Synthesis and SAR of NPY5 Receptor Antagonists
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 14 2355
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-3-(4-(4-
ch lor op h en oxy)p h en yl)-1-m eth ylu r ea (44d ). Triphosgene
(0.35 g, 1.2 mmol) was dissolved in anhydrous CH2Cl2 (12 mL)
in a 100 mL round-bottomed flask equipped with magnetic
stirring. A solution of 4-amino-4′-chlorodiphenyl ether (0.77
g, 3.5 mmol) and N,N-diisopropylethylamine (1.3 mL, 7.3
mmol) in CH2Cl2 (12 mL) was added to the reaction flask
dropwise through a 25 mL addition funnel over 45 min. Five
minutes after the addition, a solution of (1S,2R)-ephedrine
hemihydrate (1.5 g, 8.6 mmol) in CH2Cl2 (12 mL) was added
all at once to the stirring reaction mixture; a precipitate
immediately formed in the solution. After 1 h, the reaction
mixture was washed with 10% HCl (3 × 30 mL), dried over
MgSO4, and concentrated in vacuo to give a purple oil. Flash
chromatography (1:3 then 1:2 EtOAc-hexanes) afforded the
title compound as a clear oil in 17% yield (0.24 g, 0.59 mmol).
1H NMR (CDCl3; 400 MHz): δ 1.27 (d, 3, J ) 7.1), 2.58 (s, 3),
4.41 (dq, 1, J ) 3.4, 7.0), 4.88 (s, 1), 6.90 (d, 2, J ) 9.0), 6.96
(d, 2, J ) 8.9), 7.25-7.40 (m, 9). MS m/z: 411 (M + 1). Anal.
(C23H23ClN2O3) C, H, N, Cl.
1H NMR (CDCl3; 500 MHz): δ 1.24 (d, 3H, J ) 7.1 Hz), 2.53
(s, 3H), 3.52 (br s, 1H), 4.34 (dq, 1H, J ) 3.3, 7.1 Hz), 4.83
(dd, 1H, J ) 2.7, 2.7 Hz), 6.66 (ddd, 1H, J ) 0.7, 1.5, 7.1 Hz),
7.01-7.38 (m, 13H). MS (ESI, pos. ion) m/z: 377 (M + 1); (ESI,
neg. ion) 375 (M - 1). Anal. (C23H24N2O3‚0.25H2O) C, H, N.
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-1-m eth -
yl-3-(2-p h en oxyp h en yl)u r ea (44j). Following the procedure
described for the synthesis of 1, compound 44j was prepared
from (1S,2R)-ephedrine hemihydrate (1 g, 6 mmol) and 2-phe-
noxyphenyl isocyanate (420 mg, 2 mmol) in CH2Cl2 (6 mL). A
white amorphous solid was isolated in a 95% yield (700 mg,
1
1.9 mmol). H NMR (CDCl3; 400 MHz): δ 1.19 (d, 3H, J ) 7
Hz), 2.48 (s, 3H), 3.71 (br s, 1H), 4.37 (m, 1H), 4.82 (m, 1H),
6.8-7.4 (m, 14H), 8.22 (d, 1H, J ) 8 Hz). MS (ESI, pos. ion)
m/z: 377 (M + 1); (ESI, neg. ion) 375 (M - 1). Anal. (C23H24
N2O3) C, H, N.
-
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-1-m eth -
yl-3-(4-p h en oxyp h en ylm et h yl)u r ea (45). Following the
procedure described for the synthesis of 44a , compound 45 was
prepared from compound 31 (1.0 g, 5 mmol), phosgene (5 mL
of a 2 M solution in toluene, 10 mmol), and (1S,2R)-ephedrine
hemihydrate (2.6 g, 15 mmol). Flash chromatography (1:1
EtOAc-hexanes) afforded an off-white foam in 66% yield (1.3
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-1-m eth -
yl-3-(4-(4-p h en ylm eth oxy)p h en yl)u r ea (44e). Following
the procedure described for the synthesis of 1, compound 44e
was prepared from (1S,2R)-ephedrine hemihydrate (1 g, 6
mmol) and 4-benzyloxyphenyl isocyanate (450 mg, 2 mmol)
in EtOH (6 mL). A white amorphous solid was isolated in a
1
g, 3.3 mmol). Mp: 46-52 °C. H NMR (CDCl3; 400 MHz): δ
1.22 (d, 3H, J ) 7.2 Hz), 2.50 (s, 3H), 4.25-4.42 (m, 4H), 4.78-
4.82 (m, 2H), 6.96-7.02 (m, 4H), 7.09-7.13 (m, 1H), 7.23-
7.38 (m, 9H). MS (ESI, pos. ion) m/z: 391 (M + 1); (ESI, neg.
ion) 389 (M - 1). Anal. (C24H26N2O3) C, H, N.
1
60% yield (460 mg, 1.2 mmol). H NMR (CDCl3; 400 MHz): δ
1.22 (d, 3H, J ) 10 Hz), 2.53 (s, 3H), 4.14 (br s, 1H), 4.33 (m,
1H), 4.81 (m, 1H), 5.03 (s, 2H), 6.84 (br s, 1H), 6.90 (d, 2H,
J ) 9 Hz), 7.22 (d, 2H, J ) 9 Hz), 7.30-7.5 (m, 10H). MS (ESI,
pos. ion) m/z: 391 (M + 1); (ESI, neg. ion) 389 (M - 1). Anal.
(C24H26N2O3‚0.25H2O) C, H, N.
1-((1R,2S)-2-Hydr oxy-1-m eth yl-2-ph en yleth yl)-3-(diben -
zo[b,d ]fu r a n -2-yl)-1-m eth ylu r ea (46). Following the proce-
dure described for the synthesis of 44a , compound 46 was
prepared from 2-aminobenzofuran (purchased as the HCl salt
and converted to the neutral form prior to the reaction) (170
mg, 0.91 mmol), phosgene (0.91 mL of a 2 M solution in
toluene, 1.8 mmol), and (1S,2R)-ephedrine hemihydrate (480
mg, 2.7 mmol). A white amorphous solid was isolated in 83%
yield (280 mg, 0.75 mmol). 1H NMR (CDCl3; 500 MHz): δ 1.30
(d, 3H, J ) 7.1 Hz), 2.64 (s, 3H), 3.61 (br s, 1H), 4.46 (dq, 1H,
J ) 3.3, 7.1 Hz), 4.92 (dd, 1H, J ) 2.8, 2.8 Hz), 7.05 (br s, 1H),
7.27 (m, 1H), 7.32 (t, 2H, J ) 7.4 Hz), 7.38 (t, 2H, J ) 7.4 Hz),
7.43-7.48 (m, 4H), 7.54 (d, 1H, J ) 8.3 Hz), 7.93 (d, 1H, J )
7.6 Hz), 8.10 (d, 1H, J ) 2.1 Hz). MS (ESI, pos. ion) m/z: 375
(M + 1); (ESI, neg. ion) 373 (M - 1). Anal. (C23H22N2O3‚0.2H2O)
C, H, N.
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-3-(9-eth -
ylca r ba zol-3-yl)-1-m eth ylu r ea (47). Following the procedure
described for the synthesis of 44a , compound 47 was prepared
from 3-amino-9-ethylcarbazole (1.1 g, 4.8 mmol), phosgene (4.8
mL of a 2 M solution in toluene, 9.6 mmol), and (1S,2R)-
ephedrine hemihydrate (2.4 g, 14 mmol). A brown amorphous
solid was isolated in 88% yield (1.7 g, 4.2 mmol). 1H NMR
(CDCl3; 500 MHz): δ 1.29 (d, 3H, J ) 7.2 Hz), 1.42 (t, 3H,
J ) 7.1 Hz), 2.64 (s, 3H), 4.15 (br s, 1H), 4.35 (q, 2H, J ) 7.3
Hz), 4.47 (dq, 1H, J ) 3.9, 6.8 Hz), 4.92 (t, 1H, J ) 2 Hz), 7.20
(t, 1H, J ) 7.2 Hz), 7.30-7.47 (m, 10H), 8.07 (d, 1H, J ) 7.2
Hz). MS (ESI, pos. ion) m/z: 402 (M + 1); (ESI, neg. ion) 400
(M - 1). Anal. (C25H27N3O2) C, H. N.
Biologica l Assa y. The radioligand binding assay and
membrane preparation for the NPY5 receptor are described
in ref 21. The functional (cAMP) assay is described here.
Human embryonic kidney cells (HEK 293) expressing the
human Y5 receptor were seeded into 96-well fibronectin coated
plates to a density of 75 000 cells/well. Plates were used for
assay roughly 48 h after seeding. To start the assay, cells were
preequilibrated in 100 µL of cAMP buffer (145 mM NaCl, 5
mM KCl, 1 mM MgSO4, 10 mM HEPES, 10 mM Glucose, 0.5%
BSA, 250 µM IBMX, pH 7.4) for 5 min at 37 °C, then
preincubated again for 5 min at room temperature with
different concentrations of test compound over six log units
(final concentration from 0.1 to 10 000 nM). NPY (10 µL, final
concentration 5 nM) and forskolin (10 µL, final concentration
10 µM) were added and incubated for 1 h at 37 °C in 5% CO2.
Intracellular cAMP was extracted with 0.2 N HCl at room
temperature for 15 min and quantified by radioimmunoassay
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-1-m eth -
yl-3-p h en ylu r ea (44f). Following the procedure described for
the synthesis of 1, compound 44f was prepared from (1S,2R)-
ephedrine hemihydrate (1 g, 6 mmol) and phenyl isocyanate
(0.22 mL, 2 mmol) in EtOH (6 mL). A white amorphous solid
was isolated in 80% yield (460 mg, 1.6 mmol). 1H NMR (CDCl3;
400 MHz): δ 1.21 (d, 3H, J ) 7 Hz), 2.5 (s, 3H), 4.1 (br s, 1H),
4.32 (m, 1H), 4.79 (m, 1H), 7.02 (t, 1H, J ) 7 Hz), 7.2-7.4 (m,
9H). MS (ESI, pos. ion) m/z: 285 (M + 1); (ESI, neg. ion) 283
(M - 1). Anal. (C17H20N2O2‚0.1H2O) C, H, N.
1-((1R,2S)-2-Hydr oxy-1-m eth yl-2-ph en yleth yl)-3-(4-ben -
zylp h en yl)-1-m eth ylu r ea (44g). Following the procedure for
the synthesis of 44a , compound 44g was prepared from
4-aminodiphenylmethane (1 g, 5.5 mmol), phosgene (5 mL of
a 2 M solution in toluene, 10 mmol), and (1S,2R)-ephedrine
hemihydrate (2.6 g, 15 mmol) to afford a white amorphous solid
1
in 93% yield (1.9 g, 5.1 mmol). H NMR (CDCl3; 500 MHz): δ
1.25 (d, 3H, J ) 7 Hz), 2.56 (s, 3H), 3.81 (br s, 1H), 3.94 (s,
2H), 4.37 (m, 1H), 4.86 (m, 1H), 6.82 (br s, 1H), 7.11 (d, 2H,
J ) 8 Hz), 7.15-7.42 (m, 12H). MS (ESI, pos. ion) m/z: 375
(M + 1); (ESI, neg. ion) 373 (M - 1). Anal. (C24H26N2O2)
C, H, N.
1-((1R,2S)-2-Hydr oxy-1-m eth yl-2-ph en yleth yl)-3-(4-(eth -
ylp h en yla m in o)p h en yl)-1-m eth ylu r ea (44h ). Following the
procedure described for the synthesis of 44a , compound 44h
was prepared from compound 29 (543 mg, 2.6 mmol), phosgene
(2.6 mL of a 2 M solution in toluene, 5.1 mmol), and (1S,2R)-
ephedrine hemihydrate (1.3 g, 7.7 mmol). Flash chromatog-
raphy (2:1 hexanes-EtOAc) afforded a brown amorphous solid
in 32% yield (330 mg, 0.82 mmol). 1H NMR (CDCl3; 400
MHz): δ 1.20 (t, 3H, J ) 7 Hz), 1.27 (d, 3H, J ) 7 Hz), 2.59 (s,
3H), 2.74 (q, 2H, J ) 7 Hz), 3.75 (br s, 1H), 4.41 (dq, 1H, J )
3, 7 Hz), 4.89 (t, 1H, J ) 3 Hz), 6.81 (t, 2H, J ) 7 Hz), 6.89 (t,
2H, J ) 7 Hz), 7.2 (m, 2H), 7.29-7.43 (m, 8H). MS m/z: 404
(M + 1). Anal. (C25H29N3O2) C, H, N.
1-((1R,2S)-2-Hyd r oxy-1-m eth yl-2-p h en yleth yl)-1-m eth -
yl-3-(3-p h en oxyp h en yl)u r ea (44i). Following the procedure
described for the synthesis of 44a , compound 44i was prepared
from 3-phenoxyaniline (170 mg, 0.91 mmol), phosgene (0.91
mL of a 2 M solution in toluene, 1.8 mmol), and (1S,2R)-
ephedrine hemihydrate (480 mg, 2.7 mmol). A white amor-
phous solid was isolated in a 76% yield (260 mg, 0.69 mmol).