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c-RAF inhibition. Compound 19g bearing a CF3 group at this posi-
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tency of the compounds was significantly improved by the
introduction of additional substituents in other positions, for
example, a chloro atom in R2 (19f) or a methoxy group in R3
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dues at R2 and R3 is less potent than the disubstituted derivatives
19c or 19f. Nevertheless, during the exploration of the SAR at posi-
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physicochemical profile of the compounds. However, the lower
activity of all these derivatives confirmed the need for electron
withdrawing residues at position R1. As for the first series, we used
position R3 for the introduction of solubilizing residues like ali-
phatic amines. Interestingly, the potency of the benzimidazoles
was less affected by this modification. We assume that the loss
of the acceptor hinge binding interaction is compensated by a salt
bridge formed by the amine of the solubility anchor to the Asp594
side chain. Moreover, these derivatives are better soluble. For
example, solubility of compound 19n is improved by a factor of
about 7 compared to compound 19c.42
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residue identity is 81.7%. The hinge region has the identical sequence.
23. Gopalsamy, A.; Ciszewski, G.; Shi, M.; Berger, D.; Hu, Y.; Lee, F.; Feldberg, L.;
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27. CCDC GOLD version 4.1 with default screening parameters and without any
constraints. The binding mode was validated by the successful reproduction of
the crystal structure via redocking, which is considered as validation for the
docking of similar structures.
28. Verschueren, K.; Toth, G.; Tourwé, D.; Lebl, M.; Van Binst, G.; Hruby, V.
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In conclusion, we have designed potent c-RAF inhibitors bearing
novel bicyclic heterocycles as key structural elements for the inter-
action with the hinge region. In both series exploration of the SAR
was mainly focussed on the substitution of the phenyl ring, which
binds to the induced fit pocket. Overall, it was confirmed that incor-
poration of lipophilic substituents was needed for potent RAF inhi-
bition and a number of potent analogues were obtained.
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33. In a final reaction volume of 25
incubated with 25 mM Tris pH 7.5, 0.02 mM EGTA, 0.66 mg/mL myelin basic
protein, 10 mM Mg acetate and [ -33P-ATP] (specific activity approx. 500 cpm/
lL, human c-RAF (5–10 mU, Millipore) was
c
pmol). The reaction was initiated by the addition of the MgATP mix. After
incubation for 40 min at room temperature, the reaction was stopped by the
addition of 3% phosphoric acid solution. The reaction was then spotted onto a
P30 filtermat and washed prior to drying and scintillation counting. All
measurements were performed in duplicates.
34. Unpublished results.
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phosphate buffer (50 mM). 10f: 4.2
lg/ml; 10m: <1
lg/ml; 10n: 16.4 lg/ml;
19c: 12.4 g/ml; 19n: 82.7 g/ml; 19q: 81.2 l
l
l
g/ml.