Diclofenac Analogues as TTR Amyloid Formation Inhibitors
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 2 329
to stir under argon for an additional hour. At the end of this
period, the solvent was evaporated yielding a syrup that
solidified when dried under vacuum. The crude product thus
obtained was purified by flash chromatography using a gradi-
the organic layer was washed with 1 N HCl (10 mL), 10%
NaHCO3 (10 mL), then brine (10 mL). The organic layer was
dried over anhydrous Na2SO4, filtered, and concentrated to
obtain crude product that was purified by flash chromatogra-
phy using a gradient of EtOAc in hexanes (5-40%) to obtain
pure 6 as a yellow-white solid. (0.42 g, 70%). 1H NMR
(CDCl3): δ 7.33 (dd, J ) 7.9, 0.9 Hz, 2H), 7.19 (d, J ) 7.5 Hz,
1H), 7.09 (dd, J ) 8.8, 8.3 Hz, 1H), 6.97 (m, 2H), 6.50 (d, J )
7.9 Hz, 1H), 5.81 (br s, 1H), 3.87 (t, J ) 7.4 Hz, 2H), 3.21 (t,
J ) 7.4 Hz, 2H). 13C NMR (CDCl3): δ 141.69, 137.34, 129.70,
128.81, 127.54, 127.30, 124.39, 122.16, 117.54, 117.52, 43.93,
34.97. HRMS: calculated for C14H12Cl3N M+ ) 299.0035, found
299.0033. Normal phase HPLC retention time: 4.3 min;
reverse phase: 45.2 min, >99% pure.
Gen er a l P r oced u r e for P d -Med ia ted Cou p lin g Rea c-
tion s to P r ep a r e 7, 8, 9, 11, 13. A round-bottom flask
equipped with a stir bar and a condenser was charged with
an aniline (1 equiv), and Cs2CO3 (1.4 equiv), Pd2(dba)3 (tris-
(dibenzylideneacetone)dipalladium (0); 4.5 mol %), Binap
(racemic 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl; 3 mol %)
and the appropriate halide or triflate (1.2 equiv) were added
in order. Finally, enough toluene to give a 0.5 M solution in
the aniline was added through the septum on the condenser
via syringe, and the reaction mixture was refluxed under argon
for 36 h. The reaction mixture was cooled and filtered through
Celite. The filtrate was concentrated by rotary evaporation and
the crude product purified by flash chromatography using a
gradient of EtOAc in hexanes (5-40%) to obtain pure product
for which the yield ranged from 47% to 85%. The methyl ester
of 11 and the ethyl ester of 13 were hydrolyzed by dissolving
them in THF:MeOH:H2O (3:1:1) to 0.125 M and then adding
4 equiv of LiOH. The reaction mixture was stirred for 4-12 h
and then acidifed to pH 4 using 1 M HCl. The reaction mixture
turned cloudy white at this time, and the product was
extracted into ethyl acetate (3 × 30 mL). The organic layer
was dried over Na2SO4 (anhydrous) and concentrated on a
rotary evaporator to afford a crude solid that was purified by
recrystallization from 1:1 EtOAc:MeOH with enough added
hexanes to cause precipitation (the final composition was
usually around 1:1:10 EtOAc:MeOH:hexanes) to obtain fluffy
white solids in 60-70% yield.
1
ent of EtOAc in hexane (5-40%) to obtain 2 (2.97 g, 96%). H
NMR (CDCl3): δ 7.98 (dd, J ) 7.9, 1.8 Hz, 1H), 7.40 (ddd, J )
7.9, 7.7, 1.3 Hz, 1H), 7.32 (d, J ) 7.9 Hz, 1H), 7.11 (d, J ) 1.7
Hz, 1H), 7.00 (dd, J ) 1.7, 1.7 Hz, 1H), 6.85 (ddd, J ) 7.9, 7.4,
0.8 Hz, 1H), 3.73 (s, 2H), 3.66 (s, 3H). 13C NMR (CDCl3): δ
168.70, 145.73, 143.31, 135.50, 134.24, 131.76, 122.49, 118.98,
118.84, 115.12, 113.59, 52.02. HRMS: calculated for C15H13
-
Cl2NO2 M+ ) 309.0323, found 309.0319.
2-[(2,6-Dich lor op h en yl)a m in o]ben zen e-eth a n -1-ol (3).
A round-bottom flask equipped with a magnetic stir bar and
a rubber septum was charged with 2 (2.34 g, 7.55 mmol), which
was then dissolved in 15 mL of THF. The 0.5 M homogeneous
solution of 2 in THF was cooled to -22 °C in a dry ice-CCl4
bath, and LiAlH4 (0.344 g, 9.06 mmol) was added in small
portions. The reaction mixture was stirred at -22 °C for 4 h,
after which the dry ice-CCl4 bath was removed, and the
reaction mixture was stirred overnight at 25 °C. The reaction
was quenched with the dropwise addition of KHSO4 (10% in
H2O, 25 mL) and transferred to a separatory funnel. The
product was extracted into the organic layer using EtOAc (3
× 50 mL). The organic layer was concentrated on a rotary
evaporator. Purification of the crude product by flash chro-
matography using a gradient of EtOAc and hexanes (5-40%)
yielded the desired product 3 (0.98 g, 46%) as an off-white solid.
1H NMR (CDCl3): δ 7.33 (d, J ) 8.3 Hz, 2H), 7.19 (dd, J )
7.5, 1.3 Hz, 1H), 7.08 (ddd, J ) 7.7, 7.7, 1.3 Hz, 1H), 6.98 (dd,
J ) 8.3, 7.9 Hz, 1H), 6.93 (dd, J ) 6.6, 6.5 Hz, 1H), 6.48 (d, J
) 7.4 Hz, 1H), 4.02 (t, J ) 5.7 Hz, 2H), 3.02 (t, J ) 5.6 Hz,
2H). 13C NMR (CDCl3): δ 142.59, 137.66, 130.62, 129.78,
129.02, 128.86, 128.63, 126.98, 124.03, 121.60, 116.83, 64.22,
34.77. HRMS: calculated for C14H13Cl2NO M+ ) 281.0374,
found 281.0371.
2-[(2,6-Dich lor op h en yl)a m in o] Ben zen ea ceta m id e (4).
A round-bottom flask was charged with a stir bar, the sodium
salt of diclofenac (1) (Sigma, 318 mg, 1 mmol), and PyBop
(benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluo-
rophosphate; 520 mg, 1 mmol), and capped with a septum. The
solvent CH2Cl2 (10 mL), DIEA (diisopropylethylamine; 391 µL,
2.25 mmol), and 30% aqueous NH4OH (1.3 mL, 19.4 mmol)
were added sequentially to the reaction mixture via syringe
through the septum. The reaction mixture was allowed to stir
at room temperature for 2 h, then concentrated to dryness on
a rotary evaporator and dissolved in EtOAc (50 mL). The
EtOAc layer was washed with brine (2 × 20 mL) and dried
with MgSO4. The organic layer was concentrated and subjected
to flash chromatography using 30% EtOAc in hexanes to yield
36 mg (12%) of 4 as a white solid. 1H NMR (CDCl3): δ 7.50 (d,
J ) 7.9 Hz, 2H), 7.32-7.39 (m, 2H), 7.19-7.21 (m, 1H), 7.08-
7.10 (m, 1H), 6.40 (d, J ) 7.9 Hz, 1H), 3.77 (s, 2H). 13C NMR
(100 MHz, CDCl3): δ 173.56, 143.21, 135.42, 130.73, 130.34,
128.97, 127.85, 124.74, 124.21, 123.00, 109.06, 35.66. HRMS:
calculated for C14H10Cl2NO (loss of NH2) M+ ) 278.0134, found
278.0132.
Characterization for 7, 8, 9, 11, and 13:
2-[(2,6-Dich lor op h en yl)a m in o]ben zen e-eth a n e (7). H
1
NMR (CDCl3): δ 7.36 (d, J ) 8.3 Hz, 2H), 7.21 (dd, J ) 7.4,
1.3 Hz, 1H), 7.04 (ddd, J ) 7.7, 7.7, 1.8 Hz, 1H), 7.02 (d, J )
8.3 Hz, 1H), 6.93 (ddd, J ) 7.4, 7.3, 1.3 Hz, 1H), 6.43 (dd, J )
8.1, 0.9 Hz, 1H), 2.75 (q, J ) 7.5 Hz, 2H), 1.34 (t, J ) 7.9 Hz,
3H). 13C NMR (CDCl3): δ 131.75, 130.39, 128.83, 128.57,
126.21, 124.61, 121.43, 115.80, 24.40, 13.48. HRMS: calculated
for C14H13Cl2N M+ ) 265.0425, found 265.0425. Normal phase
HPLC retention time: 3.4 min; reverse phase: 45.1 min, >99%
pure.
2-[(2,6-Dich lor op h en yl)a m in o]ben zen e-2-m eth yl-eth -
a n e (8). 1H NMR (CDCl3): δ 7.26 (d, J ) 8.0 Hz, 2H), 7.20
(dd, J ) 7.5, 1.5 Hz, 1H), 6.90 (m, 2H), 6.38 (dd, J ) 7.9, 1 Hz,
1H), 5.60 (bs, 1H), 3.21 (m, 1H), 1.275 (d, J ) 6.8 Hz, 6H). 13
C
NMR (CDCl3): δ 140.28, 137.66, 136.77, 129.99, 128.85,
125.94, 125.54, 124.26, 121.91, 116.64, 27.71, 22.53. HRMS:
calculated for C15H15Cl2N M+ ) 279.0582, found 279.0573.
Normal phase HPLC retention time: 3.6 min; reverse phase:
46.3 min, >99% pure.
2-[(2,6-Dich lor op h en yl)a m in o]ben zoic Acid (5). Pre-
pared as described by Chalmers et al.42 Melting point: 219-
1
221 °C (lit. 220-222 °C). H NMR (DMSO-d6): δ 9.55 (d, J )
7.7 Hz, 1H), 7.62 (d, J ) 7.7 Hz, 2H), 7.32-7.40 (m, 2H), 6.81
(t, J ) 7.3 Hz, 1H), 6.24 (d, J ) 8.1 Hz, 1H). 13C NMR
(CDCl3): δ 170.00, 147.01, 134.77, 134.06, 133.42, 131.49,
129.11, 128.27, 117.44, 112.99, 111.93. HRMS: calculated for
2-[(2,6-Dich lor op h en yl)a m in o]b en zen e-p r op a n e (9).
1H NMR (300 MHz, CDCl3): δ 7.38 (d, J ) 8.1 Hz, 2H),
7.21 (d, J ) 7.2 Hz, 1H), 7.05 (m, 2H), 6.93 (dd, J ) 7.5,
7.2 Hz, 1H), 6.45 (d, J ) 8.1 Hz, 1H), 5.66 (br s, 1H), 2.72
(t, J ) 7.5 Hz, 2H), 1.78 (m, 2H), 1.06 (t, J ) 7.5 Hz, 3H).
13C NMR (75 MHz): δ 141.47, 137.82, 130.91, 130.72, 130.10,
129.26, 126.67, 124.95, 121.75, 116.44, 34.08, 22.82, 14.66.
LRMS: calculated for C15H15Cl2N M+ ) 279/281/283, found
279/281/283.
2-[(3,5-Dich lor op h en yl)a m in o]ben zoic Acid (11). 1H
NMR (DMSO-d6): δ 9.56 (bs, 1H), 7.93 (dd, J ) 7.9, 1.3 Hz,
1H), 7.49 (ddd, J ) 7.9, 7.7, 1.7 Hz, 1H), 7.36 (d, J ) 8.3 Hz,
1H), 7.23 (d, J ) 1.7 Hz, 2H), 7.12 (d, J ) 1.7 Hz, 1H), 6.96
C
13H9Cl2NO2Na M+Na+ ) 303.9904, found 303.9903.
1-Ch lor o-2-[(2,6-d ich lor op h en yl)a m in o]b en zen e-et h -
a n e (6). A round-bottom flask was charged with compound 3
(0.56 g, 2.0 mmol), a stir bar, and a rubber septum. Triphenyl-
phosphine (0.58 g, 2.2 mmol) was added, and the reaction flask
was cooled to 0 °C using an ice water bath. Finally, pyridine
(2 mL, 25 mmol) was added slowly followed by CCl4 (1 mL,
10.4 mmol). The resulting solution was allowed to warm
gradually to room temperature. The reaction mixture was
partitioned between water and ethyl acetate (10:30 mL), and