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MedChemComm
Page 6 of 10
DOI: 10.1039/C8MD00089A
ARTICLE
MedChemComm
identified if the crystal structure of the corresponding complex is
resolved. Furthermore, regarding the mechanism of action of
compound 1, even though targeting of the MAPK/ERK pathway
cannot be completely ruled out, other mechanisms may be involved
and, thus, further studies will be pursued.
with a Varian Prostar 335 diode array detector and a manual
injector (20 μL). For purity assessment, UV detection was
performed at 245 nm and peak purity was confirmed using a purity
channel. The stationary phase consisted of an ACE 5 C18-AR column
(150 x 4.6 mm), and the mobile phase used the following gradient
system, eluting at 1 mL min-1: aqueous formate buffer (30 mM, pH
3.0) for 10 min, linear ramp to 85% methanol buffered with the
same system over 25 min, hold at 85% buffered methanol for 10
min. Minimum requirement for purity was set at 95%.
Experimental
4-{3-[3-(4-Chloro-3-trifluoromethylphenyl)guanidino]phenoxy}
phenylcarbamimidate dihydrochloride (2).
A solution of the
Computational details
corresponding Boc-protected precursor 15 (100 mg, 0.13 mmol) in
10 mL of a 50% v/v solution of TFA and CH2Cl2 was stirred at room
temperature. Once disappearance of starting material was
observed by TLC (3 h), the excess of TFA and CH2Cl2 were removed
under vacuum to generate the trifluoroacetate salt. The residue
was dissolved in water (10 mL) and 500 mg of IRA400 Amberlite
resin in its chloride-activated form was added, allowing the reaction
to proceed overnight. The resin was then removed by filtration and
the aqueous solution washed with CH2Cl2 (2 × 5 mL). Removal of
water under vacuum yielded the final isouronium hydrochloride 2
The geometry of the monomers and the complexes were fully
optimized at DFT ωB97XD/6-31+G(d,p)39 and then MP2/6-
311+G(d,p) to obtain binding energies. All these calculations were
carried out with Gaussian09 program.40 Frequency calculations
were performed at the same computational level to confirm that
the resulting optimized structures are energetic minima. Interaction
energies, Ei, (kJ mol-1) were calculated as the difference between
the total energy of the complex and the sum of the isolated
monomers. The effect of water solvation was then accounted for
using the SCFR-PCM approach implemented in the Gaussian09
package including dispersing, repulsing and cavitation energy terms
of the solvent in the optimization. For the sake of clarity during the
discussion, the atoms involved in each interaction have been
labelled as indicated in Figure S1. The bonding characteristics were
analysed by means of the atoms in molecules (AIM) theory.29 For
this purpose we have located the most relevant bond critical points
(BCP) and evaluated the electron density at each of them, by means
of AIMAll program.41 Electron density shift maps (EDS) have been
obtained in order to provide an insight into the changes in the
electron density of the monomers upon complexation. All the EDS
maps have been obtained following the procedure previously
reported.42
as
a white/yellow solid (67 mg, 95%). Absence of the
trifluoroacetate salt was confirmed by 19F NMR. Mp: decomposes
over 120 °C. δH (400 MHz, CD3OD): 7.02 (dd, J = 8.2, 2.0 Hz, 1H, Ar),
7.09 (t, J = 2.1 Hz, 1H, Ar), 7.17 (dd, J = 8.0, 1.3 Hz, 1H, Ar), 7.20 (d, J
= 9.0 Hz, 2H, Ar), 7.35 (d, J = 9.0 Hz, 2H, Ar), 7.47 (t, J = 8.1 Hz, 1H,
Ar), 7.60 (dd, J = 8.6, 2.4 Hz, 1H, Ar), 7.70 (d, J = 8.6 Hz, 1H, Ar), 7.75
(d, J =2.3 Hz, 1H, Ar). δC (100 MHz, CD3OD): 116.5 (CH, Ar), 118.6
(CH, Ar), 121.1 (CH, Ar), 122.2 (2 CH, Ar), 123.8 (d, J = 271.0 Hz,
qCF3), 124.0 (2 CH, Ar), 125.3 (q, J = 4.3 Hz, CH, Ar), 130.5 (d, J =
31.8 Hz, qC), 130.8 (CH, Ar), 131.3 (qC), 132.5 (CH, Ar), 134.3 (CH,
Ar), 136.1 (qC), 137.9 (qC), 146.8 (qC), 156.3 (qC), 157.5 (qC), 159.5
(qC), 163.3 (qC). δF (376 MHz, CD3OD): -64.33 (s). νmax (ATR)/cm-1:
3183 (NH), 2963 (CH), 1574 (C=N), 1477, 1250 (CF3), 1096, 1030 (C-
O), 1012 (C-Cl), 785, 667. HRMS (m/z ES+) calcd for C21H17ClF3N5O2
([M + H]+): 464.1096, found 464.1101. HPLC: 98.4% (tR 27.01 min)
Synthetic procedures
All commercially available chemicals were obtained from Sigma-
Aldrich or Fluka and used without further purification. Deuterated
solvents for NMR use were purchased from Apollo and Euriso-top.
Chromatographic columns were run using silica gel 60 (230–400
mesh ASTM). Solvents for synthesis purposes were used at GPR
grade. Analytical TLC was performed using Merck Kieselgel 60 F254
silica gel plates or Polygram Alox N/UV254 aluminium oxide plates.
Visualisation was by UV light (254 nm). NMR spectra were recorded
on Agilent and Bruker Avance spectrometers, operating at 400.13
4-[3’-(4-Chloro-3-trifluoromethylbenzamido)phenoxy]phenyl
guanidine hydrochloride (3). To a stirred solution of 19 (90 mg, 0.14
mmol) in EtOAc was added SnCl4 (0.06 mL, 0.56 mmol). After 1 h of
stirring at room temperature, the solvent and the excess of SnCl4
were evaporated in vacuum. The product was purified by flash
chromatography (silica gel, CHCl3:MeOH, 100:0 → 95:5) and the
purified fraction was then dissolved in MeOH and recrystallized
from Et2O to obtain 3 as a white solid (32 mg, 47%). Mp:
decomposes over 120 °C. δH (400 MHz, CD3OD): 6.86 (d, J = 7.8 Hz,
1H, Ar), 7.12 (d, J = 8.6 Hz, 2H, Ar), 7.30 (d, J = 8.7 Hz, 2H, Ar), 7.35 –
7.43 (m, 2H, Ar), 7.62 (s, 1H, Ar), 7.77 (d, J = 8.3 Hz, 1H, Ar), 8.16
(dd, J = 8.3, 1.5 Hz, 1H, Ar), 8.32 (s, 1H, Ar). δC (100 MHz, CD3OD):
112.9 (CH, Ar), 116.3 (CH, Ar), 117.3 (CH, Ar), 121.0 (2 CH, Ar), 124.0
(d, J = 272.5 Hz, qCF3), 128.2 (q, J = 5.5 Hz, CH, Ar), 128.9 (2 CH Ar),
129.4 (d, J = 31.6, qC), 130.9 (qC), 131.2 (CH, Ar), 133.1 (CH, Ar),
133.6 (CH, Ar), 135.3 (qC), 136.5 (qC), 141.2 (qC), 158.1 (qC), 158.3
(qC), 158.4 (qC), 166.0 (qC). δF (376 MHz, CD3OD): -64.11 (s). νmax
(ATR)/cm-1: 3413 (NH), 3343 (NH), 1602 (C=O), 1504 (C=N), 1450,
1412, 1261 (C-N), 1216 (C-O), 1134 (CF3), 1035 (C-Cl), 924, 845.
1
MHz and 600.1 MHz for H NMR; 100.6 MHz and 150.9 MHz for 13C
NMR. Shifts are referenced to the internal solvent signals. NMR
data were processed using MestreNova software. HRMS spectra
were measured on a Micromass LCT electrospray TOF instrument
with a WATERS 2690 autosampler and methanol as carrier solvent.
Melting points were determined using a Stuart Scientific Melting
Point SMP1 apparatus and are uncorrected. Infrared spectra were
recorded on a Perkin Elmer Spectrum One FTIR Spectrometer
equipped with a Universal ATR sampling accessory. HPLC purity
analysis was carried out using a Varian ProStar system equipped
6 MedChemComm, 2018, 00, 1-3
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