1,2,3,4-Tetrahydroquinoline-containing αVβ 3 integrin antagonists with enhanced oral bioavailability

Article abstract of DOI:10.1016/j.bmcl.2004.08.067

Selective reduction of the quinoline yielded potent α _vβ5₃ antagonists with improved oral bioavailability relative to the corresponding quinoline derivatives. Reduction of the quinoline ring in an α_vβ₃ antagonist yielded a 1,2,3,4-tetrahydro derivative as two diastereomers, the four isomers of which were separated by sequential chiral HPLC. Two isomers had significant α_Vβ₃ antagonist activity with improved oral bioavailability, relative to the corresponding quinoline derivative.

Full text of DOI:10.1016/j.bmcl.2004.08.067

Bioorganic & Medicinal Chemistry Letters 14 (2004) 5937–5941
1,2,3,4-Tetrahydroquinoline-containing aVb3 integrin
antagonists with enhanced oral bioavailability
Shyamali Ghosh,a Rosemary J. Santulli,a William A. Kinney,a,* Bart L. DeCorte,a Li Liu,a
Joan M. Lewis,a Jef C. Proost,b Gregory C. Leo,a John Masucci,a William E. Hageman,a
Andrew S. Thompson,c Ian Chen,c Reiko Kawahama,c Robert W. Tuman,a
Robert A. Galemmo, Jr.,a Dana L. Johnson,a Bruce P. Damianoa and Bruce E. Maryanoffa
aDrug Discovery, Johnson & Johnson Pharmaceutical Research & Development, L.L.C., Welsh & McKean Roads, Spring House,
PA 19477-0776, USA
bDrug Discovery, Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 2340 Beerse, Belgium
cJ-Star Research, Inc., 3001 Hadley Road, Suite 3, South Plainfield, NJ 07080, USA
Received 27 May 2004; accepted 31 August 2004
Available online 7 October 2004
Abstract—Reduction of the quinoline ring in an avb3 antagonist yielded a 1,2,3,4-tetrahydro derivative as two diastereomers, the
four isomers of which were separated by sequential chiral HPLC. Two isomers had significant aVb3 antagonist activity with
improved oral bioavailability, relative to the corresponding quinoline derivative.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Interactions between the aVb3 integrin and its extracellu-
lar matrix ligands are a basis of cell adhesion events,
leading to the migration, invasion, proliferation, and
survival of cells. The aVb3 integrin is expressed in several
cell types, such as osteoclasts, endothelial cells, vascular
smooth muscle cells, and some tumor cells. Although
the normal level of expression is typically low, expres-
sion is greatly enhanced in pathological conditions
involving tissue remodeling and growth. Hence, this
integrin has attracted attention as a therapeutic target
for the treatment of cancer, osteoporosis, rheumatoid
arthritis, and diabetic retinopathy.1 Monoclonal anti-
bodies to aVb3 (Vitaxin, CNTO 95) and peptide antago-
nists based on the Arg-Gly-Asp (RGD) motif have been
the most studied to date and have shown good efficacy
in various animal models.1,2 Interesting efficacy for oral-
ly bioavailable, small-molecule aVb3 integrin antago-
nists3 in models of osteoporosis4 and arthritis5 has
been reported.
N
N
O
O
O
O
O
N
H
OH
NH
N
N
H
OH
N
HN
N
N
H
O
1
2
N
O
O
N
H
OH
N
O
N
N
N
N
N
H
H
OH
O
O
3
4
Figure 1. Evolution of series from nipecotamide (1) to isonipecot-
amides (2 and 3) to carba-analog (4).
with reversed selectivity for aVb3 relative to aIIbb3.7,8
This compound represented a good starting point, but
it was deficient in showing only moderate selectivity
and low oral bioavailability (F = 4%, Table 1). In this
case, antagonism of the integrin aIIbb3 would be an
undesirable activity as it causes blockade of platelet
aggregation. Recently, we reported8 the introduction
of the tetrahydronaphthyridine group9 in 3 and the
Starting from the nipecotamide-based aIIbb3 antagonist,
elarofiban (1, Fig. 1),6 we identified the isonipecotamide
structure 2 (aVb3 IC50 = 3.6nM, aIIbb3 IC50 = 170nM)
*
Corresponding author. Tel.: +1 215 628 5908; fax: +1 215 628
4985; e-mail: wkinney1@prdus.jnj.com
0960-894X/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2004.08.067

5938
S. Ghosh et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5937–5941
a
Table 1. Binding studies at aVb3, aVb5, and aIIbb3 integrins by quinoline based derivatives (IC50
)
(CH )
OH
2 n
N
Ring O
N
H
N
(CH )
2 m
O
23
Isomer designation ð½aŠD Þ
No.
Structural description
aVb3 (nM)b
aVb5 (nM)b
aIIbb3 (nM)c
Fd (%)
m
n
Ring
2
S
See figure
See figure
3.6 0.9
2.6 0.6
0.8 0.2
1.6 0.7
2.5 0.4
470 110
270 50
2.2 0.7
170 30
2900
1100
4
3
27
S
R, S
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
3-Quinoline
4
0
28
29
R, S
f
3-(5,6,7,8-THQ)e
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
11
17
4
2
3000
14,000
>50,000
4700
29a
29d
29b
29c
33
a (+16ꢁ)
d (À15ꢁ)
b(+24 ꢁ)
26
8
1000
2.7 0.7
1.2 0.1
52 14
8.7 2.1
7.8 1.4
2200
22
8
13,000
>50,000
>50,000
6100
c (À25ꢁ)
f
3-(1-Me-1,2,3,4-THQ)
3-(6-MeOPy)g
3-(6-MeOPy)
49
2
180 20
2.7 0.8
3.1 1.5
98 39
34
R, S
a (À22ꢁ)h
0.7 0.2
0.4 0.1
8
2
34a
34b
30
1800
>50,000
870
b(+22 ꢁ)h
R, S
3-(6-MeOPy)
3-Quinoline
16
6
0.5 0.1
3.7 1.5
1.6 0.5
5.4 0.2
36
9
1
100
46
f
31
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
3-(1,2,3,4-THQ)
260 60
44 12
160 60
2500
15,000
13,000
17,000
>50,000
>50,000
1200
31a
31d
31b
31c
SB 265123k
a (+20ꢁ)i
d (À20ꢁ)j
b(+17 ꢁ)i
c (À26ꢁ)j
52
70
7
100 40
4.0 1.3
1500
2.9 0.5
100k
a 29a and 29d, 29b and 29c, 34a and 34b, 31a and 31d, 31b and 31c are enantiomeric pairs.
b Inhibition of human vitronectin binding to immobilized aVb3 and aVb5 (N P 3).15
c Inhibition of biotinylated fibrinogen binding to immobilized aIIbb3 (N P 2).16
d See Ref. 18.
e THQ = tetrahydroquinoline.
f Mixture of two diastereomers (four isomers).
g MeOPy = methoxypyridine.
h Separated by chiral HPLC on Chiralcelꢂ OJ (96/4hexane/EtOH elution) at same Boc-protected intermediate stage as 15.
23
D
23
D
i Prepared from isomers 18a (½aŠ +43) and 18b (½aŠ +53), which were separated from 18c/18d on a Chiralpakꢂ OD column (MeOH elution), and
from each other on Chiralpakꢂ AD column (EtOH elution) as described above.13
23
D
23
D
j Prepared from isomers 18c (½aŠ À62) and 18d (½aŠ À46), which were separated on the initial Chiralpakꢂ OD column from the mixture of 18a/18b.
k See Ref. 4a
ꢀevolvedꢁ carba-analogs (e.g., 4) that lack the amide
group beta to the carboxylic acid. These derivatives
had improved selectivity relative to aIIbb3 and in the case
of some b-aryl substituted carba-analogs, such as 4, sig-
nificant improvements in oral bioavailability were ob-
served. However, no b-heterocyclic groups were found
to exhibit good oral bioavailability (e.g., pyridyl) ini-
tially. This paper focuses on quinoline-containing struc-
tures of general formula 5. The structure was modified
by varying the spacer units and taking advantage of
the selective reduction of the quinoline ring that oc-
curred during hydrogenation.
spacer between the piperidine and the quinoline substit-
uent so that the optimum arrangement could be deter-
mined.10 Boc-protected piperidine carboxylic acids 6
and 7 were converted to their corresponding Weinreb
amides 8 and 9, which were reacted with the lithium rea-
gent derived from 3-bromoquinoline to yield the ketones
10 and 11. The latter reaction was best performed by
premixing the Weinrebamide and aryl rbomide in
THF, followed by the addition of butyl lithium.11 The
resultant ketones were elaborated to the unsaturated
esters 12 and 13 by reaction with the sodium salt of
trimethyl phosphonoacetate. The mixture of E- and
Z-isomers of 12 was hydrogenated in the presence of
10% palladium on carbon to give three different prod-
ucts, depending on the reduction conditions. One could
produce quinoline 14 by conducting the hydrogenation
at low pressure (8psig). Over-reduced products 15 and
16 resulted from using intermediate pressure (30psig)
for two days. The optimal conditions for producing
the 1,2,3,4-tetrahydroquinoline 15 were to hydrogenate
in toluene with triethylamine present at higher pressure
and temperature.12 The stereoisomers of 15 (four iso-
mers) were separated at this stage by chiral HPLC.13
The isomer lettering order is based on the elution order
n = 0-1
(CH2)n
N
O
N
(CH2)m
m = 1-2
N
H
N
OH
O
5
The syntheses of targets 5 are described in Scheme 1. A
strategy was required that would allow variation of the

S. Ghosh et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5937–5941
5939
ine (NMM) were effective with 20–23. For 24, the usual
coupling conditions were unacceptable because of oxi-
dation to the quinoline. The coupling reagent, bromo-
(CH2)n
O
(CH2)n
N
R
N
t-BuO
a, b
c
O
trispyrrolidinophosphonium
hexafluorophosphate
N
t-BuO
O
(PyBroP), was found to be suitable, without accompa-
nying oxidation. Hydrolysis of the methyl ester was per-
formed under acidic or basic conditions to afford targets
of type 5 (27–31, Table 1).
6, n = 1; 7, n = 0,
R = OH
8, n = 1; 9, n = 0,
R = NMe(OMe)
10, n = 1
11, n = 0
O
The N–Me derivative 33 was produced by alkylation of
the intermediate 1,2,3,4-tetrahydroquinoline 15 (2,6-di-
(t-butyl)pyridine (1.2molequiv), MeI (1.2molequiv),
DMF, 20h, 31%) to give the N-methyl intermediate
32, which was converted to 33 as described above. Com-
pound 34 (Table 1) was prepared by the same method as
described in Scheme 1, beginning with 5-bromo-2-meth-
oxypyridine. The isonipecotamide structures (2, 3) were
prepared as described earlier.8 Full experimental meth-
ods for the preparation and chiral HPLC separation of
a related series are discussed elsewhere.15
(CH2)n
N
(CH2)n
N
d
O
N
O
t-BuO
N
O
t-BuO
OMe
O
OMe
12, n = 1
13, n = 0
14, n = 1
17, n = 0
(CH2)n
(CH2)n
NH
N
O
O
N
N
t-BuO
t-BuO
OMe
OMe
O
O
15, n = 1
18, n = 0
16, n = 1
19, n = 0
The target compounds were evaluated as antagonists of
vitronectin binding to aVb3 and aVb5, and fibrinogen
binding to aIIbb3 (Table 1). SB 265123, included as a ref-
erence compound, is reported to be a potent antagonist
of both aV integrins and to be selective relative to aIIb
(300-fold).4a The original quinoline-substituted isonipe-
cotamide lead 2 was a potent antagonist of aVb3, b ut
was weakly active against aVb5 and not selective relative
to aIIbb3. It was thought that dual antagonism of aVb3
and aVb5 might be an advantage in certain disease
states.2 Replacement of the cyclic guanidine group with
the tetrahydronaphthyridine group in 3 led to a great
improvement in selectivity, which was first observed by
Coleman et al.9 and noted by us in other series.15,17
When the amide of 3 was replaced by a carbon linker
in 27, good dual potency at aVb3 and aVb5 was achieved,
along with excellent selectivity (1400-fold). Compound
27 was compared to 2 in a rat pharmacokinetics (PK)
study,18 but there was no improvement in oral bioavail-
ability for 27 (F = 4%, Cmax = 0.5lM, t1/2 = 3h) versus 2
(F = 4%, Cmax = 0.8lM, t1/2 = 7h, dosed 30mg/kg po).
This result was surprising since a related aVb3 antagonist
containing the tetrahydronaphthyridine and quinoline
groups was orally bioavailable in dogs.9 Analogs of 27
with the quinoline reduced to 5,6,7,8- and 1,2,3,4-tetra-
hydroquinolines (THQ), 28 and 29, were obtained as
byproducts. Compounds 28 and 29 have potency and
selectivity comparable to 27, so it was of interest to test
their PK properties. Although 5,6,7,8-THQ 28 was not
detectable following oral administration, 1,2,3,4-THQ
29 was observed at high levels in the plasma in a pilot
rat PK experiment (21lM at 2h; 15mg/kg, po). There-
fore, the four isomers of 29 (two dl pairs) were prepared
and evaluated. Two of the isomers, 29b and 29d had
good potency in binding assays, so they were examined
in rat PK experiments.19 A dramatic improvement in
oral absorption was noted with 29d (F = 22%,
Cmax = 3lM, t1/2 = 2h) versus quinoline 27. Although
the quinolinyl group has been used extensively in inte-
grin antagonists, the THQ-group has not yet been
described. The N–Me analog 33 showed decreased
potency relative to 29.
(CH2)n
NH
N
(CH2)n
e
N
O
HN
O
HN
HN
O
OMe
OMe
OMe
20, n = 1
23, n = 0
21, n = 1
24, n = 0
22
f, g
(CH2)n
N
O
N
(CH2)m
OH
N
N
(CH2)m
N
N
OH
H
O
H
O
5
25, m = 1
26, m = 2
Scheme 1. (a) MeONHMeÆHCl, NMM (6molequiv), HOBt (0.5mol
equiv), HBTU (1.2molequiv), MeCN, 6–8h, 85–95%. (b) 3-Bromo-
quinoline (2molequiv), THF, BuLi (2molequiv), À90ꢁC (10 or 11,
62%). (c) (MeO)2P(O)CH2–CO2Me (4molequiv), NaHMDS (3mol
equiv), THF, À50ꢁC, reflux after ketone addn., 4h (12, 100%; 13,
65%). (d) Equal wt of 10% Pd/C, MeOH, H2, at 0–8psig for 24h (14,
50%; 17, 68%); at 30psig for 48h (15, 37%, 16, 28%; 18, 49%, 19, 18%);
or half wt of 10% Pd/C, toluene, Et3N, 50ꢁC, 50psig, 28h (15, 73%, 16,
3%). (e) 2N HCl in dioxane, anisole (cat.), 2h, 100%. (f) For 20–23,
NMM (5molequiv), HOBT (0.5molequiv), HBTU (1.2molequiv),
MeCN, DMF, 8–12h (87–93%); for 24, PyBroP, DMF, CH2Cl2, i-
Pr2NEt, 0ꢁC, 1.5h (80–94%). (g) 3N NaOH, MeOH, 24h (79–97%) or
4N HCl, 48h (75–95%).
(isomer-a is faster eluting) of intermediate 15. The
related intermediates 17–19 were prepared similarly
from 13. Intermediates 14–19 were converted to targets
5 by similar methods. The Boc-group was removed with
HCl to give the piperidines, which were individually
coupled with tetrahydronaphthyridine acids 2514 or
26.10 Conditions using O-benzotriazol-1-yl-N,N,N0,N0-
tetramethyluronium hexafluorophosphate (HBTU), 1-
hydroxybenzotriazole (HOBT), and N-methylmorphol-

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S. Ghosh et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5937–5941
It was of interest to compare the 2-methoxypyridine
analog 34, as this group has displayed good PK proper-
ties.4b In our series, neither the racemate 34 (F = 8%,
Cmax = 0.9lM, t1/2 = ND) nor the active isomer 34a
(F = 2%, Cmax = 0.1lM, t1/2 = 2h) had the oral bioavail-
ability seen for 29d. However, the aVb3 potency of 34a
was noteworthy.
References and notes
1. (a) Mousa, S. A. Med. Res. Rev. 2003, 23, 190; (b) Tucker,
G. C. Curr. Opin. Invest. Drugs 2003, 4, 722.
2. Trikha, M.; Zhou, Z.; Nemeth, J. A.; Chen, Q.; Sharp, C.;
Emmell, E.; Giles-Komar, J.; Nakada, M. T. Int. J.
Cancer 2004, 110, 326–335.
3. Miller, W. H.; Keenan, R. M.; Willette, R. N.; Lark, M.
W. Drug Discovery Today 2000, 5, 397.
The quinoline and THQ compounds 30 and 31 (m = 2,
n = 0, Table 1), which lack a carbon atom between the
piperidine and b-position of the carboxylic acid, were
evaluated; they have one additional linker carbon at-
tached to the tetrahydronaphthyridine group. Racemic
30 and 31 had good potency against aVb3, but lesser po-
tency against aVb5 as compared to 27 and 29. The most
active THQ isomer, 31a, was 30-fold more potent
against aVb3 than aVb5. Both of the active THQ isomers,
31a (F = 46%, Cmax = 8lM, t1/2 = 2h) and 31d (F =
52%, Cmax = 58lM, t1/2 = 1h), showed even better
oral bioavailability than what was seen above. The cor-
responding quinoline, 30, was not well absorbed
(F = 1%).
4. (a) Miller, W. H.; Bondinell, W. E.; Cousins, R. D.;
Erhard, K. F.; Jakas, D. R.; Keenan, R. M.; Ku, T. W.;
Newlander, K. A.; Ross, S. T.; Haltiwanger, R. C.;
Bradbeer, J.; Drake, F. H.; Gowen, M.; Hoffman, S. J.;
Hwang, S.-M.; James, I. E.; Lark, M. W.; Lechowska, B.;
Rieman, D. J.; Stroup, G. B.; Vasko-Moser, J. A.;
Zembryki, D. L.; Azzarano, L. M.; Adams, P. C.; Salyers,
K. L.; Smith, B. R.; Ward, K. W.; Johanson, K. O.;
Huffman, W. F. Bioorg. Med. Chem. Lett. 1999, 9, 1807;
(b) Hutchinson, J. H.; Halczenko, W.; Brashear, K. M.;
Breslin, M. J.; Coleman, P. J.; Duong, L. T.; Fernandez-
Metzler, C.; Gentile, M. A.; Fisher, J. E.; Hartman, G. D.;
Huff, J. R.; Kimmel, D. B.; Leu, C.-T.; Meissner, R. S.;
Merkle, K.; Nagy, R.; Pennypacker, B.; Perkins, J. J.;
Prueksaritanont, T.; Rodan, G. A.; Varga, S. L.; Weso-
lowski, G. A.; Zartman, A. E.; Rodan, S. B.; Duggan, M.
E. J. Med. Chem. 2003, 46, 4790.
The relationship of stereochemistry to biological activity
is different in the THQ analogs 29 and 31. The enantio-
meric pairing of isomers was determined by measuring
optical rotations of the intermediates (15, 18) and final
products (29, 31; Table 1). The absolute values of the
four optical rotations were not that different for the four
isomers of 31, making it more difficult to pair the final-
product isomers. For this reason, 1H and 13C NMR
studies were done (D2O, 600MHz) on the four isomers
of 31. The spectra of 31a and 31d were identical to each
other and distinct from the spectra of 31b and 31c; the
spectra of 31b and 31c were also identical. From this
analysis, the two more potent isomers of 29 (b and d)
have a diastereomeric relationship, whereas the two
more potent isomers of 31 (a and d) are enantiomers
of each other. Therefore, the absolute stereochemistry
at the b-position is different for the more potent isomers
of 31, which is not commonly the case with aryl
substituents.
5. Badger, A. M.; Blake, S.; Kapadia, R.; Sarkar, S.; Levin,
J.; Swift, B. A.; Hoffman, S. J.; Stroup, G. B.; Miller, W.
H.; Gowen, M.; Lark, M. W. Arthritis Rheum. 2001, 44,
128.
6. Hoekstra, W. J.; Maryanoff, B. E.; Damiano, B. P.;
Andrade-Gordon, P.; Cohen, J. H.; Costanzo, M. J.;
Haertlein, B. J.; Hecker, L. R.; Hulshizer, B. L.; Kaufman,
J. A.; Keane, P.; McComsey, D. F.; Mitchell, J. A.; Scott,
L.; Shah, R. D.; Yabut, S. C. J. Med. Chem. 1999, 42, 5254.
7. Others have shown that selectivity can be reversed by
utilizing similar templates: Duggan, M. E.; Duong, L. T.;
Fisher, J. E.; Hamill, T. G.; Hoffman, W. F.; Huff, J. R.;
Ihle, N. C.; Leu, C.-T.; Nagy, R. M.; Perkins, J. J.; Rodan,
S. B.; Wesolowski, G.; Whitman, D. B.; Zartman, A. E.;
Rodan, G. A.; Hartman, G. D. J. Med. Chem. 2000, 43,
3736.
8. DeCorte, B. L.; Kinney, W. A.; Liu, L.; Ghosh, S.;
Brunner, L.; Hoekstra, W. J.; Santulli, R. J.; Tuman, R.
W.; Baker, J.; Burns, C.; Proost, J. C.; Tounge, B. A.;
Damiano, B. P.; Maryanoff, B. E.; Johnson, D. L.;
Galemmo, R. A., Jr. Bioorg. Med. Chem. Lett. 2004, 14,
5227.
9. Coleman, P. J.; Askew, B. C.; Hutchinson, J. H.;
Whitman, D. B.; Perkins, J. J.; Hartman, G. D.; Rodan,
G. A.; Leu, C.-T.; Prueksaritanont, T.; Fernandez-Met-
zler, C.; Merkle, K. M.; Lynch, R.; Lynch, J. J.; Rodan, S.
B.; Duggan, M. E. Bioorg. Med. Chem. Lett. 2002, 12,
2463.
Conclusion
The quinoline containing carba-analog 27 was modified
by hydrogenation, which improved its oral bioavailabil-
ity. Conditions were developed to selectively reduce the
quinoline to the 1,2,3,4-tetrahydroquinoline unit. These
1,2,3,4-THQ-containing aV antagonists had good po-
tency and the highest oral bioavailability in this series
thus far. The four individual isomers of the THQ-ana-
logs 29 and 31 were obtained by using chiral HPLC.
Biological activity resided primarily in two of the iso-
mers in each case.
10. Procedures were adapted from those described in: Askew,
B. C.; Coleman, P. J.; Duggan, M. E.; Halczenko, W.;
Hartman, G. D.; Hunt, C. A.; Hutchinson, J. H.;
Meissner, R. S.; Patane, M. A.; Smith, G. R.; Wang, J.
U. S. Patent 6,048,861, 2000; Chem. Abstr. 1999, 404930.
11. To a rapidly stirred, cold (À90ꢁC) solution of the Weinreb
amide 8 (51.2g, 179mmol) and 3-bromo-quinoline (74.7g,
358mmol) in THF (205mL) was added a 1.6M solution
BuLi in hexanes (225mL, 358mmol), maintaining the
internal temperature 6À84ꢁC. The mixture was stirred at
À90ꢁC for 1.5h and the cold bath was removed. The
mixture was stirred for 1h and placed in an ice/water bath
until the internal temperature rose to À6ꢁC. Saturated
aqueous NH4Cl (500mL) was added at such a rated that
the internal temperature was 610ꢁC and the resulting
Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.
bmcl.2004.08.067.

S. Ghosh et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5937–5941
5941
mixture was stirred under nitrogen for 18h. The aqueous
phase was extracted with EtOAc and the organic extracts
were combined, dried over Na2SO4, filtered, and evapo-
rated to give 105g of a dark oil, which was purified by
column chromatography (1.7kg of flash grade silica gel;
eluant: toluene 3L, 15% EtOAc in toluene 14L, 22%
EtOAc in toluene 9L, 28% EtOAc in toluene 7L and
finally 60% EtOAc in toluene 1.8L). Evaporation of
appropriate fractions gave 40.57g of a solid, which was
triturated with 12:1hexane/EtOAc (130mL) and allowed
to stand for 18h. The resulting solid was collected by
filtration and washed with portions of hexane to give
37.8g of the product as a yellow solid. The mother liquors
were concentrated, treated with hexane, EtOAc, and
acetone and filtered to give 2.06g of the product as a
yellow solid. The two batches were combined to give 39.8g
of 10 (62% yield, mp 114–116ꢁC). 1H NMR (CDCl3,
300MHz): d 1.17–1.34 (m, 2H), 1.46 (s, 9H), 1.74–1.84 (m,
2H), 2.16–2.33 (m, 1H), 2.69–2.84 (m, 2H), 3.04 (d,
J = 7.6Hz, 2H), 4.03–4.23 (m, 2H), 7.61–7.68 (m, 1H),
7.83–7.89 (m, 1H), 7.97 (dd, J = 1.5, 9.1Hz, 1H), 8.16 (d,
J = 9.1Hz, 1H), 8.70 (d, J = 1.2Hz, 1H), 9.43 (d,
J = 1.2Hz, 1H). MS (ES+) m/z 396.1 (M+MeCN+H+).
Anal. Calcd for C21H26N2O3Æ0.2 C6H14: C, 71.74; H, 7.84;
N, 7.54. Found: C, 71.77; H, 7.55; N, 7.98.
with isomer-a eluting first) 15a and 15b were separated
from isomers 15c and 15d using a Chiralpakꢂ OD column
[cellulose tris-(3,5-dimethyl-phenylcarbamate) coated on
20-lm silica gel, 41 · 5cm; using methanol as eluant:
23
100vol% at 80mL/min; 220nM]. The isomers 15a (½aŠ
D
+62, c 0.54,
23
D
+30,
c
0.59, MeOH) and 15b (½aŠ
MeOH) were separated using a Chiralpakꢂ AD column
[amylose tris-(3,5-dimethyl-phenylcarbamate) coated on
20-lm silica gel, using ethanol as eluant under the same
23
D
conditions as above]. The isomers 15c (½aŠ À65, c 0.68,
23
MeOH) and 15d (½aŠ À31, c 0.55, MeOH) were separated
D
similarly on a Chiralpakꢂ AD column. The purity of each
isomer was greater than 99% by HPLC.
14. Duggan, M. E.; Hartman, G. D.; Meissner, R. S.; Perkins,
J. J. U. S. Patent 6,410,526, 2002; Chem. Abstr. 2000,
861451.
15. Luci, D. K.; Santulli, R. J.; Gauthier, D. A.; Ghosh, S.;
Kinney, W. A.; DeCorte, B.; Galemmo, R. A., Jr.; Lewis,
J. M.; Proost, J. C.; Tounge, B. A.; Dorsch, W. E.;
Wagaman, M. W.; Damiano, B. P.; Maryanoff, B. E.
Heterocycles 2004, 62, 543.
16. Hoekstra, W. J.; Beavers, M. P.; Andrade-Gordon, P.;
Evangelisto, M. F.; Keane, P. M.; Press, J. B.; Tomko, K.
A.; Fan, F.; Kloczewiak, M.; Mayo, K. H.; Durkin, K. A.;
Liotta, D. C. J. Med. Chem. 1995, 38, 1582.
12. A solution of 12 (17.1g, 41.7mmol) was combined with
10% Pd/C (8.6g) in toluene (210mL) with Et3N (2.1mL).
The reaction mixture was shaken on a Parr apparatus at
50ꢁC and 50psig for about 28h. It was stopped when the
hydrogen uptake slowed. The reaction mixture was filtered
through Celiteꢂ and evaporated. After purification by flash
chromatography on silica gel (11-cm diameter, gradient
elution with 20–30% EtOAc in heptane), 15 was isolated as
17. Lawson, E. C.; Kinney, W. A.; Costanzo, M. J.; Hoekstra,
W. J.; Kauffman, J. A.; Luci, D. K.; Santulli, R.; Tounge,
B. A.; Yabut, S. C.; Andrade-Gordon, P.; Maryanoff, B.
E. Lett. Drug Des. Discovery 2004, 1, 14.
18. Rat PK experiments were done in animals dosed po at
10mg/kg (N = 4) versus iv at 2mg/kg (N = 4), unless
otherwise noted. The drug levels in plasma were compared
by LC/MS. Oral dosing was done in D5W (5% Dextrose
Injection USP, Baxter) adjusted to pH2 with 0.1N HCl
solution. All compounds were fully soluble in this
formulation.
19. As a precaution, analytical reference and plasma samples
of 29 and 31 were treated with acidified (0.1% CF3CO2H)
MeCN during the protein precipitation step, because
significant oxidation to the quinoline occurs in neutral
MeCN.
1
a gum (12.5g, 72%). H NMR (CDCl3, 300MHz): d 1.0–
1.6 (m, 6H), 1.45 (s, 9H), 2.0–2.7 (m, 8H), 3.00 (m, 1H),
3.26 (m, 1H), 3.67 (s, 3H), 3.83 (m, 1H), 4.11 (m, 2H), 6.49
(d, J = 8Hz, 1H), 6.62 (t, J = 7Hz, 1H), 6.97 (m, 2H). MS
(ES+) m/z 417.1 (M+H+). HRMS (FAB+) m/z (M+) Calcd
for C24H36N2O4: 416.2675. Found: 416.2662.
13. The four isomers of 15 were separated by sequential chiral
chromatography. Isomers (lettered based on elution order,