Journal of Medicinal Chemistry
Article
and washed with a sat. aq. solution of NaHCO3 (2×) followed by
brine, dried over MgSO4, filtered, and concentrated in vacuo. The
residue was purified by flash chromatography (silica gel; EtOAc) to
afford benzimidazole 6 (second elute, tan foam, 3.98 g, 41%) and the
bis-acylated side-product tert-butyl (2S)-2-({5-bromo-2-[(2S)-1-[(tert-
butoxy)carbonyl]pyrrolidine-2-amido]phenyl}carbamoyl)pyrrolidine-
1.97H), 7.51 (dd, J = 8.4, 1.4 Hz, 0.33H), 7.38−7.27 (m, 3.54H),
7.27−7.20 (m, 4.97H), 7.20−7.08 (m, 0.90H), 7.08−7.00 (m, 0.61H),
5.52 (dd, J = 8.0, 2.0 Hz, 0.31H), 5.29 (dd, J = 8.4, 3.1 Hz, 1.69H),
3.98−3.87 (m, 1.63H), 3.79 (t, J = 1.0 Hz, 3.72H), 3.72−3.49 (m,
2.35H), 3.38 (d, J = 15.6 Hz, 0.30H), 2.50−2.28 (m, 2.12H), 2.26−
2.01 (m, 5.15H), 2.01−1.77 (m, 0.73H). Note: signals for the two
exchangeable NH protons were not observed. LC (method A): tR =
3.38 min. LC/MS (ESI) m/z calcd for C40H37N6O2, 633.30; found,
633.35 [M + H]+. HRMS (ESI) m/z calcd for C40H37N6O2, 633.2978;
found, 633.2958 [M + H]+.
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1-carboxylate (brown foam, 1.3 g, 8%). Bromide 6: H NMR (400
MHz, DMSO-d6) δ 12.53 (br s, 0.32H), 12.47 (br s, 0.27H), 12.44 (br
s, 0.23H), 12.37 (br s, 0.18H), 7.75 (d, J = 1.8 Hz, 0.54H), 7.67−7.59
(m, 0.46H), 7.52 (d, J = 8.5 Hz, 0.45H), 7.42 (d, J = 8.5 Hz, 0.55H),
7.34−7.23 (m, 1H), 5.02−4.94 (m, 0.41H), 4.90 (dd, J = 7.8, 3.8 Hz,
0.59H), 3.69−3.50 (m, 1H), 3.50−3.38 (m, 1H), 2.46−2.15 (m, 1H),
2.12−1.77 (m, 3H), 1.41 (s, 3.64H), 1.07 (s, 5.36H). 13C NMR (101
MHz, DMSO-d6) δ 158.0, 157.6, 157.3, 156.8, 153.1, 152.5, 144.0,
141.6, 141.6, 134.6, 134.5, 132.4, 123.5, 123.2, 120.1, 120.0, 119.4,
119.3, 113.2, 113.0, 112.9, 112.4, 112.3, 112.1, 78.2, 77.7, 54.9, 54.4,
54.4, 46.0, 45.7, 32.5, 31.1, 27.4, 27.0, 23.2, 22.5. LC/MS (ESI) m/z
calcd for C16H21N3O2Br, 366.08; found, 366.21 [M + H]+. HRMS
(ESI) m/z calcd for C16H21N3O2Br, 366.0817; found, 366.0800 [M +
(2R)-2-(Dimethylamino)-1-[(2S)-2-[5-(2-{2-[(2S)-1-[(2R)-2-(di-
methylamino)-2-phenylacetyl] pyrrolidin-2-yl]-1H-1,3-benzo-
diazol-5-yl}ethynyl)-1H-1,3-benzodiazol-2-yl]pyrrolidin-1-yl]-
2-phenylethan-1-one (9b). Title compound 9b (TFA salt, light
yellow solid) was prepared from 8 and (R)-2-(dimethylamino)-2-
phenylacetic acid·HCl according to the procedure described for 9a.
For purposes of comparing the activities of different forms in replicon
medium, a portion of the sample was free-based with MCX cartridge
(MeOH wash, 2.0 N NH3/MeOH elution) to afford a light yellow
1
1
solid. TFA salt: H NMR (400 MHz, DMSO-d6) δ 10.25 (br s, 2H),
H]+. Side product: H NMR (400 MHz, DMSO-d6) δ 9.97−9.05 (m,
7.86 (s, 1.69H), 7.69 (s, 0.86H), 7.67 (s, 0.98H), 7.66−7.55 (m,
8.69H), 7.55−7.46 (m, 1.81H), 7.45−7.30 (m, 0.67H), 7.07−6.97 (m,
0.51H), 6.97−6.88 (m, 0.29H), 6.88−6.76 (m, 0.50H), 5.81 (d, J = 8.3
Hz, 0.24H), 5.54 (s, 1.70H), 5.47 (br s, 0.30H), 5.27 (dd, J = 8.4, 2.6
Hz, 1.76H), 4.18−4.02 (m, 1.73H), 3.95−3.81 (m, 0.27H), 3.76−3.63
(m, 0.24H), 3.18−3.07 (m, 1.76H), 3.05−2.69 (m, 6H), 2.46 (br s,
5H), 2.35 (app s, 1H), 2.31−2.20 (m, 1.78H), 2.19−2.01 (m, 3.85H),
2.01−1.77 (m, 2.37H). LC (method J): tR = 0.99 min. LC/MS (ESI)
m/z calcd for C44H47N8O2, 719.38; found, 719.38 [M + H]+. HRMS
(ESI) m/z calcd for C44H47N8O2, 719.3822; found, 719.3799 [M +
H]+.
Methyl N-[(1R)-2-[(2S)-2-[5-(2-{2-[(2S)-1-[(2R)-2-
[(Methoxycarbonyl)amino]-2-phenylacetyl]pyrrolidin-2-yl]-1H-
1,3-benzodiazol-5-yl}ethynyl)-1H-1,3-benzodiazol-2-yl]-
pyrrolidin-1-yl]-2-oxo-1-phenylethyl]carbamate (9c). Title com-
pound 9c (TFA salt, light yellow solid) was prepared from 8 and (R)-
2-((methoxycarbonyl) amino)-2-phenylacetic acid according to the
procedure described for 9a. 1H NMR (400 MHz, DMSO-d6) δ 7.96 (s,
1.59H), 7.94−7.83 (m, 0.54H), 7.78 (app d, J = 8.5 Hz, 1.66H), 7.73
(app d, J = 8.0 Hz, 1.80H), 7.69−7.60 (m, 1.62H), 7.51 (app s,
0.66H), 7.47−7.40 (m, 5.90H), 7.40−7.27 (m, 2.77H), 6.98−6.88 (m,
0.62H), 6.88−6.77 (m, 0.86H), 5.77 (app d, J = 8.0 Hz, 0.29H), 5.57
(d, J = 8.0 Hz, 1.63H), 5.40 (d, J = 7.8 Hz, 0.37H), 5.29 (dd, J = 8.4,
2.1 Hz, 1.71H), 4.07−3.89 (m, 1.80H), 3.88−3.66 (m, 0.46H), 3.65−
3.54 (m, 3.40H), 3.51 (s, 3H), 3.30−3.19 (m, 1.34H), 2.46−2.20 (m,
1.85H), 2.20−2.02 (m, 3.84H), 2.01−1.80 (m, 2.31H). Note: signals
for the two exchangeable NH protons were not observed. LC (method
A): tR = 3.40 min. LC/MS (ESI) m/z calcd for C44H43N8O6, 779.33;
found, 779.45 [M + H]+. HRMS (ESI) m/z calcd for C44H43N8O6,
779.3306; found, 779.3273 [M + H]+.
2H), 8.22−7.16 (m, 3H), 4.39−4.20 (m, 2H), 3.52−3.36 (m, 4H),
2.34−2.08 (m, 2H), 1.96−1.72 (m, 6H), 1.43 (s, 8H), 1.33 (s, 10H).
LC/MS (ESI) m/z calcd for C26H37N4O6BrNa, 603.18; found, 603.24
[M + Na]+.
To a reaction vessel containing a solution of 1,2-bis-
(trimethylstannyl)ethyne (1.00 g, 2.84 mmol) and 6 (2.19 g, 5.97
mmol) in DMF (25 mL) was added Pd(Ph3P)4 (0.329 g, 0.284
mmol). The mixture was thoroughly flushed with N2 before being
sealed and heated at 80 °C for 23 h. After it was allowed to cool to rt,
the volatile component was removed in vacuo. The residue was
purified by flash chromatography (silica gel; EtOAc) to afford a light
yellow foam (811.6 mg). The foam was dissolved in EtOH (6 mL)
with heating and allowed to cool to rt to afford 7 as a light yellow solid
(421 mg). The filtrate was heated and allowed to cool again to afford a
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second crop of 7 (120 mg), resulting in a combined yield of 32%. H
NMR (400 MHz, DMSO-d6) δ 12.57−12.47 (series of s, 1.18H),
12.47−12.36 (series of s, 0.82H), 7.76 (app d, J = 6.0 Hz, 1H), 7.69−
7.62 (m, 1H), 7.58 (dd, J = 8.3, 1.8 Hz, 1H), 7.49 (app d, J = 8.0 Hz,
1H), 7.42−7.27 (m, 2H), 5.06−4.97 (m, 0.81H), 4.97−4.87 (m,
1.19H), 3.70−3.53 (m, 2H), 3.53−3.39 (m, 2H), 2.48−2.17 (m, 2H),
2.16−1.82 (m, 6H), 1.42 (s, 7.26H), 1.08 (s, 10.74H). 13C NMR (101
MHz, DMSO-d6) δ 158.1, 157.9, 157.4, 157.2, 153.1, 152.5, 142.7,
142.4, 133.5, 133.2, 124.6, 124.0, 120.6, 117.9, 114.9, 114.5, 113.5,
113.2, 111.0, 110.7, 88.4, 88.3, 87.9, 87.8, 78.2, 77.7, 55.0, 54.5, 46.1,
45.8, 32.6, 31.2, 27.4, 27.0, 23.2, 22.5. LC/MS (ESI) m/z calcd for
C34H41N6O4, 597.32; found, 597.43 [M + H]+. HRMS (ESI) m/z
calcd for C34H41N6O4, 597.3189; found, 597.3184 [M + H]+.
To a suspension of 7 (0.410 g, 0.687 mmol) in 4 N HCl in dioxane
(80 mL) was added MeOH (20 mL), and the mixture was stirred at rt
for 17 h. The volatile component was removed in vacuo, and the
resultant solid was dissolved in MeOH (25 mL) and treated with Et2O
to cause precipitation. The solid was filtered and dried in vacuo to
afford the HCl salt of 8 as a tan solid (315 mg, 85% assuming 4 equiv
of HCl). 1H NMR (400 MHz, DMSO-d6) δ 10.74 (br s, 2H), 9.79 (br
s, 2H), 9.68 (br s, 4H), 7.96 (s, 2H), 7.77 (d, J = 8.5 Hz, 2H), 7.59
(dd, J = 8.4, 1.4 Hz, 2H), 5.20−4.94 (m, 2H), 3.63−3.24 (m, 4H),
2.63−2.53 (m partially hidden under DMSO, 2H), 2.47−2.31 (m,
2H), 2.27−2.13 (m, 2H), 2.13−1.99 (m, 2H). 13C NMR (101 MHz,
DMSO-d6) δ 149.9, 135.3, 135.3, 126.5, 117.3, 116.8, 114.7, 88.4, 53.7,
44.6, 29.1, 22.9. LC/MS (ESI) m/z calcd for C24H25N6, 397.21; found,
397.23 [M + H]+. HRMS (ESI) m/z calcd for C24H25N6, 397.2141;
found, 397.2126 [M + H]+.
2-Phenyl-1-[(2S)-2-[5-(2-{2-[(2S)-1-(2-phenylacetyl)-
pyrrolidin-2-yl]-1,3-benzoxazol-5-yl}ethynyl)-1,3-benzoxazol-
2-yl]pyrrolidin-1-yl]ethan-1-one (15a). To a mixture of 2-amino-
4-bromophenol (5.0 g, 27 mmol), (S)-1-(tert-butoxycarbonyl)
pyrrolidine-2-carboxylic acid (5.72 g, 26.6 mmol), and HOBT (3.95
g, 29.3 mmol) in CH2Cl2 (130 mL) at rt was added EDCI (5.61 g,
29.3 mmol), and the mixture was stirred for 20 h. It was diluted with
CH2Cl2 and washed with water (2×) and brine, dried over MgSO4,
filtered, and concentrated in vacuo to afford a tan foam. To a solution
of the foam and Ph3P (7.67 g, 29.3 mmol) in THF (150 mL) at rt was
added DIAD (5.69 mL, 29.3 mmol) dropwise over a few minutes, and
the mixture was stirred for 21 h. The volatile component was removed
in vacuo, and the residue was triturated with Et2O and hexanes (30:1
v/v), and the precipitate was filtered off. The filtrate was concentrated
in vacuo, and the residue was purified by flash chromatography (silica
gel; 15−25% EtOAc/hexanes) to afford 12a as a viscous orange oil
containing residual EtOAc in a 1.0:0.17 product/EtOAc mole ratio
To a solution of the HCl salt of 8 (60.0 mg, 0.111 mmol), 2-
phenylacetic acid (0.033 g, 0.24 mmol), and DIEA (0.16 mL, 0.89
mmol) in DMF (2 mL) was added HATU (88.0 mg, 0.232 mmol).
The reaction mixture was stirred at rt for 1.5 h. It was then diluted
with MeOH (2 mL) and purified by reverse-phase HPLC (MeOH/
H2O/TFA) to afford the TFA salt of title compound 9a as an off-white
solid (42 mg, 44%). 1H NMR (400 MHz, DMSO-d6) δ 7.95 (s,
1.67H), 7.88−7.81 (m, 0.34H), 7.81−7.72 (m, 1.67H), 7.69−7.58 (m,
1
(7.44 g, ∼75%). H NMR (400 MHz, DMSO-d6) δ 8.06−7.92 (m,
1H), 7.80−7.66 (m, 1H), 7.56 (dd, J = 8.5, 1.8 Hz, 1H), 5.09−5.01
(m, 0.38H), 4.99 (dd, J = 8.0, 4.5 Hz, 0.62H), 3.64−3.50 (m, 1H),
3.50−3.38 (m, 1H), 2.49−2.24 (m, 1H), 2.18−1.83 (m, 3H), 1.39 (s,
2003
dx.doi.org/10.1021/jm4016203 | J. Med. Chem. 2014, 57, 1995−2012