Highly potent, water soluble benzimidazole antagonist for activated α4β1 integrin

Article abstract of DOI:10.1021/jm070790o

The cell surface receptor α₄β₁ integrin, activated constitutively in lymphoma, can be targeted with the bisaryl urea peptidomimetic antagonist 1 (LLP2A). However, concerns on its preliminary pharmacokinetic (PK) profile provided an impetus to change the pharmacophore from a bisaryl urea to a 2-arylaminobenzimidazole moiety, resulting in improved solubility while maintaining picomolar potency [5 (KLCA4); IC₅₀ = 305 pM]. With exceptional solubility, this finding has the potential for improving PK to help diagnose and treat lymphomas.

Full text of DOI:10.1021/jm070790o

J. Med. Chem. 2007, 50, 5863-5867
5863
Highly Potent, Water Soluble Benzimidazole Antagonist for Activated r4â1 Integrin
Richard D. Carpenter,† Mirela Andrei,‡ Edmond Y. Lau,§ Felice C. Lightstone,§ Ruiwu Liu,‡ Kit S. Lam,*,‡ and
Mark J. Kurth*,†
Department of Chemistry, UniVersity of California, DaVis, DaVis, California 95616, DiVision of Hematology and Oncology, Department of
Internal Medicine, UniVersity of California DaVis Cancer Center, UniVersity of California, DaVis, Sacramento, California 95817, Chemistry,
Materials, and Life Sciences Directorate, Lawrence LiVermore National Laboratory, 7000 East AVenue, LiVermore, California 94550
ReceiVed July 2, 2007
The cell surface receptor R4â1 integrin, activated constitutively in lymphoma, can be targeted with the bisaryl
urea peptidomimetic antagonist 1 (LLP2A). However, concerns on its preliminary pharmacokinetic (PK)
profile provided an impetus to change the pharmacophore from a bisaryl urea to a 2-arylaminobenzimidazole
moiety, resulting in improved solubility while maintaining picomolar potency [5 (KLCA4); IC50 ) 305
pM]. With exceptional solubility, this finding has the potential for improving PK to help diagnose and treat
lymphomas.
Introduction
proton (pKa ) 6.4-7.5).16,17 The latter three factors combine
to improve aqueous solubility and possibly improve PK, while
alleviating kidney uptake. Indeed, these physicochemical prop-
erties of benzimidazoles result in diverse pharmaceutical ap-
plications addressing a variety of ailments,18-25 making it an
important member of the class of heterocycles having heteroa-
toms at the 1- and 3-positions.26 As a consequence, N-aryl-2-
aminobenzimidazoles facilitate favorable pharmacodynamics
and PKs, thereby making them ideal components of drug
candidates.23,25 Herein, we report the design and synthesis,
employing solution- and solid-phase chemistries, of benzimi-
dazole analogs 2-10 (KLCA1-9), with the solubility measured
by computational and analytical methods and the potency of
which were evaluated by cell adhesion competitive inhibition
assays.
The integrin family of membrane proteins, comprised of 24
noncovalent heterodimeric combinations employing 18 R- and
8 â-glycoproteins, are cell surface receptors that respond to and
modulate a broad array of extracellular matrix proteins.1
Specifically, R4â1 integrin regulates lymphocyte trafficking as
well as homing in normal adult cells,2,3 while the activated form
of R4â1 regulates tumor growth, metastasis, and angiogenesis,
as well as promotes the dissemination of tumor cells to distal
organs while facilitating tumor cell extravasation.3-10 This
activated R4â1 integrin is expressed in patients with leukemias,
lymphomas, melanomas, and sarcomas;3 it appears to inhibit
apoptosis in malignant chronic lymphocytic leukemia (B-CLL)
cells.6
Through the use of one-bead one-compound (OBOC) com-
binatorial library methods,11,12 we recently reported the discovery
of the bisaryl urea peptidomimetic 1 (LLP2A; see Figure 1)13-15
as a highly potent and selective ligand for the activated form
of R4â1 integrin. We further demonstrated that 1 labeled with
near-infrared fluorescent dye, can target lymphoma xenograft
with high specificity, making 1 a good candidate for the
development of lymphoma imaging and therapeutic agents.
Although the water solubility of 1 when conjugated to a
hydrophilic linker is good, 1 by itself is not very water soluble.
Furthermore, in vivo optical and radioimaging studies in a
xenograft model showed rather high uptake in the kidneys, a
pharmacokinetic (PKa) issue which may stem from physiological
solubility.15 Therefore, we sought to transform the bisaryl urea
pharmacophore of 1 to a conformationally constrained 2-aryl-
aminobenzimidazole system to exploit benzimidazole-mediated
physicochemical properties, in particular, its extensive pi-orbital
system, combination of hydrogen bond acceptors/donors, polar-
ity, and relative acidity of the 2-aminobenzimidazole N-H
Results and Discussion
Chemistry. To aid in designing rational analogs, continuum-
solvent quantum mechanical calculations were performed on
the urea 1 and the benzimidazole moieties of 7 and 10 to ensure
that the bisaryl urea f benzimidazole modification would not
drastically change the spatial orientation of the highly potent
1. Figure 2 shows the low energy and most polar solvated
conformations of benzimidazoles 7 and 10 juxtaposed to the
bisaryl urea moiety of 1. Indeed, while the number of rotatable
bonds is decreased in the benzimidazole moiety, its aryl rings
tend to have a staggered orientation that is similar to the urea
moiety of 1, therefore making the bisaryl urea f benzimidazole
modification spatially tolerable. For 7, the 2-arylaminobenz-
imidazole moiety has two low-energy conformations and a
rotamer around the amide carbonyl. Several low-energy con-
formations exist for 10: the 2-arylamino N-H as well as the
3-benzimidyl N-H are able to exist in either syn or anti
geometries with the o-tolyl moiety in a staggered conformation
and placement of the carboxamide occurs in either the 5-position
or the 6-position. Furthermore, the energy difference between
syn and anti geometries of the 2-arylamino N-H and the
3-benzimidyl N-H are small and therefore able to meet the
binding demands of the integrin. Most interestingly, the benz-
imidazole moiety has a larger dipole moment than the urea
moiety of 1, leading to complete water solubility. These
computational quantum calculations revealed that a bisaryl urea
f benzimidazole alteration does not cause a major change in
spatial orientation of the aryl rings and that water solubility,
* To whom correspondence should be addressed. Telephone: (916) 734-
8012 (K.S.L.); (530) 752-8192 (M.J.K.). Fax: (916) 734-7946 (K.S.L.);
(530) 752-8995 (M.J.K.). E-mail: kit.lam@ucdmc.ucdavis.edu (K.S.L.);
mjkurth@ucdavis.edu (M.J.K.).
† Department of Chemistry, University of California.
‡ Department of Internal Medicine, University of California.
§ Lawrence Livermore National Laboratory.
a Abbbreviations: PK, pharmacokinetic; HOBt, hydroxybenzotriazole;
DIC, 1,3-diisopropylcarbodiimide; DMF, N,N-dimethylformamide; HBTU,
2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate;
DIEA, diisopropylethylamine; TFA, trifluoroacetic acid; BSA, bovine serum
albumin; PBS, phosphate-buffered saline.
10.1021/jm070790o CCC: $37.00 © 2007 American Chemical Society
Published on Web 10/19/2007

5864 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 23
Brief Articles
Scheme 1. Synthetic Route to m-/p-Benzimidazole Acid
Precursors via an Amidine Thiocarbonate Intermediate
esters were not prepared due to the respective ester undergoing
a 6-exo-trig cyclization to give the pharmaceutically interesting
benzimidazoquinazolinone.28
With these m- and p-heterocyclic acids in hand, our focus
turned to the synthesis of the target molecules 2-10. As outlined
in Scheme 2, Rink amino resin, prepared by first swelling Rink
amide resin and then treatment with 20% piperidine/DMF, was
treated with an activated amino acid solution (appropriately
protected amino acid + DIC/HOBt in DMF). This process was
repeated twice to yield the resin-bound tripeptide 21. This resin
was then divided into nine flasks, and the heterocyclic acid
precursors 11-19, each dissolved in a solution of HBTU/DIEA
in DMF, were added to the divided resin tripeptide 21 suspended
in DMF. Protection of the electron-deficient 2-arylaminoben-
zimidyl moiety was unnecessary as minimal polymerization
occurred. Following reaction completion, as judged by the
Kaiser test, the heterocyclic tripeptide was cleaved from the
solid support under acidic conditions (TFA/i-Pr3SiH/H2O) and
purified by reverse-phase HPLC to afford 2-10 in 50-71%
overall yield from Rink amide resin and in 98-100% purity.
To further supplement the computational solubility results,
we focused on experimentally measuring solubility by determin-
ing the logP of the 2-10 analogs and contrasting these to 1 as
shown in Figure 3a (see Supporting Information for tabulated
values). The partition coefficient P is defined as the concentra-
tion of a compound in octanol over the concentration of the
same substance in water.29,30 The hydrocarbon-water partition
coefficient P can be related to the experimentally determined
capacity factor k by measuring the retention time of the
compound using reverse-phase HPLC.31,32 A standard calibration
curve was determined using compounds with known logP
values,33,34 and after calculation of the capacity factor, the
extrapolated logP values for 2-10 and 1 shown in Table 1 and
the graph in Figure 3a indicate that all of the 2-10 compounds
are appreciably more water soluble than 1.
Figure 1. (a) Structure of Bio-1211;15 (b) Structure of 1 (IC50 37 pM);
(c) Ex vivo NIRF images of tumors and organs excised 24 h after
postinjection with 1-biotin-streptavidin-Alexa680;13 and (d) Structure,
retrosynthetic analysis, and diversity elements of benzimidazoleanalogs.
based on dipole moment, is higher for the benzimidazole
analogs, thereby improving solubility and potentially PK.
With these computational studies in hand, we then focused
on the preparation of the benzimidazole acid precursors. As
depicted in Scheme 1, m- and p-aniline esters, either available
commercially or prepared from a Fisher esterification of the
corresponding aniline acid, were treated with thiophosgene to
afford the respective aryl isothiocyanate ester 20a-e in yields
ranging from 89 to 93%. In a one-pot transformation, these aryl
isothiocyanate esters react with o-phenylenediamines to deliver
unisolated thiourea intermediates, which subsequently cyclodes-
ulferize in the presence of carbodiimide reagents delivering
benzimidazole esters. Finally, saponification affords the m- and
p-benzimidazole acids 11-19 in 71-84% yields from the aryl
isothiocyanate ester and require minimal purification following
workup, in part due to the high water solubility of the dianionic
benzimidazole acid.27 The acids derived from o-benzimidazole
Biological Evaluation. Integrin expression and function
mediate cell activation and changes in integrin affinity, avidity,
or activation state are implicated in cell migration, apoptosis,

Brief Articles
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 23 5865
Figure 2. Conformational analysis (∆H, energy difference between shown structure and lowest energy structure) and dipole moment (µ) solution-
phase calculations for the bisaryl urea moiety of 1 and benzimidazoles 7 and 9.
Scheme 2a
induced in nude mice and, therefore, will be used in our future
in vivo PK and imaging studies. The IC50 of 1, in this current
study, was determined to be 37 pM, and this value will be used
for comparison with that of the benzimidazole compounds.
The potency of the 47-methylbenzimidazole acetamide 9, the
compound that is most structurally similar to 1, is in the low
nanomolar range (IC50 ) 28 nM; see Supporting Information
for 2-10 structures). The SAR data indicates that removing
the methylene unit as exemplified in the 47-methylbenzimidazole
carboxamide 8 leads to a 23-fold decrease in potency (with
respect to 9). While holding the carboximide unit constant,
removal of the 47-methyl (7; 15-fold decrease), reversing the
benzimidyl and phenyl moieties (10; 14-fold decrease), and
m-orientation of the carboxamide (2; 7-fold decrease) all were
frivolous at increasing potency. Extending the methylene chain
exemplified in the unsubstituted propanamide (6; 12-fold
decrease) or the substituted 2-methylpropanamide (3; 16-fold)
was also ineffective at improving potency. Returning to the
acetamide, changing from 47- to 56-substitution, as depicted by
the 56-bromobenzimidazole acetamide (4; 12-fold decrease) was
futile, however, removing substitution altogether as shown in
5 lead to an 11-fold increase in potency into the picomolar range
(IC50 ) 305 pM), as shown in Figure 3b. While the bisaryl
urea of 1 did have o-tolyl substitution, the unsubstituted
benzimidazole 5 proved to be the most potent of this new class
of compounds. This process of heterocyclization has two
consequences: reducing a degree of rotational freedom reduces
flexibility and accessibility of the acceptor, which may account
for the 8-fold decrease in potency into the low picomolar range
with respect to 1. However, heterocyclizing of the bisaryl urea
pharmacophore to a conformationally constrained 2-arylami-
nobenzimidazole pharmacophore yields a more water soluble
compound thanks to the acidity of the 2-arylamino N-H and a
higher dipole moment, which may in turn lead to improved PK.
a Reagents and conditions: (a) swell/DMF, 3 h; (b) piperidine/DMF;
(c) Fmoc-Ach-OH, DIC, HOBt, DMF; (b) f (e) Fmoc-Aad(Ot-Bu)-OH,
DIC, HOBt, DMF; (b) f (f) Dde-K(Fmoc)-OH, DIC, HOBt, DMF; (b) f
(g) (E)-3-(pyridin-3-yl)acrylic acid, DIC, HOBt, DMF; (h) H2NNH2/DMF;
(i) 11-18 or 9 HBTU, EtN(i-Pr)2, DMF; (j) TFA, (i-Pr)3SiH, H2O.
cancer development, and metastasis.35 Morever, R4â1 integrin
mediates cell adhesion to vascular cell adhesion molecule-1
(VCAM-1 or CD 106) as well as to extracellular matrix protein
fibronectin.4 We measured binding affinities (IC50) of 2-10 in
a Molt-4 T-cell leukemia adhesion assay by inhibiting the R4â1-
mediated cell adhesion to CS-1 peptide (DELPQLVTLPHPN-
LHGPEILDVPST), which is derived from the binding site of
fibronectin to activated R4â1 receptor.
We prepared 96-well plates by coating them with neutravidin,
followed by adding biotin-conjugated CS-1 peptide. The wells
were then blocked with BSA in PBS solution, followed by
adding Molt-4 cells, and finally the addition of serially diluted
2-10 to each well. The plates were incubated, washed (PBS),
fixed (formalin), and stained (crystal violet). After washing and
drying at room temperature, the absorbance at 570 nm was
measured using a UV/vis spectrophotometer equipped to read
96-well plates. Inhibition was calculated as a percentage
resulting from the concentration-dependent curve, and the IC50
data is shown in Table 1. The IC50 of 1 was previously reported
to be 2 pM with Jurkat cells.13 The IC50 value tends to vary
somewhat with different batch of cells and the specific cell line
used. We used Molt-4 cells, instead of Jurkat cells, for our
current binding studies because Molt-4 xenograft can be readily
Conclusion
The SAR data derived from the benzimidazole analogs differ
from the previously reported SAR data of 114 in that substitution
at the R1, R2, or R3 positions of the analogs was ineffective at
increasing potency. However, 5 (IC50 ) 305 pM) is still in the
picomolar range and potent enough to sustain in vivo selectivity,
in addition to having a higher dipole moment, a more acidic
N-H proton, and subsequently, a lower logP value rendering
5 more water soluble than 1. Using computational, synthetic,
and analytical chemistries, in conjunction with a cell adhesion
assay, we have successfully modified 1 from a bisaryl urea to
a novel, highly water soluble 2-arylaminobenzimidazole 5, while
maintaining picomolar potency as an antagonist for activated
R4â1 integrin. Subtle changes in the structure of a compound
lead to enhanced physicochemical properties (dipole moment
and pKa) that result in increased solubility (logP), which is an
important factor with potential to improve PK. Given the history

5866 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 23
Brief Articles
ously reported procedure,27 to a solution of o-phenylenediamine
(1.76 g, 16.3 mmol) in CH2Cl2 (75 mL) was added a solution of
the aryl isothiocyanate ester (for 20a, 3.0 g, 15.5 mmol) in CH2Cl2
(75 mL) dropwise over 30 min, followed by stirring for 16 h at
room temperature. After TLC showed that the aryl isothiocyanate
was consumed, the appropriate carbodiimide reagent [1,3-diiso-
propylcarbodiimide (DIC) or N-(3-dimethylaminopropyl)-N′-eth-
ylcarbodiimide hydrochloride (EDCI)] was added (for 11, DIC (46.5
mmol, 7.2 mL)), and the reaction proceeded at room temperature
until TLC showed the intermediate thiourea was consumed. In most
instances, this was between 4 and 8 h, but in some cases this took
as long as 16 h (11, 6 h). If DIC was employed (11), the
concentrated crude product was recrystallized from hot CHCl3 and
petroleum ether to give the benzimidazole ester (3.67 g). If EDC
was utilized, then the residue was taken up in ethyl acetate/H2O
followed by washing (H2O, brine), drying (MgSO4), and concentra-
tion to give the benzimidazole ester (4.08 g), which was used
without further purification. A solution of the benzimidazole ester
(4.08 g, 15.3 mmol) in dioxane/H2O (125 mL/80 mL) was treated
with LiOH (1.83 g, 76.4 mmol), and the solution was refluxed for
16 h. The reaction mixture was concentrated, and the residue was
taken up in aqueous 2 M NaOH. This basic water layer (pH ∼10)
was washed twice with ether before being acidified with concen-
trated HCl to pH ∼2-3, at which point 11 precipitated as a white
solid (3.38 g, 86%). The analytical data are in accord with literature
values.37
Figure 3. (a) Graph of logP vs capacity factor (k) for 1-10 (see
Supporting Information for values) and (b) chemical structure of 5 and
its inhibitory effects on Molt-4 cell adhesion to immobilized CS-1
peptide. Based on the three cell adhesion inhibition curves (triplicate
each), the IC50 was determined to be 305 ( 58 pM (triplicates for each
curve).
H2N-K[(E)-3-(pyridin-3-yl)acrylamide]-Aad(Ot-Bu)-Ach-
Rink Polystyrene (21). Rink amide resin (2.35 g, 1.19 mmol) was
swollen in DMF (30 mL) for 3 h, followed by treatment with 20%
piperidine in DMF (20 mL). After washing, the resin was then
treated with a premixed solution of Fmoc-Ach-OH (Fmoc-Ach-
OH; 1.30 g, 3.57 mmol), DIC (3.57 mmol, 553 µL), and hydroxy-
benzotriazole (HOBt; 482 mg, 3.57 mmol) in DMF (20 mL),
followed by shaking for 6 h. After a negative Kaiser test38 washing,
this sequence of deprotection/coupling was repeated thrice more
with Fmoc-Aad(t-Bu)-OH (1.57 g, 3.57 mmol), Dde-K(Fmoc)-OH
(1.85 g, 3.57 mmol), and (E)-3-(pyridin-3-yl)acrylic acid (532 mg,
3.57 mmol). After washing, the Dde-tripeptide resin was washed
and treated with 2% H2NNH2 in DMF (20 mL) for 20 min, followed
by washing to afford the free amino-tripeptide resin 21: IR (neat)
3430 (sh), 3370 (sh), 3084, 1740 (st), 1684 (st), 1680 (st), 1662
Table 1. Overall Yield, Purity, [M + H]+ Peak, Experimentally
Determined LogP, and IC50 of 2-10
yield
(%)
purity
(%)
logP
(exptl)
cmpd
(M + H)+
IC50 ( SD
1
2
3
4
5
6
7
8
9
3.26
2.12
2.63
1.96
2.23
2.80
1.83
1.86
2.58
1.88
37.2 ( 24.3 pM
185.6 ( 74.79 nM
444 ( 26.8 nM
340 ( 23.33 nM
305 ( 58 pM
344 ( 266 nM
419.5 ( 333 nM
655 ( 79 nM
27.5 ( 1.76 nM
379 ( 138.5 nM
63
60
57
62
71
64
59
53
50
100
98
100
99
98
98
99
98
99
780
808
872, 874
794
808
780
794
808
794
(st), 1654 (st) cm-1
.
General Procedures for Benzimidazole Analogs: (R)-5-((R)-
2-(3-(1H-Benzo[d]imidazol-2-ylamino)benzamido)-6-((E)-3-(py-
ridin-3-yl)acrylamido)hexanamido)-6-(1-carbamoylcyclohexyl-
amino)-6-oxohexanoic Acid (2). Benzimidazole acid 11 (253 mg,
0.180 mmol), 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium
hexafluorophosphate (HBTU; 67 mg, 0.180 mmol), and DIEA (54.7
mL, 0.360 mmol) were dissolved in DMF (3 mL), and the
homogeneous solution was allowed to stand for 10 min. This
solution was then added to the free amino tripeptide resin 21 (120
mg, 0.06 mmol) and was shaken for 4 h. After washing, the resin
was then cleaved with 3 mL of a 95:2.5:2.5 cleavage solution of
TFA/H2O/TIPS for 2 h, followed by draining and washing with
the cleavage solution. This cleavage process was repeated once
more, and the combined filtrates were concentrated under a gentle
stream of nitrogen, precipitated with ether, centrifuged, and
decanted. The precipitate was then purified by preparatory HPLC,
and the combined fractions were lyophillized to afford 2 (29 mg,
63% from Rink Amide resin) as a white powder: ESI MS (m/z)
780 (M + H)+; MALDI HRMS (m/z) calcd for C41H50N9O7,
780.3828 (M + H)+; found, 780.3835. Purity was determined to
be 99% by HPLC analysis on the basis of absorption at 220 nm.
This procedure was used 3-10 and analytical data are shown in
Table 1 of the Supporting Information.
10
of successful benzimidazole drug candidates, this transformation
has the potential to allow for improved PK without sacrificing
potency or selectivity to aid in diagnosing/treating patients with
lymphoma. In vivo therapeutic and imaging studies on lymphoid
malignancies are under study and will be reported in due course.
Experimental Section
General Procedure for Aryl Isothiocyanate Esters: Ethyl
4-Isothiocyanatobenzoate (20a). Following our previously reported
procedure,27 a solution of an appropriate aniline ester (4.5 g, 27.3
mmol) and triethylamine (60.1 mmol, 8.37 mL) in ethyl acetate
(160 mL), was treated with thiophosgene (30.0 mmol, 2.30 mL) in
ethyl acetate (130 mL) dropwise over 30 min at 0 °C. After addition,
the cooling bath was removed and the reaction mixture was allowed
to gradually warm up to room temperature over 12 h. The workup
consisted of diluting with ethyl acetate, followed by washing
sequentially with water (200 mL × 2) and brine (200 mL). The
organic layer was dried (MgSO4) and concentrated, and the crude
product was purified via short path CC (hexanes/ethyl acetate, 9:1)
to give 20a (5.03 g, 89%). The analytical data are in accord with
literature values.36
Acknowledgment. The authors thank the Howard Hughes
Medical InstitutesIntegrating Medicine into Basic Science
Fellowship Program, the National Cancer Institute (NCDDG
U19CA113298), the National Institute for General Medical
Sciences (RO1-GM076151), and the National Science Founda-
General Procedure for Benzimidazole Acids: 3-(1H-Benzo-
[d]imidazol-2-ylamino)benzoic Acid (11). Following our previ-

Brief Articles
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 23 5867
Rahfeld, J.-U.; Hoffmann, T.; Wermann, M.; Zunkel, K.; Wasternack,
C.; Demuth, H.-U. Identification of human glutaminyl cyclase as a
metalloenzyme: Potent inhibition by imidazole derivatives and
heterocyclic chelators. J. Biol. Chem. 2003, 278, 49773-49779.
(18) Janssens, F.; Torremans, J.; Janssen, M.; Stokbroekx, R. A.; Luyckx,
M.; Janssen, P. A. New antihistaminic N-heterocyclic 4-piperidi-
namines. 1. Synthesis and antihistaminic activity of N-(4-piperidinyl)-
1H-benzimidazol-2-amines. J. Med. Chem. 1985, 28, 1925-1933.
(19) Bovet, D.; Bovet-Nitti, F. Medicaments du Systeme NerVeux Vegetatif,
5th ed.; Karger: Basel, 1948; p 741.
tion (NMR spectrometers; CHE-0443516 and CHE-9808183)
for their generous financial support. This work was in part
performed under the auspices of the United States Department
of Energy by the University of California, Lawrence Livermore
National Laboratory under Contract Number W-7405-ENG-48.
Supporting Information Available: Structures and analytical
data for 1-10 and precursors 11-21 are provided in addition to
cell adhesion assay graphs. This material is available free of charge
via the Internet at http://pubs.acs.org.
(20) Wade, A., Ed. The Extra Pharmacopeia, 27th ed; The Pharmaceutical
Press: London, 1978; pp 1287-1309.
(21) Chong, C. R.; Chen, X.; Shi, L.; Liu, J. O.; Sullivan, D. J. A clinical
drug library screen identifies astemizole as an antimalarial agent.
Nat. Chem. Biol. 2006, 2, 415-416.
(22) Wright, D. H.; Ford-Hutchinson, A. W.; Chadee, K.; Metters, K. M.
The human prostanoid DP receptor stimulates mucin secretion in
LS174T cells. Br. J. Pharmacol. 2000, 131, 1537-1545.
(23) Arimura, A.; Yasui, K.; Kishino, J.; Asanuma, F.; Hasegawa, H.;
Kakudo, S.; Ohtani, M.; Arita, H. Prevention of allergic inflammation
by a novel prostaglandin receptor antagonist, S-5751. J. Pharm. Exp.
Ther. 2001, 298, 411-419.
(24) Beaulieu, C.; Wang, Z.; Denis, D.; Greig, G.; Lamontagne, S.;
O’Neill, G.; Slipetz, D.; Wang, J. Benzimidazoles as new potent and
selective DP antagonists for the treatment of allergic rhinitis. Bioorg.
Med. Chem. Lett. 2004, 14, 3195-3199.
(25) Rastogi, R.; Sharma, S. 2-Aminobenzimidazoles in organic syntheses.
Synthesis 1983, 861-882.
References
(1) Lin, K. C.; Castro, A. C. Very late antigen 4 (VLA4) antagonists as
anti-inflammatory agents. Curr. Opin. Chem. Biol. 1998, 2, 453-
457.
(2) Yusut-Makagiansar, H.; Anderson, M. E.; Yakovleva, T. V.; Murray,
J. S.; Siahaan, T. J. Inhibition of LFA-1/ICAM-1 and VLA-4/
VCAM-1 as a therapeutic approach to inflammation and autoimmune
diseases. Med Res. ReV. 2002, 22, 146-167.
(3) Holzman, B.; Gosslar, U.; Bittner, M. R4 integrins and tumor
metastasis. Curr. Top. Microbiol. Immunol. 1998, 231, 125-141.
(4) Vincent, A. M.; Cawley, J. C.; Burthem, J. Integrin function in chronic
lymphocytic leukemia. Blood 1996, 87, 4780-4788.
(5) Marco, R. A.; Diaz-Montero, C. M.; Wygant, J. N.; Kleinerman, E.
S.; McIntyre, B. W. Alpha 4 integrin increases anoikis of human
osteosarcoma cells. J. Cell. Biochem. 2003, 88, 1038-1047.
(6) de la Fuente, M. T.; Casanova, B.; Garcia-Gila, M.; Silva, A.; Garcia-
Pardo, A. “Fibronectin interaction with R4â1 integrin prevents
apoptosis in B cell chronic lymphocytic leukemia: correlation with
Bcl-2 and Bax.” Leukemia 1999, 13, 266-274.
(26) Martin, E. J.; Critchlow, R. E. Beyond mere diversity: Tailoring
combinatorial libraries for drug discovery. J. Comb. Chem. 1999, 1,
32-45.
(7) Oldon, D. L.; Burkly, L. C.; Leone, D. R.; Dolinski, B. M.; Lobb,
R. R. Anti-R4 integrin monoclonal antibody inhibits multiple
myeloma growth in a murine model. Mol. Cancer Ther. 2005, 4,
91-99.
(8) Matsunaga, T.; Takemoto, N.; Sato, T.; Takimoto, R.; Tanaka, I.;
Fujimi, A.; Akiyama, T.; Kuroda, H.; Kawano, Y.; Kobune, M.; Kato,
J.; Hirayama, Y.; Sakamaki, S.; Kohda, K.; Miyake, K.; Niitsu, Y.
Interaction between leukemic-cell VLA-4 and stromal fibronectin is
a decisive factor for minimal residual disease of acute myelogenous
leukemia. Nat. Med. 2003, 9, 1158-1165.
(9) Garmy-Susini, B.; Jin, H.; Zhu, Y.; Sung, R.-J.; Hwang, R.; Varner,
J. Integrin R4â1-VCAM-1-mediated adhesion between endothelial
and mural cells is required for blood vessel maturation. J. Clin. InVest.
2005, 115, 1542-1551.
(10) Damiano, J. S.; Dalton, W. S. Integrin-mediated drug resistance in
multiple myeloma. Leuk. Lymphoma 2000, 38, 71-81.
(11) Lam, K. S.; Salmon, S. E.; Hersh, E. M.; Hruby, V. J.; Kazmierski,
W. M.; Knapp, R. J. A new type of synthetic peptide library for
identifying ligand-binding activity. Nature 1991, 354, 82-84.
(12) For an OBOC review, see: Lam, K. S.; Lebl, M.; Krchnak, V. The
‘‘one-bead-one-compound” combinatorial library method. Chem. ReV.
1997, 97, 411-448.
(13) (a) Peng, L.; Liu, R.; Marik, J.; Wang, X.; Takada, Y.; Lam, K. S.
Combinatorial chemistry identifies high-affinity peptidomimetics
against R4â1 integrin for in vivo tumor imaging. Nat. Chem. Biol.
2006, 2, 381-389. (b) Liu, R.; Peng, L.; Han, H.; Lam, K. S.
Structure-activity relationship studies of a series of peptidomimetic
ligands for R4â1 integrin on Jurkat T-leukemia cells. Biopolymers
(Pept. Sci.) 2006, 84, 595-604.
(14) Chen, X.; Gambhir, S. S. Significance of one-bead-one-compound
combinational chemistry. Nat. Chem. Biol. 2006, 2, 351-352.
(15) Lin, K.-c.; Ateeq, H. S.; Hsiung, S. H.; Chong, L. T.; Zimmerman,
C. N.; Castro, A.; Lee, W.-c.; Hammond, C. E.; Kalkunte, S.; Chen,
L.-L.; Pepinsky, R. B.; Leone, D. R.; Sprague, A. G.; Abraham, W.
M.; Gill, A.; Lobb, R. R.; Adams, S. P. Selective, tight-binding
inhibitors of integrin R4â1 that inhibit allergic airway responses. J.
Med. Chem. 1999, 42, 920-934.
(27) Carpenter, R. D.; DeBredt, P. B.; Lam, K. S.; Kurth, M. J.
Carbodiimide-based benzimidazole library method. J. Comb. Chem.
2006, 8, 907-914.
(28) Carpenter, R. D.; Lam, K. S.; Kurth, M. J. Microwave-mediated
heterocyclization to benzimidazo[2,1-b]quinazoline-12(5H)-ones. J.
Org. Chem. 2007, 72, 284-287.
(29) Malik, I. Sedlarova, M. A.; Csollei, C. S.; Andrianainty, P.; Kurfurst,
P.; Vanco, J. Synthesis, spectral description, and lipophilicity
parameters determination of phenylcarbamic acid derivatives with
integrated N-phenylpiperazine moiety in the structure. Chem. Pap.
2006, 60, 42-47.
(30) Saunders, R. A.; Platts, J. A. Scaled polar surface area descriptors:
Development and application to three sets of partition coefficients.
New J. Chem. 2004, 28, 166-172.
(31) Bechalany, A.; Tsantili-Kakoulidou, A.; El Tayar, N.; Testa, B.
Measurement of lipophilicity indices by reversed-phase high-
performance liquid chromatography: Comparison of two stationary
phases and various eluents. J. Chromatogr. 1991, 541, 221-229.
(32) Braumann, T. Determination of hydrophobic parameters by reversed-
phase liquid chromatography: Theory, experimental techniques, and
application in studies on quantitative structure-activity relationships.
J. Chromatogr. 1986, 373, 191-225.
(33) Vrakas, D.; Tsantili-Kakoulidou, A.; Hadjipavlou-Litina, D. Exploring
the consistency of logP estimation for substituted coumarins. QSAR
Comb. Sci. 2003, 22, 622-629.
(34) Poole, S. K.; Poole, C. F. Separation methods for estimating octanol-
water partition coefficients. J. Chromatogr., B: Biomed. Sci. Appl.
2003, 797, 3-19.
(35) Luscinskas, F.; Lawler, J. Integrins as dynamic regulators of vascular
function. FASEB J. 1994, 8, 929-938.
(36) Sayigh, A. A. R.; Ulrich, H.; Potts. J. S. The reaction of arylamines
with diethylthiocarbamoyl chloride. A new synthesis of aryl isothio-
cyanates. J. Org. Chem. 1965, 30, 2465-2466.
(37) Jacobsen, C. M.; Denmeade, S. R.; Isaacs, J. T.; Gady, A.; Olsen,
C. E.; Christensen, S. B. Design, synthesis, and pharmacological
evaluation of thapsigargin analogues for targeting apoptosis to
prostatic cancer cells. J. Med. Chem. 2001, 44, 4696-4703.
(38) Kaiser, E.; Colescott, R. L.; Bossinger, C. D.; Cook, P. I. Color test
for detection of free terminal amino groups in the solid-phase
synthesis of peptides. Anal. Biochem. 1970, 34, 595-598.
(16) Perkins, J. J.; Zartman, A. E.; Meissner, R. S. Synthesis of
2-(alkylamino)benzimidazoles. Tetrahedron Lett. 1999, 40, 1103-
1106.
(17) (a) Hajduk, P. J.; Boyd, S.; Nettesheim, D.; Nienaber, V.; Severin,
J.; Smith, R.; Davidson, D.; Rockway, T.; Fesik, S. W. Identification
of novel inhibitors of urokinase via NMR-based screening. J. Med.
Chem. 2000, 43, 3862-3866. (b) Schilling, S.;; Niestroj, A. J.;
JM070790O