Bicyclic heterocyclic anthranilic diamides as ryanodine receptor modulators with insecticidal activity

Article abstract of DOI:10.1016/j.bmc.2015.11.035

The diamide insecticides act on the ryanodine receptor (RyR). The synthesis of various bicyclic anthranilic derivatives is reported. Their activity against the insect ryanodine receptor (RyR) and their insecticidal activity in the greenhouse is presented,

Full text of DOI:10.1016/j.bmc.2015.11.035

Bioorganic & Medicinal Chemistry 24 (2016) 403–427
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Bicyclic heterocyclic anthranilic diamides as ryanodine receptor
modulators with insecticidal activity
a
André Jeanguenat a,b, , Patricia Durieux , Andrew J. F. Edmunds a,b, Roger G. Hall a,b, Dave Hughes c,
⇑
Olivier Loiseleur a,b, Jagadish Pabba d, André Stoller a,b, Stephan Trah a,b, Jean Wenger a, Anna Dutton b,
Andrew Crossthwaite c
a Syngenta AG, Crop Protection Research, Chemistry, Schwarzwaldallee 215, CH-4058 Basel, Switzerland
b Syngenta Crop Protection Muenchwilen AG, Schaffhauserstrasse, CH-4332 Stein, Switzerland
c Syngenta, Jealotts Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
d Syngenta Research and Technology Centre, Santa Monica Works, Corlim, Goa 403110, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The diamide insecticides act on the ryanodine receptor (RyR). The synthesis of various bicyclic anthranilic
derivatives is reported. Their activity against the insect ryanodine receptor (RyR) and their insecticidal
activity in the greenhouse is presented, as well as structure activity relationship considerations.
Ó 2015 Elsevier Ltd. All rights reserved.
Received 1 October 2015
Revised 21 November 2015
Accepted 25 November 2015
Available online 26 November 2015
Keywords:
Ryanodine receptor
Insecticide
Anthranilamides
Diamides
1. Introduction
cell differentiation.3 Calcium mobilization through the RyR in mus-
cle cells governs excitation/contraction coupling, and impairment
The insect ryanodine receptor (RyR) modulators belong to the
most successful class of commercial insecticides introduced
recently. Flubendiamide 1, chlorantraniliprole 2 and cyantranili-
prole 3 (Scheme 1) have captured a significant market share only
a few years after introduction.1 Even though the insecticidal prop-
erties of the natural product ryanodine have been known and
exploited for a long time,2 the potential of this mode of action
has been realized only in the late 1990s, when the diamide insec-
ticides were discovered, originating from a herbicide program at
Nihon Nohyaku. Beside their unusual high activity (in some crops,
rates as low as 5 g/ha are used), the toxicological profile of the dia-
mides is remarkable, due in part to the high selectivity which these
compounds exhibits, between insect and mammalian RyR.
of the RyR channels leads to serious muscle and neuronal disorders
such as paralysis. The molecular details of the interaction of the
diamides with the RyR are not understood and probably vary from
species to species.4 Recently, the crystal structure of this giant
homotetrameric protein (2.2 MDa), obtained from mouse and rab-
bit by cryo-electron microscopy5 is a breakthrough in the area;
however due to the poor homology between insect and mam-
malian RyR, these structures cannot be used to build homology
models for the design of new insecticides.
2. Results and discussion
Attracted by the high insecticidal activity of the diamides 1 to 3,
and particularly of the anthranilamides 2 and 3, we wanted to
investigate the potential of bicyclic anthranilamides. First results
of compounds having a naphthalene core such as 4 were encourag-
ing: the activity in vitro, measured in a displacement assay of a tri-
tiated chlorantraniliprole analog (see Supplementary part of Ref. 6)
as well as the insecticidal activity against leaf feeding insects such
as Lepidoptera were outstanding and reached the level of the stan-
dards. Naphthalene derivatives have, however relatively high logP
The RyR are ion channels which regulate the release of calcium
from intracellular stores located in the sarcoplasmic reticulum. The
regulation of intracellular calcium concentration is fundamental
for a series of biological processes such as muscle contraction, neu-
rotransmission, hormonal release, gene expression, cell growth and
⇑
Corresponding author. Tel.: +41 62 8660242.
E-mail address: andre.jeanguenat@syngenta.com (A. Jeanguenat).
http://dx.doi.org/10.1016/j.bmc.2015.11.035
0968-0896/Ó 2015 Elsevier Ltd. All rights reserved.

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A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
CF3
Br
Br
F
CF3
N
N
O
O
HN
N
N
Cl
Cl
NH
NH
O
O
N
N
O
O
Cl
NC
I
H N
HN
HN
S
O
O
1
2
3
Flubendiamide
Chlorantraniliprole
Cyantraniliprole
Scheme 1.
R
R
3
3
R
3
N
N
O
O
N
N
N
R
1
R
R
1
R
4
4
O
N
R
4
NH
NH
N
N
NH
N
O
O
O
R
R
R
5
5
HN
HN
R
5
R
R
6
6
HN
6
bicyclic anthranilamide type II
bicyclic anthranilamide type I
bicyclic anthranilamide type III
CF
3
N
O
N
Cl
Cl
NH
N
O
Cl
H N
4
Spodoptera activity:
in vitro: IC50: 5nM
in vivo: EC80: 0.2 ppm
Scheme 2.
(>4) and our objective was to reduce this lipophilicity by introduc-
ing heteroatoms in the bicyclic system, to hopefully expand the
biological spectrum of the lead 4; more hydrophilic compounds
have the potential to be systemic in the plant and thus be ingested
by sap feeding insects.7 Three types of bicyclic anthranilamides can
be envisaged (types I, II and III as depicted in Scheme 2): For the
types II and III, a substituent R1 (methyl or halogen) ortho to the
amino group is required for optimal biological activity: this sub-
stituent R1 deconjugates the adjacent amide from the aromatic ring
to which it is attached, and forces a conformation which is believed
to be required for biological activity.
diamide 8. Compounds of type I were generally poorly active in the
insecticidal screen.
2.2. Bicyclic anthranilamides of type II
Naphthalene derivatives of type II such as 11 was easily pre-
pared from the corresponding commercially available anthranilic
acid (Scheme 4). Analogous quinolines and quinoxalines were
prepared according to Schemes 5 and 6. The synthetic route is
somewhat lengthy but efficient and appropriate to deliver gram
quantities of the desired targets. The key step is the cycloaddition
of a quinodimethane intermediate9 such as 14 with maleic diester.
The mono acid mono ester 17 was prepared through opening of the
corresponding phthalanhydride with methanol. In the case of
the pyridine derivatives 17, this reaction was not regioselective
and yielded a 1:1 mixture of 17a and 17b. Curtius rearrangement
of the mono-acid mixture yielded a BOC protected anthranilic
ester mixture which after deprotection gave a mixture of the
amino esters 18 and 19 which could be separated with
2.1. Bicyclic anthranilamides of type I
The synthesis of a naphthalene derivative of type I is depicted in
Scheme 3. A benzoxazinone intermediate 7 was prepared in one
step from commercially available anthranilic derivative 5 and an
acid 6, in the presence of an excess of mesyl chloride and pyridine.8
The benzoxazinone reacted with an amine to yield the anthranilic

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
405
CF3
CF3
CF3
N
N
O
Cl
iPrNH2
MsCl, pyridine
N H2
O
N
N
N
N
+
N
N H
Cl
N
O
Cl
O
N
O
OH
OH
N
O
HN
5
6
7
8
Scheme 3.
CF3
CF3
CF3
N
Cl
MsCl,
Cl
O
N
N
Cl
iPrNH2
NH2
pyridine
Cl
N
N
N
N
+
N
NH
Cl
O
O
Cl
O
O
N
OH
OH
N
O
HN
9
6
10
11
Scheme 4.
CO2Et
1) KOH
Br
Br
Br
CO2Et
2) Ac2O
COOR1
COOR2
CO2Et
CO2Et
NaI, DMF
NBS
quant.
15
3) MeOH, Δ
Br
Br
N
N
N
N
N
33%
Br
17a (R1 = H, R2 = Me)
12
13
14
16
17b (R1 = Me, R2 = H)(1:1)
"o-quinodimethane"
Br
N
Cl
O
N
Cl
Cl
NH2
N
N
NH
1) NCS, DMF
2) KOH
NH2
N
N
O
CO2Me
CO2H
1) dppa, tBuOH
2) TFA
92%
HN
18
20
22
3) separation (FC)
Br
N
N
Cl
Cl
O
NH2
Cl
1) NCS, DMF
2) KOH
NH2
NH
N
CO2Me
N
92%
CO2H
N
O
N
HN
19
21
23
Scheme 5.
flash-chromatography. Each of the anthranilic esters were elabo-
rated separately to the diamides 22 and 23. Starting from dimethyl-
pyrazine 24, the same approach delivered the quinoxaline analog
31, without a regioselectivity issue (Scheme 6).
The triazolopyridine 41 was made from the de novo prepared
ethyl 4,6-dichloropyridine-3-carboxylate 3410 as depicted in
Scheme 7. Noteworthy is the preferred reactivity of amines or
hydrazines on the position 4 rather than 2 of the pyridine 34.
Triazolopyridines are relatively basic and polar, making their
isolation and purification tedious.
An anthranilic derivative with an indoline core 48 was easily
made from methyl indoline-6-carboxylate 42 via regioselective
nitration and halogenation (Scheme 8).
The dihydrobenzothiophene derivative 58 was made de novo
from 2-chloro, 5-nitro benzaldehyde 49 as depicted in Scheme 9.
Introduction of the carboxylic functionality ortho to the amine of
53 was performed through the isatin intermediate 55. This versa-
tile method11 was used for various other heterocycles as described
below. The isatin intermediate is prepared in two steps, first acy-
lating with chloral to give 54, followed by Friedel–Crafts acylation

406
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
CO2Et
Br
CO2Et
15
1) NaOH
2) Ac2O
CO2Et
CO2Et
N
N
N
N
N
N
NBS, AIBN
Br
Br
CCl4
74%
NaI, DMF
37%
3) MeOH, D
63%
Br
24
25
26
Cl
NH
N
N
NH
N
N
2
CO H
2
2
N
1) NCS, DMF
1) dppa, tBuOH
CO H
2
CO Me
2) NaOH
88%
2) HCl 6 N
33%
2
N
CO Me
2
27
28
29
CF3
CF3
HO2
C
N
CF3
N
N
N
Cl
Cl
Cl
O
N
6
N
Cl
N
N
N
N
MeNH2
Cl
N
NH
O
N
O
N
MsCl, py
87%
N
O
HN
30
31
Scheme 6.
H
N
1) CH(OEt)3, Ac2O
2) NH3
HO
OH
CO2Et
Cl
Cl
Cl
H2
N
POCl3
89%
O
O
N
N
N
dioxane, D
95%
OEt
CO2Et
CO2Et
CO2Et
55%
32
33
34
35
MeC(OEt)3,
EtOH,
H
H
N
H
N
Pd/C, EtOH
BF3.OEt2
NH2NH2
N
N
H2N
H2SO4 (cat.)
N
or MeSO3H
dioxane, D
80%
N
N
CO2Et
CO2Et
53%
41%
36
37
Br
Br
N
HOOC
N
Cl 40
N
N
1)
Cl
O
N
1) NCS, DMF
2) NaOH
Cl
Cl
NH2
CO2Et
NH2
CO2H
N
N
NH
N
py, MsCl
2) iPrNH2
N
N
N
N
N
N
40%
N
O
HN
38
39
41
Scheme 7.
to 55. After hydrogenation of the thiophene ring, 56 was oxidized
under Baeyer–Villiger conditions to give the anthranilic acid which
was directly chlorinated with NCS to give 57. This method turned
out to be robust and amenable to upscale (100 g batches).
to the amine was made according to the isatin methodology
(63–66).
Benzotriazole 70 was obtained by diazotization of one amino
group of 61 followed by cyclization under elimination of N2
(Scheme 11). Benzothiadiazole 74 was made from the condensa-
tion of the diamine 61 with thionyl chloride14 (Scheme 11). The
anthranilic intermediate 75 was prepared by a Pd-catalyzed car-
boxylation, since the isatin methodology was not successful
(Scheme 11).
Indazole 87 was prepared from the commodity 2,4-dimethy-
laniline 77 (Scheme 12). The key step was the diazotization of
the nitration product 78, which spontaneously cyclized under the
elimination of N2. We believe that the nitro group enhances the
2.3. Bicyclic anthranilamides of type III
Benzimidazole 68, benzotriazole 71 and benzothiadiazole 76
were all prepared from the same intermediate, 4-methyl-5-nitro-
benzene-1,2-diamine 61,12 which was obtained by the selective
Zinin reduction13 of a dinitroaniline 60. Benzimidazole 68 was
made by cyclization of the diamine 61 with formic acid
(Scheme 10). The introduction of the carboxylic functionality ortho

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
407
NO
2
NH
2
KNO3, H2SO4
H2/Pd
quant.
AcCl, Et3N
80%
N
Ac
CO Me
N
Ac
N
Ac
CO Me
2
2
CO Me
2
N
H
CO Me
2
quant.
42
43
44
45
Br
Br
N
N
HO
1)
C
2
N
Cl
N
Cl
O
Cl
NCS
AcOH/DMF
N
Cl
NH
Cl
2
NH
2
NaOH
N H
N
N
Ac
CO H
N
Ac
2
O
CO Me
2
N
Ac
pyridine, MsCl
2) iPrNH2
HN
46
47
48
Scheme 8.
NO
1) HSCH2CO2Me,
MeONa
2
NO
2
NO
2
NO
2
Cu
mCPBA
95%
quinoline
O
2) NaOH
S
C
Cl
S
S
O
CHO
70%
74%
HO
2
49
50
51
52
H
N
Cl3CCH(OH)2
H
N
NH2
O
Fe, AcOH
45%
Na2SO4, NH2OH.HCl
H2SO4
O
O
O
NOH
S
S
S
O
O
48%
>90%
O
O
O
53
54
55
Br
N
HO
C
Br
2
N
Cl
N
N
N
1)
O
1. H2O2, NaOH
2. NCS
Cl
H
N
H2, Pd/C
THF
Cl
40
Cl
NH2
CO H
NH
O
N
S
pyridine, MsCl
2) iPrNH2
O
S
62%
S
O
78%
O
O
2
O
O
O
O
HN
57
56
58
Scheme 9.
acidity of the proton on the methyl substituent, which favors the
cyclization. The final diamide was made from the aminolysis of
the isatoic anhydride intermediate 84. Upscale of these last steps
proved to be difficult.
by a Snieckus–Fries rearrangement, as described by Novartis
researchers.16
2.4. Biological results
The key step in the synthesis of benzoxazole 97 was the cycliza-
tion of oxime 90 under aromatic nucleophilic displacement of a
nitro group at 150 °C (Scheme 13). Once again the second nitro
group is activating the desired cyclization reaction. Initial transfor-
mation of a benzoic acid 88 to an acetophenone 89 was made on a
larger scale (10 g) by condensation with a malonate followed by
bis-decarboxylation.
The preparation of the corresponding 3-amino-benzisoxazole
108 was less straightforward (Scheme 14). The key intermediate
103, an ortho fluoro benzonitrile derivative, was prepared in six
steps from the fluoro aniline 98. Cyclization of 103 with N-acetyl
hydroxylamine15 to the benzisoxazole 104 was quantitative. Bis-
protection of the more reactive amino group with BOC was
required to elaborate the intermediate 107 to the final diamide
108.
Results of the biological testing against plant herbivorous
insects as well as results from a binding assay (in vitro activity)
are presented in Table 1. Bicyclic anthranilamides of type I were
generally poorly active in vivo (see 8). This is believed to be due
to steric clash at the receptor level. In contrast, the best compounds
of type II and III showed activity comparable the standards 2 and 3
in vitro as well as in vivo (see 4, 23, 68 and 87).
There are clear differences at the receptor level across the target
insects.4 This is clearly seen for some compounds in the binding
assay (23 and 68). Compounds with low logP are prone to be sys-
temic in the plant, and activity in vivo is seen against the green
peach aphids Myzus persicae. The naphthalene derivative 4 is active
at the nM range in vitro against Spodoptera (chewing) and Myzus
(sucking). However it is active in vivo only against Spodoptera since
it is not plant systemic due to its high logP (4.86). By contrast, the
indazole derivative 87 is active in vivo against both insect species:
Finally, the preparation of triazolo-pyridine 116 is depicted in
Scheme 15. The monocyclic anthranilic derivative 111 was made

408
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
1) H2SO4
HNO3
NO
2
Na2S,
NH4OH
NO
NO
2
2
HCO2H
O
N
H
H2N
H2N
2) H2SO4
50%
N
HCl conc.
74%
85%
NO
NH2
N
H
2
Zinin reduction
59
60
61
62
H
H
N
chloral hydrate
NH2OH.HCl
OH
NH2
N
N
H2SO4
SnCl2, HCl 8N
86%
O
O
N
N
N
O
N
N
H
N
(48% over 2 steps)
H
H
63
64
65
Br
Br
H O
Br
N
N
N
N
O
O
Cl
Cl
N
N
NH2
N
O
NaOH, H2O2
81%
N
Cl
40
NH
iPrNH2
N
O
O
N
O
N
N
80%
N
MsCl, Py
70%
N
H
OH
N
N
H
HN
68
H
66
67
Scheme 10.
1) NBS, DMF
2) PdCl2, CO, MeOH
BINAP, NEt3
NH2
NH2
1) SOCl2, NEt3
2) SnCl2, HCl
1) NaNO2 HCl
2) H2, Pd/C
NO2
N
N
N
S
H2N
75%
N
H
60%
N
20%
NH2
69
61
74
1) chloral hydrate
NH2OH.HCl
Br
N
2) H2SO4
1) LiOH
3) H2O2, NaOH
O
N
Cl
NH2
O
NH2
O
2) 40, MsCl, py
3) MeNH2
44%
NH
N
N
N
S
N
N
O
N
H
O
OH
N
S
N
HN
76
1) 40, MsCl, Py
2) iPrNH2
70
75
Br
Br
Br
N
N
N
N
N
N
O
O
O
Cl
Cl
Cl
NaOH, MeCN
MeI
NH
NH
NH
O
N
N
N
+
56%
O
O
N
N
N
N
N
N
N
N
N
HN
HN
HN
1 : 1
H
71
72
73
Scheme 11.
with a logP of 1.71, it is expected to be present in the sap from
which the sucking pests feed.
bicyclic system of type II or III. Introducing heteroatoms in the
bicycle was indifferent in the case of the quinoline derivative
23. However introducing a nitrogen atom such as in the regioiso-
meric quinoline 22 or in the quinoxaline 31 was detrimental for
activity. Similarly for the bicyclic systems of type III, varying
the position of the heteroatoms in the five-membered ring shows
that the benzimidazole 68 and the indazole 87 are by far the
In the absence of any structural information at the receptor
level, one can develop a pharmacophore model rationalizing the
experimental data. For example, the high activity of the naph-
thalene derivative 4 of type II or of the indazole 87 of type III
shows that the active site is large enough to accommodate a

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
409
Cl3CCH(OH)2
NH2OH.HCl
Na2SO4
H
N
Pd/C, H2
MeOH
O
NO2
NO2 NaNO2, AcOH
73%
NH2
HNO3, H2SO4
78%
N
OH
88%
59%
N
H
N
H
N
NH2
NH2
N
N
H
N
77
78
79
80
81
H
N
H
H2O2, NaOH
H2O, RT
NH2
CO2H
H2SO4, 80oC
93%
N
O
ClCO2CCl3
quant.
O
O
94%
O
N
H
N
H
N
N
N
H
O
N
82
83
84
OMe
N
OMe
N
Cl
O
N
NH2
O
Cl
O
N
AcOH, D
60%
NH
86
N
Cl
N
O
N
HN
N
H
N
H
HN
87
N
85%
85
Scheme 12.
CO2Me
1)
EtONa
NO2
CO Me
NO2
NO2
2
NaH, diglyme,
150oC
NH2OH
90%
HO
2) AcOH, H2SO4
70%
O
NO2
NO2
NO2
O
N
HO
- 2 CO2
90%
88
89
90
H
N
NO2
NH2
OH
SnCl2,
1) H2SO4
chloral hydrate
NH2OH
N
HCl 8N
2) H2O2, NaOH
O
quant.
93%
O
O
N
N
22% (2 steps)
O
N
91
92
93
OMe
N
OMe
N
N
Cl
Cl
O
Cl
O
N
1)
Cl
NH2
NH2
OH
N
NCS, DMF
80%
NH
N
96
COOH
COOH
O
O
O
N
N
2) iPrNH2
O
HN
97
N
94
95
Scheme 13.
most active derivatives. Intermediate activity was observed for
the benzotriazoles 71 and 72 or benzisoxazole 97 while benzoth-
iadiazole 76 was completely inactive.
Only a few analogs were active against both insect types in vivo.
A good combination of intrinsic activity against both species and
good bioavailability properties (low logP and aqueous solubility)
are clearly required. Compounds 3 and the indazole 87 are the
most interesting in this respect, and one can see the indazole moi-
ety in 87 as a bioisosteric replacement of the cyano phenyl moiety
in 3.
insecticides chlorantraniliprole 2 or cyantraniliprole 3. High levels
of insecticidal activity in the greenhouse was observed against
chewing pests and in some cases even against sucking pests. LogP
is a good bioavailability model to understand the translation of
in vitro activity to potent insecticidal activity against sucking pests
in the greenhouse.
4. Experimental section
All new compounds were characterized by standard spectro-
scopical methods. 1H NMR spectra were recorded on a Varian Unity
400 spectrometer at 400 MHz using CDCl3 or DMSO-d6 as solvent.
Chemical shifts are reported in ppm downfield from the standard
(d = 0.00). Mass spectra were recorded on a Micromass LCT mass
spectrometer. Melting points were determined on a Büchi 535
3. Conclusions
New bicyclic anthranilic diamides have been prepared and were
shown to reach the level of activity of the best anthranilamide

410
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
chloral hydrate
NH2OH
H
NH2
1) H2SO4
NH2
N
OH
NH2
NIS, DMF
98%
2) H2O2, NaOH
N
HCl
CO2H
O
I
CO2H
76%
84% (2 steps)
F
F
F
F
98
99
100
101
O
OH
N
H
NH2
O
(Boc)2O, DMAP
Et3N, CH2Cl2
NH2
O
1) SOCl2
2) MeNH2
CuCN, CuI
Pd(PPh3)4
NH2
O
DMF, K2CO3, RT
H2N
NC
45%
I
O
HN
N
83%
93%
quant.
F
HN
F
HN
102
103
104
Br
N
Br
N
Br
N
O
N
O
Cl
N
ClOC
N
Cl
Cl
TFA
47%
NH2
O
N
O
O
NH
NH
O
O
N
N
106
O
O
N
O
N
H2N
O
O
HN
N
O
HN
no base
51%
N
O
HN
N
O
O
105
107
108
Scheme 14.
Boc
N
Boc
NH
Boc
NH
LiHMDS
(Boc)2O
NH2
LDA
-78oC
NH2NH2
N
Boc
N
N
OtBu
N
quant.
dioxane, D
75%
72%
COOtBu
111
Cl
109
Cl
NH
O
Cl
H2N
N-Snieckus-Fries
110
112
Boc
NH
OtBu
NH2
OH
MeC(OEt)3
EtOH,
H2SO4 (drops)
60%
1) SOCl2
NH2
O
TFA
83%
2) MeNH2, EtOH
N
N
N
N
O
N
N
O
N
N
HN
N
55%
113
114
115
OMe
OMe
N
N
O
N
Cl
Cl
N
O
96
N
Cl
NH
N
N
O
no base
N
HN
116
N
Scheme 15.
melting point apparatus and are uncorrected. Analytical thin-layer
chromatography (TLC) was performed using silica gel 60 F524 pre-
coated plates. Preparative flash chromatography was performed
using silica gel 60 (40–63 ml, E. Merck). Reactions were generally
carried out under anhydrous conditions in an inert atmosphere
(nitrogen or argon) with dry solvents.
4.1. 2-(3-Chloro-2-pyridyl)-N-[1,6-dichloro-3-(isopropylcarba-
moyl)-2-naphthyl]-5-methyl-pyrazole-3-carboxamide (4)
(a) 0.14 ml (1.86 mmol) methanesulfonyl chloride was stirred in
2 ml acetonitrile under nitrogen and the solution was cooled to 0 °C.
A solution of 418 mg (1.43 mmol) 2-(3-chloro-2-pyridyl)-5-(trifluo-

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
411
Table 1
Structure
Type
In vitro IC50 (nM)*
Spo
In vitro IC50 (nM)*
Myzus
In vivo EC80 (ppm)**
Spo
In vivo EC80 (ppm)**
Myzus
logP***
Br
N
O
N
Cl
2
—
3
2
0.8
200
2.78 (e)
NH
N
O
Cl
HN
Br
N
O
N
Cl
3
—
5
1
0.2
3.1
1.91 (e)
N H
N
O
NC
H N
CF
3
N
O
N
N
Cl
Cl
N H
4
II
5
5
0.2
>200
4.86 (c)
O
Cl
H N
CF
3
N
Cl
O
N
N H
8
I
570
nd
>200
>200
3.82 (c)
N
O
H N
Br
N
N
Cl
O
Cl
Cl
Cl
22
23
31
II
II
II
102
nd
50
>200
1.86 (e)
2.34 (e)
2.41 (c)
N
NH
N
O
H N
Br
N
N
Cl
O
3
50
0.8
50
NH
N
O
N
HN
CF
3
N
N
Cl
O
200
600
12.5
>200
N
N
N H
N
O
HN
(continued on next page)

412
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
Table 1 (continued)
Structure
Type
In vitro IC50 (nM)*
Spo
In vitro IC50 (nM)*
Myzus
In vivo EC80 (ppm)**
Spo
In vivo EC80 (ppm)**
Myzus
logP***
Br
N
O
N
Cl
Cl
NH
N
41
II
>4000
>4000
>200
>200
1.16 (e)
N
N
N
O
HN
Br
N
O
N
N
Cl
Cl
NH
O
48
II
nd
nd
3.1
>200
2.85 (c)
N
Ac
HN
Br
N
O
N
Cl
Cl
NH
58
II
nd
nd
ꢀ200
50
2.44 (c)
N
O
S
O
O
HN
Br
N
O
N
Cl
NH
NH
NH
68
III
8
40
0.8
200
2.37 (c)
N
O
N
N
H
HN
Br
N
O
N
N
Cl
71
III
40
65
0.8
>200
2.10 (e)
O
N
N
N
H
HN
Br
N
O
N
Cl
72
III
258
315
0.8
>200
2.12 (c)
N
O
N
N
N
HN
Br
N
O
N
N
Cl
76
III
>4000
>4000
>200
>200
2.09 (c)
NH
O
N
S
N
HN

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
413
Table 1 (continued)
Structure
Type
In vitro IC50 (nM)*
Spo
In vitro IC50 (nM)*
Myzus
In vivo EC80 (ppm)**
Spo
In vivo EC80 (ppm)**
Myzus
logP***
OMe
N
N
O
Cl
NH
87
III
5
16
<0.2
12.5
1.71 (e)
N
O
N
H
HN
N
OMe
N
N
Cl
O
Cl
NH
97
III
98
45
12.5
>200
2.14 (e)
N
O
O
HN
N
Br
N
N
Cl
O
108
III
nd
nd
50–12.5
ꢀ200
1.52 (e)
NH
N
O
H
N
2
O
O
HN
N
OMe
N
N
Cl
116
III
nd
nd
12.5
>200
(c)
NH
O
N
H
N
N
N
N
nd: not determined.
*
Displacement assay as described in Ref. 6, supplementary part.
**
In vivo microscreening as described in Ref. 8: example B8 p 196: Spo: Spodoptera littoralis, example B6 p 195: Myzus: Myzus persicae.
logP (e): experimental, (c): calculated.
***
romethyl)pyrazole-3-carboxylic acid and 0.2 ml (2.4 mmol) pyri-
dine in 2 ml acetonitrile were added dropwise to the reaction mix-
ture over 10 minutes. The reaction mixture was stirred for a further
30 min, then 367 mg (1.43 mmol) 3-amino-4,7-dichloro-naph-
thalene-2-carboxylic acid was added in portion in a suspension with
2 ml acetonitrile and a second portion of 0.41 ml (5.0 mmol) pyri-
dine. After stirring for 40 min a solution of 0.14 ml (1.86 mmol)
methanesulfonyl chloride in 1 ml acetonitrile was added dropwise
over 5 min. After stirring for a further 45 min a second portion of
methanesulfonyl chloride (0.44 ml, 5.7 mmol) was added portion-
wise, again maintaining the temperature at 0 °C. The reaction mix-
ture was then allowed to warm to RT and stirred for 2 h at RT. The
reaction was quenched by the addition of water and was stirred
for 10 min. The suspended solid was collected by filtration and
washed with water and hexane to afford 606 mg 7,10-dichloro-2-
[2-(3-chloro-2-pyridyl)-5-methyl-pyrazol-3-yl]benzo[g][3,1]benzox-
azin-4-one (83%) as a pale yellow solid.
which time TLC showed no remaining starting material. The reac-
tion mixture was then concentrated in vacuum. The residue was
purified by flash-chromatography [silica gel; hexane, followed by
hexane/ethyl acetate (2:1)], to give 2-(3-chloro-2-pyridyl)-N-[1,6-
dichloro-3-(isopropylcarbamoyl)-2-naphthyl]-5-methyl-pyra-
zole-3-carboxamide (4) (152 mg, 68%) as a white powder. 1H NMR
(DMSO-d6): 1.05 (d, 6H), 3.9 (m, 1H), 7.65 (m, 1H), 7.75 (dd, 1H),
7.89 (s, 1H), 8 (s, 1H), 8.2 (d, 1H), 8.25 (d, 1H), 8.3 (d, 1H), 8.35
(b, 1H), 8.5 (d, 1H), 10.8 (s, 1H); MS (electrospray): m/z = 570
[M+1].
4.2. 2-[2-(3-Chloro-2-pyridyl)-5-(trifluoromethyl)pyrazol-3-yl]
benzo[h][3,1]benzoxazin-4-one (7)
To
a solution of 93 mg (0.5 mmol) 1-aminonaphthalene-
2-carboxylic acid in 3 ml pyridine was added 155 mg (0.5 mmol)
of 2-(3-chloro-2-pyridyl)-5-(trifluoromethyl)pyrazole-3-carbonyl
chloride whilst stirring. The reaction was stirred at RT for 2 h before
further addition of acid chloride (80 mg, 0.25 mmol). After one addi-
tional hour of stirring at RT, the reaction mixture was concentrated
under vacuum. The residue was triturated in water and the resulting
yellowish solid was filtered off, washed with water and dried under
vacuum. The resulting solid was treated with chloroform and some
MS (electrospray): m/z = 456 [M+1].
(b) In a nitrogen atmosphere 0.1 ml (1.17 mmol) of isopropy-
lamine in anhydrous THF was added with stirring to a solution of
0.2 g (0.15 mmol) of 7,10-dichloro-2-[2-(3-chloro-2-pyridyl)-5-
methyl-pyrazol-3-yl]benzo[g][3,1]benzoxazin-4-one in 5 ml of
anhydrous THF. The clear solution was stirred for one hour after

414
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
insoluble impurities were removed by filtration. Evaporation of the
chlorinated solvent gave 2-[2-(3-chloro-2-pyridyl)-5-(trifluo-
romethyl)pyrazol-3-yl]benzo[h][3,1]benzoxazin-4-one (7) (82 mg,
37%) as a yellow solid.
azin-4-one in 5 ml anhydrous THF under nitrogen was added
0.037 ml (0.45 mmol) isopropyl amine and the reaction was heated
at 50 °C for 1 h. The solvent was removed under vacuum and the
residue purified by flash-chromatography (SiO2; hexane then
EtOAc–hexane, 1:3) to give 30 mg N-[1-chloro-3-(isopropyl-
carbamoyl)-2-naphthyl]-2-(3-chloro-2-pyridyl)-5-(trifluoromethyl)
pyrazole-3-carboxamide (11) (37%).
1H NMR (CDCl3, 400 MHz): 7.45 (m, 2H), 7.6 (s, 1H), 7.7 (m, 2H),
7.9 (m, 2H), 8.1 (m, 2H), 8.65 (s, 1H); MS (electrospray): m/z = 443
[M+1].
1H NMR (CDCl3, 400 MHz): 1.2 (d, 6H), 4.2 (m, 1H), 6.2 (d, 1H), 7.2
(m, 1H), 7.35 (m, 2H), 7.6 (m, 2H), 7.65 (s, 1H), 7.8 (d, 1H), 7.9 (s, 1H),
8.4 (d, 1H), 10.7 (s, 1H); MS (electrospray): m/z = 536 [M+1].
4.3. 2-(3-Chloro-2-pyridyl)-N-[2-(isopropylcarbamoyl)-1-naph-
thyl]-5-(trifluoromethyl)pyrazole-3-carboxamide (8)
To a solution of 45 mg (0.1 mmol) 2-[2-(3-chloro-2-pyridyl)-5-
(trifluoromethyl)pyrazol-3-yl]benzo[h][3,1]benzoxazin-4-one in
2 ml THF was added 60 mg (1 mmol) isopropylamine. The reaction
was stirred at RT overnight and was concentrated under vacuum to
give an orange solid (45 mg). TLC (EtOAc–hexane, 1:1) indicated a
mixture, the lowest spot being the desired material. The crude pro-
duct was purified by TLC preparative (DCM–MeOH, 10:1) to give 2-
(3-chloro-2-pyridyl)-N-[2-(isopropylcarbamoyl)-1-naphthyl]-5-
(trifluoromethyl)pyrazole-3-carboxamide (8) (17 mg, 33%) as a
white solid.
4.7. 2,3-Bis(dibromomethyl)pyridine (13)
A solution of 20.0 g (186 mmol) 2,3-dimethylpyridine and 150 g
(835 mmol) N-bromo-succinimide in 1.2 L CCl4 was irradiated with
a 150 Watt lamp at reflux temperature during 20 h. After cooling,
the solution was filtered and the organic phase was washed with
a 5% sodium thiosulfate solution and water. Evaporation of the
organic phase afforded 62.0 g 2,3-bis(dibromomethyl)pyridine
(13) (78%).
1H NMR (CDCl3): 6.92 (s, 1H), 7.4 (s, 1H), 7.45 (m, 1H), 8.25
(m, 1H), 8.5 (m, 1H). LC–MS: tR = 1.91 min, m/z = 419 [M+1], 421
[M+3], 423 [M+5], 425 [M+7], 427 [M+9]. Mp: 157–160 °C.
1H NMR (CDCl3, 400 MHz): 1.2 (d, 6H), 4.2 (m, 1H), 6.15 (d, 1H),
7.1 (d, 1H), 7.35 (m, 2H), 7.5 (m, 1H), 7.6 (m, 1H), 7.75 (s, 1H), 7.85
(m, 2H), 8.45 (s, 1H), 11 (s, 1H); MS (electrospray): m/z = 502 [M+1].
4.8. Diethyl quinoline-6,7-dicarboxylate (16)
4.4. 1-Chloro-3-methyl-naphthalen-2-amine (9)
To a solution of 62.0 g (144 mmol) 2,3-bis(dibromomethyl)pyr-
idine (13) and 70.0 g (400 mmol) diethyl maleate in 500 ml DMF
was added 61.5 g (400.0 mmol) NaI and the mixture was heated
at 80 °C during 6 h. After evaporation of the solvent, the residue
was dissolved in 2000 ml ethyl acetate and washed with a sodium
bicarbonate solution and water (6 times). Evaporation of the sol-
vent and purification of the residue with flash-chromatography
afforded 8.0 g diethyl quinoline-6,7-dicarboxylate (16) as a dark
oil (20%).
1.9 g (14.7 mmol) of N-chlorosuccinimide and 10 mg of 2,20-
azoisobutyric nitrile were added to
a suspension of 2.5 g
(13.3 mmol) of 2-amino-3-carboxy-naphthalene in 100 ml of tetra-
chloromethane. The reaction mixture was stirred for 18 h at RT,
treated with 250 ml of aqueous sodium chloride solution and
extracted with ethyl acetate (3 ꢁ 250 ml). The combined organic
layers were dried over MgSO4, filtered and concentrated in vacuum
to afford 2.78 g 1-chloro-3-methyl-naphthalen-2-amine (9) (95%)
in the form of a brown solid.
1H NMR (CDCl3, 400 MHz): 1.45 (t, 6H), 4.45 (q, 4H), 7.55 (q,
1H), 8.25 (m, 2H), 8.25 (s, 1H), 9.05 (m, 1H). MS (electrospray):
m/z = 274 [M+1].
1H NMR (CDCl3): 8.53 (s, 1H), 7.98 (d, 1H), 7.73 (d, 1H), 7.55 (t,
1H), 7.25 (t, 1H). MS (electrospray): m/z = 222 [M+1].
4.5. 10-Chloro-2-[2-(3-chloro-2-pyridyl)-5-(trifluoromethyl)pyr-
azol-3-yl]benzo[g][3,1]benzoxazin-4-one (10)
4.9. 7-Methoxycarbonylquinoline-6-carboxylic acid and 6-
methoxycarbonylquinoline-7-carboxylic acid (17a) and (17b)
In a nitrogen atmosphere 0.5 ml (5.75 mmol) oxalyl chloride
was added dropwise at RT while stirring to a suspension of
295 mg (1.0 mmol) of 5-carboxy-1-(3-chloropyrid-2-yl)-3-trifluo-
romethyl-pyrazole in 2 ml dichloromethane. The reaction mixture
was stirred for 1 h and then added dropwise to a solution of 0.25 g
(1 mmol) 1-chloro-3-methyl-naphthalen-2-amine (9) in 20 ml
dichloromethane and 0.38 ml (2.81 mmol) triethylamine. The reac-
tion mixture was subsequently stirred for 3 h. Further 0.7 ml tri-
ethylamine (5 mmol) was added, followed by the addition in a
single portion of 0.22 ml (2.8 mmol) methane sulfonic acid chlo-
ride. The reaction mixture was then stirred for 18 h and concen-
trated in vacuum, and the residue was purified by flash-
chromatography [silica gel; hexane/ethyl acetate (3:1)], to afford
(a) 14 g (51.2 mmol) diethyl quinoline-6,7-dicarboxylate and
5.0 g (86 mmol), 14.6 g (270 mmol) KOH were dissolved in
100 ml dioxane and 50 ml water. The reaction mixture was stirred
at RT overnight. After evaporation of the dioxane, the solution was
made acidic (pH ꢀ2) with HCl 2 N and was extracted with ethyl
acetate and THF. After evaporation of the solvent, the residue
was crystallized successively in diethyl ether and acetonitrile to
give 3.6 g quinoline-6,7-dicarboxylic acid (64%).
1H NMR (DMSO-d6, 400 MHz): 7.7 (dd, 1H), 8.25 (s, 1H), 8.4 (s,
1H), 8.55 (d, 1H), 9.05 (m, 1H), 13.3 (br, 2H).
(b) 4.83 g (22.3 mmol) quinoline-6,7-dicarboxylic acid was
heated at 140 °C in 30 ml (317.0 mmol) acetic anhydride for one
day. After completion, the reaction mixture was cooled and con-
centrated under vacuum. The crude furo[3,4-g]quinoline-6,8-dione
(4.45 g, 92%) was used directly in the following step.
96 mg
10-chloro-2-[2-(3-chloro-2-pyridyl)-5-(trifluoromethyl)
pyrazol-3-yl]benzo[g][3,1]benzoxazin-4-one (10) (20%).
1H NMR (CDCl3): 8.78 (s, 1H), 8.61 (m, 1H), 8.30 (m, 2H), 8.03
(dd, 1H), 7.78 (m, 1H), 7.67 (m, 1H), 7.56 (m, 2H); MS (electro-
spray): m/z = 477 [M+1], 479 [M+3], 481 [M+5].
(c) 4.45 g (22.3 mmol) furo[3,4-g]quinoline-6,8-dione dissolved
in 50 ml methanol was heated at 75° overnight. After evaporation
of the methanol, the residue was crystallized in hexane to give
4.67 g (90%) of a 1:1 mixture 7-methoxycarbonylquinoline-6-car-
boxylic acid and 6-methoxycarbonylquinoline-7-carboxylic acid
(17a) and (17b).
4.6. N-[1-Chloro-3-(isopropylcarbamoyl)-2-naphthyl]-2-(3-chl-
oro-2-pyridyl)-5-(trifluoromethyl)pyrazole-3-carboxamide (11)
1H NMR (DMSO-d6, 400 MHz): 3.85 (s, 6H), 7.7 (dd, 2H), 8.2 (s,
1H), 8.35 (s, 1H), 8.4 (s, 1H), 8.5 (s, 1H), 8.55 (m, 2H), 9.05 (m, 2H),
13.5 (s, 1H). MS (electrospray): m/z = 230 [Mꢂ1]. Mp: 195–198 °C.
To a solution of 70 mg (0.15 mmol) 10-chloro-2-[2-(3-chloro-
2-pyridyl)-5-(trifluoromethyl)pyrazol-3-yl]benzo[g][3,1]benzox-

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
415
4.10. Methyl 7-aminoquinoline-6-carboxylate (18) and methyl
6-aminoquinoline-7-carboxylate (19)
2-[5-bromo-2-(3-chloro-2-pyridyl)pyrazol-3-yl]-10-chloro-pyrido
[3,2-g][3,1]benzoxazin-4-one (76%).
1H NMR (CDCl3, 400 MHz): 7.35 (s, 1H), 7.5 (dd, 1H), 7.6 (dd,
1H), 8 (d, 1H), 8.35 (d, 1H), 8.6 (d, 1H), 8.7 (s, 1H), 9.15 (s, 1H).
Mp >250 °C.
(a) To 4.67 g (20 mmol) of a 1:1 mixture of 7-methoxycar-
bonylquinoline-6-carboxylic acid and 6-methoxycarbonylquino-
line-7-carboxylic acid (17a) and (17b) in 80 ml tert-butanol was
added 8 ml (37 mmol) diphenylphosphoryl azide and (7 ml,
51.8 mmol) triethylamine. The reaction mixture was heated at
80 °C overnight. After evaporation of the solvent, the residue was
taken up in 500 ml ethyl acetate and 100 ml THF and the resulting
organic was washed with water twice. The organic was dried and
concentrated under vacuum. The crude compound was purified
by flash-chromatography using dichloromethane and ethyl acetate
as solvent to afford 8.0 g (55%) of a 1:1 mixture methyl 7-(tert-
butoxycarbonylamino)quinoline-6-carboxylate and methyl 6-
(tert-butoxycarbonylamino)quinoline-7-carboxylate.
(d) 0.40 g (0.8 mmol) 2-[5-bromo-2-(3-chloro-2-pyridyl)pyra-
zol-3-yl]-10-chloro-pyrido[3,2-g][3,1]benzoxazin-4-one and 1 ml
methylamine 2 M in THF were added successively to 20 ml THF
and stirred for 8 h. After evaporation, the residue was crystallized
in diethyl ether to give 0.42 g 7-[[5-bromo-2-(3-chloro-2-pyridyl)
pyrazole-3-carbonyl]amino]-8-chloro-N-methyl-quinoline-6-car-
boxamide (22) (97%).
1H NMR (DMSO-d6, 400 MHz): 2.7 (d, 3H), 7.55 (s, 1H), 7.6 (dd,
1H), 7.7 (dd, 1H), 8.1 (s, 1H), 8.15 (d, 1H), 8.45 (d, 1H), 8.5 (m, 2H),
9.1 (s, 1H), 10.75 (s, 1H). MS (electrospray): m/z = 519 [M+1], 521
[M+3], 523 [M+5]. Mp 221–224 °C.
1H NMR (CDCl3, 400 MHz): 1.5 (s, 18H), 3.9 (d, 6H), 7.2 (m, 1H),
7.35 (m, 1H), 8 (m, 2H), 8.5 (s, 1H), 8.7 (m, 1H), 8.75 (m, 2H), 8.85
(m, 2H), 8.95 (s, 1H), 10.1 (s, 1H), 10.2 (s, 1H). MS (electrospray):
m/z = 303 [M+1]. Mp: 169–180 °C.
4.12. 6-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-5-chloro-N-methyl-quinoline-7-carboxamide (23)
(b) To 8.0 g (26.4 mmol) of a 1:1 mixture of methyl 7-(tert-
butoxycarbonylamino)quinoline-6-carboxylate and methyl 6-
(tert-butoxycarbonylamino)quinoline-7-carboxylate in 80 ml diox-
ane was added 60 ml HCl 6 M. The reaction mixture was stirred at
50 °C overnight. After evaporation of the solvent, the residue was
taken up in THF and washed with alkaline water. The organic phase
was dried and concentrated under vacuum. The crude compound
was purified by flash-chromatography to yield 0.84 g of methyl
6-aminoquinoline-7-carboxylate (19) and (0.71 g, 13.2%) of methyl
7-aminoquinoline-6-carboxylate (18) (15.5%).
(a) 0.84 g (4.1 mmol) methyl 6-aminoquinoline-7-carboxylate
and 0.56 g (4.1 mmol) N-chloro-succinimide were suspended in
10 ml DMF and heated at 80 °C during 4 h. Further 50 mg
(0.4 mmol) NCS was added and the reaction was further heated
3 h at 90 °C. After cooling, the mixture was poured into 100 ml
ice water. The mixture was stirred 30 min and the resulting solid
was filtered and dried to give methyl 6-amino-5-chloro-quino-
line-7-carboxylate (0.90 g, 92%) as a yellow solid.
1H NMR (CDCl3, 400 MHz): 4 (s, 3H), 6.3 (b, 2H), 7.45 (dd, 1H),
8.3 (d, 1H), 8.7 (s, 1H). MS (electrospray): m/z = 237 [M+1], 239
[M+3].
Methyl 7-aminoquinoline-6-carboxylate (18): 1H NMR (CDCl3,
400 MHz): 4 (s, 3H), 5.85 (s, 2H), 7.1 (m, 1H), 7.2 (s, 1H), 8 (d,
1H), 8.45 (s, 1H), 8.8 (m, 1H). MS (electrospray): m/z = 203 [M+1].
Methyl 6-aminoquinoline-7-carboxylate (19): 1H NMR (CDCl3,
400 MHz): 4 (s, 3H), 5.7 (s, 2H), 6.9 (s, 1H), 7.3 (m, 1H), 7.85
(d, 1H), 8.65 (m, 1H), 8.75 (s, 1H). MS (electrospray): m/z = 203
[M+1].
(b) 0.9 g (3.8 mmol) methyl 6-amino-5-chloro-quinoline-7-car-
boxylate and 0.5 g (9 mmol) KOH were suspended in 5 ml water
and 15 ml dioxane. The reaction mixture was stirred 4 h at RT
and then concentrated under vacuum to yield the crude potassium
salt of 6-amino-5-chloro-quinoline-7-carboxylic acid (570 mg,
58%) which was directly used in the next step.
(c) 570 mg (2.2 mmol) 6-amino-5-chloro-quinoline-7-car-
boxylic acid as the potassium salt obtain in the previous step
was suspended in 20 ml acetonitrile. 660 mg (2.2 mmol)
5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carboxylic acid and
1.3 ml (15 mmol) pyridine were added. A solution of 0.850 ml
(10.7 mmol) mesylchloride in 5 ml acetonitrile was slowly added
at 0 °C and the mixture was warmed up to RT and further stirred
for 1 h. The mixture was then poured on ice water and filtered after
15 min to afford 880 mg 2-[5-bromo-2-(3-chloro-2-pyridyl)pyra-
zol-3-yl]-10-chloro-pyrido[2,3-g][3,1]benzoxazin-4-one (83%).
1H NMR (CDCl3, 400 MHz): 7.35 (s, 1H), 7.5 (dd, 1H), 7.65 (dd,
1H), 8 (d, 1H), 8.6 (m, 2H), 8.95 (s, 1H), 9.1 (m, 1H). Mp >250 °C.
(d) To a solution of 0.40 g (0.8 mmol) 2-[5-bromo-2-(3-chloro-
2-pyridyl)pyrazol-3-yl]-10-chloro-pyrido[2,3-g][3,1]benzoxazin-
4-one in 20 ml THF was added 1 ml methylamine 2 M in THF and
the mixture was stirred for 8 h at RT. After evaporation, the residue
was crystallized in diethyl ether to afford 0.42 g 6-[[5-bromo-2-(3-
chloro-2-pyridyl)pyrazole-3-carbonyl]amino]-5-chloro-N-methyl-
quinoline-7-carboxamide (23) (97%).
4.11. 7-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-8-chloro-N-methyl-quinoline-6-carboxamide (22)
(a) 0.71 g (3.5 mmol) methyl 7-aminoquinoline-6-carboxylate
and 0.47 g (3.5 mmol) N-chloro-succinimide was suspended in
10 ml DMF and heated at 80 °C for 4 h. Further 50 mg (0.4 mmol)
NCS was added and the reaction was heated 3 h at 90 °C. After
cooling, the mixture was poured into 150 ml ice water. The mix-
ture was stirred 30 min and the resulting solid was filtered and
dried to yield 0.77 g methyl 7-amino-8-chloro-quinoline-6-car-
boxylate as a yellow solid (92%).
1H NMR (CDCl3, 400 MHz): 4 (s, 3H), 6.50 (b, 2H), 7.2 (dd, 1H),
8.05 (d, 1H), 8.45 (s, 1H), 8.95 (d, 1H). MS (electrospray):
m/z = 237 [M+1], 239 [M+3].
(b) 0.77 g (3.25 mmol) methyl 7-amino-8-chloro-quinoline-6-
carboxylate and 0.5 g (9 mmol) KOH were suspended in 5 ml of
water and 15 ml dioxane. The reaction mixture was stirred 4 h at
RT and concentrated under vacuum. The resulting crude potassium
salt of 7-amino-8-chloro-quinoline-6-carboxylic acid (570 mg,
68%) was directly used in the next step.
(c) 570 mg (2.2 mmol) 7-amino-8-chloro-quinoline-6-car-
boxylic acid as the potassium salt was suspended in 20 ml
acetonitrile. 660 mg (2.2 mmol) 5-bromo-2-(3-chloro-2-pyridyl)
pyrazole-3-carboxylic acid (40) and 1.3 ml (15 mmol) pyridine
were added. A solution of 0.850 ml (10.7 mmol) mesylchloride in
5 ml acetonitrile was slowly added at 0 °C and the mixture was
warmed up to RT and further stirred for 1 h. The mixture was then
poured on ice water and filtered after 15 min to afford 810 mg
1H NMR (CDCl3, 400 MHz): 3 (d, 3H), 6.65 (b, 1H), 7.3 (m, 2H),
7.8 (d, 1H), 7.85 (s, 1H), 8.15 (d, 1H), 8.45 (d, 1H), 8.75 (d, 1H),
10.25 (s, 1H). MS (electrospray): m/z = 519 [M+1], 521 [M+3], 523
[M+5]. Mp 209–212 °C.
4.13. Quinoxaline-6,7-dicarboxylic acid diethyl ester (26)
(a) A solution of 10.0 g (93.0 mmol) 2,3-dimethylpyrazine and
70.0 g (390 mmol) N-bromo-succinimide in 800 ml CCl4 was irradi-
ated with a 250 Watt lamp at reflux temperature during 20 h. After

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A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
cooling the solution was filtered and the organic phase was
washed with a 5% sodium thiosulfate solution and water. After
evaporation of the organic phase, the residue was crystallized in
ethanol to give 29.1 g 2,3-bis-dibromomethyl-pyrazine (25) (74%).
1H NMR (CDCl3, 400 MHz): 7.1 (s, 2H), 8.6 (s, 2H). MS (electro-
spray): m/z = 420 [M+1], 422 [M+3], 424 [M+5], 426 [M+7], 428 [M
+9]. Mp: 167–170 °C.
4.16. 7-Amino-8-chloro-quinoxaline-6-carboxylic acid methyl
ester (29)
2.07 g (10.2 mmol) 7-amino-quinoxaline-6-carboxylic acid
methyl ester (28) and 1.36 g (10.2 mmol) N-chloro-succinimide
were suspended in 5 ml DMF and heated at 95 °C during 30 min.
After cooling, the mixture was poured into 150 ml ice water. The
mixture was stirred 15 min and filtered. The compound was dried
and crystallized in hexane to give 2.15 g 7-amino-8-chloro-quinox-
aline-6-carboxylic acid methyl ester (29) (88%).
(b) To a solution of 38.0 g (90.0 mmol) 2,3-bis-dibromomethyl-
pyrazine (25) and 70.0 g (400 mmol) diethyl maleate in 450 ml
DMF was added 40.0 g (270.0 mmol) NaI and the mixture was
heated at 80 °C during 20 h. After evaporation of the solvent, the
residue was dissolved in 1000 ml t-butyl-methyl ether and washed
with a 5% sodium thiosulfate solution and water (5 times). Evapo-
ration of the solvent and purification of the residue with flash-
chromatography gave 9.1 g quinoxaline-6,7-dicarboxylic acid
diethyl ester (26) (37%) as a dark oil.
1H NMR (CDCl3, 400 MHz): 4 (s, 3H), 6.6 (br, 2H), 8.55 (d, 1H)
8.65 (s, 1H) 8.7 (s, 1H). LC (electrospray): m/z = 238 [M+1], 240
[M+3]. Mp: 182–184 °C.
4.17. 9-Chloro-2-[2-(3-chloro-pyridin-2-yl)-5-trifluoromethyl-
2H-pyrazol-3-yl]-3-oxa-1,5,8-triaza-anthracen-4-one (30)
1H NMR (CDCl3, 400 MHz): 1.45 (t, 6H), 4.45 (q, 4H), 8.5 (s, 2H),
9.0 (s, 2H). MS (electrospray): m/z = 275 [M+1].
A solution of 2.15 g (9.05 mmol) 7-amino-8-chloro-quinoxa-
line-6-carboxylic acid methyl ester (29) in 20 ml methanol, 20 ml
dioxane and 12 ml NaOH 1 N was stirred 20 h at RT. The mixture
was evaporated and the residue was taken twice in toluene and
evaporated. The sodium salt obtained was suspended in 70 ml ace-
tonitrile and 2.65 g (9.1 mmol) 2-(3-chloro-pyridin-2-yl)-5-trifluo-
romethyl-2H-pyrazole-3-carboxylic acid (6) followed by 3.5 ml
(40.7 mmol) pyridine were added. A solution of 2.5 ml (31.7 mmol)
mesylchloride in 10 ml acetonitrile was slowly added at 0 °C and
the mixture was warmed up to RT and further stirred for 1 h. The
mixture was then poured onto ice water (400 ml) and filtered after
15 min. The resulting solid was crystallized in isopropanol to give
4.14. Quinoxaline-6,7-dicarboxylic acid monomethyl ester (27)
11.8 g (43.0 mmol) quinoxaline-6,7-dicarboxylic acid diethyl
ester and 5.0 g (86 mmol) KOH dissolved in 100 ml dioxane and
50 ml water was stirred at RT during 20 h. After evaporation of
the solvent, the solution was made slightly acidic (pH ꢀ5) with
HCl 2 N and was extracted with methylene chloride. After evapora-
tion of the organic phase, 6.6 g quinoxaline-6,7-dicarboxylic acid
was isolated. This product was directly dissolved in 25 ml
(265 mmol) acetanhydride and heated at reflux during 8 h. Acetan-
hydride was evaporated and 6.2 g furo[3,4-g]quinoxaline-6,8-
dione was isolated. Without purification, this material was dis-
solved in 50 ml methanol and heated at reflux during 1 h. After
evaporation of the solvent, the residue was crystallized in diiso-
propyl ether to give 6.25 g quinoxaline-6,7-dicarboxylic acid
monomethyl ester (27) (63%).
3.77 g
9-chloro-2-[2-(3-chloro-pyridin-2-yl)-5-trifluoromethyl-
2H-pyrazol-3-yl]-3-oxa-1,5,8-triaza-anthracen-4-one (30) (87%).
1H NMR (DMSO-d6, 400 MHz): 7.55 (m, 1H), 7.60 (s, 1H), 8.05
(d, 1H), 8.60 (d, 1H), 9.00 (s, 1H), 9.02 (s, 1H), 9.10 (s, 1H). MS (elec-
trospray): m/z = 478 [M+1], 479 [M+3].
1H NMR (DMSO-d6, 400 MHz): 3.73 (s, 3H), 8.20 (s, 1H), 8.35
(s, 1H), 9.0 (2 s, 2H), 13.6 (s, b, 1H). MS (electrospray): m/z = 231
[M+1].
4.18. 8-Chloro-7-[[2-(3-chloro-2-pyridyl)-5-(trifluoromethyl)py-
razole-3-carbonyl]amino]-N-methyl-quinoxaline-6-carboxam-
ide (31)
A solution of 55 mg (1.15 mmol) 9-chloro-2-[2-(3-chloro-pyri-
din-2-yl)-5-trifluoromethyl-2H-pyrazol-3-yl]-3-oxa-1,5,8-triaza-
anthracen-4-one (30) in 15 ml (15.0 mmol) methylamine 1 N in
THF was stirred for 4 h at RT. The mixture was then concentrated
under vacuum. The crude material was triturated in diethyl ether.
The resulting solid was isolated by filtration, washed with ether to
4.15. 7-Amino-quinoxaline-6-carboxylic acid methyl ester (28)
(a) 7.1 g (30.6 mmol) quinoxaline-6,7-dicarboxylic acid mono-
methyl ester (27) (8 ml, 59.2 mmol) NEt3, 1 g molecular sieve 4 Å
and 10 ml (46.4 mmol) diphenylphosphonic azide were succes-
sively added to 100 ml tert-butanol. The mixture was heated at
85 °C during 20 h. After cooling, the mixture was filtered and the
solid was washed with 1000 ml THF. The filtrate was evaporated
and submitted to flash-chromatography to give 7.45 g 7-tert-
butoxycarbonylamino-quinoxaline-6-carboxylic acid methyl ester
(80%).
give
470 mg
8-chloro-7-[[2-(3-chloro-2-pyridyl)-5-(trifluo-
romethyl)pyrazole-3-carbonyl]amino]-N-methyl-quinoxaline-6-
carboxamide (31) (81%) as a crystalline solid.
1H NMR (CDCl3, 400 MHz): 2.7 (d, 3H), 7.65 (dd, 1H), 7.9 (s, 1H),
8.15 (s, 1H), 8.25 (d, 1H), 8.55 (d,12H), 8.65 (s, 1H), 9.1 (d, 2H),
11.05 (s, 1H); MS (electrospray): m/z = 510 [M+1], 512 [M+3].
Mp: 205–208 °C.
1H NMR (CDCl3, 400 MHz): 1.6 (s, 9H), 4.05 (s, 3H), 8.75 (d, 1H),
8.8 (s, 1H) 8.85 (dd, 1H) 9.5 (s, 1H). LC–MS: tR = 2.06 min, m/z = 304
[M+1]. Mp: 196–198 °C.
4.19. Ethyl 4-(allylamino)-6-chloro-pyridine-3-carboxylate (35)
(b) 7.1 g (24.0 mmol) 7-tert-butoxycarbonylamino-quinoxaline-
6-carboxylic acid methyl ester was added to 50 ml dioxane and
110 ml HCl 6 N and heated at 50 °C. The organic phase was evapo-
rated and the residue was diluted with 150 ml water. The water
phase was neutralized with NaOH 2 N (ꢀpH 8), saturated with
NaCl and extracted with ethyl acetate and THF. After evaporation
of the solvent, the residue was submitted to flash-chromatography
to give 2.2 g 7-amino-quinoxaline-6-carboxylic acid methyl ester
(28) (41%).
To a solution of 43.0 g (195 mmol) ethyl 4,6-dichloropyridine-
3-carboxylate (34) in 250 ml dioxane was slowly added 43.0 ml
(526 mmol) prop-2-en-1-amine. The addition was slightly
exothermic and the temperature reached 40 °C. The reaction was
stirred overnight at RT. The reaction mixture was concentrated
under vacuum, taken up in 500 ml water and stirred 30 min at
RT. The resulting solid was collected by filtration, washed with
water and dried. The resulting solid was taken up again in
500 ml water and 60 ml ethanol. The mixture was stirred 30 min.
The solid was filtered off and dried to give 44.8 g ethyl 4-(ally-
lamino)-6-chloro-pyridine-3-carboxylate (35) (95%).
1H NMR (CDCl3, 400 MHz): 4 (s, 3H), 6.00 (br, 2H), 7.15 (s, 1H),
8.55 (d, 1H) 8.65 (d, 1H) 8.7 (s, 1H). LC (electrospray): m/z = 204 [M
+1]. Mp: 180–182 °C.

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
417
1H NMR (CDCl3, 400 MHz): 1.4 (t, 3H), 3.4 (m, 2H), 4.4 (q, 2H),
5.3 (m, 2H), 5.9 (m, 1H), 6.55 (s, 1H), 8.35 (s, 1H), 8.7 (s, 1H);
mp: 67–69 °C]. LC–MS: tR = 1.52 min, m/z = 241 [M+1].
chlorosuccinimide were suspended in 5 ml DMF and heated at
90 °C for 90 min. After cooling, the mixture was poured into ice
water. The mixture was stirred 15 min and filtered. The collected
solid was washed with diisopropyl ether. The compound was dried
to give 90 mg ethyl 7-amino-8-chloro-3-methyl-[1,2,4]triazolo
[4,3-a]pyridine-6-carboxylate (40%) as a yellow solid.
4.20. Ethyl 4-(allylamino)-6-hydrazino-pyridine-3-carboxylate
(36)
1H NMR (DMSO-d6, 400 MHz): 1.35 (t, 3H), 2.65 (s, 3H), 4.4 (q,
2H), 6.8 (s, 2H), 8.7 (s, 1H). MS (electrospray): m/z = 255 [M+1].
Mp: 212–214 °C.
To a solution of 38.0 g (158.0 mmol) ethyl 4-(allylamino)-6-
chloro-pyridine-3-carboxylate (35) in 500 ml 1,4-dioxane was
added under stirring 45.0 ml (840.0 mmol) hydrazine hydrate .
The mixture was heated at 120 °C during 20 h. After evaporation
of the solvent, the residue was dissolved in ethyl acetate and
washed with water (2 times) and brine. The organic phase was
dried over MgSO4 and concentrated under vacuum. The crude com-
pound was purified by crystallization using petroleum ether and
diisopropyl ether to afford 30.3 g ethyl 4-(allylamino)-6-hydra-
zino-pyridine-3-carboxylate (36) was obtained (81%).
(b) 90 mg (0.35 mmol) ethyl 7-amino-8-chloro-3-methyl-
[1,2,4]triazolo[4,3-a]pyridine-6-carboxylate and 54 mg (1 mmol)
KOH were suspended in 1 ml water and 3 ml 1,4-dioxane. The
reaction mixture was stirred 4 h at RT. The reaction mixture was
then concentrated under vacuum and the resulting crude contain-
ing the product as a potassium salt of 7-amino-8-chloro-3-methyl-
[1,2,4]triazolo[4,3-a]pyridine-6-carboxylic acid (39) was used as
such in the next step.
(c) 700 mg (3.1 mmol) 7-amino-8-chloro-3-methyl-[1,2,4]tria-
zolo[4,3-a]pyridine-6-carboxylic acid as the potassium salt (39)
was suspended in 20 ml acetonitrile. 930 mg (2.2 mmol) 5-
bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carboxylic acid (40) and
1.3 ml (15 mmol) pyridine were added. 0.850 ml (10.7 mmol)
mesylchloride in 5 ml acetonitrile were slowly added at 0 °C and
the mixture was warmed up to RT and stirred for 1 h. The mixture
was then poured into ice water and filtered after 15 min.
The resulting solid, 9-chloro-2-[2-(3-chloro-pyridin-2-yl)-5-triflu-
oromethyl-2H-pyrazol-3-yl]-3-oxa-1,5,8-triaza-anthracen-4-one
(30) was poorly soluble in any solvent and was used directly in the
next step.
1H NMR (CDCl3, 400 MHz): 1.4 (t, 3H), 3.4 (m, 2H), 4.3 (q, 2H),
5.2 (d, 1H), 5.3 (d, 1H), 5.9 (s, 1H), 5.95 (m, 1H), 6.25 (s, 1H), 8.2
(s, 1H), 8.6 (s, 1H).). MS (electrospray): m/z = 237 [M+1]. Mp:
110–112 °C.
4.21. Ethyl 7-(allylamino)-3-methyl-[1,2,4]triazolo[4,3-a]pyrid-
ine-6-carboxylate (37)
To a solution of 2.7 g (11.4 mmol) ethyl 4-(allylamino)-6-hydra-
zino-pyridine-3-carboxylate (36) in 35 ml methanol was added 2
drops conc. sulfuric acid and 3.5 ml (17.1 mmol) triethylorthoac-
etate. The mixture was heated at 85 °C for 90 min. After evapora-
tion of the solvent, the residue was dissolved in ethyl acetate and
washed with water (2 times) and brine. The solvent was removed
under vacuum and the residue purified by flash-chromatography
(SiO2; EtOAc then EtOAc–MeOH, 9:1) to give 1.55 g ethyl 7-(ally-
lamino)-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-6-carboxylate
(37) (53%) as a yellow solid.
(d)
Crude
9-chloro-2-[2-(3-chloro-pyridin-2-yl)-5-trifluo-
romethyl-2H-pyrazol-3-yl]-3-oxa-1,5,8-triaza-anthracen-4-one as
described above was dissolved in 5 ml (58 mmol) isopropylamine
and stirred at RT overnight. The reaction was then concentrated
under vacuum. The residue was purified by successive crystalliza-
tion and trituration in acetonitrile, isopropanol and diethyl ether to
give 240 mg (14% over two steps) 7-[[5-bromo-2-(3-chloro-2-pyr-
idyl)pyrazole-3-carbonyl]amino]-8-chloro-N-isopropyl-3-methyl-
[1,2,4]triazolo[4,3-a]pyridine-6-carboxamide (41).
1H NMR (CDCl3, 400 MHz): 1.45 (t, 3H), 2.7 (s, 3H), 3.85 (m, 2H),
4.45 (q, 2H), 5.25 (d, 1H), 5.35 (d, 1H), 5.95 (m, 1H), 6.45 (s, 1H), 7.6
(s, 1H), 8.5 (s, 1H). LC–MS: tR = 0.67 min, m/z = 261 [M+1]. Mp:
121–123 °C.
1H NMR (DMSO-d6, 400 MHz): 1.05 (d, 3H), 2.7 (s, 3H), 3.85 (m,
1H), 7.5 (s, 1H), 7.6 (dd, 1H), 8.15 (d, 1H), 8.25 (s, 1H), 8.45 (s, 1H),
8.5 (d, 1H), 10.75 (s, 1H). MS (electrospray): m/z = 553 [M+1]. Mp:
245–248 °C.
4.22. Ethyl 7-amino-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-6-
carboxylate (38)
1.3 g (5 mmol) ethyl 7-(allylamino)-3-methyl-[1,2,4]triazolo
[4,3-a]pyridine-6-carboxylate (37), 1.0 ml (7.96 mmol) boron tri-
fluoride diethyl etherate and 100 mg Pd/C 10% were successively
added to 15 ml ethanol. The mixture was heated at 100 °C for
4 days. The mixture was allowed to cool down, filtered on cellite
and concentrated under vacuum. The solid residue was taken up
in water and ethyl acetate and the organic phase was successively
washed with a saturated sodium bicarbonate solution and water.
The organic phase was dried over MgSO4 and concentrated under
vacuum. The residue was purified by flash-chromatography
(SiO2; EtOAc to EtOAc–MeOH, 9:1) to give 225 mg ethyl 7-
amino-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-6-carboxylate (38)
(18%) as a yellow solid.
4.24. Methyl 1-acetylindoline-6-carboxylate (43)
A
solution of methyl indoline-6-carboxylate (42) (50 mg,
0.28 mmol) in dichloromethane (10 mL) was cooled to ꢂ30 °C,
treated with triethylamine (0.04 mL, 0.3 mmol) followed by drop-
wise addition of acetyl chloride (0.02 mL, 0.3 mmol), and warmed
to RT. The reaction mixture was quenched with water and
extracted with dichloromethane. The combined organic layers
were washed with water, brine solution, dried with anhydrous
sodium sulfate and concentrated under reduced pressure. The resi-
due was purified by flash-chromatography using ethyl acetate/
hexane (3:7) to afford 49 mg 1-acetylindoline-6-carboxylate (43)
as a white solid (80%).
1H NMR (DMSO-d6, 400 MHz): 1.35 (t, 3H), 2.6 (s, 3H), 4.35 (q,
2H), 6.5 (s, 1H), 6.6 (s, 2H), 8.7 (s, 1H); MS (electrospray):
m/z = 221 [M+1].
1H NMR (CDCl3, 400 MHz): 8.73 (s, 1H), 7.67 (d, 1H), 7.16
(d, 1H), 4.04 (t, 2H), 3.82 (s, 3H), 3.17 (t, 2H), 2.18 (s, 3H).); MS
(electrospray): m/z = 220 [M+1].
4.23. 7-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-8-chloro-N-isopropyl-3-methyl-[1,2,4]triazolo[4,3-a]
pyridine-6-carboxamide (41)
4.25. Methyl 1-acetyl-5-nitro-indoline-6-carboxylate (44)
A
solution of methyl 1-acetylindoline-6-carboxylate (43)
(40 mg, 0.18 mmol) stirred in cold sulfuric acid (20 mL) was cooled
to 0 °C, treated with potassium nitrate (15 mg, 0.15 mmol) and
stirred for 30 min. The reaction mixture was quenched with ice
(a) 200 mg (0.91 mmol) ethyl 7-amino-3-methyl-[1,2,4]triazolo
[4,3-a]pyridine-6-carboxylate (38) and 125 mg (0.91 mmol) N-

418
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
and extracted with ethyl acetate (20 mL ꢁ 2). The combined
organic layers were washed with brine solution, dried with anhy-
drous sodium sulfate and concentrated under reduced pressure
to get 50 mg 1-acetyl-5-nitro-indoline-6-carboxylate (44) (quant.).
1H NMR (DMSO, 400 MHz): 8.23 (s, 1H), 8.00 (s, 1H), 4.22
(t, 2H), 3.83 (S, 3H), 3.25 (t, 2H), 2.22 (s, 3H). MS (electrospray):
m/z = 265 [M+1].
with brine, dried with anhydrous sodium sulfate, and concentrated
to afford 600 mg crude 6-acetyl-2-[5-bromo-2-(3-chloro-2-pyri-
dyl)pyrazol-3-yl]-9-chloro-7,8-dihydropyrrolo[2,3g][3,1]benzox-
azin-4-one which was directly used in the next step.
The above crude product (600 mg) was dissolved in THF
(40 mL), treated with isopropyl amine (2 mL, 23 mmol), and stirred
at RT for 8 h. After completion of the reaction, THF was distilled out
and the residue was then purified by flash-chromatography using
ethyl acetate/hexane (8:2) to get 100 mg 1-acetyl-5-[[5-bromo-2-
(3-chloro-2-pyridyl)pyrazole-3-carbonyl]amino]-4-chloro-N-isopropyl-
indoline-6-carboxamide (48) (15%).
4.26. Methyl 1-acetyl-5-amino-indoline-6-carboxylate (45)
A solution of 1-acetyl-5-nitro-indoline-6-carboxylate (44) (3 g,
11.36 mmol) in methanol (200 mL) and THF (200 mL) was treated
with 5% Pd/C (300 mg, 10 mol %) and stirred for 4 h under H2
(1 bar). A white turbid precipitate was formed after 15 min. The
reaction mixture was filtered through Celite and the residue was
repeatedly washed with hot dichloromethane, hot methanol, and
hot ethanol. The filtrate was then concentrated, and the residue
obtained was washed with hexane, diethyl ether and finally dried
under high vacuum to obtain 2.6 g 1-acetyl-5-amino-indoline-6-
carboxylate (45) (quant.).
1H NMR (CDCl3, 400 MHz): 9.91 (s, 1H), 8.40 (d, 1H), 8.38
(s, 1H), 7.74 (d, 1H), 7.45 (s, 1H), 6.92 (s, 1H), 5.98 (d, 1H), 4.05
(m, 3H), 3.16 (t, 2H), 2.17 (s, 3H), 1.22 (d, 6H). MS (electrospray):
m/z = 580 [M+1]. Mp 155–165 °C.
4.28. 5-Nitrobenzothiophene-2-carboxylic acid (50)
To a solution of methyl thioglycolate (530 mg, 5 mmol) in abso-
lute methanol (20 mL) at 40 °C was added a solution of sodium
methoxide (320 mg, 6 mmol) in methanol (5 mL). The reaction
mixture was heated to 50 °C and treated drop wise a solution of
2-chloro-5-nitro benzaldehyde (49) (1 g, 5 mmol) in methanol
(10 mL) was added drop wise. A precipitate was formed during
the addition. The resulting suspension was heated at 60 °C for
1.5 h and cooled to RT. A solution of sodium hydroxide (2 mL,
2.5 N solution) was added and the reaction mixture was refluxed
for 2 h, cooled to 0 °C and acidified with conc. hydrochloric acid
(pH 4). The resulting solid was isolated by filtration, redissolved
in hot sodium hydroxide solution, and acidified with drop wise
addition of conc. hydrochloric acid. The solid obtained was isolated
by filtration, washed with water, co-evaporated with toluene, and
dried to get 880 mg 5-nitrobenzothiophene-2-carboxylic acid (50)
(74%).
1H NMR (DMSO, 400 MHz): 8.38 (s, 1H), 6.65 (s, 1H), 6.54 (s,
2H), 3.99 (t, 2H), 3.76 (s, 3H), 3.05 (t, 2H), 2.09 (s, 3H). MS (electro-
spray): m/z = 235 [M+1].
4.27. 1-Acetyl-5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-car-
bonyl]amino]-4-chloro-N-isopropyl-indoline-6-carboxamide (48)
(a) To a solution of methyl 1-acetyl-5-amino-indoline-6-car-
boxylate (45) (982 mg, 4.19 mmol) in acetic acid (100 mL) and N,
N-dimethyl formamide (100 mL) was added N-chlorosuccinimide
(586 mg, 4.4 mmol) and stirred for 12 h. A further 30 mL of acetic
acid was added and stirred for 4 h, and the reaction mixture was
quenched with water (10 mL). N,N-Dimethyl formamide and acetic
acid were distilled of under reduced pressure. The black residue
obtained was stirred in 1:1 mixture of dichloromethane–water,
and the organic layer was then separated. The aqueous layer was
washed with dichloromethane (3ꢁ). The combined organic layers
were washed with saturated sodium bicarbonate solution followed
by brine, and dried with anhydrous sodium sulfate and concen-
trated under reduced pressure to obtain 140 mg 1-acetyl-5-
amino-4-chloro-indoline-6-carboxylate (46) (10%), which was
used directly in the next step.
1H NMR (DMSO, 400 MHz): 8.90 (d, 1H), 8.75 (d, 1H), 8.32 (t,
1H), 8.05 (d, 1H), 3.33 (s, 3H). MS (electrospray): m/z = 222 [Mꢂ1].
4.29. 5-Nitrobenzothiophene (51)
To a solution of 5-nitrobenzothiophene-2-carboxylic acid (50)
(40 g, 179 mmol) in quinoline (350 mL) was added copper powder
(11.3 g, 179 mmol) with good mechanical stirring. The reaction
mixture was heated to 190 °C until gas evolution was complete,
then cooled to RT, poured into crushed ice and acidified with conc.
hydrochloric acid. The resulting suspension was warmed with
ethyl acetate, layers separated, and the organic layer washed with
2 N hydrochloric acid, water, brine solution, dried with anhydrous
sodium sulfate, and concentrated to obtain 30.5 g 5-nitrobenzoth-
iophene (51) (95%).
MS (electrospray): m/z = 269 [M+1], 271 [M+3].
(b) To a solution of methyl 1-acetyl-5-amino-4-chloro-indoline-
6-carboxylate (46) (300 mg, 1.1 mmol) in methanol (40 mL) and
THF (10 mL) was added 1 N sodium hydroxide (1.1 mL, 1.1 mmol)
solution. The reaction mixture was stirred at 55 °C for 1 h (LCMS
showed only 5% conversion), treated with a few drops of water
and 2 equiv sodium hydroxide solution, and stirred for 4 h. The
reaction mixture was cooled to RT and passed through Dowex
(H+) ion exchange column. The column was washed with methanol
and the eluent was concentrated reduced pressure to obtain
300 mg 1-acetyl-5-amino-4-chloro-indoline-6-carboxylic acid
(47) (quant.). MS (electrospray): m/z = 255 [M+1].
1H NMR (DMSO, 400 MHz): 8.85 (d, 1H), 8.31 (d, 1H), 8.18 (dd,
1H), 8.06 (d, 1H), 7.73 (d, 1H). LC–MS: (electrospray): m/z = 180 [M
+1].
4.30. 5-Nitrobenzothiophene 1,1-dioxide (52)
(c)
A solution of 1-acetyl-5-amino-4-chloro-indoline-6-car-
boxylic acid (47) (150 mg, 0.5 mmol) in THF and acetonitrile
(1:1, 40 mL) was cooled to 10 °C, treated with pyridine
(0.3 mL, 4.3 mmol), N-(3-chloropyridin-2-yl)-3-bromopyrazole-5-
carboxylic acid (40) (170 mg, 0.5 mmol) and methanesulfonyl
chloride (0.4 mL, 3.7 mmol) and stirred for 6 h. Another 7.4 equiv
of pyridine and 6.4 equiv methanesulfonyl chloride was added at
10 °C and stirred for 3 h. Acetonitrile and THF were distilled off
and the residue was dissolved in dichloromethane and water
(1:1). The organic layer was separated and washed with saturated
sodium bicarbonate solution. The aqueous layer was extracted
with ethyl acetate and the combined organic layers were washed
To a solution of 5-nitrobenzothiophene (51) (23.8 g, 132 mmol)
in dichloromethane (400 mL) was added meta-chloroperbenzoic
acid (45.8 g, 265 mmol) portion wise at 0 °C under N2. The reaction
mixture was stirred overnight at RT and was poured into water.
The organic layer was separated, washed with 1 N sodium hydrox-
ide solution, brine solution, dried with anhydrous sodium sulfate,
and concentrated to afford 20.2 g 5-nitrobenzothiophene-1,1-diox-
ide (52) (72%) was obtained after recrystallization with acetone/
hexane.
1H NMR, (DMSO, 400 MHz): 8.44 (m, 2H), 8.16 (d, 1H), 7.78 (d,
1H), 7.63 (d, 1H). LC–MS: (electrospray): m/z = 211 [M+1].

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
419
4.31. 1,1-Dioxobenzothiophen-5-amine (53)
cooled to RT, added with water (10 mL), and acidified with 10%
hydrochloric acid to pH 1. The solid precipitated was filtered,
washed with water and diethyl ether, and dried to get 900 mg
(1Z,3E)-1-(1,1-dioxo-2,3-dihydrothiophen-5-yl)-2-methyl-penta-
1,3-dien-3-amine (94%).
To a solution of 5-nitrobenzothiophene-1,1-dioxide (52) (1.6 g,
7.5 mmol) in acetic acid (30 mL) was added iron powder (1.3 g,
22 mmol) under N2. The reaction mixture was refluxed for 3 h
and filtered through Celite. The filtrate was evaporated under
reduced pressure. The residue was co-evaporated with toluene
and was then purified by flash-chromatography using ethyl acet-
ate/hexane (1:1) to get 610 mg 1,1-dioxobenzothiophen-5-amine
(53) (45%).
1H NMR (DMSO, 400 MHz): 7.91 (s, 1H), 6.73 (s, 1H), 3.48
(t, 2H), 3.22 (t, 2H). MS (electrospray): m/z = 228 [M+1].
(b) To a solution of above compound (900 mg, 3.96 mmol) in N,
N-dimethylformamide (30 mL) was added N-chlorosuccinimide
(630 mg, 4.75 mmol) under N2 atm, and stirred at RT for 12 h.
The solvent was evaporated under vacuum. The residue poured
into crushed ice, extracted with ethyl acetate, layers separated,
organic layer washed with water (3ꢁ), brine solution, and
dried with anhydrous sodium sulfate concentrated. The residue
was washed with diethyl ether and dried to get crude 800 mg
5-amino-4-chloro-1,1-dioxo-2,3-dihydrobenzothiophene-6-carbo-
xylic acid (57) (80%).
1H NMR (DMSO, 400 MHz): 7.41 (m, 2H), 7.15 (d, 1H), 6.61 (d,
1H), 6.58 (dd, 1H), 6.17 (s, 2H). MS (electrospray): m/z = 182 [M+1].
4.32. (2Z)-N-(1,1-Dioxobenzothiophen-5-yl)-2-hydroxyimino-
acetamide (54)
A suspension of chloral hydrate (410 mg, 2.48 mmol), sodium
sulfate (2.3 g, 16.57 mmol) and hydroxyl amine hydrochloride
(370 mg, 5.41 mmol) in water (10 mL) was heated at 40 °C into a
colorless solution. To this solution was added a solution of 1, 1-
dioxobenzothiophen-5-amine (53) (300 mg, 1.65 mmol) in ethanol
(2 mL) and 1 N hydrochloric acid (1.6 mL, 1.65 mmol). The result-
ing brown solution was stirred at 60 °C for 4.5 h (turned into a yel-
low solution). The reaction mixture was poured into crushed ice
and extracted with ethyl acetate. The combined organic layers
were washed with water, brine solution, dried with anhydrous
sodium sulfate, and concentrated to get 320 mg crude (2Z)-N-
(1,1-dioxobenzothiophen-5-yl)-2-hydroxyimino-acetamide (54)
(78%).
1H NMR (DMSO, 400 MHz): 13.63 (s, 1H, br), 7.97 (s, 1H), 7.52
(s, 2H, br), 3.61 (t, 2H), 3.30 (t, 2H). MS (electrospray): m/z = 260
[Mꢂ1].
4.36. 5-Bromo-N-[4-chloro-6-(isopropylcarbamoyl)-1,1-dioxo-
2,3-dihydrobenzothiophen-5-yl]-2-(3-chloro-2-pyridyl)pyra-
zole-3-carboxamide (58)
N-(3-Chloropyridin-2-yl)-3-bromopyrazole-5-carboxylic acid
(40) (460 mg, 1.53 mmol) was dissolved in dichloromethane
(15 mL) and added with 1 drop of N,N-dimethylformamide fol-
lowed by addition of oxalyl chloride (0.14 mL, 1.68 mmol) and stir-
red at RT 15 min. The solvent was evaporated under N2, and the
residue was dissolved in acetonitrile (7 mL) and added drop wise
to a mixture of 5-amino-4-chloro-1,1-dioxo-2,3-dihydrobenzoth-
iophene-6-carboxylic acid (57) (400 mg, 1.53 mmol) in pyridine
(5 mL) at 0 °C. The reaction mixture was stirred for 1 h at RT.
Methanesulfonyl chloride (0.4 mL, 5.2 mmol) was added to the
reaction mixture, stirred for 2 h, treated with isopropyl amine
(2.6 mL) and stirred for 12 h. The solvent was evaporated under
vacuum and dissolved in dichloromethane (30 mL), washed with
water, satd sodium bicarbonate solution, brine solution, dried with
anhydrous sodium sulfate, and concentrated to afford 210 mg
5-bromo-N-[4-chloro-6-(isopropylcarbamoyl)-1,1-dioxo-2,3-dihy-
drobenzothiophen-5-yl]-2-(3-chloro-2-pyridyl)pyrazole-3-carbox-
amide (58) (24%) was obtained by prep HPLC.
1H NMR (DMSO, 400 MHz): 12.34 (s, 1H), 10.63 (s, 1H), 8.00 (s,
1H), 7.80 (s, 2H), 7.67 (s, 1H), 7.65 (d, 1H), 7.36 (d, 1H). MS (elec-
trospray): m/z = 251 [Mꢂ1].
4.33. 1,1-Dioxo-5H-thieno[2,3-f]indole-6,7-dione (55)
Concentrated sulfuric acid (3 mL) was warmed up to 70 °C and
treated portionwise (2Z)-N-(1,1-dioxobenzothiophen-5-yl)-2-
hydroxyimino-acetamide (54) (140 mg, 0.55 mmol), and stirred
at 90 °C for 30 min under N2. The reaction mixture was poured into
crushed ice and extracted with ethyl acetate. The combined
organic layers were washed with sodium bicarbonate solution,
brine solution, dried with anhydrous sodium sulfate, and concen-
trated to get 80 mg crude compound 1,1-dioxo-5H-thieno[2,3-f]in-
dole-6,7-dione (55) (58%).
1H NMR (DMSO, 400 MHz): 10.73 (s, 1H), 8.48 (dd, 1H), 8.40
(d, 1H), 8.16 (dd, 1H), 7.73 (s, 1H), 7.61 (m, 1H)), 7.50 (s, 1H),
3.92 (m, 1H), 3.74 (t, 2H), 3.38 (t, 2H), 1.05 (d, 6H). MS (electro-
spray): m/z = 587 [M+1].
1H NMR (DMSO, 400 MHz): 7.71 (s, 1H), 7.60 (d, 1H), 7.49 (d,
1H), 6.94 (s, 1H). MS (electrospray): m/z = 236 [M+1].
4.34. 1,1-Dioxo-3,5-dihydro-2H-thieno[2,3-f]indole-6,7-dione (56)
4.37. 5-Methyl-2,4-dinitro-aniline (60)
To
a solution of 1,1-dioxo-5H-thieno[2,3-f]indole-6,7-dione
(55) (50 mg, 0.2 mmol) in THF (20 mL) was added 5% Pd/C
(10 mg, 20% wt) and stirred at RT under H2 (1 bar) for 30 min,
and filtered through Celite. The filtrate was evaporated under
reduced pressure. The residue was then purified by flash-chro-
matography using ethyl acetate/hexane (1:1) to get 10 mg 1,1-
dioxo-3,5-dihydro-2H-thieno[2,3-f]indole-6,7-dione (56) (20%).
1H NMR (DMSO, 400 MHz): 11.46 (s, 1H), 7.81 (s, 1H), 6.96 (s,
1H), 3.61 (t, 2H), 3.40 (t, 2H). MS (electrospray): m/z = 235 (Mꢂ1).
Nitric acid (29.5 ml) was added in several portions in sulfuric
acid (178 ml) at 2–5 °C. Then N-(meta-tolyl)acetamide (50 g,
0.335 mol) was added and the reaction mixture was warmed to
RT. After 4 h, the reaction mixture was poured into ice water
(2 L) and an orange precipitate was formed. The resulting suspen-
sion was stirred overnight at RT, filtered and the precipitate
obtained was washed with water and dried. The collected solid
was solved in sulfuric acid 50% (350 ml) and stirred 4 h at 80 °C.
The reaction mixture was cooled down to RT, water (1 L) was
added and the suspension obtained was stirred overnight at RT.
The precipitate obtained was filtered, and dried. The solid obtained
was crystallized in ethyl acetate and cyclohexane to give 23.4 g 5-
methyl-2,4-dinitro-aniline (60) as a yellow solid (37%).
4.35. 5-Amino-4-chloro-1,1-dioxo-2,3-dihydrobenzothiophene-
6-carboxylic acid (57)
(a) A solution of 1,1-dioxo-3,5-dihydro-2H-thieno[2,3-f]indole-
6,7-dione (56) (1.0 g, 4.2 mmol) in 1 M sodium hydroxide (40 mL)
was warmed to 40 °C, treated drop wise with 30% hydrogen perox-
ide (1 mL, 0.8 mmol) and stirred for 1 h. The reaction mixture was
1H NMR (DMSO-d6, 400 MHz): 8.78 (s, 1H); 8.15 (br s, 2H); 6.9
(s, 1H); 2.5 (s, 3H). MS (electrospray): m/z = 198 [M+1].

420
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
4.38. 4-Methyl-5-nitro-benzene-1,2-diamine (61)
1.05 g
5-methyl-1,6-dihydropyrrolo[3,2-e]benzimidazole-7,
8-dione (65) (60%).
5-Methyl-2,4-dinitro-aniline (60) (5 g, 25.36 mmol) was dis-
solved in ethanol (150 ml) and the resulting solution was heated
at 100 °C. Sodium sulfide (9 g, 115 mmol) dissolved in 150 ml
water was added to the reaction mixture. The resulting mixture
was cooled down to RT and further stirred for 2 h. The reaction
mixture was then poured into water and extracted with ethyl acet-
ate. The combined organic layer was washed with brine, dried over
MgSO4, filtered and evaporated. The crude product was purified by
flash-chromatography over silica gel to give 2.9 g 4-methyl-5-
nitro-benzene-1,2-diamine (61) as a yellow solid (68%).
1H NMR (DMSO-d6, 400 MHz): 13.1 (br s, 1H); 10.9 (s, 1H); 8.15
(s, 1H); 7.7 (s, 1H); 2.25 (s, 3H). LC–MS: tR = 0.23 min, m/z = 202
[M+1].
4.42. 5-Amino-6-methyl-3H-benzimidazole-4-carboxylic acid
(66)
5-Methyl-1,6-dihydropyrrolo[3,2-e]benzimidazole-7,8-dione
(65) (1 g, 4.97 mmol) was dissolved in 5.7 ml NaOH 3 N. The solu-
tion was heated at 80 °C, and 0.7 ml H2O2 30% was added. The
resulting mixture was stirred 2 h at 80 °C. The reaction mixture
was cooled down at 0 °C and quenched with HCl concentrated to
pH 4–5. The resulting mixture was diluted with water and filtered.
The precipitate obtained was washed with diethyl ether to give
773 mg 5-amino-6-methyl-3H-benzimidazole-4-carboxylic acid
(66) as a beige solid (81%).
1H NMR (400 MHz, CDCl3): 7.5 (s, 1H), 6.4 (s, 1H), 4.35 (br s, 2H),
3.6 (br s, 2H), 2.45 (s, 3H). LC–MS: tR = 0.92 min, m/z = 168 [M+1].
4.39. 6-Methyl-3H-benzimidazol-5-amine (63)
(a)
4-Methyl-5-nitro-benzene-1,2-diamine
(61)
(3.0 g,
17.9 mmol) was dissolved in formic acid (2.5 ml) and water
(5 ml) and HCl concentrated (5 ml) were added. The resulting mix-
ture was stirred 2 h at 100 °C. The reaction mixture was basified
with a 2 M solution of NaOH and the aqueous layer was extracted
with ethyl acetate. The organic layer was dried over MgSO4, filtered
and evaporated. The crude product was crystallized in ethyl acet-
ate and THF to give 2.34 g 5-methyl-6-nitro-1H-benzimidazole
(62) as a beige solid (74%).
1H NMR (DMSO-d6, 400 MHz): 12.5–11.5 (br s, 1H); 8 (br s, 1H);
7.55 (s, 1H); 2.25 (s, 3H). LC–MS: tR = 0.25 min, m/z = 190 [Mꢂ1].
4.43. 5-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-6-methyl-3H-benzimidazole-4-carboxam-
ide (68)
(a) Under inert and dry atmosphere, 5-amino-6-methyl-3H-
benzimidazole-4-carboxylic acid (65) (380 mg, 1.98 mmol) and 5-
LC–MS: tR = 0.84 min, m/z = 178 [M+1].
(b) 5-Methyl-6-nitro-1H-benzimidazole (62) (2.3 g, 13.0 mmol)
was dissolved in HCl 8 N (40 ml). Tin(II) chloride anhydrous
(10.0 g, 52.7 mmol) was added and the resulting mixture was stir-
red 2 h at RT. The reaction was then quenched at 0 °C with NaOH.
The aqueous layer was extracted with ethyl acetate (3 times) and
the combined organic layers were dried over MgSO4, filtered and
evaporated under vacuum to give 1.64 g 6-methyl-3H-benzimida-
zol-5-amine (63) (86%).
bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carboxylic
acid
(40)
(631 mg, 2.08 mmol) were dissolved in acetonitrile (20 ml) and
pyridine (0.72 ml, 8.94 mmol) was added. The resulting mixture
was cooled down at 0–5 °C and methanesulfonyl chloride
(0.540 ml, 6.95 mmol) was added slowly. The reaction was stirred
overnight at RT. The reaction mixture was then filtered and the
precipitate was washed with ice water, diethyl ether and dried
under vacuum to give 655 mg crude 7-[5-bromo-2-(3-chloro-2-
pyridyl)pyrazol-3-yl]-5-methyl-1H-imidazo[4,5-f][3,1]benzox-
azin-9-one (67) as a beige solid.
1H NMR (DMSO-d6, 400 MHz): 11.00–1 2.00 (br s, 1H); 7.8
(s, 1H); 7.15 (s, 1H); 6.75 (s, 1H); 4–5 (br s, 2H); 2.15 (s, 3H).
LC–MS: tR = 0.19 min, m/z = 148 [M+1].
LC–MS: tR = 0.66 min, m/z = 459 [Mꢂ1].
(b) 7-[5-Bromo-2-(3-chloro-2-pyridyl)pyrazol-3-yl]-5-methyl-
1H-imidazo[4,5-f][3,1]benzoxazin-9-one (67) (250 mg, 0.54 mmol)
was dissolved in THF (10 ml) then isopropylamine (2.5 ml,
29 mmol) and dimethylformamide (1 ml) were added. The reaction
mixture was heated at 80 °C and stirred one night at 80 °C. The
resulting mixture was evaporated and the crude residue was
purified by flash-chromatography over silica gel to give 132 mg
5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]amino]-
N-isopropyl-6-methyl-3H-benzimidazole-4-carboxamide (68) (47%).
1H NMR (400 MHz, CDCl3): 12.35 (s, 1H), 11.9 (s, 1H), 10.4 (d,
1H), 8.45 (dd, 2H), 7.95 (s, 1H), 7.8 (dd, 1H), 7.4 (s, 1H), 7.35 (m,
1H), 7.15 (s, 1H), 4,4 (m, 1H), 2.3 (s, 3H), 1.35 (d, 6H). LC–MS:
tR = 1.41 min, m/z = 518 [M+1].
4.40. (2E)-2-Hydroxyimino-N-(6-methyl-3H-benzimidazol-5-yl)
acetamide (64)
Sodium sulfate (27.8 g, 0.195 mol) was dissolved in water
(65 ml) and 2,2,2-trichloroethane-1,1-diol (1.98, 11.9 mmol) was
added. Then 6-methyl-3H-benzimidazol-5-amine (63) (1.6 g,
10.8 mmol) dissolved in 12 ml HCl 1 N (11.9 mmol) was added to
the reaction mixture, followed by 2.42 g (34.8 mmol) hydroxy-
lamine hydrochloride. The resulting mixture was slowly heated
over 3 h until 80 °C. The reaction mixture was then cooled down
to 0 °C and filtered. The precipitate obtained was washed with
water and dried under vacuum to give 1.9 g (2E)-2-hydroxy-
imino-N-(6-methyl-3H-benzimidazol-5-yl)acetamide (64) (80%).
1H NMR (DMSO-d6, 400 MHz): 12.25 (s, 1H); 9.6 (s, 1H); 8.8 (s,
1H); 7.9 (s, 1H); 7.75 (s, 1H); 7.55 (s, 1H); 2.25 (s, 3H). LC–MS:
tR = 0.20 min, m/z = 219 [M+1].
4.44. 6-Methyl-3a,7a-dihydro-3H-benzotriazol-5-amine (69)
(a)
4-Methyl-5-nitro-benzene-1,2-diamine
(61)
(1.4 g,
8.37 mmol) was dissolved in hydrochloric acid (20 ml, 1 N), the
solution was cooled to 0 °C and sodium nitrite (635 mg,
9.212 mmol) was added. The beige suspension was stirred for 2 h
at RT. The mixture was filtered to give 5-methyl-6-nitro-3a,7a-
dihydro-1H-benzotriazole as a beige crystal (1.12 g, 75%).
4.41.
5-Methyl-1,6-dihydropyrrolo[3,2-e]benzimidazole-7,8-
dione (65)
1H NMR (DMSO-d6, 400 MHz): 2.65 (s, 3H), 7.90 (br, 1H), 7.75
(br, 1H), 16.4 (br, 1H). LC–MS: tR = 1.22 min, m/z = 179 [M+1].
(b) To 5-methyl-6-nitro-3a,7a-dihydro-1H-benzotriazole (1.1 g,
6.17 mmol) in ethanol (20 ml) was added Pd/C (10%, 0.5 g) and the
flask was filled with hydrogen. Reaction mixture was stirred at RT
for 3 h. As the reaction was not complete, 100 mg Pd/C (10%) were
(2E)-2-Hydroxyimino-N-(6-methyl-3H-benzimidazol-5-yl)ac-
etamide (64) (1.9 g, 8.7 mmol) was dissolved in concentrated sul-
furic acid (30 mL) and the reaction mixture was stirred 3 h at
80 °C. Then reaction mixture was cooled down at RT, NaOH 30%
was added up to pH 3–4. The resulting mixture was poured into
water; the precipitate formed was filtered and dried to give

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
421
added and the reaction mixture was further heated at 50 °C for 2 h.
The reaction mixture was filtered on cellite and washed with etha-
nol. The filtrate was concentrated on vacuum to give 6-methyl-
3a,7a-dihydro-3H-benzotriazol-5-amine (69) (922 mg, 100%).
1H NMR (DMSO-d6, 400 MHz): 2.18 (s, 3H), 5.35 (br, 2H), 6.7
(s, 1H), 7.55 (s, 1H), 14.7 (br, 1H). LC–MS: tR = 0.24 min,
m/z = 149 [M+1].
(b) 7-[5-Bromo-2-(3-chloro-2-pyridyl)pyrazol-3-yl]-5-methyl-
3a,9b-dihydro-1H-triazolo[4,5-f][3,1]benzoxazin-9-one (500 mg,
1.09 mmol) was dissolved in THF (30 ml) and 2 ml (48.4 mmol)
isopropylamine were added. The reaction mixture was heated at
80 °C and stirred overnight at 80 °C. The resulting mixture was
evaporated and the residue was purified by flash-chromatography
over silica gel to give 5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-
3-carbonyl]amino]-N-isopropyl-6-methyl-3a,7a-dihydro-3H-ben-
zotriazole-4-carboxamide (71) (190 mg, 33.7%).
4.45.
5-Amino-6-methyl-3a,7a-dihydro-3H-benzotriazole-4-
carboxylic acid (70)
1H NMR (400 MHz, CDCl3): 12.7 (br, 1H), 12.3 (br, 1H), 9.5 (br,
1H), 8.45 (dd, 1H), 7.85 (q, 1H), 7.40 (m, 2H), 7.20 (s, 1H), 4.35
(m, 1H), 2.30 (s, 3H), 1.4 (d, 6H). LC–MS: tR = 1.65 min, m/z = 519
[M+1].
(a) To a solution of sodium sulfate (1.91 g, 13.44 mmol) in water
(60 ml) was added chloral hydrate (1.31 g, 7.92 mmol) at RT. To the
resulting clear solution was added a solution of 6-methyl-3a,7a-
dihydro-3H-benzotriazol-5-amine (69) (910 mg, 6.14 mmol) in
1 N aqueous hydrochloric acid (1 ml). The resulting mixture turned
cloudy and hydroxylamine hydrochloride (1.6 g, 23.09 mmol) was
then added. The resulting reaction mixture was heated gradually
from RT to 80 °C. It was then stirred for an additional 30 min at
80 °C. The reaction mixture was then cooled down to RT with an
ice bath and the solid formed was filtrated. The compound was
washed thoroughly with water and dried at 50 °C overnight to
4.47. 5-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-2,6-dimethyl-benzotriazole-4-carboxam-
ide (72) and 5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-
carbonyl]amino]-N-isopropyl-1,6-dimethyl-3a,7a-dihydroben-
zotriazole-4-carboxamide (73)
To a solution of 5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-
carbonyl]amino]-N-isopropyl-6-methyl-3a,7a-dihydro-3H-benzo-
triazole-4-carboxamide (71) (350 mg, 0.675 mmol) in acetonitrile
(10 ml) was added sodium hydroxide (27 mg, 675 mmol) with
one drop of water, the solution was stirred at RT for 1 h. Then
methyl iodide (96 mg, 675 mmol) was added, and the reaction
mixture was stirred overnight at RT. To have a complete conver-
sion, more sodium hydroxide (10 mg, 250 mmol) and methyl
iodide (30 mg, 212 mmol) were added, and the mixture was fur-
ther stirred at 40 °C for 2 h. Ammonium chloride was then added
and the mixture was extracted with ethyl acetate. The organic
phase was dried over MgSO4 and concentrated on vacuum. The
residue was purified on silica gel to give the two isomers.
5-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]amino]-
N-isopropyl-2,6-dimethyl-benzotriazole-4-carboxamide (72) (93 mg,
26%) and 5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-1,6-dimethyl-3a,7a-dihydrobenzotriazole-4-
carboxamide (73) (106 mg, 29%).
5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-2,6-dimethyl-benzotriazole-4-carboxamide
(72): 1H NMR (DMSO-d6): 10.5 (br, 1H), 8.5 (m, 1H), 8.18 (q, 1H),
8.00 (d, 1H), 7.85 (s, 1H), 7.6 (m, 1H), 7.4 (s, 1H), 4.50 (s, 1H),
2.25 (s, 3H), 1.10 (d, 6H). LC–MS: tR = 1.76 min, m/z = 533 [M+1].
5-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-1,6-dimethyl-3a,7a-dihydrobenzotriazole-4-
carboxamide (73): 1H NMR (DMSO-d6): 10.5 (br, 1H), 8.5 (m, 1H),
8.3 (d, 1H), 8.15 (dd, 1H), 7.80 (s, 1H), 7.60 (m, 1H), 7.45 (s, 1H),
4.30 (s, 3H), 2.3 (s, 3H), 1.10 (d, 6H). LC–MS: tR = 1.76 min, m/
z = 533 [M+1].
afford
(2E)-2-hydroxyimino-N-(6-methyl-3H-benzotriazol-5-yl)
acetamide (520 mg, 38.6%).
1H NMR (DMSO-d6, 400 MHz): 2.4 (s, 3H), 7.75 (s, 1H), 7.8 (br,
1H), 8.1 (s, 1H), 12.3 (s, 1H). LC–MS: tR = 0.83 min, m/z = 220 [M+1].
(b) (2E)-2-Hydroxyimino-N-(6-methyl-3H-benzotriazol-5-yl)
acetamide (509 mg, 2.32 mmol) was dissolved in concentrated sul-
furic acid (10 mL) and the reaction mixture was stirred 3 h at 80 °C.
Then reaction mixture was cooled down at RT, sodium hydroxide
30% was added to get a pH value of 3–4. The resulting mixture
was poured into water, the precipitate formed was filtered and
dried to give 5-methyl-1,6-dihydropyrrolo[3,2-e]benzotriazole-
7,8-dione (312 mg, 68%).
1H NMR (DMSO-d6, 400 MHz): 11.2 (br s, 1H); 8.2 (s, 1H); 2.30
(s, 3H). LC–MS: tR = 0.90 min, m/z = 203 [M+1].
(c) 5-Methyl-1,6-dihydropyrrolo[3,2-e]benzotriazole-7,8-dione
(3.21 g, 15.89 mmol) was dissolved in sodium hydroxide 3 N
(18.5 ml) and heated at 80 °C. At that temperature, 2.3 ml H2O2
30% were added. The resulting mixture was stirred 2 h at 80 °C.
The reaction mixture was cooled down to 0 °C and neutralized
with concentrated HCl to pH 4–5. The resulting mixture was
diluted with water and filtered. The precipitate obtained was
washed with diethyl ether to give 5-amino-6-methyl-3a,7a-dihy-
dro-3H-benzotriazole-4-carboxylic acid (70) as
a beige solid
(1.75 g, 60%).
1H NMR (DMSO-d6, 400 MHz): 14.6 (br s, 1H); 7.80 (s, 1H); 2.20
(s, 3H). LC–MS: tR = 0.95 min, m/z = 191 [Mꢂ1].
4.46. 5-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]
amino]-N-isopropyl-6-methyl-3a,7a-dihydro-3H-benzotriazole-
4-carboxamide (71)
4.48. 6-Methyl-2,1,3-benzothiadiazol-5-amine (74)
Under dry atmosphere, 4-methyl-5-nitro-benzene-1,2-diamine
(61) (10 g, 59.8 mmol) was dissolved in dichloromethane
(500 ml) and triethylamine (24.21 g, 239.3 mmol) was added fol-
lowed by the slow addition of thionylchloride (14.23 g,
119.63 mmol). The suspension was stirred 5 h at RT. The reaction
mixture was evaporated under vacuum, the residue was taken up
in water (700 ml) and HCl was added to pH 1. The resulting mix-
ture was stirred 1 h and the precipitate formed was filtered to
get brown solid. This solid (1 g, 5.122 mmol) was dissolved in
HCl 8 N (60 ml), Tin(II) chloride anhydrous (5 g, 26.3 mmol) was
added and the resulting mixture was stirred 2 h at RT. The reaction
was then quenched at 0 °C with NaOH. The aqueous layer was
extracted with ethyl acetate 3 times and the combined organic
layer was dried over MgSO4, filtered and evaporated under vacuum
(a) Under inert and dry atmosphere, 5-amino-6-methyl-3a,7a-
dihydro-3H-benzotriazole-4-carboxylic
acid
(70)
(1.3 g,
6.76 mmol) and 5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-car-
boxylic acid (40) (2.15 g, 7.10 mmol) were dissolved in acetonitrile
(30 ml) and pyridine (2.5 ml, 30.43 mmol) was added. The result-
ing mixture was cooled to 0–5 °C and methanesulfonyl chloride
(1.84 ml, 23.67 mmol) was added slowly. The reaction was stirred
overnight at RT. The reaction mixture was filtered and the precip-
itate formed was washed with ice water, diethyl ether and dried
under vacuum to give crude 7-[5-bromo-2-(3-chloro-2-pyridyl)
pyrazol-3-yl]-5-methyl-3a,9b-dihydro-1H-triazolo[4,5-f][3,1]ben-
zoxazin-9-one as a beige solid (2.2 g, 66%).
LC–MS: tR = 1.73 min, m/z = 460 [M+1].

422
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
to give 600 mg 6-methyl-2,1,3-benzothiadiazol-5-amine (74)
(71%).
under vacuum and the residue was dissolved in ethylacetate. The
organic layer was washed with brine, dried over MgSO4, filtered
and evaporated under vacuum. The crude was purified by
flash-chromatography to give 5-[[5-bromo-2-(3-chloro-2-pyridyl)
pyrazole-3-carbonyl]amino]-N,6-dimethyl-2,1,3-benzothiadiazole-
4-carboxamide (76) (100 mg, 9.5%).
1H NMR (400 MHz, CDCl3,): 7.69 (s, 1H), 7.02 (s, 1H), 2.4 (s, 3H).
LC–MS: tR = 1.18 min, m/z = 166 [M+1].
4.49.
Methyl
5-amino-6-methyl-2,1,3-benzothiadiazole-4-
carboxylate (75)
1H NMR (400 MHz, CDCl3): 12 (s, 1H), 9.65 (br s, 1H), 8.2 (d, 1H),
8.45 (dd, 2H), 7.9 (s, 1H), 7.6 (t, 1H), 7 (d, 1H), 6.9 (t, 1H), 3.1 (d,
3H), 2.25 (s, 3H). MS (electrospray): m/z = 504 [M+1], 506 [M+3],
508 [M+5].
(a) 6-Methyl-2,1,3-benzothiadiazol-5-amine (74) (4.4 g,
26.6 mmol) was dissolved in 300 ml DMF and NBS (4.5 g,
25.3 mmol) was added. The reaction mixture was stirred 6 h at
80 °C. The solvent was removed under vacuum and the residue
was dissolved in ethyl acetate and washed with water and brine.
The combined organic layer was dried over MgSO4, filtered and
evaporated under vacuum to give 5.8 g crude 4-bromo-6-methyl-
2,1,3-benzothiadiazol-5-amine as a solid (89%), which was further
used without purification.
(b) To a solution of 4-bromo-6-methyl-2,1,3-benzothiadiazol-5-
amine (5.8 g, 23.77 mmol) in methanol (80 mL) in an autoclave
was added palladium[II] chloride (90 mg, 0.51 mmol), (2,2’-bis
(diphenylphosphino)-1,10-binaphthyl, BINAP, 504 mg, 0.81 mmol)
and triethylamine (6.6 mL). The autoclave was flushed with carbon
monoxide, and then pressurized at 8 bar with carbon monoxide
and heated at 100 °C for 16 h. After this time, TLC analysis showed
the reaction was incomplete and thus palladium[II] chloride
(90 mg, 0.51 mmol), and BINAP (504 mg, 0.81 mmol) were added
and heating continued for a further 5 h at 100 °C under 8 bar of car-
bon monoxide. TLC analysis indicated that the reaction was incom-
plete and thus a further portion of palladium[II] chloride (90 mg,
0.51 mmol), and BINAP (504 mg, 0.81 mmol) were added and the
reaction heated at 100 °C for 16 h under 8 bar of carbon monoxide.
TLC analysis after this time showed complete consumption of the
starting material. The reaction mixture was concentrated in vac-
uum, adsorbed onto silica gel and purified by flash-chromatogra-
phy eluting with hexane/ethyl acetate (5:1) to give 1.97 g methyl
4.51. 2-[(E)-Hydroxyimino]-N-(5-methyl-1H-indazol-6-yl)-acet-
amide (81)
To a solution of sodium sulfate (8.69 g, 61.15 mmol) in 20 ml
water was added chloral hydrate (0.62 g, 3.74 mmol) at RT. To
the resulting clear solution was added a solution of 5-methyl-6-
aminoindazol (80) (0.5 g, 3.4 mmol, prepared as described in Ref.
17) solved in 3.7 ml 1 N hydrochloric acid. The resulting mixture
turned cloudy and hydroxylamine hydrochloride (0.75 g,
10.9 mmol) was added. The resulting reaction mixture was heated
gradually to 80 °C and further stirred for an additional 30 min at
that temperature. The reaction mixture was then cooled down to
RT with an ice bath. The solid formed was filtrated, washed thor-
oughly with water and dried at 50 °C overnight to afford 2-[(E)-
hydroxyimino]-N-(5-methyl-1H-indazol-6-yl)-acetamide as
a
brown powder of >95% purity according to HPLC.
1H NMR (DMSO, 400 MHz): 2.40 (s, 3H), 3.75 (br, 1H).7.65 (s,
1H), 7.85 (s, 1H), 7.80 (s, 1H), 9.45 (s, 1H), 12.3 (br, 1H) 12.9 (br,
1H). LC–MS: tR = 1.02 min, m/z = 219 [M+1].
4.52. 5-Methyl-1,6-dihydro-pyrrolo[2,3-g]indazole-7,8-dione (82)
To concentrated sulfuric acid (119 ml) was added portion-wise
2-[(E)-hydroxyimino]-N-(5-methyl-1H-indazol-6-yl)-acetamide
(81) (34.7 g, 146.3 mmol). The addition was strongly exothermic
and the internal temperature was maintained to 70 °C with an
ice bath. At the end of the addition, the resulting reaction mixture
was heated at 80 °C and stirred for 45 min at that temperature.
According to LC–MS analysis, the reaction had then reached com-
pletion. The reaction mixture was cooled down to RT. The reaction
mixture was poured onto 3.00 kg of ice. The resulting dark-brown
suspension was stirred for 30 min and then filtrated. The com-
pound isolated was washed extensively with water and dried in
vacuum at 55 °C. 5-Methyl-1,6-dihydro-pyrrolo[2,3-g]indazole-
7,8-dione (82) was obtained as a red-brown powder (27.6 g, 94%).
1H NMR (DMSO, 400 MHz): 2.25 (s, 3H), 7.90 (s, 1H), 8.00 (s,
1H), 11.1 (br, 1H). LC–MS: tR = 1.01 min, m/z = 202 [M+1].
5-amino-6-methyl-2,1,3-benzothiadiazole-4-carboxylate
(22%) as a yellow solid.
(75)
1H NMR (400 MHz, CDCl3): 7.8 (s, 1H), 7.15 (br, 2H), 4.15 (s, 3H),
2.4 (s, 3H). LC–MS: tR = 1.34 min, m/z = 224 [M+1].
4.50. 5-[[5-Bromo-2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl]am-
ino]-N,6-dimethyl-2,1,3-benzothiadiazole-4-carboxamide (76)
5-Amino-6-methyl-2,1,3-benzothiadiazole-4-carboxylate (75)
(470 mg, 2.10 mmol) was dissolved in a mixture of dioxane/water
1:1 (20 ml) and lithium hydroxide monohydrate (97 mg,
2.315 mmol) was added. The reaction was stirred 2 days at RT
and then evaporated under vacuum. Under inert and dry atmo-
sphere, the crude obtained and 5-bromo-2-(3-chloro-2-pyridyl)
pyrazole-3-carboxylic acid (40) (583 mg, 1.92 mmol) were dis-
solved in acetonitrile (20 ml) and pyridine (0.72 ml, 8.94 mmol)
was added. The resulting mixture was cooled down to 0–5 °C and
methanesulfonyl chloride (0.540 ml, 6.95 mmol) was slowly
added. The reaction was stirred 2 days at RT. After 2 days, the reac-
tion mixture was evaporated under vacuum and the residue was
dissolved in ethylacetate. The organic layer was washed with brine,
dried over MgSO4, filtered and evaporated under vacuum. The
crude obtained was purified by flash-chromatography to give 7-
[5-bromo-2-(3-chloro-2-pyridyl)pyrazol-3-yl]-5-methyl-[1,2,5]
thiadiazolo[3,4-f][3,1]benzoxazin-9-one as an intermediate. This
intermediate (125 mg) was dissolved in a 1 M methylamine etha-
nol solution (10 ml) and the resulting mixture was stirred over-
night at RT. A few drops DMF were added to get a clear solution
and the resulting mixture was stirred 16 more hours at RT. The sus-
pension obtained was filtered. The mother liquid was evaporated
4.53. 6-Amino-5-methyl-1H-indazole-7-carboxylic acid (83)
To a solution of 5-methyl-1,6-dihydro-pyrrolo[2,3-g] indazole-
7,8-dione (82) (23 g, 114.3 mmol) in a 4 N aqueous sodium
hydroxide solution (160 ml) at RT, was added dropwise 30% aque-
ous hydrogen peroxide solution (27 ml) maintaining the tempera-
ture below 30 °C with external cooling. The resulting reaction
mixture was stirred at RT for 2 h. According to TLC, the reaction
was complete after 2 h. The pH was adjusted to pH 3.5 by addition
of concentrated hydrochloric acid. The resulting brown suspension
was filtered and the compound isolated was washed with cold
water and dried in vacuum at 50 °C to afford 6-amino-5-methyl-
1H-indazole-7-carboxylic acid (83) as brown solid (21 g, 94%).
1H NMR (DMSO, 400 MHz): 2.20 (s, 3H), 7.55 (s, 1H), 7.75
(s, 1H), 12.1 (br, 1H). LC–MS: tR = 1.01 min, m/z = 192 [M+1].

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
423
4.54.
5-Methyl-1,6-dihydro-8-oxa-1,2,6-triaza-cyclopenta[a]-
16 g (210 mmol) hydroxylamine hydrochloride and the reaction
was heated and stirred at 80 °C for 3 h. The solvent was removed
under vacuum and the residue was taken up in ethyl acetate. The
organic phase was washed with water (2 times) and brine, dried
and concentrated under vacuum. The crude compound was then
purified by crystallization in petroleum ether to yield 42.5 g
(90%) 1-(2,4-dinitrophenyl)ethanone oxime (90) (42.5 g, 90%) as
a mixture of E and Z isomers.
naphthalene-7,9-dione (84)
In a solution of 180 ml 1,4-dioxane and 100 ml THF, 10 g
(52.2 mmol) 6-amino-5-methyl-1H-indazole-7-carboxylic acid
(83) was suspended. Triphosgen (31 g, 104.6 mmol) was added
and the suspension was heated at 50 °C for 18 h. The suspension
was filtered and washed with diethyl ether. The mother liquor
was diluted with 200 ml diethyl ether and the precipitated crystals
were filtered. 5-Methyl-1,6-dihydro-8-oxa-1,2,6-triaza-cyclopenta
[a]naphthalene-7,9-dione (84) (9.97 g, quant.) was directly sub-
mitted to the next step.
1H NMR (CDCl3, 400 MHz): 8.94 and 8.80 (2s, 1H), 8.55 and 8.48
(2d, 1H), 8.18 (2b, 1H), 7.20 and 7.50 (2d, 1H), 2.32 and 2.24
(2s, 3H). MS (electrospray): m/z = 224 [Mꢂ1]. Mp: 115–125 °C.
1H NMR (DMSO, 400 MHz): 2.40 (s, 3H), 4.50 (br, 1H), 8.00 (s,
1H), 8.10 (s, 1H). LC–MS: tR = 1.05 min, m/z = 218 [M+1].
4.58. 3-Methyl-6-nitro-1,2-benzoxazole (91)
To a suspension of 1.2 g sodium hydride (65%, 32.5 mmol) in
25 ml diglyme was added dropwise a solution of 5 g (22 mmol)
1-(2,4-dinitrophenyl)ethanone oxime in 15 ml diglyme. The result-
ing reaction mixture was heated at 150 °C and stirred for 4 h at
that temperature. The reaction mixture was then cooled down to
RT and slowly poured into 250 ml water. The aqueous phase was
extracted with ethyl acetate dried with magnesium sulfate and
concentrated under vacuum. The resulting residue was purified
by flash-chromatography using a mixture of heptane/dichloro-
methane/ethyl acetate 10:10:1 as eluent to yield 2 g (51%) 3-
methyl-6-nitro-1,2-benzoxazole (91) as a yellow solid.
4.55. 6-Amino-5-methyl-1H-indazole-7-carboxylic acid isopro-
pylamide (85)
5-Methyl-1,6-dihydro-8-oxa-1,2,6-triaza-cyclopenta[a]naph-
thalene-7,9-dione (84) (1.1 g, 5.1 mmol) was suspended in 30 ml
acetic acid and 1.5 ml isopropylamine (36.9 mmol) was added.
The suspension was heated at reflux at reflux for 18 h. Another
1.5 ml (36.9 mmol) isopropyl amine was added and the mixture
was further heated 8 h at reflux. The mixture was cooled down
and poured onto 200 ml water. After 30 min stirring, the solid
formed was filtered and washed with water. It was dissolved in
ethyl acetate and filtered over a short pad of silica gel and crystal-
lized from petrol ether and diisopropylether to give 6-amino-5-
methyl-1H-indazole-7-carboxylic acid isopropylamide (85)
(0.71 g, 60%).
1H NMR (DMSO-d6, 400 MHz): 2.65 (s, 3H), 8.15 (d, 1H), 8.25 (d,
1H), 8.65 (s, 1H). MS (electrospray): m/z = 178 [M+1]. Mp: 110–
111 °C.
4.59. 3-Methyl-1,2-benzoxazol-6-amine (92)
1H NMR (CDCl3, 400 MHz): 1.30 (d, 6H), 2.25 (s, 3H), 4.35 (m,
1H), 6.45 (br, 2H), 7.48 (s, 1H), 7.85 (s, 1H), 8.40 (br, 1H). LC–MS:
tR = 1.37 min, m/z = 233 [M+1].
To a solution of 1 g (5.6 mmol) 3-methyl-6-nitro-1,2-benzoxa-
zole (91) in 60 ml 6 N HCl solution at RT was added portion-wise
5 g (22 mmol) Tin(II) chloride dihydrate . The resulting reaction
mixture was stirred at RT for 6 h. The pH was adjusted to pH 12–
13 by the addition of concentrated sodium hydroxide. The aqueous
phase was extracted with ethyl acetate, dried over magnesium
sulfate and concentrated under vacuum. This yielded 0.72 g (86%)
3-methyl-1,2-benzoxazol-6-amine (92) as an off-white solid.
1H NMR (DMSO-d6, 400 MHz): 2.35 (s, 3H), 5.8 (s, 2H), 6.55 (s,
1H), 6.6 (d, 1H), 7.4 (s, 1H). LC–MS: tR = 1.22 min, m/z = 190 [M
+42 (CH3CN)]. Mp: 111–113 °C.
Melting point: 173.5 °C.
4.56. 6-{[2-(3-Chloro-pyridin-2-yl)-5-methoxy-2H-pyrazole-3-
carbonyl]-amino}-5-methyl-1H-indazole-7-carboxylic
acid
isopropylamide (87)
(a) 2-(3-Chloro-pyridin-2-yl)-5-methoxy-2H-pyrazole-3-car-
boxylic acid (110 g, 434 mmol) was solved in 1200 ml methylene
chloride. Oxalyl chloride (74.5 ml, 867 mmol) was slowly added
at RT. After addition of 2 ml dimethylformamide, the mixture
was stirred for 18 h at RT. Oxalyl chloride (10 ml, 116 mmol) was
added and the mixture was heated at 40 °C for 30 min. The mixture
was concentrated, evaporated and dried to give 2-(3-chloro-pyri-
din-2-yl)-5-methoxy-2H-pyrazole-3-carbonyl chloride (86) which
was directly used in the next step.
4.60.
(2E)-2-Hydroxyimino-N-(3-methyl-1,2-benzoxazol-6-yl)
acetamide (93)
To a solution of 0.7 g (4.7 mmol) of 3-methyl-1,2-benzoxazol-6-
amine (92) and 1.6 g (11.2 mmol) sodium sulfate in 30 ml water
was added 1.1 g (7.4 mmol) chloral hydrate, 0.5 ml concd HCl
and 1.3 g (18.8 mmol) hydroxylamine hydrochloride at RT. The
resulting reaction mixture was heated gradually to 80 °C and stir-
red for 4 h at that temperature. The reaction mixture was then
cooled down to RT with an ice bath. The solid formed was filtrated,
washed thoroughly with water and diisopropylether and dried at
50 °C overnight to afford 0.89 g (81%) (2E)-2-hydroxyimino-N-(3-
methyl-1,2-benzoxazol-6-yl)acetamide (93) as an off-white
powder.
(b) 6-Amino-5-methyl-1H-indazole-7-carboxylic acid isopropy-
lamide (85) (1.0 g, 4.3 mmol) was suspended in 20 ml CH3CN. 2-(3-
Chloro-pyridin-2-yl)-5-methoxy-2H-pyrazole-3-carbonyl chloride
(86) (1.23 g, 4.51 mmol) was added in several portions. The mix-
ture was stirred at RT for 39 h. A saturated solution of NaHCO3 in
water (15 ml) was added and the mixture was stirred for a few
minutes. After filtration and trituration in diisopropylether, 6-
{[2-(3-chloro-pyridin-2-yl)-5-methoxy-2H-pyrazole-3-carbonyl]-
amino}-5-methyl-1H-indazole-7-carboxylic acid isopropylamide
(87) was isolated as a solid material (1.94 g, 85%).
1H NMR (DMSO-d6, 400 MHz): 2.5 (s, 3H), 7.55 (d, 1H), 7.7 (s,
1H), 7.75 (d, 1H), 8.2 (s, 1H), 10.55 (s, 1H), 12.3 (s, 1H). LC–MS:
tR = 1.39 min, m/z = 220 [M+1]. Mp: 225–227 °C.
1H NMR (400 MHz, CDCl3): 10.8 (br s, 1H), 9.6 (br s, 1H), 8.40 (d,
1H), 7.86 (s, 1H), 7.81 (d, 1H), 7.30 (dd, 1H), 7.20 (s, 1H), 6.95–6.70
(br s, 1H), 6.82 (s, 1H), 4.27–4.18 (m, 1H), 4.03 (s, 3H), 2.03 (s, 3H),
1.13 (d, 6H). MS (electrospray): m/z = 452 [M+1].
4.61. 6-Amino-3-methyl-1,2-benzoxazole-7-carboxylic acid (94)
4.57. 1-(2,4-Dinitrophenyl)ethanone oxime (90)
A solution of (2E)-2-hydroxyimino-N-(3-methyl-1,2-benzoxa-
zol-6-yl)acetamide (93) (0.89 g, 4 mmol) in concentrated sulfuric
acid (10 mL) was stirred 8 h at 85 °C. The reaction mixture was
To a stirred solution of 44.5 g (210 mmol) 1-(2,4-dinitrophenyl)
ethanone (89) and 17 ml pyridine in 200 ml ethanol was added

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A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
poured into a mixture of ice and water, stirred and filtered. The
precipitate obtained was washed with diisopropyl ether to give
0.46 g (57.5%) 3-methyl-6H-pyrrolo[2,3-g][1,2]benzoxazole-7,8-
dione. This material was solved in 10 mL water and sodium
hydroxide (0.4 g, 10 mmol) followed by 0.8 ml hydrogen peroxide
30% (8.4 mmol) were added slowly. The resulting mixture was stir-
red 6 h at 70 °C and then overnight at RT. The reaction mixture was
neutralized with concd HCl to pH 4–5. The aqueous layer was
extracted with ethyl acetate, dried over MgSO4, filtered and evap-
orated. The residue was purified by chromatography with the San-
doz eluent. The product obtained was solved in water, acidified to
pH 4–5 with 2 N HCl and extracted again with ethyl acetate, dried
over MgSO4, filtered and evaporated to give 6-amino-3-methyl-
1,2-benzoxazole-7-carboxylic acid (94) as an orange solid.
1H NMR (DMSO-d6, 400 MHz): 2.4 (s, 3H), 6.75 (d, 1H), 7.55 (d,
1H). LC–MS: tR = 1.12 min, m/z = 191 [Mꢂ1].
nyl]amino]-N-isopropyl-3-methyl-1,2-benzoxazole-7-carboxam-
ide (97) after crystallization in petrol ether and diisopropylether.
1H NMR (400 MHz, CDCl3): 11.37 (br s, 1H), 8.46 (m, 1H), 7.79
(m, 1H), 7.75 (s, 1H), 7.30 (m, 1H), 7.06 (br, 1H), 6.55 (s, 1H),
4.33 (m, 1H), 4.02 (s, 1H), 2.56 (s, 1H), 1.33 (d, 6H). MS (electro-
spray): m/z = 503 [M+1], 505 [M+3], 507 [M+5].
4.64. (2E)-N-(5-Fluoro-2-methyl-phenyl)-2-hydroxyimino-acet-
amide (99)
To a solution of sodium sulfate (600 g, 4.22 mol) in 1500 ml
water was added chloral hydrate (42.75 g, 258 mmol) at RT. To
the resulting clear solution was added a solution of 5-fluoro-2-
methyl-aniline (30 g, 239 mmol) in 1 N aqueous hydrochloric acid
(261 ml). The resulting mixture turned cloudy and hydroxylamine
hydrochloride (52.23 g, 751 mmol) was then added. The resulting
reaction mixture was heated to 80 °C and stirred for an additional
3 h at that temperature. The reaction mixture was then cooled
down to RT with an ice bath and the solid formed was filtrated.
The filter cake was washed thoroughly with water and dried at
50 °C overnight to afford (2E)-N-(5-fluoro-2-methyl-phenyl)-2-
hydroxyimino-acetamide (99) (35.86 g, 76%).
4.62. 6-Amino-5-chloro-3-methyl-1,2-benzoxazole-7-carboxylic
acid (95)
6-Amino-3-methyl-1,2-benzoxazole-7-carboxylic acid (94)
(9.6 g, 50.0 mmol) was dissolved in dimethylformamide (70 ml)
and 6.7 g N-chlorosuccinimide (50.0 mmol) were added. The
resulting mixture was stirred at 90 °C for 90 min, cooled down
and poured into water. The precipitate formed was filtered, dried
and washed with diisopropylether to give 6-amino-5-chloro-3-
1H NMR (DMSO-d6, 400 MHz): 2.20 (s, 3H), 6.95 (m, 1H), 7.25 (t,
1H), 7.5 (q, 1H), 7.7 (s, 1H), 9.5 (s, 1H) 12.25 (s, 1H). LC–MS:
tR = 1.29 min, m/z = 196 [M+1].
4.65. 2-Amino-6-fluoro-3-methyl-benzoic acid (100)
methyl-1,2-benzoxazole-7-carboxylic acid (95) as
a powder
(9.0 g, 80%).
1H NMR (DMSO-d6, 400 MHz): 13.35 (s, 1H), 8 (s, 1H), 7.55 (s,
2H), 2.45 (s, 3H).MS (electrospray): m/z = 227 [M+1], 229 [M+3].
A
solution of (2E)-N-(5-fluoro-2-methyl-phenyl)-2-hydroxy-
imino-acetamide (99) (35.8 g, 182 mmol) in 200 mL concentrated
sulfuric acid was stirred 8 h at 85 °C. The reaction mixture was
then poured into a mixture of ice and water (3 L), stirred and fil-
tered. The precipitate obtained was washed with diisopropyl ether
to give 4-fluoro-7-methyl-indoline-2,3-dione (26.8 g, 149 mmol).
This intermediate was dissolved in a 2 N solution of sodium
hydroxide (175 ml) and 37.0 ml hydrogen peroxide 30%
(388 mmol) was added slowly. The resulting mixture was heated
3 h at 80 °C. The reaction mixture was cooled down and acidified
to pH 4–5 with 2 M HCl. The aqueous layer was extracted with
ethyl acetate, dried over MgSO4, filtered and evaporated. The resi-
due was purified by flash-chromatography. The product obtained
was solved again in water, acidified to pH 4–5 with 2 M HCl,
extracted with ethyl acetate, dried over MgSO4 and evaporated to
give 22.24 g 2-amino-6-fluoro-3-methyl-benzoic acid (100) (88%).
1H NMR (DMSO-d6, 400 MHz): 2.2 (s, 3H), 6.25 (t, 1H), 7.1
(t, 1H). LC–MS: tR = 1.25 min, m/z = 170 [M+1].
4.63. 5-Chloro-6-[[2-(3-chloro-2-pyridyl)-5-methoxy-pyrazole-
3-carbonyl]amino]-N-isopropyl-3-methyl-1,2-benzoxazole-7-
carboxamide (97)
(a)
2-(3-Chloro-2-pyridyl)-5-methoxy-pyrazole-3-carboxylic
acid (96) (10 g, 39.45 mmol) was dissolved in dichloromethane
(150 ml) and 3 drops of DMF was added followed by the dropwise
addition of 15.0 mL oxalyl chloride (78.9 mmol). The brown sus-
pension turned to a red solution. The reaction mixture was stirred
for 3 h at 40 °C and evaporated to give crude 2-(3-chloro-2-pyri-
dyl)-5-methoxy-pyrazole-3-carbonyl chloride (10.2 g, 95%) which
was directly used in the next step.
(b) In a solution of 20 ml THF and 50 ml acetonitrile, 2.3 ml
methanesulfonyl chloride (29.85 mmol) and 4 ml pyridine were
added followed by 2.25 g 6-amino-5-chloro-3-methyl-1,2-benzox-
azole-7-carboxylic acid (95) (9.95 mmol) and 2.53 g 2-(3-chloro-2-
4.66. 2-Amino-6-fluoro-5-iodo-3-methyl-benzoic acid (101)
pyridyl)-5-methoxy-pyrazole-3-carbonyl
chloride
(step
a,
9.3 mmol) was added in several portions. The mixture was stirred
at RT for 39 h. A saturated solution of NaHCO3 in water (15 ml) was
added and the mixture was stirred for a few minutes. After filtra-
To a solution of 2-amino-6-fluoro-3-methyl-benzoic acid (100)
(22.24 g, 0.131 mol) in N,N-dimethylformamide (500 ml) was
added N-iodosuccinimide (28.1 g, 0.124 mol).The reaction mixture
was heated at 80 °C for 2 h. After cooling, the reaction mixture was
concentrated in vacuum. The residue was diluted with ethyl acet-
ate and washed with water. The aqueous phase was extracted 3
times with ethyl acetate. The combined organic phases were dried
on MgSO4 and concentrated to afford 37.97 g 2-amino-6-fluoro-5-
iodo-3-methyl-benzoic acid (101) (98%).
tion,
5-chloro-7-[2-(3-chloro-2-pyridyl)-5-methoxy-pyrazol-3-
yl]-3-methyl-3a,6,7,9b-tetrahydroisoxazolo[5,4-f][3,1]benzoxazin-
9-one (4.2 g, 93%) was isolated as a solid which was directly used
in the next step.
(c) 5-Chloro-7-[2-(3-chloro-2-pyridyl)-5-methoxy-pyrazol-3-
yl]-3-methyl-3a,6,7,9b-tetrahydroisoxazolo[5,4-f][3,1]benzoxazin-
9-one (1.05 g, 2.28 mmol) obtained from the previous step was
suspended in 15 ml acetonitrile and 0.38 ml isopropylamine
(9.2 mmol) was added. The suspension was heated at reflux for
18 h. The mixture was cooled down and poured on 100 ml water.
After 30 min stirring, the crystalline material was filtered and
washed with water. The solid was dissolved in ethyl acetate and
filtered over a short pad of silica gel to afford (0.92 g, 80%). 5-
Chloro-6-[[2-(3-chloro-2-pyridyl)-5-methoxy-pyrazole-3-carbo-
1H NMR (DMSO-d6, 400 MHz): 2.00 (s, 3H), 7.45 (t, 1H). LC–MS:
tR = 1.60 min, m/z = 296 [M+1].
4.67. 2-Amino-6-fluoro-5-iodo-N,3-dimethyl-benzamide (102)
(a) 2-Amino-6-fluoro-5-iodo-3-methyl-benzoic acid (101)
(37.9 g, 0.128 mol) was solved in 600 ml toluene. Thionyl chloride
(46.6 ml, 0.642 mol) was slowly added at RT. The mixture was stir-

A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
425
red for 18 h at RT. The mixture was concentrated in vacuum, and
the residual acid chloride was directly used in the next step.
(b) To a cooled solution of the acid chloride obtained in the pre-
vious step in 600 ml THF was slowly added 21.6 ml triethylamine
(0.154 mol) and 36.7 ml of solution of methylamine 33% in metha-
nol (0.390 mol) at 0–5 °C. The reaction mixture was stirred at RT
overnight. The solution was concentrated in vacuum and water
and ethyl acetate were added. The organic phase was separated,
dried over MgSO4, and concentrated in vacuum to give 25.53 g 2-
amino-6-fluoro-5-iodo-N,3-dimethyl-benzamide (102) (65%).
1H NMR (CDCl3, 400 MHz): 2.10 (s, 3H), 3.00 (d, 3H), 6.00 (br,
2H), 6.60 (br, 1H), 7.40 (d, 1H). LC–MS: tR = 1.52 min, m/z = 309
[M+1].
1H NMR (CDCl3, 400 MHz): 1.30 (s, 18H) 2.13 (s, 3H), 3.00 (d,
3H), 6.80 (br, 1H), 7.40 (br, 2H). LC–MS: tR = 1.90 min, m/z = 421
[M+1].
4.71. tert-Butyl N-[6-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-
3-carbonyl]amino]-5-methyl-7-(methylcarbamoyl)-1,2-benzo-
xazol-3-yl]-N-tert-butoxycarbonyl-carbamate (107)
To a solution of tert-butyl N-[6-amino-5-methyl-7-(methylcar-
bamoyl)-1,2-benzoxazol-3-yl]-N-tert-butoxycarbonyl-carbamate
(105) (0.4 g, 0.949 mmol) in 20 ml THF was slowly added 5-bromo-
2-(3-chloro-2-pyridyl)pyrazole-3-carbonyl
chloride
(0.416 g,
1.30 mmol). The reaction mixture was stirred at RT overnight.
Water was added and product was extracted with ethyl acetate.
The organic phase was dried on MgSO4 and concentrated in vac-
uum. The crude product was purified by flash-chromatography to
give 370 mg tert-butyl N-[6-[[5-bromo-2-(3-chloro-2-pyridyl)
pyrazole-3-carbonyl]amino]-5-methyl-7-(methylcarbamoyl)-1,2-
benzoxazol-3-yl]-N-tert-butoxycarbonyl-carbamate (107) as beige
crystals (55.3%).
4.68. 2-Amino-5-cyano-6-fluoro-N,3-dimethyl-benzamide (103)
To
a
degassed solution of 2-amino-6-fluoro-5-iodo-N,3-
dimethyl-benzamide (102) (13.7 g, 44.5 mmol), in 250 ml DMF
was added copper iodide (847.1 mg, 44.4 mmol), Pd(PPh3)4
(2.56 g, 2.2 mmol) and copper cyanide (19.91 g, 222.3 mmol). The
mixture was heated at 90 °C for 48 h. After cooling, the mixture
was filtered on cellite. After concentration in vacuum, the residue
was solved in ethyl acetate and washed with water. The aqueous
phase was extracted with ethyl acetate (3 times), the combined
organic phases were dried on MgSO4 and concentrated in vacuum
to give 8.63 g 2-amino-5-cyano-6-fluoro-N,3-dimethyl-benzamide
(103) (77%).
1H NMR (CDCl3, 400 MHz): 1.25 (s, 18H) 2.13 (s, 3H), 3.00
(d, 3H), 7.00 (s, 1H), 7.15 (m, 1H) 7.15 (m, 1H) 7.20 (m, 1H) 7.30
(s, 1H), 7.7 (m, 1H), 8.3 (m, 1H), 11.8 (s, H). LC–MS: tR = 2.02 min,
m/z = 706 [M+1].
4.72. 3-Amino-6-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-
carbonyl]amino]-N,5-dimethyl-1,2-benzoxazole-7-carboxam-
ide (108)
1H NMR (CDCl3, 400 MHz): 2.10 (s, 3H), 2.75 (d, 3H), 6.50 (br,
2H), 7.40 (d, 1H), 8.45 (br, 1H). LC–MS: tR = 1.17 min, m/z = 208
[M+1].
tert-Butyl
N-[6-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-
carbonyl]amino]-5-methyl-7-(methylcarbamoyl)-1,2-benzoxazol-
3-yl]-N-tert-butoxycarbonyl-carbamate (107) (100 mg, 110 mmol)
was dissolved in 5 ml CH2Cl2 and 5 ml trifluoroacetic acid were
added. The reaction mixture was stirred at RT for 3 h. Water was
added and the product was extracted with ethyl acetate. The
organic phase was dried on MgSO4 and concentrated in vacuum.
The crude residue was purified by flash-chromatography to give
4.69.
3,6-Diamino-N,5-dimethyl-1,2-benzoxazole-7-carboxa-
mide (104)
To a solution of acetohydroxamic acid (3.26 g, 43.43 mmol) in
150 ml DMF was added potassium carbonate (10.67 g,
77.21 mmol) followed by 2 ml water. The mixture was stirred at
RT for 30 min and 2-amino-5-cyano-6-fluoro-N,3-dimethyl-benza-
mide (103) (4 g, 19.30 mmol) was added. The reaction mixture was
stirred at RT overnight. The reaction was quenched with water and
the product was extracted with ethyl acetate (5 times). The organic
phases were dried on MgSO4 and concentrated. The residue was
dissolved in a minimum of ethyl acetate/dichloromethane and
cyclohexane was added to get 2.49 g 3,6-diamino-N,5-dimethyl-
1,2-benzoxazole-7-carboxamide (104) as brown crystals (59%).
1H NMR (CDCl3, 400 MHz): 2.13 (s, 3H), 2.85 (d, 3H), 6.15 (br,
2H), 7.30 (br, 2H), 7.50 (s, 1H), 7.75 (br, 1H). LC–MS: tR = 1.07 min,
m/z = 221 [M+1].
33 mg
3-amino-6-[[5-bromo-2-(3-chloro-2-pyridyl)pyrazole-3-
carbonyl]amino]-N,5-dimethyl-1,2-benzoxazole-7-carboxamide
(108) as beige crystals (60%).
1H NMR (DMSO, 500 MHz): 2.21 (s, 3H), 2.72 (d, 3H), 6.44 (s,
2H), 7.41 (s, 1H) 7.60 (m, 1H) 7.73 (s, 1H) 8.16 (m, 1H), 8.22 (q,
1H), 8.50 (m, 1H), 10.44 (s, 1H). LC–MS: tR = 1.50 min, m/z = 504
[M+1], 506 [M+3].
4.73. tert-Butyl N-tert-butoxycarbonyl-N-(2-chloro-4-pyridyl)-
carbamate (110)
A solution of 5.9 g 2-chloropyridin-4-amine (46.0 mmol) in
400 ml THF under nitrogen atmosphere was cooled down to 0 °C.
Lithium bis(trimethylsilyl)amide 1 M in THF (100 ml, 100 mmol)
was added dropwise. After the addition, the reaction mixture
was stirred 30 min at 0 °C. A solution of di-tert-butyl dicarbonate
(22 g, 101 mmol) in 100 ml THF was added slowly at 0–5 °C. The
reaction mixture was stirred one night at RT and then quenched
with ammonium chloride and brine. The organic layer was washed
with brine, dried over MgSO4, filtered and evaporated under vac-
uum to give tert-butyl N-tert-butoxycarbonyl-N-(2-chloro-4-
pyridyl)carbamate (110) as an orange solid (15.8 g, quant.).
1H NMR (400 MHz, CDCl3): 8.37 (d, 1H), 7.19 (d, 1H), 7.05 (dd,
1H), 1.45 (s, 18H). MS (electrospray): m/z = 329 [M+1].
4.70. tert-Butyl N-[6-amino-5-methyl-7-(methylcarbamoyl)-
1,2-benzoxazol-3-yl]-N-tert-butoxycarbonyl-carbamate (105)
To a solution of 3,6-diamino-N,5-dimethyl-1,2-benzoxazole-7-
carboxamide (104) (2.3 g, 10.44 mmol) in 100 ml dichloromethane
was added triethylamine (14.6 ml) followed by di-tert-butyl dicar-
bonate (2.28 g, 10.44 mmol), and a catalytic amount of 4-dimethy-
laminopyridine. The reaction mixture was stirred at RT overnight.
A second portion of di-tert-butyl dicarbonate (22.8 g, 104.4 mmol)
dissolved in 50 ml dichloromethane was added. After 3 h at RT, the
conversion was complete. After evaporation of the solvent, the
residue was taken in ethyl acetate and washed with water. The
organic phase was dried on MgSO4 and concentrated in vacuum.
The crude product was purified by flash-chromatography to give
1.84 g tert-butyl N-[6-amino-5-methyl-7-(methylcarbamoyl)-1,2-
benzoxazol-3-yl]-N-tert-butoxycarbonyl-carbamate (105) as beige
crystals (42%).
4.74. tert-Butyl 4-(tert-butoxycarbonylamino)-2-chloro-pyri-
dine-3-carboxylate (111)
According to Ref. 16: under inert atmosphere, a solution of
diisopropylamine (23 ml, 160 mmol) in 350 ml THF was cooled to

426
A. Jeanguenat et al. / Bioorg. Med. Chem. 24 (2016) 403–427
ꢂ75 °C. A solution of 100 ml nBuLi (1.6 M in hexane, 160 mmol)
was added and the resulting mixture was stirred 30 min at
ꢂ75 °C. tert-Butyl N-tert-butoxycarbonyl-N-(2-chloro-4-pyridyl)-
carbamate (110) (15.6 g, 46 mmol) in 50 ml THF was added to
the reaction mixture at ꢂ75 °C. After the addition, the reaction
was stirred 1 h at ꢂ75 °C and then carefully quenched with ammo-
nium chloride and brine. The aqueous layer was extracted with
ethyl acetate. The combined organic layers were dried over MgSO4,
filtered, evaporated under vacuum and washed with heptane to
give 11.2 g tert-butyl 4-(tert-butoxycarbonylamino)-2-chloro-pyri-
dine-3-carboxylate (111) as a yellow solid (72%).
1H NMR (DMSO-d6, 400 MHz): 14.05 (s, 2H), 8.75 (br s, 1H), 8.7
(br s, 1H), 8.4 (d, 1H), 6.95 (d, 1H), 2.6 (s, 3H). LC–MS: tR = 0.16 min,
m/z = 193 [M+1]. Mp: 233–235.
4.78. 7-Amino-N,3-dimethyl-[1,2,4]triazolo[4,3-a]pyridine-8-car-
boxamide (115)
To a solution of 7-amino-3-methyl-[1,2,4]triazolo[4,3-a]pyri-
dine-8-carboxylic acid trifluoroacetate salt (114) (1.1 g, 3.6 mmol)
in 20 ml water was added sodium hydroxide (144 mg, 7.2 mmol).
The resulting mixture was stirred 1 h at RT and evaporated under
vacuum to give 7-amino-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-
8-carboxylic acid as a sodium salt. This salt was taken in 20 ml
thionyl chloride and the resulting suspension was stirred 20 h at
90 °C. The reaction mixture was evaporated and the residue was
taken in 20 ml THF. The resulting suspension was slowly added
to a 10 ml ethanol solution of methylamine (10 mmol) in 100 ml
THF. After 5 min, the reaction mixture was quenched with water
and brine. The organic layer was separated, dried over MgSO4, fil-
tered and evaporated under vacuum to give 0.58 g 7-amino-N,3-
dimethyl-[1,2,4]triazolo[4,3-a]pyridine-8-carboxamide (115) as
solid (55%).
1H NMR (400 MHz, CDCl3): 8.7 (br s, 1H), 8.2 (dd, 1H), 1.65 (s,
9H), 1.52 (s, 9H). LC–MS: tR = 2.07 min, m/z = 329 [M+1], 331 [M
+3]. Mp: 135–137 °C.
4.75. tert-Butyl N-(3-acetyl-2-hydrazino-4-pyridyl)carbamate
(112)
To a solution of tert-butyl 4-(tert-butoxycarbonylamino)-2-
chloro-pyridine-3-carboxylate (111) (1.1 g, 3.3 mmol) in 15 ml
dioxane was added hydrazine hydrate (0.23 g, 3.63 mmol) fol-
lowed by ethyl diisopropylamine (0.48 g, 3.63 mmol). The resulting
mixture was stirred one night at 60 °C. Hydrazine hydrate (0.2 g,
3.3 mmol) was added and the mixture was stirred overnight at
60 °C. The reaction mixture was evaporated under vacuum and
the residue was solved in ethyl acetate. The organic layer was
washed with water, dried over MgSO4, filtered, evaporated under
vacuum. The solid obtained was washed in diisopropylether to give
0.89 g tert-butyl N-(3-acetyl-2-hydrazino-4-pyridyl)carbamate
(112) as a yellow solid (40%).
1H NMR (DMSO-d6, 400 MHz): 9.62 (d, 1H), 9.05 (br s, 1H), 8.1
(d, 1H), 7.4 (br s, 1H), 6.55 (d, 1H), 2.85 (d, 3H), 2.55 (s, 3H). LC–
MS: tR = 0.24 min, m/z = 193 [M+1].
4.79. 7-[[2-(3-Chloro-2-pyridyl)-5-methoxy-pyrazole-3-carbonyl]
amino]-N,3-dimethyl-[1,2,4]triazolo[4,3-a]pyridine-8-carboxam-
ide (116)
1H NMR (DMSO-d6, 400 MHz): 10.12 (s, 1H), 8.4 (br s, 1H), 8.1
(d, 1H), 7.4 (d, 1H), 4.42 (br s, 2H), 1.6 (s, 9H), 1.45 (s, 9H). LC–
MS: tR = 1.25 min, m/z = 325 [M+1]. Mp: 152–154 °C.
To a solution of 7-amino-N,3-dimethyl-[1,2,4]triazolo[4,3-a]
pyridine-8-carboxamide (115) (250 mg, 1.2 mmol) in 10 ml THF
was added 2-(3-chloro-2-pyridyl)-5-methoxy-pyrazole-3-carbonyl
chloride (326 mg, 1.2 mmol) was added. The reaction was stirred
1 week at RT. The reaction mixture was poured into water and
the mixture obtained was basified (pH 7–8) with potassium car-
bonate. The aqueous layer was extracted with a mixture of ethyl
acetate/THF 2:1. The combined organic layers were washed with
brine, dried over MgSO4, filtered and evaporated. The residue
was purified by flash-chromatography to give 7 mg 7-[[2-(3-
chloro-2-pyridyl)-5-methoxy-pyrazole-3-carbonyl]amino]-N,3-
dimethyl-[1,2,4]triazolo[4,3-a]pyridine-8-carboxamide (116) (1%).
1H NMR (400 MHz, CDCl3): 8.52 (d, 1H), 8.48 (d, 1H), 7.9 (d, 1H),
7.75 (d, 1H), 7.4 (m, 1H), 6.7 (s, 1H), 4 (s, 3H), 3.1 (d, 3H), 2.75 (s,
3H). LC–MS: tR = 1.58 min, m/z = 441 [M+1].
4.76. tert-Butyl N-(8-acetyl-3-methyl-[1,2,4]triazolo[4,3-a]pyri-
din-7-yl)carbamate (113)
To a solution of tert-butyl N-(3-acetyl-2-hydrazino-4-pyridyl)-
carbamate (112) (1.1 g, 4.1 mmol) in 30 ml ethanol was added 3
drops concentrated sulfuric acid, followed by triethylorthoacetate
(1 ml, 5.4 mmol). The resulting mixture was stirred 30 min at
70 °C. The reaction mixture was evaporated and the residue was
solved in ethyl acetate, washed with water and a saturated bicar-
bonate solution. The aqueous layer was extracted with ethyl acet-
ate. The combined organic phases were dried over MgSO4, filtered
and evaporated under vacuum to give 0.49 g tert-butyl N-(8-
acetyl-3-methyl-[1,2,4]triazolo[4,3-a]pyridin-7-yl)carbamate
(113) as a solid (45%).
Acknowledgments
We would like to thank Daniela Ost and Bernard Frid, for their
skillful work in the chemistry lab, Penny Cutler and Melissa Blacker
for generating in vitro data, Andy Pierce for generating physical
data, and Leonhard Hagmann, Katharina Gaus and Marie-Made-
leine Stempien for NMR measurements and helpful discussion.
Bahiya Atouioual, Dorothée Henryon and Damien Bonvalot are
acknowledged for their help in the preparation of the experimental
part.
1H NMR (400 MHz, CDCl3): 11.0 (br s, 1H), 8.3 (d, 1H), 7.8 (d,
1H), 2.69 (s, 3H) 1.71 (s, 9H), 1.55 (s, 9H). LC–MS: tR = 1.42 min,
m/z = 349 [M+1]. Mp: 220–222 °C.
4.77. 7-Amino-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-8-carbo-
xylic acid (114)
A solution of tert-butyl N-(8-acetyl-3-methyl-[1,2,4]triazolo
[4,3-a]pyridin-7-yl)carbamate (113) (0.48 mg, 1.38 mmol) in 2 ml
trifluoroacetic acid was stirred 45 min at 70 °C. The reaction mix-
ture was cooled, evaporated under vacuum and taken in water, fol-
lowed by a saturated bicarbonate solution and 3–4 drops of
potassium carbonate solution. The aqueous layer was acidified
until pH 3 with HCl 2 M, brine was added and a precipitate was
formed. The solid was filtered, washed with acetonitrile and dried
to afford 0.18 g 7-amino-3-methyl-[1,2,4]triazolo[4,3-a]pyridine-
8-carboxylic acid (114) as a trifluoroacetate salt (42%).
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