Journal of Medicinal Chemistry
Article
acid, v/v) as the mobile phase. The flow rate was 0.7 mL/min, and the
absorbance at 260 nm was monitored.
11.59 (1H, s), 7.60 (1H, s), 6.39 (1H, s), 1.87 (2H, t, J = 6.5 Hz),
1.85 (2H, t, J = 6.5 Hz), 1.66 (2H, t, J = 1.9 Hz), 1.65 (2H, t, J = 1.9
−
6-[N-Ethyl-N-(2-benzamido-5-isobutoxy-4-isopropylphenyl)-
amino]nicotinic Acid (6). 16a (92 mg, 0.18 mmol) was dissolved in 4
N HCl/EtOAc (1 mL). The solution was stirred at room temperature
for 0.25 h, then evaporated under reduced pressure, and neutralized
with sat. NaHCO3 aq. The aqueous layer was extracted with EtOAc
(3 × 20 mL). The combined organic layer was washed with H2O (2 ×
20 mL) and brine (20 mL) and then dried over MgSO4. The solvent
was evaporated under reduced pressure to afford 82 mg of 6 as a
white solid (96%), which was recrystallized from EtOAc/n-hexane to
Hz), 1.02 (4H, m). MS (ESI−) m/z: 284 [M − H] .
Ethyl 6-[N-Ethyl-N-(5-isobutoxy-4-isopropylphenyl)amino]-
nicotinate (11). To a solution of 3 (356 mg, 1.0 mmol) in EtOH
(10 mL) was added concentrated H2SO4 (160 μL, 3.0 mmol). The
reaction mixture was refluxed for 21 h and then poured into ice water
(50 mL). The aqueous layer was extracted with EtOAc (2 × 100 mL).
The combined organic layer was washed with H2O (2 × 100 mL) and
brine (50 mL) and dried over MgSO4. The solvent was evaporated
under reduced pressure to afford 385 mg of 11 as a brown oil (q.y.).
1H-NMR (300 MHz, CDCl3): δ 8.86 (1H, d, J = 2.3 Hz), 7.80 (1H,
1
afford 60 mg of 6 as white needles. mp 193.1−194.5 °C. H-NMR
(400 MHz, CDCl3): δ 8.96 (1H, dd, J = 2.4, 1.0 Hz), 8.37 (1H, brs),
7.94 (1H, dd, J = 8.8, 2.4 Hz), 7.85 (1H, br s), 7.59−7.57 (2H, m),
7.48 (1H, tt, J = 7.3, 1.5 Hz), 7.41−7.36 (2H, m) or 7.38 (2H, tt, J =
7.3, 1.5 Hz), 6.63 (1H, s), 6.25 (1H, dd, J = 8.8, 1.0 Hz), 4.05 (2H, s),
3.67 (2H, d, J = 6.6 Hz), 3.40 (1H, sep, J = 6.8 Hz), 2.13 (1H, sep, J =
6.6 Hz), 1.32 (6H, d, J = 6.8 Hz), 1.28 (3H, t, J = 6.8 Hz), 1.06 (6H,
d, J = 6.6 Hz). 13C-NMR (100 MHz, CDCl3): δ: 171.23, 170.78,
165.20, 160.54, 154.09, 151.98, 138.97, 134.53, 131.79, 128.80,
128.29, 126.67, 120.77, 115.08, 110.68, 107.32, 74.62, 60.40, 45.13,
28.45, 27.28, 22.46, 21.01, 19.36, 14.15, 13.06. Calcd for C28H33N3O4:
C, 70.71; H, 6.99; N, 8.84. Found: C, 70.45; H, 7.08; N, 8.71. HRMS
(ESI−) m/z: [M − H]− Calcd for C28H32N3O4 474.2398; Found
474.2402. Analytical HPLC (MeOH/H2O = 80:20 + 0.1% formic
acid): 8.7 min; 99.80% purity.
dd, J = 9.1, 2.3 Hz), 7.25 (1H, d, J = 8.1 Hz), 6.76 (1H, dd, J = 8.1,
2.0 Hz), 6.64 (1H, d, J = 2.0), 6.25 (1H, d, J = 9.1 Hz), 4.32 (2H, q, J
= 7.2 Hz), 4.03 (2H, q, J = 6.8 Hz), 3.67 (2H, d, J = 6.0 Hz), 3.36
(1H, sep, J = 6.9 Hz), 2.12 (1H, sep, J = 6.8 Hz), 1.35 (3H, t, 7.2 Hz),
1.26 (6H, d, J = 6.9 Hz), 1.24 (3H, t, J = 6.8 Hz), 1.06 (6H, d, J = 6.8
Hz).
Ethyl 6-[N-Ethyl-N-(5-isobutoxy-4-isopropyl-2-nitrophenyl)-
amino]nicotinate (12). To a solution of 11 (910 mg, 2.4 mmol) in
Ac2O (12 mL) was added a mixture of concentrated HNO3 (0.5 mL,
7.2 mmol) and Ac2O (1.6 mL) on ice. The reaction mixture was
stirred at room temperature for 0.5 h and then neutralized with sat.
NaHCO3 aq. The aqueous layer was extracted with EtOAc (3 × 50
mL). The combined organic layer was washed with H2O (2 × 100
mL) and brine (100 mL) and dried over MgSO4. The solvent was
evaporated under reduced pressure, and the residue was purified by
flash column chromatography (n-hexane/EtOAc = 10:1) to afford
768 mg of 12 as a brown oil (75%). 1H-NMR (300 MHz, CDCl3): δ
8.82 (1H, d, J = 2.4 Hz), 8.02 (1H, s), 7.93 (1H, dd, J = 9.0, 2.4 Hz),
6.69 (1H, s), 6.24 (1H, d, J = 9.0 Hz), 4.32 (2H, q, 7.2 Hz), 3.78 (2H,
d, J = 6.4 Hz), 3.36 (1H, sep, J = 6.9 Hz), 2.16 (1H, sep, J = 6.4 Hz),
1.35 (3H, t, J = 7.2 Hz), 1.32−1.24 (11H, m), 1.07 (6H, d, J = 6.4
Hz). 13C-NMR (75 MHz, CDCl3): δ 165.86, 161.05, 159.68, 150.96,
139.52, 138.13, 137.41, 137.21, 124.35, 115.83, 112.94, 106.30, 75.05,
60.35, 45.83, 28.27, 27.00, 22.05, 20.99, 19.18, 14.30, 13.08.
6-[N-Ethyl-N-(5-isobutoxy-4-isopropyl-2-nitrophenyl)amino]-
nicotinic Acid (13). To a solution of 12 (669 mg, 1.56 mmol) in
EtOH (8 mL) was added 2 N NaOHaq (8 mL). The mixture was
stirred at 80 °C for 1 h and then evaporated under reduced pressure.
The residue was poured into 2 N HCl aq. and extracted with EtOAc
(50 mL × 2). The combined organic layer was washed with H2O (2 ×
50 mL) and brine (50 mL) and dried over MgSO4. The solvent was
evaporated under reduced pressure to afford 530 mg of 13 as a yellow
6-[N-Ethyl-N-(5-isobutoxy-4-isopropyl-2-(11-oxo-2,3,6,7-tetrahy-
dro-1H,5H,11H-pyrano[2,3-f ]pyrido[3,2,1-ij]quinoline-10-
carboxamido)phenyl)amino]nicotinic Acid (7). A solution of 16b
(105 mg, 0.15 mmol) in 4 N HCl/EtOAc (4 mL) was stirred at room
temperature for 0.5 h and then evaporated under reduced pressure.
The residue was recrystallized from EtOH/EtOAc to afford 65 mg of
1
7 as an orange solid (58%). mp 293.8−296.1 °C. H-NMR (400
MHz, CDCl3): δ 10.99 (1H, s), 9.03 (1H, s), 8.59 (1H, s), 8.38 (1H,
s), 8.18 (1H, d, J = 7.4 Hz), 6.99 (1H, s), 6.60 (1H, s), 6.50 (1H d, J
= 7.4 Hz), 4.34 (2H, q, J = 7.1 Hz), 3.68 (2H, d, J = 6.0 Hz), 3.40
(1H, sep, J = 3.0 Hz), 3.35 (2H, t, J = 5.8 Hz), 3.33 (2H, t, J = 6.8
Hz), 2.85 (2H, t, J = 6.2 Hz), 2.77 (2H, t, J = 6.0 Hz), 2.14 (1H, sep, J
= 6.5 Hz), 1.96 (4H, m), 1.42 (3H, t, J = 7.1 Hz), 1.33−1.28 (8H, m),
1.07 (6H, d, J = 6.5 Hz). 13C-NMR (75 MHz, CDCl3): δ 175.61,
171.14, 163.95, 163.40, 161.82, 153.99, 152.92, 152.43, 148.78,
148.12, 140.94, 139.67, 127.69, 127.28, 127.08, 121.37, 120.07,
116.85, 108.15, 106.66, 105.45, 74.53, 60.21, 50.08, 49.66, 48.35,
28.14, 27.14, 27.06, 22.13, 22.04, 20.79, 20.70, 19.63, 19.08, 13.90,
12.18. Calcd for C37H42N4O6·1/2 H2O: C, 68.61; H, 6.69; N, 8.65.
Found: C, 68.41; H, 6.58; N, 8.57. HRMS (ESI−) m/z: [M − H]−
Calcd for C37H41N4O6 637.3032; Found 637.3035. Analytical HPLC
(MeOH/H2O = 95:5 + 0.1% formic acid): 6.3 min; 95.03% purity.
Ethyl 11-Oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f ]-
pyrido[3,2,1-ij]quinoline-10-carboxylate (9). 2,3,6,7-Tetrahydro-8-
hydroxy-1H,5H-benzo[ij]quinolizine-9-carboxaldehyde (435 mg, 2.0
mmol) was added to a mixture of diethyl malonate (8) (1.0 mL, 66
mmol) and piperidine (390 μL, 4.0 mmol). The reaction mixture was
stirred at 30 °C for 3 h, and then H2O (10 mL) was added to afford a
brown precipitate, which was collected and dissolved in EtOAc (120
mL). The solution was washed with H2O (2 × 120 mL) and brine
(120 mL), dried over MgSO4, filtered, and evaporated under reduced
pressure. The residue was purified by flash column chromatography
(n-hexane/EtOAc = 2:1) to afford 272 mg of 9 as colorless needles
1
solid (85%). H-NMR (400 MHz, CDCl3): δ 8.88 (1H, d, J = 2.2
Hz), 8.03 (1H, s), 7.96 (1H, dd, J = 9.1, 2.2 Hz), 6.68 (1H, s), 6.23
(1H, d, J = 9.1 Hz), 3.78 (2H, d, J = 6.3 Hz), 3.36 (1H, sep, J = 6.9
Hz), 2.17 (1H, sep, J = 6.6 Hz), 1.32−1.26 (11H, m), 1.07 (6H, d, J =
6.6 Hz). 13C-NMR (100 MHz, CDCl3): δ 171.35, 161.15, 160.14,
151.90, 139.37, 138.62, 137.70, 136.92, 124.43, 114.67, 113.02,
106.53, 75.10, 45.95, 28.26, 27.02, 22.04, 19.19, 13.02. MS (ESI−) m/
−
z: 400 [M − H]
.
Methoxymethyl 6-[N-Ethyl-N-(5-isobutoxy-4-isopropyl-2-
nitrophenyl)amino]nicotinate (14). To a solution of 13 (476 mg,
1.20 mmol) in anhydrous DMF (8 mL) were added chloromethyl
methyl ether (0.1 mL, 1.3 mmol) and triethylamine (0.18 mL, 1.3
mmol) under an Ar atmosphere. The mixture was stirred on ice for 1
h and then neutralized with sat. NH4Claq. The aqueous layer was
extracted with EtOAc (3 × 50 mL). The combined organic layer was
washed with H2O (2 × 50 mL) and brine (50 mL) and dried over
MgSO4. The solvent was evaporated under reduced pressure to afford
1
(43%). H-NMR (300 MHz, CDCl3): δ 8.32 (1H, s), 6.04 (1H, s),
4.36 (2H, q, J = 7.2 Hz), 3.34 (2H, t, J = 5.6 Hz), 3.32 (2H, t, J = 5.6
Hz), 2.88 (2H, t, J = 6.5 Hz), 2.76 (2H, t, J = 6.0 Hz), 2.01−1.92
(4H, m), 1.38 (3H, t, J = 7.2 Hz).
11-Oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f ]pyrido-
[3,2,1-ij]quinoline-10-carboxylic Acid (Coumarin 343, 10). A
solution of 9 (238 mg, 0.76 mmol) in conc. HCl (7.0 mL) was
stirred at room temperature for 20 h and then cooled to 0 °C, and
28% NH3aq was added to it. The resulting orange precipitate was
collected and recrystallized from DMSO/CH3CN to afford 128 mg of
10 as orange needles (59%). 1H-NMR (400 MHz, DMSO-d6): δ
1
629 mg of 14 as a yellow oil (q.y.). H-NMR (400 MHz, CDCl3): δ
8.86 (1H, d, J = 2.1 Hz), 8.03 (1H, s), 7.96 (1H, dd, J = 8.5, 2.1 Hz),
6.71 (1H, s), 6.26 (1H, d, J = 8.5 Hz), 5.43 (2H, s), 3.80 (2H, d, J =
6.0 Hz), 3.51 (3H, s), 3.38 (1H, sep, J = 6.9 Hz), 2.17 (1H, sep, J =
6.7 Hz), 1.32−1.24 (11H, m), 1.08 (6H, d, J = 6.7 Hz). 13C-NMR
(100 MHz, CDCl3): δ 165.29, 161.13, 159.95, 151.35, 139.46, 138.33,
137.58, 137.05, 124.39, 115.09, 112.95, 106.46, 90.28, 75.10, 57.51,
45.92, 28.28, 27.03, 22.06, 19.21, 14.15, 13.08. MS (FAB+) m/z: 446
[M + H]+.
866
J. Med. Chem. 2021, 64, 861−870