L. Altucci, A. Mai, et al.
MED
nophenyl]-N-hydroxy-2-propenamide (1c): Ethyl chloroformate
(1.2 equiv, 1.38 mmol, 0.11 mL) and Et3N (1.1 equiv, 1.26 mmol,
0.17 mL) were added to a cooled (08C) solution of 6c (1.0 equiv,
1.15 mmol, 0.39 g) in dry THF (10 mL), and the mixture was stirred
for 10 min. The solid was filtered off, and O-(2-methoxy-2-propyl)-
hydroxylamine[47] (3.0 equiv, 3.45 mmol, 0.25 mL) was added to the
filtrate. The solution was stirred for 15 min at 08C, then evaporated
under reduced pressure, and the residue was diluted in MeOH
(10 mL). Amberlyst 15 ion-exchange resin (115 mg) was added to
the solution of the O-protected hydroxamate, and the mixture was
stirred at RT for 1 h. Afterward, the reaction was filtered and the fil-
trate was concentrated in vacuo to give the crude 1c, which was
and 4 (4g, 4h, 4n, and 4o) series furnished the same as or
higher activity than MS-275.
The highest-scoring derivatives in terms of apoptosis and
antiproliferative activity (1k, 1l) or cytodifferentiation (2c, 4n)
will be studied further to assess their effects in a panel of
cancer cell lines and to investigate their drug-like properties.
Experimental Section
Chemistry
1
purified by crystallization. H NMR ([D6]DMSO): d=0.80–0.83 (t, 3H,
Melting points were determined on a Bꢂchi 530 melting point ap-
paratus and are uncorrected. IR spectra (KBr) were recorded on a
PerkinElmer Spectrum One instrument. 1H NMR spectra were re-
corded at 400 MHz on a Bruker AC 400 spectrometer; chemical
shifts (d) are reported in ppm relative to the internal reference
(CH3)4Si. All compounds were routinely checked by TLC and
1H NMR. TLC was performed on aluminum-backed silica gel plates
(Merck DC, Alufolien Kieselgel 60 F254) with spots visualized by UV
light. All solvents were reagent grade and, when necessary, were
purified and dried by standard methods. Concentration of solu-
tions after reactions and extractions involved the use of a rotary
evaporator operating at reduced pressure of ~20 Torr. Organic sol-
utions were dried over anhydrous Na2SO4. Analytical results are
within ꢀ0.40% of the theoretical values. A SAHA sample for bio-
logical assays was prepared as previously reported by us.[56] MS-
275 and HDAC42 were synthesized according to the literature.[57,29]
All chemicals were purchased from Aldrich Chimica, Milan (Italy), or
from Lancaster Synthesis GmbH, Milan (Italy), and were of the
highest purity.
PhCHCH2CH3CO), 1.66–1.68 (m, 1H, PhCHCH2CH3CO), 2.03–2.05 (m,
1H, PhCHCH2CH3CO), 3.53–3.57 (m, 1H, PhCHCO), 6.29–6.33 (d, 1H,
PhCH=CHCO), 7.19–7.36 (m, 5H, benzene and PhCH=CHCO), 7.43–
7.45 (m, 2H, benzene), 7.59–7.61 (m, 5H, benzene), 9.05 (s, 1H,
CONHPh), 10.25 (bs, 1H, NHOH), 10.66 ppm (bs, 1H, NHOH);
13C NMR ([D6]DMSO, 400 MHz): d=15.1, 29.2, 48.2, 118.8, 121.5
(2C), 126.0, 128.1, 128.8 (2C), 129.0 (2C), 130.8, 137.7, 139.2, 141.7,
161.6, 172.0 ppm.
General procedure for the synthesis of N-(2-aminophenyl)-3-(4-
acylaminophenyl)-2-propenamides 2a–l. N-(2-Aminophenylami-
no)-3-[4-(2-phenylbutyryl)aminophenyl]-2-propenamide (2c): Et3N
(4.0 equiv, 1.93 mmol, 0.27 mL) and BOP reagent (1.2 equiv, 0.57.
mmol, 0.254 g) were added under N2 atmosphere to a solution of
compound 6c (1.0 equiv, 0.48 mmol, 0.15 g) in dry DMF (5 mL),
and the resulting mixture was stirred for 30 min. After this time,
1,2-phenylendiamine (1.0 equiv, 0.48 mmol, 0.052 g) was added,
and stirring was continued for a further 30 min. The reaction was
quenched by H2O (30 mL) and the precipitate was filtered, washed
with H2O (3ꢃ30 mL), and dried. The solid residue was subjected to
chromatography on silica gel eluting with EtOAc/CHCl3 1:1 to pro-
vide the desired compound 2c, which was recrystallized from
CH3CN/MeOH. 1H NMR ([D6]DMSO): d=0.84–0.87 (t, 3H,
PhCHCH2CH3CO), 1.68–1.73 (m, 1H, PhCHCH2CH3CO), 2.01–2.07 (m,
1H, PhCHCH2CH3CO), 3.55–3.59 (m, 1H, PhCHCO), 4.92 (bs, 2H,
PhNH2), 6.53–6.58 (m, 1H, aniline), 6.72–6.79 (d, 2H, aniline), 6.87–
6.89 (m, 1H, aniline), 7.23–7.25 (d, 1H, PhCH=CHCO), 7.30–7.54 (m,
8H, PhCH=CHCO and benzene), 7.65–7.67 (m, 2H, benzene), 9.31
(s, 1H, CONHPh), 10.26 ppm (bs, 1H, CONH aniline); 13C NMR
([D6]DMSO, 400 MHz): d=15.1, 29.2, 48.2, 114.5, 118.8, 121.5 (2C),
122.8, 125.1, 126.0, 128.1 (2C), 128.8 (2C), 129.0, (2C), 130.8, 137.7,
139.2, 141.7, 149.5, 168.0, 172.0 ppm.
General procedure for the synthesis of ethyl 3-(4-acylamino-
phenyl)-2-propenoates 5a–n. Ethyl 3-[4-(2-phenylbutyryl)amino-
phenyl]-2-propenoate (5c): 2-Phenylbutyryl chloride (1.2 equiv,
7.32 mmol, 1.33 g) and Et3N (2.5 equiv, 15.22 mmol, 2.12 mL) were
added to a solution of ethyl 3-(4-aminophenyl)-2-propenoate hy-
drochloride[43] (1.0 equiv, 6.1 mmol, 1.39 g) in dry dichloromethane
(20 mL) at 08C. After stirring at RT for 4 h, the reaction mixture was
poured into H2O (50 mL), the organic layer was separated, and the
aqueous one was extracted with CHCl3 (2ꢃ50 mL). The combined
organic solution was washed with H2O (100 mL) and brine
(100 mL), and was dried and evaporated to dryness. The residual
solid was purified by crystallization from cyclohexane to yield pure
5c. 1H NMR (CDCl3): d=0.91–0.95 (t, 3H, OCH2CH3), 1.30–1.34 (t,
3H, PhCHCH2CH3CO), 1.98–2.01 (m, 1H, PhCHCH2CH3CO), 2.20–2.23
(m, 1H, PhCHCH2CH3CO), 3.39–3.41 (m, 1H, PhCHCO), 4.22–4.28 (q,
2H, OCH2CH3), 6.32–6.36 (d, 1H, PhCH=CHCOOEt), 7.27–7.49 (m,
10H, benzene and CONHPh), 7.58–7.62 ppm (d, 1H, PhCH=
CHCOOEt).
General procedure for the synthesis of ethyl 3-[4- (arylmethyla-
mino)phenyl]-2-propenoates 7a–o. Ethyl 3-[4-(benzofuran-2-ylme-
thylamino)phenyl]-2-propenoate (7k): Ethyl-4-aminocinnamate
(1.1 equiv, 7.52 mmol, 1.44 g) and AcOH (1 mL) were added to a so-
lution of benzofuran-2-carboxaldehyde (1.0 equiv, 6.84 mmol, 1.0 g)
in MeOH (10 mL), and the resulting mixture was stirred at RT for
1 h. Then the mixture was cooled to 08C, and NaCNBH3 (2.0 equiv,
13.68 mmol, 0.80 g) was added. After 30 min, the solvent was re-
moved and the residue was eluted with H2O (50 mL) and extracted
with EtOAc (3ꢃ30 mL). The organic layers were washed with a so-
lution of NaCl (3ꢃ30 mL), dried with Na2SO4 and concentrated. The
organic residue was subjected to chromatography on silica gel
eluting with EtOAc/n-hexane 1:5, to afford pure product 7k as a
yellow solid that was recrystallized from cyclohexane. 1H NMR
(CDCl3): d=1.28–1.32 (t, 3H, OCH2CH3), 4.19–4.24 (q, 2H, OCH2CH3),
4.47 (s, 1H, ArCH2NH), 4.49 (s, 2H, ArCH2NH), 6.18–6.22 (d, 1H,
PhCH=CHCO), 6.59 (s, 1H, benzofuran), 6.64–6.66 (d, 2H, benzene),
7.18–7.24 (m, 2H, benzofuran), 7.35–7.37 (d, 2H, benzene), 7.41–
General procedure for the synthesis of 3-(4-acylaminophenyl)-2-
propenoic acids 6a–n. 3-[4-(2-Phenylbutyryl)aminophenyl]-2-pro-
penoic acid (6c): A mixture of 5c (1.0 equiv, 0.65 mmol 0.20 g),
LiOH·H2O (2.0 equiv, 1.30 mmol, 0.054 g), and THF (15 mL) was
stirred at RT. After 24 h, 2n HCl was added to the mixture to give
pH 5, and the obtained solid was filtered and recrystallized to yield
pure 6c. 1H NMR ([D6]DMSO): d=0.83–0.85 (t, 3H, PhCHCH2CH3CO),
1.68–1.71 (m, 1H, PhCHCH2CH3CO), 2.05–2.08 (m, 1H,
PhCHCH2CH3CO), 3.60–3.62 (m, 1H, PhCHCO), 6.40–6.44 (d, 1H,
PhCH=CHCOOH), 7.21–7.64 (m, 10H, benzene and PhCH=
CHCOOH), 10.43 (s, 1H, COOH), 12.20 ppm (s, 1H, CONHPh).
General procedure for the synthesis of the 3-(4- acylaminophen-
yl)-N-hydroxy-2-propenamides 1a–n. 3-[4-(2- Phenylbutyryl)ami-
708
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemMedChem 2011, 6, 698 – 712