P. Dao et al. / Bioorg. Med. Chem. Lett. 23 (2013) 4552–4556
4553
groups on the position 2, 4 or 6, such as tretamine, furazil and
dioxadet, have been reported as anticancer agents.11 Diarylamino-
triazines have been claimed as ALK kinase inhibitors,12 which may
represent an effective and innovative therapy for ALCL, NSCLC, and
neuroblastoma patients whose tumors harbor ALK genetic altera-
tions.13 Moreover, an anti-gastric ulcer agent that is commonly
used in Japan, isogladine (2,4-diamino-6-(2,5-dichlorophenyl)-
1,3,5-triazine), was shown to possess antiangiogenic properties in
connexion with an anticancer effect.14 The appeal of the 1,3,5-tri-
azine core in medicinal chemistry is largely due to the ease of suc-
cessive substitutions of chlorine atoms of commercially available
cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) with nucleophilic
groups to generate a large variety of substitutions. As a part of
our research program aimed at the development for new inhibitors
of FAK, a series of novel diarylamino-1,3,5-triazine derivatives was
prepared, according to Schemes 1 and 2.
Starting from cyanuric chloride (Scheme 1), the first chlorine
was displaced by nucleophilic substitution with arylamines at
À10 °C to produce the mono substituted intermediates. These were
further converted to the compounds 1–20 through the agency of
the corresponding arylamines at room temperature. These two
steps could also be performed in a one pot procedure without iso-
lating intermediates. The displacement of the last chlorine by
methylamino group was more difficult and realized under heating
conditions or was made by hydrogen under catalytic hydrogena-
tion, affording the compounds 41–42 and 21–35, respectively, in
good yields. Compounds 36–40 were finally obtained by cleavage
of their protective group.
with esters and further with 1-bromo-2-nitrobenzene, using Pd-
catalyzed heteroarylamination procedure.15,16
All compounds were evaluated for their ability to inhibit FAK ki-
nase activity using a TR-FRET based kinase assay.17 For detecting
FAK phosphorylation activity by TR-FRET, a recombinant full length
FAK protein pre-activated by Src was used with ATP and an ULight-
labeled substrate poly(Glu/Tyr). Phosphorylation of the substrate
was detected using an Europium-labeled phospho-specific
antibody (W1024-PY20). One reported inhibitor of FAK, TAE-226,
designed by Novartis Pharma AG, was included to validate the
screening conditions. Under the experimental conditions, TAE-
226 inhibited the activity of FAK with IC50 value of 7 nM (Table 1),
which was similar to previously reported data.18 As presented in
Tables 1 and 2, the compounds tested demonstrated a range of
potencies, clearly showing the contributions of the diarylaminotri-
azinic structure in terms of structure–activity relationships.
As shown in Table 1, we firstly introduced 3,4,5-trimethoxyphe-
nylamino group on the triazine ring and a comparison of different
substitutions at the position R on the triazinic ring (compounds 1,
21, 41 and 48) indicated that replacement of the chlorine atom
with a methylamino group for compound 41 resulted in a marginal
decrease in inhibitory potency on FAK kinase activity. In contrast,
removing the chlorine atom from the triazinic ring in 1 for com-
pound 21, displayed a about eightfold increase in inhibitory activ-
ity. Similar results were also observed for compound 22 as
compared with compounds 2 and 42. Moreover, replacement of
the chlorine atom by a methyl group in compound 48 resulted in
a substantial improvement in inhibitory potency as compared with
1, but it was in the same range of 21. This could be due to the fact
that the groups R is too close to the CO of the backbone amide
group of Glu-500 in the hinge (Fig. 2a), leading to steric clashes
with this residue. Decreased FAK inhibitory activity might result
from predisposed conformation of inhibitors less favorable to bind-
ing to the hinge region.
The synthesis of compounds 48–52 was accomplished by cata-
lytic hydrogenation and further substitution by acetic anhydride or
methanesulfonyl chloride or methyl chloroformate or dimethylcar-
bamoyl chloride as described in Scheme 2, from the precursors 46–
47, which were obtained in three steps from the microwave-
assisted (MW) reaction of cyanoguanidine with arylamines and
N
N
NH
HN
N
R1
R2
R
Cl
N
Cl
N
c,d
N
N
a,b
N
N
21-40
NH
Cl
Cl
HN
R1
R2
HN
e
R
N
N
NH
HN
N
1-20
R1
R2
R
41-42
Scheme 1. Reagents and conditions: (a) ArNH2/THF/DIEA/À10 °C; (b) RPhNH2/THF/DIEA/rt; (c) H2/Pd/THF/MeOH; (d) TFA/CH2Cl2; (e) CH3NH2/reflux.
R1
NO2
NH2
NH
NH2
NH
R
N
NH2
R
N
NH
R
N
NH
a
b
c
d,e
HN
HN
HN
N
N
N
N
N
N
NH
HN
O
HN
O
HN
O
N
O
O
O
O
O
O
O
O
O
44-45
43
46-47
48-52
Scheme 2. Reagents and conditions: (a) 3,4,5-trimethoxy PhNH2/dioxane/MW, 90 °C, 15 min; (b) RCO2Et/MeONa/THF/MW, 70 °C, 20 min; (c) 1-bromo-2-nitrobenzene/
dioxane/Pd(OAc)2/xantphos/Cs2CO3/MW, 150 °C, 15–30 min; (d) H2/Pd/MeOH; (e) acetic anhydride or CH3SO2Cl or RCOCl/pyridine.