
of non-peptide Ras CAAX mimetics as potent farnesyltrans-
ferases inhibitors. J . Med. Chem. 1996, 39, 217-223.
(14) (a) Lerner, E. C.; Qian, Y.; McGuire, T. F.; Hamilton, A. D.; Sebti,
S. M. Disruption of oncogenic K-Ras4B processing and signaling
by a potent geranylgeranyltransferase inhibitor. J . Biol. Chem.
1995, 270, 26770-26773. (b) Qian, Y.; Vogt, A.; Vasudevan, A.;
Sebti, S.; Hamilton, A. D. Selective inhibition of type-I geranyl-
geranyltransferase in vitro and in whole cells by CAAL pepti-
domimetics. Bioorg. Med. Chem. 1998, 6, 293-299.
(15) Zhang, F. L.; Casey, P. J . Influence of metal ions on substrate
binding and catalytic activity of mammalian protein geranyl-
geranyltransferase type-I. Biochem. J . 1996, 320, 925-932.
(16) Cecchi, R.; Ciabatti, R.; Favara, D.; Barone, D.; Baldoli, E.
Imidazolyl derivatives of enalapril as potential angiotensin
converting enzyme inhibitors. Farmaco Ed. Sci. 1985, 40, 541-
554.
(1) Sirtan, W. G.; Poulter, C. D. Yeast protein geranylgeranyltrans-
ferase type-I: steady-state kinetics and substrate binding.
Biochemistry 1997, 36, 4552-4557. Yokoyama, K.; McGeady, P.;
Gelb, M. H. Mammalian protein geranylgeranyltransferase-I:
substrate specificity, kinetic mechanism, metal requirements,
and affinity labeling. Biochemistry 1995, 34, 1344-1354. Sirtan,
W. G.; Poulter, C. D. Yeast protein geranylgeranyltransferase
type-I: overproduction, purification, and characterization. Arch.
Biochem. Biophys. 1995, 321, 182-190. Zhang, F. L.; Moomaw,
J . F.; Casey, P. J . Properties and kinetic mechanism of recom-
binant mammalian protein geranylgeranyltransferase type-I. J .
Biol. Chem. 1994, 269, 23465-23470.
(2) Casey, P. J . Biochemistry of protein prenylation. J . Lipid Res.
1992, 33, 1731-1740.
(3) Witter, D. J .; Poulter, C. D. Yeast geranylgeranyltransferase
type-II: steady state kinetic studies of the recombinant enzyme.
Biochemistry 1996, 35, 925-932.
(4) Gibbs, J . B.; Oliff, A.; Kohl, N. E. Farnesyltransferase inhibi-
tors: Ras research yields a potential cancer therapeutic. Cell
1994, 77, 175-178. Buss, J . E.; Marsters, J . C. Farnesyltrans-
ferase inhibitors: the successes and suprises of a new class of
potential cancer chemotherapeutics. Chem. Biol. 1995, 2, 787-
791. Sebti, S. M.; Hamilton, A. D. Inhibition of Ras prenylation:
a novel approach to cancer chemotherapy. Pharmacol. Ther.
1997, 71, 1-12.
(17) Hunt, J . T.; Lee, V. G.; Leftheris, K.; Seizinger, B.; Carboni, J .;
Mabus, J .; Ricca, C.; Yan, N.; Manne, V. Potent, cell-active, non-
thiol tetrapeptide inhibitors of farnesyltransferase. J . Med.
Chem. 1996, 39, 353-358.
(18) The exceptions were ethers 13 and 14 and aminomethylenes 11
and 12 which were prepared from the corresponding 4-hydroxy-
and 4-cyanobenzoic acid derivatives, respectively.
(5) Olson, M. F.; Ashworth, A.; Hall, A. An essential role for Rho,
Rac and Cdc42 GTPases in cell cycle progression through G1.
Science 1995, 269, 1270-1272.
(6) Vogt, A.; Qian, Y.; McGuire, T. F.; Blaskovich, M. A.; Hamilton,
A. D.; Sebti, S. M. Protein geranylgeranylation, not farnesyl-
ation, is required for G1 to S phase transition in mouse
fibroblasts. Oncogene 1996, 13, 1991-1999.
J M9900873