Synthesis and biological evaluation of N-arylbenzo[b]thieno[3,2-d] pyrimidin-4-amines and their pyrido and pyrazino analogues as Ser/Thr kinase inhibitors

Article abstract of DOI:10.1016/j.ejmech.2012.10.006

A useful and rapid access to libraries of N-arylbenzo[b]thieno[3,2-d] pyrimidin-4-amines and their pyrido and pyrazino analogues was designed and optimized for the first time via microwave-accelerated condensation and Dimroth rearrangement of the starting anilines with N′-(2-cyanoaryl)-N,N- dimethylformimidamides obtained by reaction of thiophene precursors with dimethylformamide dimethylacetal. The inhibitory potency of the final products against five protein kinases (CDK5/p25, CK1δ/ε, GSK3α/β, DYRK1A and CLK1) was estimated. N-arylpyrido[3′,2′:4,5]thieno[3,2-d] pyrimidin-4-amine series of compounds (4a-j) turned out to be particularly promising for the development of new pharmacological inhibitors of CK1 and CLK1 kinases.

Full text of DOI:10.1016/j.ejmech.2012.10.006

European Journal of Medicinal Chemistry 58 (2012) 171e183
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological evaluation of N-arylbenzo[b]thieno[3,2-d]pyrimidin-
4-amines and their pyrido and pyrazino analogues as Ser/Thr kinase inhibitors
Yvonnick Loidreau a, Pascal Marchand b, Carole Dubouilh-Benard a, Marie-Renée Nourrisson b,
,
,
*
Muriel Duflos b, Olivier Lozach c, Nadège Loaëc c d, Laurent Meijer d, Thierry Besson a
a Université de Rouen, Laboratoire de Chimie Organique et Bio-organique, Réactivité et Analyse (C.O.B.R.A.), CNRS UMR 6014 & FR3038, Institut de Recherche en
Chimie Organique Fine (I.R.C.O.F.) rue Tesnière, 76130 Mont Saint-Aignan, France
b Université de Nantes, Nantes Atlantique Universités, Laboratoire de Chimie Thérapeutique, Cibles et Médicaments des Infections et du Cancer, IICiMed UPRES EA 1155,
UFR des Sciences Pharmaceutiques et Biologiques, 1 rue Gaston Veil, 44035 Nantes, France
c Protein Phosphorylation & Human Disease’ Group, Station Biologique, 29680 Roscoff, France
d Manros Therapeutics, Centre de Perharidy, 29680 Roscoff, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A useful and rapid access to libraries of N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amines and their pyrido
and pyrazino analogues was designed and optimized for the first time via microwave-accelerated
condensation and Dimroth rearrangement of the starting anilines with N0-(2-cyanoaryl)-N,N-dime-
thylformimidamides obtained by reaction of thiophene precursors with dimethylformamide dimethy-
Received 20 July 2012
Received in revised form
3 October 2012
Accepted 4 October 2012
Available online 16 October 2012
lacetal. The inhibitory potency of the final products against five protein kinases (CDK5/p25, CK1
d/ 3 ,
GSK3
a/b
, DYRK1A and CLK1) was estimated. N-arylpyrido[30,20:4,5]thieno[3,2-d]pyrimidin-4-amine
series of compounds (4aej) turned out to be particularly promising for the development of new phar-
macological inhibitors of CK1 and CLK1 kinases.
Keywords:
Microwave-assisted chemistry
Dimroth rearrangement
Thieno[3,2-d]pyrimidine
Dimethylformamide dimethylacetal
Kinase inhibitor
Ó 2012 Elsevier Masson SAS. All rights reserved.
Alzheimer’s disease
1. Introduction
target compounds were conceived as 6,5,6-tricyclic homologues of
the basic 4-aminoquinazoline pharmacophore which is present in
Kinases are one of the largest families of the genome. More than
500 kinases play an important role in the regulation of various
cellular processes. These enzymes are involved in all major
diseases, including cancer, neurodegenerative disorders and
cardiovascular diseases. Our research groups are mainly invested in
the synthesis of C,N,S- or C,N,O-containing heterocyclic precursors
of bioactive molecules able to modulate the activity of kinases in
signal transduction [1,2]. In the course of our work, the synthesis of
4-anilinopyrido[20,30:4,5]furo[3,2-d]pyrimidines was described for
the first time via a microwave-accelerated Dimroth rearrangement
[3,4]. In the same time we envisioned to apply this chemical
method to the synthesis of various benzo-, pyrido- and pyr-
azinothieno[3,2-d]pyrimidines derivatives, themselves substituted
in position 4 of the pyrimidine ring by an aromatic amine. These
approximately 80% of ATP-competitive kinases inhibitors that have
received approval for the treatment of cancer [5].
The use of microwave-assisted dielectric heating to perform
organic reactions is gaining an increasing popularity in process
chemistry [6]. In recent applications of the thermal-dependent
Dimroth rearrangement published in the literature, it was
demonstrated that the strong heating due to specific moleculee
microwave interactions was particularly suitable for the synthesis
of the target compounds [6]. This paper describes the development
of a simple and reliable method that allows the preparation of
a library of new thieno[3,2-d]pyrimidines for which interesting
kinase inhibitory activities were observed. The main part of the
chemistry described in this paper was realized under microwaves
in a combinatorial chemistry approach. The evaluation of kinase
inhibition of the products obtained was realized on Ser/Thr kinases
(CDK5, GSK3, DYRK1A, CLK1 and CK1) chosen for their strong
implication in various regulation processes, especially Alzheimer’s
disease [7].
* Corresponding author. Tel.: þ33 (0)235522904; fax: þ33 (0)235522962.
E-mail address: thierry.besson@univ-rouen.fr (T. Besson).
0223-5234/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2012.10.006

172
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
2. Chemistry
addition of nitrite salt (KNO2) and hydrogen bromide, while at the
same time an activated bromide nucleophile was prepared readily in
situ from hydrogen bromide and dimethylsulfoxide. Thus, the trans-
formation of an amine groupto halogen group in aromatic compound
may occur in a single-step process.
In the next step, reaction of 11 with copper (I) cyanide afforded
3-nitropyridine-2-carbonitrile (12) with 68% yield [13].
Finally, commercially available pyrazine-2-carbonitrile (13)
reacted with sulfuryl chloride in toluene and N,N-dimethylforma-
mide, as co-solvent, at room temperature to afford 3-
chloropyrazine-2-carbonitrile (14) with moderate yield [14]. 7-
Aminothieno[2,3-b]pyrazine-6-carbonitrile (1d) was prepared by
reaction between compound 14 and sodium hydrosulfide. The
resulting thiol cyclised in the presence of bromoacetonitrile and
potassium carbonate, as a base, to give the thienopyrazine 1d [8b].
The target molecules we studied were benzo[b]thieno[3,2-d]
pyrimidines (3) and their pyrido (4 and 5) and pyrazino analogues
(6) substituted in position 4 of the pyrimidine ring by an aromatic
amine. The retrosynthetic pathway depicted in Scheme 1 started
from 3-aminobenzothiophene-2-carbonitrile (1a) and amino-
thienoazinecarbonitriles 1bed which could be transformed into
their corresponding N,N-dimethylformamidine derivatives 2aed.
The next step consisted in nucleophilic attack of the intermediate
amidines by aromatic amines to give the expected tricyclic
compounds 3e6 via a Dimroth rearrangement [4]. A literature
survey revealed that the synthesis of such derivatives had not been
previously described. Usually the described route required
synthesis of pyrimidin-4-one derivatives which reacted with thi-
onyl chloride, phosphoryl chloride or oxalyl chloride to afford 4-
chloro-substituted pyrimidine derivatives before transformation
into the expected products after nucleophilic substitution using
various aromatic amines [8].
2.2. Synthesis of N,N-dimethylformimidamides (2aed)
With starting compounds 1aeb now available, the second step
in the synthesis consisted of formation of N,N-dimethylformimi-
damide intermediates 2aed. It was realized by the reaction of
cyanoenamines 1aed with N,N-dimethylformamide dimethylace-
tal (DMFeDMA). After various attempts to optimize the reaction
parameters (time, temperature and applied microwave power), the
expected products 2aed were obtained with good to excellent
yields (79e99%) after short times of irradiation (15e30 min) at 70e
90 ꢀC. Note that microwave heating was realized at atmospheric
pressure in a controlled multimode cavity and not in pressurized
vials as often described in various processes [4d,15]. Concerning the
technical aspect, the choice of a reactor able to work at atmospheric
pressure was guided by our previous experience in microwave-
assisted heterocyclic synthesis, especially in the chemistry of qui-
nazolines [4a,16]. Open vessel microwave experiments have some
advantages, such as the possibility of easier scale-up and to apply
usual laboratory glassware. Our choice was also guided by a recent
work describing the tendency of pressure to accumulate when
DMFeDMA was heated into pressurized vials, especially under
microwaves [17]. Irradiation wattage at 800 W was enough to
efficiently reach the programmed temperature. This parameter was
mainly monitored via a contactless-infrared pyrometer which was
2.1. Synthesis of the starting 3-aminoarylthiophene-2-carbonitriles
(1aed)
The benzothiophene 1a and thienoazine precursors (1b, 1d)
were obtained by methods already described in the literature
(compounds 1a [9], 1b [10] and 1d [8b]). Compound 1c was
synthesized by adaptation of the method used for its benzo
analogue 1a [11] (Scheme 2).
3-Amino-2-benzo[b]thiophene-2-carbonitrile
(1a)
was
prepared by treatment of 2-nitrobenzonitrile (7) with 3-
mercaptopropionitrile and aqueous potassium hydroxide in DMF
at 0 ꢀC. Ring closure of the cyanomethyl thioether intermediate (not
isolated) was performed by addition of the alkylating agent, in the
presence of potassium hydroxide (KOH), to give the expected
product with a very good yield (89%) [9].
3-Aminothieno[2,3-b]pyridine-2-carbonitrile (1b) was obtained
by a previously described procedure [10]. Condensation of 2-
chloronicotinonitrile (8) with thiourea in ethanol at 120 ꢀC under
microwaves (sealed tubes) for 45 min gave the intermediate 2-
mercaptonicotinonitrile or its tautomeric form 9 (drawn in Scheme
2) which was stirred for 4 h at room temperature, in the presence of
chloroacetonitrile and potassium carbonate to give the final product
1b with a good overall yield (57% for the two steps). In order to obtain
3-aminothieno[3,2-b]pyridine-2-carbonitrile (1c) by transferring the
methodology used for the synthesis of compound 1a, it was first
necessary to provide 3-nitropyridine-2-carbonitrile (12) as starting
material. For this purpose, 3-nitropyridine-2-amine (10) was con-
verted to 2-bromo-3-nitropyridine (11), without isolating the corre-
sponding diazonium salt, by one-pot transformation using
bromodimethylsulfonium bromide generated in situ [12]. In this
reaction, a diazonium saltwasformed froman aromaticamine, by the
calibrated in control experiments with
thermometer.
a fibre-optic contact
2.3. Synthesis of benzo (3), pyrido (4 and 5) and pyrazino (6)
thieno[3,2-d]pyrimidin-4-amine derivatives
Before introducing a substituted amino group on the skeleton of
the targeted products, synthesis of the unsubstituted thieno[3,2-d]
pyrimidin-4-amine derivatives (3a, 4a, 5a and 6a) was realized in
good yield by strong heating of intermediate formimidamides 2ae
d in the presence of formamide which played the dual role of
Scheme 1. Envisioned synthesis of the target benzo[b]thieno[3,2-d]pyrimidines (3) and their pyrido (4 and 5) and pyrazino analogues (6).

Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
173
Scheme 2. Reagents and conditions: a) HSCH2CH2CN, KOH/DMF, 0 ꢀC, 15 min then BrCH2CN, 0 ꢀC, 2 h; b) thiourea, ethanol, 120 ꢀC (
m
W), 45 min; c) ClCH2CN, K2CO3, acetone, r.t., 4 h;
d) KNO2, CuBr, HBr 48%, DMSO, 35 ꢀC, 4 h; e) CuCN, fusion 150 ꢀC, 2 h; f) SO2Cl2, toluene-DMF, r.t., 5 h; g) NaHS, r.t., 3 h then BrCH2CN, K2CO3, acetone, r.t., 3 h.
solvent and reactant (Scheme 3) [18]. Its temperature-dependent
ability to generate ammonia synthon and its intrinsic properties
of heating under microwave irradiation (its loss dissipation factor,
of pyrazine derivatives 6bej from formimidamide 2d was achieved
with the shorter times.
tan d, is greater than 0.5) [19] were combined in a comfortable
3. Biological activities
process constituting a safe alternative to the extreme conditions
usually described in the literature [20].
The final products were tested on five different in vitro kinase
The last part of the synthesis consisted of heating the for-
mimidamide derivatives 2aed with various anilines in the pres-
ence of acetic acid which serves as a relatively good solvent for
assays (CDK5/p25 (cyclin-dependent kinase), CK1
d/ 3 (casein kinase
1), GSK3 (Glycogen Synthase Kinase 3), DYRK1A (dual speci-
a/b
ficity, tyrosine phosphorylation regulated kinase) and CLK1 (cdc2-
like kinase 1)) to evaluate their inhibition potency. Results given
in Table 2 demonstrated that the compounds prepared in this paper
are definitively inactive against GSK3. Except for compound 3a
heating under microwaves (tan
d
¼ 0.174 at 2.45 GHz [19]) and also
initiates the reaction. The starting mixture was irradiated at 400 W
in a multimode cavity. After 3 min, the temperature at which the
solvent could be refluxed (118 ꢀC) was reached (this time, called
“the ramp period”, is not added to the reaction time described in
Table 1). The evolution of all reactions was followed by thin-layer
chromatography and the reaction times given correspond to
a complete disappearance of the starting material (Table 1). A
library of thirty-six thieno[3,2-d]pyrimidin-4-amine derivatives
was rapidly prepared via Dimroth translocation of the endocyclic
and exocyclic nitrogen atoms present in the pyrimidine moiety
[4a,9]. This process led to the thermodynamically stable 4-anilino-
substituted isomers of the final products (3, 4, 5 and 6) (Scheme 3).
Obviously, as described in previous works [3,9], kinetics and
yield of the reaction depended on the nucleophilicity of starting
aniline, as well as the presence of electron-withdrawing groups on
benzene ring. Steric hindrance due to the position of the substitu-
ents may also play a role and caused an increase of reaction time.
Table 1 provided us interesting structure-reactivity information,
concerning heating time and resulting from pyridine nitrogen atom
position on starting compounds such as 2b and 2c. The presence of
a nitrogen atom on the same side as a sulphur atom for fused
heterocyclic ring 2b induced a sharp increase in time of heating
necessary to complete the reaction. On the contrary, the presence of
a nitrogen atom opposite to the sulphur atom (e.g. 2c) induced
shorter heating times, comparable to those obtained with the
benzene derivative 2a. Finally introducing two nitrogen atoms, the
opposite effects discussed above were cancelled since the synthesis
(entry 1) for which a micromolar IC50 value (5.2 mM) was observed,
none of the tricyclic derivatives have shown any affinity against
CDK5/p25. On a general aspect, the nine 4-anilino-substituted
derivatives 3bej series were completely inactive on the tested
kinases. Note that among the four families of tested molecules,
thieno[3,2-d]pyrimidin-4-amine derivatives (3a, 4a, 5a and 6a)
were judged relatively active (in the micromolar range) against
three kinases (CDK5, CK1 and DYRK1A for 3a; CK1, CLK1 and
DYRK1A for 4a and 5a) or one kinase (CK1 for 6a).
Concerning compounds 5aej and 6aej (entries 21e40) the main
part of their activity was linked to CK1 inhibition with eight
products (5a, 5b, 5f and 5j; 6a, 6b, 6e and 6j) which exhibited an
inhibitory activity in the micromolar and submicromolar ranges
(7.8
kinases was sometimes centred on DYRK1A (products 5a, 5d, 5i and
5j: 7.3 M < IC50 < 3.7 M).
mM < IC50 < 0.12 mM). For compounds of 5aej series, affinity for
m
m
The most promising results were obtained with products from
the 4aej series, which showed a rather good inhibition of both CK1
and CLK1 kinases with submicromolar IC50 values for most of them.
Among these compounds, 4a and 4i (entries 11 and 19) can be
considered as the most active products with submicromolar IC50
values for two of the three kinases (CKI, CLK1 and DYRK1A). The
values obtained for 4a are particularly interesting, especially
towards CK1 (31 nM) and CLK1 (680 nM). However 4a and 4i are
also the least selective products.

174
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
Scheme 3. Synthesis of compounds 2aed and thieno[3,2-d]pyrimidine derivatives (3aej, 4aej, 5aej and 6aej); for reaction times and yields see Table 1.
It may be noted that derivative 4i is the one of the forty mole-
inhibitors may alter the splicing of microtubule-associated protein
tau implicated in AD and Parkinson diseases. In this respect, our
cules prepared in this study that had submicromolar affinity
(IC50 ¼ 890 nM) for the DYRK1A kinase. Looking more closely at
results of the 4aed series, we observed three products of interest:
4b, 4c and 4g (entries 12, 13 and 17), with submicromolar IC50
values ranging from 180 nM (4b) to 520 nM (4c) for CK1. These
tricyclic 6,5,6-heterocyclic derivatives constitute
a promising
source of inspiration for the synthesis of novel bioactive molecules.
The factors governing their dual activity towards CK1 and CLK1 will
be investigated.
molecules also showed micromolar IC50 values between 2.1
and 4.5 M (4b) for CLK1. These three compounds showed no
affinity for DYRK1A.
mM (4i)
m
4. Conclusion
In view of these results it is difficult to define any role for the
varioussubstituents of the aminelocated at position 4 of pyridinering.
It is interesting to note that the presence of two methyl ether groupsin
the meta position of the amine on the aromatic ring (compounds 4e
and 4f, entries 15 and 16) induced a loss of affinity for all kinases. On
the contrary, the presence of two adjacent OMe groups in meta and
para positions (4d, entry 14), abolished the inhibitory activity on CK1
in favour of DYRK1A without lowering it to a submicromolar level.
CK1 is a Ser/Thr protein kinase family consisting of multiple
isoforms which are highly homologous within their kinase
domains. Recently, several studies have highlighted the important
role of CK1 in neurodegenerative diseases, especially in tauopathies
such as Alzheimer disease (AD) [21]. As the involvement of CK1 in
cell regulation and neurodegenerative diseases pathogenesis has
recently been identified, there has been little work regarding
inhibitors of this family of protein kinases [22]. CLK1 is one of the
four isoforms of the cdc2-like kinase family. It was described that
inhibitors of CLK1 could prove to be useful agents in disease
phenotypes characterized by abnormal splicing. In this sense CLK
The synthesis of a library of novel N-arylbenzo[b]thieno[3,2-d]
pyrimidin-4-amines and their pyrido and pyrazino analogues was
realized under microwaves via a Dimroth rearrangement. Good
control of the reaction parameters allowed efficient heating of the
reaction mixture, resulting in a shorter reaction time and very good
yields. On the chemical aspect this article is a further example
illustrating how microwave heating can be a very powerful tool for
medicinal chemists. The inhibitory potency of the final products
against five kinases was evaluated. Among all prepared compounds,
three of them turned out to be interesting. N-Arylpyrido[30,20:4,5]
thieno[3,2-d]pyrimidin-4-amine series of compounds (4aej) is
particularly promising for the development of new inhibitors of CK1
and CLK1 kinases. The most effective compounds towards these two
kinasefamilies arethepyrido[30,20:4,5]thieno[3,2-d]pyrimidines 4b,
4c and 4g which showed interesting selectivity towards CK1 and
CLK1 kinases over the other tested kinases. These results are the
starting pointof a larger project within our group, in the hope to lead
to the discovery of novel kinase inhibitors.

Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
175
Table 1
Synthesis of thieno[3,2-d]pyrimidine derivatives (3bej, 4bej, 5bej and 6bej).a
Compound
R
3
4
5
6
Time (min)
(Yield) (%)b
Time (min)
(Yield) (%)b
Time (min)
(Yield) (%)b
Time (min)
(Yield) (%)b
b
c
15
20
(77)
(61)
30
30
(69)
(57)
15
15
(87)
(66)
5
(88)
(99)
10
d
e
20
30
(99)
(84)
30
50
(58)
(73)
15
20
(75)
(65)
10
10
(96)
(96)
f
15
(80)
30
(79)
15
(78)
10
(99)
g
30
30
(68)
(84)
180
90
(67)
(84)
45
30
(31)
(59)
20
20
(79)
(76)
h
i
j
210
30
(76)
(66)
300
135
(60)
(71)
120
30
(55)
(62)
90
30
(78)
(68)
a
Reaction were performed under microwaves (
Yield of isolated product.
m
W) at 400 W, on a 0.5 mmol scale from 2aed with 1 equiv. of aniline (MultiSYNTHÔ from Milestone S.r.l. Italy).
b
5. Experimental section
magnetic stir bar inside the vessel. Temperature and power profiles
were monitored in both cases through the EASY-Control software
provided by the manufacturer.
5.1. Chemistry
Melting points of powder compounds were measured on
a STUART-Advanced apparatus. IR spectra were recorded on a Per-
kinElmer Spectrum 100 Series FT-IR spectrometer. 1H, 13C NMR
spectra were recorded on a Bruker DXP 300 spectrometer at 300,
75 MHz, respectively and a Bruker AVANCE 400 MHz high resolu-
tion NMR spectrometer at 400,100 MHz, respectively. Multiplicities
were abbreviated as follows: singlet (s), doublet (d), triplet (t),
multiplet (m), and broad (br). Reactions were monitored by TLC
analysis using Merck silica gel 60F-254 thin layer plates. Column
chromatography was carried out on silica gel Merck 60 (70e230
mesh ASTM). Elemental analyses were found within ꢁ0.4% of the
theoretical values. Mass spectra were performed by the Mass
Spectrometry Laboratory of the University of Rouen. Mass spectra
(EI) were recorded with a Waters ZQ 2000 and a Waters LCP 1er XR
spectrometer.
5.1.1. Synthetic routes for the preparation of 3-aminoarylthiophene-
2-carbonitriles (1aed)
5.1.1.1. Synthesis of 3-amino-2-cyanobenzo[b]thiophene (1a). A
solution of potassium hydroxide (3.8 g, 67.7 mmol) in water (12 mL)
was added dropwise under vigorous magnetic stirring to a cooled
(ice bath) solution of 2-nitrobenzonitrile 7 (3.40 g, 22.9 mmol) and
3-mercaptopropionitrile (2.40 g, 27.5 mmol) in DMF (45 mL). The
cold mixture was stirred for 15 min and bromoacetonitrile
(2.30 mL, 33.0 mmol) was added dropwise. After 2 h at 0 ꢀC, the
mixture was poured into ice water. The crude product was collected
by filtration and purified with silica gel column chromatography
using 100% dichloromethane. The desired product (1a) was isolated
as a white powder (3.56 g, 89%); mp 156e157 ꢀC (lit. [11]: 155e
156 ꢀC); IR (KBr) nmax (cmꢂ1): 3319, 2210 (CN), 1644, 1571, 1532,
1467, 1432, 1399, 1326, 1270, 1198, 1150, 1132, 1059, 1022, 754, 721,
Microwave experiments were conducted in
a
commercial
680, 644; 1H NMR (400 MHz, DMSO-d6):
d
8.14 (d, J ¼ 8.0 Hz, 1H),
microwave reactor especially designed for synthetic chemistry.
RotoSYNTHÔ (Milestone S.r.l. Italy) is a multi-mode cavity with
a microwave power delivery system ranging from 0 to 1200 W. The
temperatures of the reactions were mainly monitored via contact-
less infrared pyrometer which was calibrated in control experi-
ments with a fibre-optic contact thermometer protected in a Teflon
coated ceramic well inserted directly in the reaction mixture. Open
vessel experiments were carried out in a 100e250 mL round
bottom flask fitted with a reflux condenser. The vessel contents
were stirred by means of an adjustable rotating magnetic plate
located below the floor of the microwave cavity and a Teflon-coated
7.91 (d, J ¼ 8.0 Hz, 1H), 7.58 (td, J1 ¼ 0.6 Hz, J2 ¼ 7.6 Hz, 1H), 7.48 (td,
J1 ¼ 0.6 Hz, J2 ¼ 7.7 Hz, 1H), 7.18 (br s, 2H); 13C NMR (100 MHz,
DMSO-d6):
d 152.4, 139.1, 130.4, 128.8, 128.7, 124.7, 123.3, 123.0,
116.4; MS (ESI) m/z (%): 174.9 [(M þ H)þ, 100].
5.1.1.2. Synthesis of 3-aminothieno[2,3-b]pyridine-2-carbonitrile (1b)
5.1.1.2.1. 2-Mercaptonicotinonitrile (9). To a mixture of 2-chloro-
3-cyanopyridine (1.0 g, 7.25 mmol) in ethanol (15 mL) was added
thiourea (0.551 g, 7.25 mmol) in a sealed tube. The solution was
irradiated at 120 ꢀC (800 W) for 45 min. The solution was cooled to
room temperature and the mixture was filtered off and washed

176
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
Table 2
8.50 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 7.53 (dd, 1H, J1 ¼ 5 Hz,
J2 ¼ 8 Hz, H-5), 7.36 (s, 2H, NH2); 13C NMR (75 MHz, DMSO-d6):
Kinase activity of thieno[3,2-d]pyrimidine derivatives 3aej, 4aej, 5aej and 6aej.a
d
159.5 (C-3a), 150.9 (C-5), 150.4 (C-1), 131.3 (C-7), 124.2 (C-7a),
Entry
Compounds
CDK5
CK1
CLK1
DYRK1A
GSK3
119.9 (C-6), 115.7 (CN), 71.2 (C-2); HRMS calcd for C8H6N3S
1
2
3
4
5
6
7
8
3a
3b
3c
3d
3e
3f
3g
3h
3i
5.2
0.79
>10
>10
>10
>10
>10
>10
>10
>10
>10
0.031
0.18
0.52
>10
>10
>10
0.44
>10
0.28
>10
1.8
n.t.b
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
0.68
4.5
3.3
3.4
>10
>10
2.2
>10
2.1
5.1
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
[M þ H]þ 176.0282 found 176.0276.
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
3.7
>10
>10
>10
>10
>10
>10
2.8
>10
>10
2.9
>10
>10
>10
>10
0.89
>10
6.0
5.1.1.3. Synthesis of 3-aminothieno[3,2-b]pyridine-2-carbonitrile (1c)
5.1.1.3.1. 2-Bromo-3-nitropyridine (11). A solution of 48% aq. HBr
(3.60 mL, 32.0 mmol) dissolved in DMSO (35 mL) was added
dropwise to a solution of 3-nitropyridine-2-amine 10, (1.0 g,
7.19 mmol) in a mixture of 35 mL of DMSO, KNO2 (2.45 g,
28.75 mmol) and CuBr (0.206 g, 1.44 mmol) at 35 ꢀC with stirring.
The added mixture was stirred at 35 ꢀC for 4 h and then transferred
to a solution of K2CO3 (7 g) in 100 mL of ice water. The reaction
mixture was then taken up in diethyl ether, and the ethereal
extracts were washed with water and dried over anhydrous
Na2SO4. Removal of the solvent under reduced pressure gave the
crude product. The crude product was purified by silica gel chro-
matography (eluent: 100% dichloromethane) to give 2-bromo-3-
nitropyridine 11 as a beige powder (0.662 g, 45%). Rf ¼ 0.75
(dichloromethane); mp 121e122 ꢀC (lit. [12]: 123e124 ꢀC); IR (KBr)
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
3j
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
>10
5.2
5a
5b
5c
5d
5e
5f
5g
5h
5i
1.6
>10
>10
>10
>10
>10
>10
>10
>10
>10
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
n.t.
>10
>10
3.7
>10
>10
>10
>10
7.3
nmax (cmꢂ1): 3042 (
1350 (nsy NO2); 1H NMR (400 MHz, DMSO-d6):
n
CHar), 1578 and 1562 (
n
C]C), 1524 (nasNO2),
8.73 (dd, 1H,
>10
>10
>10
4.1
>10
>10
11
0.12
2.4
5.0
>10
>10
7.8
>10
>10
>10
>10
1.4
d
J1 ¼1.6 Hz, J2 ¼ 4.8 Hz, H-6), 8.54 (dd, 1H, J1 ¼1.6 Hz, J3 ¼ 8.0 Hz, H-
4), 7.79 (dd, 1H, J2 ¼ 4.8 Hz, J3 ¼ 8.0 Hz, H-5); 13C NMR (100 MHz,
DMSO-d6):
d 153.26 (C-6), 147.08 (C-3), 134.48 (C-4), 132.08 (C-2),
124.44 (C-5); MS (ESI) m/z (%): 202.9 (100) [M þ H]þ, 204.9 (100)
[M þ H þ 2]þ. Anal. calcd for C5H3BrN2O2: C, 29.58; H,1.49; N,13.80.
Found: C, 29.63; H, 1.50; N, 13.83.
5j
5.8
6a
6b
6c
6d
6e
6f
6g
6h
6i
>10
>10
>10
>10
>10
>10
>10
>10
>10
>10
5.1.1.3.2. 3-Nitropyridine-2-carbonitrile
(12). 2-Bromo-3-nitr-
opyridine 11 (0.500 g, 2.46 mmol) was mixed with copper (I)
cyanide (0.450 g, 5.02 mmol) in a 50 mL round-bottom flask. The flask
was slowly heated in an oil bath. When the temperature reached
150 ꢀC (takes 2 h), the reaction mass began to turn black. The mixture
was cooled to room temperature and reaction mass were treated with
hot acetone (100 mL). The resulting mixture was filtered, and the
mother liquor evaporated to dryness to yield the crude title
compound as a dark brown solid. This solid was purified by column
chromatography (eluent: 100% dichloromethane) to give 3-
nitropyridine-2-carbonitrile 12 as a white powder (0.250 g, 68%).
Rf ¼ 0.54 (dichloromethane); mp 74e75 ꢀC (lit. [23]: 75e78 ꢀC); IR
6j
n.t.
Values in bold shows interesting micromolar or submicromolar values in the table.
a
IC50 values are reported in
n.t.: not tested.
mM.
b
(KBr) nmax (cmꢂ1): 3091 (
n
CHar), 2160 (
n
CN), 1600 and 1566 (
n
C]C),
with ethanol. The crude solid was purified by column chromatog-
raphy over silica gel using dichloromethane/petroleum ether (5:5,
v/v) as the eluent to give 2-mercaptonicotinonitrile (9) as a yellow
powder (0.552 g, 58%); mp 249e250 ꢀC (lit. [10]: 248e250 ꢀC); IR
(KBr) nmax (cmꢂ1): 2871, 2226 (CN), 1584, 1489, 1440, 1318, 1236,
1173, 1159, 1079, 1059, 1033, 982, 968, 854, 813, 775, 712; 1H NMR
(300 MHz, DMSO-d6):
(dd,1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 6.67 (dd,1H, J1 ¼7 Hz, J2 ¼ 8 Hz, H-
5); 13C NMR (75 MHz, DMSO-d6):
171.2 (C-2), 145.5 (C-6), 142.7 (C-
1531 (nasNO2), 1348 (nsy NO2); 1H NMR (400 MHz, DMSO-d6):
d
9.10
(dd, 1H, J1 ¼ 1.2 Hz, J2 ¼ 4.8 Hz, H-6), 8.83 (dd, 1H, J1 ¼ 1.2 Hz,
J3 ¼ 8.4 Hz, H-4), 8.08 (dd, 1H, J2 ¼ 4.8 Hz, J3 ¼ 8.4 Hz, H-5); 13C NMR
(100 MHz, DMSO-d6): d 154.90 (C-6), 146.95 (C-3),134.08 (C-4),128.64
(C-5),127.69 (C-2), 115.20 (CN); MS (ESI) m/z (%): 150.1 (100) [M þ H]þ.
Anal. calcd for C6H3N3O2: C, 48.33; H, 2.03; N, 28.18. Found: C, 48.51;
H, 2.04; N, 28.22.
d
8.13 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 7 Hz, H-4), 7.95
d
5.1.1.3.3. 3-Aminothieno[3,2-b]pyridine-2-carbonitrile
(1c).
4), 116.8 (CN), 116.6 (C-3), 112.4 (C-5); HRMS calcd for C6H5N2S
A solution of potassium hydroxide (1.06 g, 18.9 mmol) in water
(3.2 mL) was added dropwise to a stirred and cold solution (ice
bath) containing 3-nitropyridine-2-carbonitrile 12 (0.950 g,
6.37 mmol) and 3-mercaptopropionitrile (0.670 g, 7.66 mmol) in
DMF (12 mL). The cold mixture was stirred for 15 min and bro-
moacetonitrile (0.64 mL, 9.18 mmol) was added dropwise. After 1 h
at 0 ꢀC, the mixture was poured into ice water. The crude product
was collected by filtration and purified with silica gel column
chromatography using 100% dichloromethane to give 3-
aminothieno[3,2-b]pyridine-2-carbonitrile 1c as a beige powder
(0.893 g, 80%). Rf ¼ 0.12 (dichloromethane); mp 198e200 ꢀC; IR
[M þ H]þ 137.0173 found 137.0171.
5.1.1.2.2. 3-Aminothieno[2,3-b]pyridine-2-carbonitrile
(1b).
To a mixture of 2-mercaptonicotinonitrile (9) (0.500 g, 3.67 mmol)
in acetone (30 mL) was added successively chloroacetonitrile
(0.280 g, 3.67 mmol) and potassium carbonate (0.560 g,
4.01 mmol). The solution was stirred at room temperature for 4 h.
The solution was then filtered and evaporated under vacuo. The
crude solid was purified by column chromatography over silica gel
using dichloromethane/petroleum ether (5:5, v/v) as the eluent to
give 3-Aminothieno[2,3-b]pyridine-2-carbonitrile (1b) as a yellow
powder (0.635 g, 99%); mp 219e220 ꢀC (lit. [10]: 215e216 ꢀC); IR
(KBr) nmax (cmꢂ1): 3135, 2201 (CN), 1661, 1638, 1586, 1577, 1569,
1536, 1527, 1410, 1391, 1378, 1262, 1202, 1074, 859, 797, 743; 1H
(KBr) nmax (cmꢂ1): 3385, 3307, 3217 and 3189 (
1630 and 1532 (
C]C); 1H NMR (400 MHz, DMSO-d6):
n
NH2), 2193 (
nCN),
n
d
8.75 (dd,
1H, J1 ¼1.4 Hz, J2 ¼ 4.6 Hz, H-5), 8.46 (dd, 1H, J1 ¼1.4 Hz, J3 ¼ 8.4 Hz,
NMR (300 MHz, DMSO-d6):
d
8.72 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-4),
H-7), 7.62 (dd, 1H, J2 ¼ 4.6 Hz, J3 ¼ 8.4 Hz, H-6), 7.16 (br s, 2H, NH2);

Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
177
13C NMR (100 MHz, DMSO-d6):
d
150.95 (CH), 147.50 (CH), 145.25
and 1c). On completion, the solution was cooled to room
temperature and crude products were extracted with ethyl
acetate. The organic layers were washed with cold water, dried
over Na2SO4, filtered and evaporated in vacuo. Purification by
column chromatography over silica gel using dichloromethane/
petroleum ether (5:5, v/v) as the eluent gave the desired
compounds 2aed.
(C), 133.71 (C), 132.11 (CH), 123.19 (CH), 115.52 (CN), 74.95 (C); MS
(ESI) m/z (%): 176.1 (100) [M þ H]þ. Anal. calcd for C8H5N3S: C,
54.84; H, 2.88; N, 23.98. Found: C, 55.01; H, 2.89; N, 24.07.
5.1.1.4. Synthesis of 7-aminothieno[2,3-b]pyrazine-6-carbonitrile
(1d)
5.1.1.4.1. 3-Chloropyrazine-2-carbonitrile (14). To a solution of
pyrazine-2-carbonitrile 13 (6.90 g, 65.65 mmol) in toluene (48 mL)
and DMF (5 mL) was added sulfuryl chloride (21.2 mL, 260.8 mmol)
over 10 min. The reaction mixture was stirred for 30 min in an ice
bath, then allowed to warm up to room temperature gradually,
after which it was stirred for 5 h. The toluene layer was decanted,
and the reddish oil residue was extracted three times with diethyl
ether. The combined toluene and ether layers were quenched with
ice water and cooled in an ice bath. The combined layers were then
neutralized with solid NaHCO3, then separated, and the aqueous
layer was extracted with diethyl ether. The combined organic layers
were washed with water, dried over anhydrous Na2SO4, filtered,
and the solvent was evaporated under reduced pressure to afford
the title compound. The crude product was purified by silica gel
chromatography (eluent: 100% dichloromethane) to give 3-
chloropyrazine-2-carbonitrile 14 as a white powder (4.7 g, 51%).
Rf ¼ 0.76 (dichloromethane); mp 44e46 ꢀC (lit. [14]: 47e48 ꢀC); IR
5.1.2.1. (E)-N0-(2-Cyanobenzo[b]thiophen-3-yl)-N,N-dimethylformi-
midamide (2a). Yellow powder (0.655 g; 99%) obtained from 3-
aminobenzothiophene-2-carbonitrile (1a) after 15 min of irradia-
tion; mp 88e89 ꢀC; IR (KBr) nmax (cmꢂ1): 2196 (CN), 1614, 1591,
1558, 1501, 1481, 1462, 1438, 1427, 1415, 1371, 1314, 111, 1043, 972,
768, 732, 663; 1H NMR (300 MHz, DMSO-d6):
d 8.18 (s, 1H, NCHN),
7.98 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-7), 7.85 (dd, 1H, J1 ¼ 1 Hz,
J2 ¼ 8 Hz, H-4), 7.59 (td, 1H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-6), 7.47 (td, 1H,
J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-5), 3.12 (s, 3H, NCH3), 3.08 (s, 3H, NCH3); 13
C
NMR (75 MHz, DMSO-d6): d 157.2 (C-3a), 156.0 (NCN), 138.7 (C-7a),
134.1 (C-1), 128.5 (C-5), 125.1 (C-6), 123.6 (C-7), 123.2 (C-4), 116.4
(C-2), 85.8 (CN), 34.1 (N(CH3)2); HRMS calcd for C12H11N3S [M þ H]þ
230.0752 found 230.0749.
5.1.2.2. (E)-N0-(2-Cyanothieno[2,3-b]pyridin-3-yl)-N,N-dime-
thylformimidamide (2b). White fibres (0.554 g; 85%) obtained from
3-aminothieno[2,3-b]pyridine-2-carbonitrile (1b) after 30 min of
irradiation; mp 113e114 ꢀC; IR (KBr) nmax (cmꢂ1): 2197 (CN), 1617,
1577, 1555, 1477, 1468, 1437, 1411, 1380, 1261, 1190, 1111, 1040, 1021,
(KBr) nmax (cmꢂ1): 3088 (
nCHar), 2242 (nCN), 1377 (nC]C), 1087 (nC-
N); 1H NMR (400 MHz, DMSO-d6):
d
8.91 (d, 1H, J ¼ 2.4 Hz, H-6),
8.88 (d,1H, J ¼ 2.4 Hz, H-5); 13C NMR (100 MHz, DMSO-d6):
d 150.67
(C-3), 147.97 (C-5), 144.26 (C-6), 129.87 (C-2), 114.66 (CN); MS (ESI)
m/z (%): 140.3 (100) [M þ H]þ, 142.3 (40) [M þ H þ 2]þ. Anal. calcd
for C5H2ClN3: C, 43.04; H, 1.44; N, 30.11. Found: C, 43.18; H, 1.45; N,
30.16.
980, 919, 862, 811, 759, 753; 1H NMR (300 MHz, DMSO-d6):
d 8.76
(dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-5), 8.24 (s, 1H, NCHN), 8.23 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 7.53 (dd, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-5), 3.14
(s, 3H, NCH3), 3.08 (s, 3H, NCH3); 13C NMR (75 MHz, DMSO-d6):
5.1.1.4.2. 7-Aminothieno[2,3-b]pyrazine-6-carbonitrile
(1d).
d 159.3 (C-3a), 156.3 (NCN), 155.3 (C-1), 150.9 (C-5), 132.1 (C-7),
To
a
solution of 3-chloropyrazine-2-carbonitrile 14 (4.60 g,
127.8 (C-7a), 120.7 (C-6), 115.8(CN), 85.1 (C-2), 34.2 (N(CH3)2);
32.96 mmol) in EtOH (120 mL) was added NaSH (3.94 g,
42.79 mmol), and the mixture was stirred at room temperature for
3 h (TLC monitoring). EtOH was evaporated under reduced pres-
sure, and the residue was dissolved in H2O and 2 M HCl was
carefully added to neutralize the suspension. After evaporation of
the solvent, the residue was dissolved in acetone (48 mL) and
ClCH2CN (2.29 mL, 32.96 mmol), K2CO3 (4.55 g, 32.96 mmol), and
a catalytic amount of KI were added. The resulting mixture was
stirred at room temperature for 3 h, and then the resulting residue
was separated by filtration and washed with acetone (3 ꢃ 30 mL).
The filtrate was evaporated under reduced pressure, the resulting
residue was dissolved in THF (240 mL), piperidine (3.26 mL,
32.96 mmol) was added, and the mixture was stirred at reflux for
5 h. After cooling, the solution was concentrated to dryness, and
the residual material was purified by column chromatography
(eluent: 100% dichloromethane) to give 7-aminothieno[2,3-b]
pyrazine-6-carbonitrile 1d as a yellow powder (3.66 g, 63%);
Rf ¼ 0.18 (dichloromethane); mp 205e207 ꢀC (lit. [8b]: 205e
206 ꢀC); IR (KBr) nmax (cmꢂ1): 3383, 3329, 3231 and 3204
HRMS calcd for C11H11N4S [M þ H]þ 231.0704 found 231.0708.
5.1.2.3. (E)-N0-(2-Cyanothieno[3,2-b]pyridin-3-yl)-N,N-dime-
thylformimidamide (2c). Yellow fibres (0.657 g; 99%) obtained from
3-aminothieno[3,2-b]pyridine-2-carbonitrile (1c) after 30 min of
irradiation; mp 120e121 ꢀC; IR (KBr) nmax (cmꢂ1): 2199 (CN), 1600,
1545,1508,1432,1394,1368,1288,1264,1237,1165,1151,1114,1089,
1075, 1059, 872, 783, 663, 635; 1H NMR (300 MHz, DMSO-d6):
d
8.91 (s, 1H, NCHN), 8.73 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-5), 8.46 (dd,
1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-4), 7.53 (dd, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-6),
3.11 (s, 3H, NCH3), 3.04 (s, 3H, NCH3); 13C NMR (75 MHz, DMSO-d6):
d
156.9 (NCN), 154.5 (C-1), 148.0 (C-6), 147.3 (C-7a), 134.0 (C-3a),
132.3 (C-4), 122.5 (C-5), 115.8(CN), 92.8 (C-2), 33.4 (N(CH3)2); HRMS
calcd for C11H11N4S [M þ H]þ 231.0704 found 231.0704.
5.1.2.4. (E)-N0-(6-Cyanothieno[2,3-b]pyrazin-7-yl)-N,N-dime-
thylformimidamide (2d). Yellow powder (0.519 g; 79%) obtained
from 7-aminothieno[2,3-b]pyrazine-6-carbonitrile (1d) after
30 min of irradiation; mp 134e135 ꢀC; IR (KBr) nmax (cmꢂ1): 2201
(CN), 1616, 1547, 1506, 1412, 1384, 1355, 1335, 1325, 1183, 1112, 1077,
(nNH2), 2197 (nCN), 1643, 1566 and 1529 (n
C]C); 1H NMR
(400 MHz, DMSO-d6):
d
8.86 (d, 1H, J ¼ 2.4 Hz), 8.84 (d, 1H,
1059, 1047, 972, 872, 785; 1H NMR (300 MHz, DMSO-d6):
d 8.87 (s,
J ¼ 2.4 Hz), 7.45 (br s, 2H, NH2); 13C NMR (100 MHz, DMSO-d6):
1H, NCHN), 8.86 (d,1H, J ¼ 2 Hz, H-5), 8.80 (d,1H, J ¼ 2 Hz, H-6), 3.14
d
154.55 (C), 149.15 (C), 145.26 (CH), 142.36 (CH), 139.76 (C), 115.37
(s, 3H, NCH3), 3.07 (s, 3H, NCH3); 13C NMR (75 MHz, DMSO-d6):
(CN), 74.27 (C); MS (ESI) m/z (%): 177.0 (100) [M þ H]þ. Anal. Calcd
for C7H4N4S: C, 47.72; H, 2.29; N, 31.80; S, 18.20. Found: C, 47.84; H,
2.30; N, 31.86.
d 157.0 (NCN), 154.4 (C-3a), 152.7 (C-1), 144.2 (C-5), 142.9 (C-6),
141.8 (C-7a), 115.1 (CN), 92.0 (C-2), 33.6 (N(CH3)2); HRMS calcd for
C
10H10N5S [M þ H]þ 232.0657 found 232.0646.
5.1.2. General procedure for the synthesis of N,N-
dimethylformimidamides derivatives (2aed)
5.1.3. General procedure for the synthesis of thieno[3,2-d]
pyrimidin-4-amine derivatives (3a, 4a, 5a and 6a)
A mixture of starting cyanoenamine 1aed (0.5 g) and dime-
thylformamide dimethylacetal (4 mL) was irradiated at 70 ꢀC (1d)
or 90 ꢀC (800 W) (1aec) for 15 min (1a and 1d) or 30 min (1b
A mixture of formamide (2 mL) and N,N-dimethylformimida-
mide derivatives (2aed) (0.1 g) was irradiated (200 W). On
completion (followed by GCeMS chromatography), the reaction

178
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
was cooled to room temperature and water was added. The solid
was filtered off, washed with water and dried. The crude solid was
purified by column chromatography over silica gel using petroleum
ether/ethyl acetate (100:0e0:100, v/v) as the eluent to give the
desired compounds (3a, 4a, 5a and 6a).
silica gel using a gradient of petroleum ether/ethyl acetate (100:0e
0:100, v/v) as the eluent to give the desired compounds (3bej).
5.1.4.1.1. N-Phenylbenzo[b]thieno[3,2-d]pyrimidin-4-amine (3b).
Yield: 77%; white powder; mp 272e273 ꢀC; IR (KBr) nmax (cmꢂ1):
1610,1561,1531, 1495, 1472,1453,1432, 1382, 1313, 1297,1259,1251,
1227, 1056, 759, 744, 723, 709, 688, 617; 1H NMR (300 MHz, DMSO-
5.1.3.1. Benzo[b]thieno[3,2-d]pyrimidin-4-amine (3a). Brown powder
(0.062 g, 71%); obtained from (E)-N0-(2-cyanobenzo[b]thiophen-3-
yl)-N,N-dimethylformimidamide 2a after 90 min of irradiation at
170 ꢀC; mp 301e302 ꢀC (lit. [9]: 280 ꢀC) IR (KBr) nmax(cmꢂ1): 3298,
3117, 1666, 1572, 1523, 1435, 1403, 1344, 1315, 1277, 1142, 1062, 1030,
958, 938, 812, 787, 740, 719, 674, 651, 609; 1H NMR (300 MHz,
d6):
d
9.82 (s, 1H, NH), 8.74 (s, 1H, H-2), 8.35 (dd, 1H, J1 ¼ 1 Hz,
J2 ¼ 7 Hz, H-9), 8.19 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-6), 7.80 (dd, 2H,
J1 ¼1 Hz, J2 ¼ 7 Hz, H-ar), 7.72 (td, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-8), 7.61
(td, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-7), 7.42 (td, 2H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-
ar), 7.12 (td,1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-ar); 13C NMR (75 MHz, DMSO-
d6):
d 156.2 (C-4), 155.4 (C-2), 154.4 (C-5a), 139.7 (C-4a), 138.4 (C-
DMSO-d6):
d
8.52 (s, 1H, H-2), 8.30 (dd, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-9),
11), 133.6 (C-7), 129.8 (C-8), 128.5 (C-13), 125.4 (C-9), 123.8 (C-14),
8.14 (dd,1H, J1 ¼ 2 Hz, J2 ¼ 7 Hz, H-8), 7.68 (td,1H, J1 ¼ 2 Hz, J2 ¼ 7 Hz,
123.7 (C-9a), 123.0 (C-6), 122.4 (C-12), 115.1 (C-9b); HRMS calcd for
H-7), 7.57 (s, 2H, NH2), 7.57 (td,1H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-6); 13C NMR
C
16H12N3S [M þ H]þ 278.0752 found 278.0759.
(75 MHz, DMSO-d6):
d
158.6 (C-4), 155.5 (C-5a), 155.1 (C-2), 140.5 (C-
5.1.4.1.2. N-(4-Methoxyphenyl)benzo[b]thieno[3,2-d]pyrimidin-4-
4a), 133.9 (C-9a), 129.4 (C-7), 125.1 (C-8), 123.7 (C-9b), 123.0 (C-9),
113.3 (C-6); HRMS calcd for C10H8N3S [M þ H]þ 202.0439 found
202.0427.
amine (3c). Yield: 61%; yellow powder; mp 221e222 ꢀC; IR (KBr)
nmax (cmꢂ1): 1599, 1571, 1560, 1504, 1473, 1451, 1435, 1415, 1251,
1228, 1172, 1059, 1030, 831, 749, 733, 726, 711, 697, 626; 1H NMR
(300 MHz, DMSO-d6): d 9.64 (s, 1H, NH), 8.66 (s, 1H, H-2), 8.33 (dd,
5.1.3.2. Pyrido[30,20:4,5]thieno[3,2-d]pyrimidin-4-amine
(4a).
1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-9), 8.15 (dd, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-6),
7.72 (td, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-8), 7.69e7.58 (m, 3H, H-ar and H-
7), 6.98 (dd, 2H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-ar), 3.79 (s, 3H, OCH3); 13C
Yellow powder (0.075 g, 86%) obtained from (E)-N0-(2-cyanothieno
[2,3-b]pyridin-3-yl)-N,N-dimethylformimidamide (2b) after 30 min
of irradiation at 200 ꢀC; mp > 320 ꢀC; IR (KBr) nmax(cmꢂ1): 3111,
1671, 1573,1557, 1525,1403,1379, 1347, 1285, 1274, 1253,1235,1071,
NMR (75 MHz, DMSO-d6):
d 156.2 (C-4), 156.0 (C-2), 154.5 (C-5a),
150.2 (C-14), 139.7 (C-4a), 133.6 (C-7), 131.3 (C-11), 129.7 (C-8),
125.3 (C-9), 125.1 (C-13), 123.6 (C-9a), 123.0 (C-6), 114.5 (C-9b),
113.7 (C-12), 55.2 (OCH3); HRMS calcd for C17H14N3OS [M þ H]þ
308.0858 found 308.0846.
5.1.4.1.3. N-(3,4-Dimethoxyphenyl)benzo[b]thieno[3,2-d]pyr-
imidin-4-amine (3d). Yield: 99%; grey powder; mp 203e204 ꢀC; IR
(KBr) nmax (cmꢂ1): 1574, 1562, 1509, 1503, 1469, 1453, 1445, 1434,
1401, 1266, 1247, 1231, 1201, 1143, 1053, 1020, 978, 744, 730; 1H
1031, 818, 810, 772, 747, 733; 1H NMR (300 MHz, DMSO-d6):
d 8.83
(dd,1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.64 (dd,1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-
9), 8.56 (s, 1H, H-2), 7.68 (s, 2H, NH2), 7.64 (td, 1H, J1 ¼ 5 Hz,
J2 ¼ 8 Hz, H-8); 13C NMR (75 MHz, DMSO-d6):
d
161.2, 158.4, 155.5,
153.3, 151.5, 131.4, 127.7, 120.8, 112.4; HRMS calcd for C9H7N4S
[M þ H]þ 203.0391 found 203.0381.
5.1.3.3. Pyrido[20,30:4,5]thieno[3,2-d]pyrimidin-4-amine
(5a).
NMR (300 MHz, DMSO-d6): d 9.63 (s, 1H, NH), 8.69 (s, 1H, H-2), 8.34
Yellow powder (0.044 g, 50%) obtained from (E)-N0-(2-cyanothieno
[3,2-b]pyridin-3-yl)-N,N-dimethylformimidamide 2c after 30 min
of irradiation at 200 ꢀC; mp > 320 ꢀC; IR (KBr) nmax(cmꢂ1): 3114,
1661, 1577, 1563, 1519, 1471, 1391, 1341, 1312, 1294, 1271, 1142, 1062,
(dd,1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-9), 8.15 (dd,1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-
6), 7.70 (td, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-8), 7.64 (td, 1H, J1 ¼ 1 Hz,
J2 ¼ 7 Hz, H-7), 7.30 (dd, 2H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 6.98 (dd, 1H,
J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 3.78 (s, 3H, OCH3), 3.77 (s, 3H, OCH3); 13
C
1016, 952, 822, 754; 1H NMR (300 MHz, DMSO-d6):
d
8.85 (dd, 1H,
NMR (75 MHz, DMSO-d6): d 156.0 (C-4), 155.8 (C-2), 154.5 (C-5a),
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.66 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-9), 8.59
148.4 (C-13), 145.9 (C-14), 139.8 (C-4a), 133.6 (C-7), 131.7 (C-11),
129.7 (C-8), 125.3 (C-9), 123.6 (C-9a), 123.0 (C-6), 115.8 (C-15), 114.6
(C-9b), 111.6 (C-16), 108.4 (C-12) 55.7 (OCH3), 55.5 (OCH3); HRMS
calcd for C18H16N3O2S [M þ H]þ 338.0963 found 338.0956.
(s, 1H, H-2), 7.73 (s, 2H, NH2), 7.64 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8);
13C NMR (75 MHz, DMSO-d6):
d 158.9, 155.6, 154.1, 149.4, 147.9,
134.6, 132.4, 123.2, 115.4; HRMS calcd for C9H7N4S [M þ H]þ
203.0391 found 203.0396.
5.1.4.1.4. N-(3,5-Dimethoxyphenyl)benzo[b]thieno[3,2-d]pyr-
imidin-4-amine (3e). Yield: 84%; grey powder; mp 194e195 ꢀC; IR
(KBr) nmax (cmꢂ1): 1584, 1568, 1533, 1513, 1487, 1463, 1441, 1415,
1194, 1146, 1064, 1009, 821, 744, 712, 669, 620, 595, 441; 1H NMR
5.1.3.4. Pyrazino[20,30:4,5]thieno[3,2-d]pyrimidin-4-amine
Grey powder (0.087 g, 99%) obtained from (E)-N0-(6-cyanothieno
(6a).
[2,3-b]pyrazin-7-yl)-N,N-dimethylformimidamide
(2d)
after
(300 MHz, DMSO-d6): d 9.68 (s, 1H, NH), 8.78 (s, 1H, H-2), 8.36 (dd,
30 min of irradiation at 180 ꢀC; mp > 320 ꢀC; IR (KBr) nmax (cmꢂ1):
1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-9), 8.20 (dd, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-6),
7.73 (td,1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-8), 7.64 (td,1H, J1 ¼1 Hz, J2 ¼ 7 Hz,
H-7), 7.13 (s, 2H, H-ar), 6.30 (s, 1H, H-ar), 3.76 (s, 3H, OCH3), 3.35 (s,
3111, 1665, 1572, 1538, 1361, 1338,1282, 1227, 1198, 1169, 1076, 1025,
852, 835, 799, 767; 1H NMR (300 MHz, DMSO-d6):
d
8.96 (d, 1H,
J ¼ 2 Hz, H-7), 8.87 (d, 1H, J ¼ 2 Hz, H-8), 8.63 (s, 1H, H-2), 7.88 (s,
3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d 156.0 (C-4), 155.8 (C-2),
2H, NH2); 13C NMR (75 MHz, DMSO-d6):
d
158.8, 156.3, 156.0, 151.8,
154.5 (C-5a), 148.4 (C-13), 145.9 (C-14), 139.8 (C-4a), 133.6 (C-7),
131.7 (C-11), 129.7 (C-8), 125.3 (C-9), 123.6 (C-9a), 123.0 (C-6), 115.8
(C-9b), 114.6 (C-15), 111.6 (C-16), 108.4 (C-12) 55.7 (OCH3), 55.5
(OCH3); HRMS calcd for C18H16N3O2S [M þ H]þ 338.0963 found
338.0956.
145.1, 143.8, 143.0, 114.8; HRMS calcd for C8H6N5S [M þ H]þ
204.0344 found 204.0334.
5.1.4. General procedures for the synthesis of thieno[3,2-d]
pyrimidine derivatives (3bej, 4bej, 5bej and 6bej)
5.1.4.1.5. N-(3,4,5-Trimethoxyphenyl)benzo[b]thieno[3,2-d]pyr-
imidin-4-amine (3f). Yield: 80%; white powder; mp 198e199 ꢀC; IR
(KBr) nmax (cmꢂ1): 1551, 1500, 1458, 1438, 1426, 1413, 1242, 1228,
1124, 1056, 1008, 1001, 747, 728, 708, 675, 631, 595, 520; 1H NMR
5.1.4.1. Synthesis of N-arylbenzo[b]thieno[3,2-d]pyrimidin-4-amines
(3bej). A mixture of (E)-N0-(2-cyanobenzo[b]thiophen-3-yl)-N,N-
dimethylformimidamide (2a, 0.1 g, 0.43 mmol) and appropriate
aniline (1.0 equiv) in acetic acid (2 mL) was irradiated at 118 ꢀC
(400 W). On completion (followed by thin-layer chromatography),
the reaction was cooled to room temperature and water was
added. The solid was filtered off, washed with water and dried.
The crude solid was purified by column chromatography over
(300 MHz, DMSO-d6):
d 9.68 (s, 1H, NH), 8.74 (s, 1H, H-2), 8.36 (dd,
1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-9), 8.19 (dd, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-6),
7.72 (td,1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-8), 7.61 (td,1H, J1 ¼1 Hz, J2 ¼ 7 Hz,
H-7), 7.21 (s, 2H, H-ar), 3.80 (s, 6H, (OCH3)2), 3.68 (s, 3H, OCH3); 13
C
NMR (75 MHz, DMSO-d6):
d 156.1 (C-4), 155.7 (C-2), 154.6 (C-5a),

Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
179
152.5 (C-13), 139.7 (C-4a), 134.8 (C-14), 134.0 (C-11), 133.6 (C-7),
129.8 (C-8), 125.4 (C-9), 123.6 (C-9a), 123.0 (C-6), 115.0 (C-9b), 100.5
(C-12), 60.1 ((OCH3)2), 55.8 (OCH3); HRMS calcd for C19H18N3O3S
[M þ H]þ 368.1069 found 368.1060.
chromatography), the reaction was cooled to room temperature
and water was added. The solid was filtered off, washed with
water and dried. The crude solid was purified by column
chromatography over silica gel using a gradient of petroleum
ether/ethyl acetate (100:0e0:100, v/v) as the eluent to give the
desired compounds (4bej).
5.1.4.1.6. N-(Benzo[d][1,3]dioxol-5-yl)benzo[4,5]thieno[3,2-d]pyr-
imidin-4-amine (3g). Yield: 68%; brown powder; mp 237e238 ꢀC;
IR (KBr) nmax (cmꢂ1): 1571, 1500, 1485, 1472, 1453, 1436, 1393,
1264, 1236, 1186, 1034, 1020, 936, 853, 803, 745, 715, 709, 597, 570,
5.1.4.2.1. N-Phenylpyrido[30,20:4,5]thieno[3,2-d]pyrimidin-4-
amine (4b). Yield: 69%; white powder; mp 310e311 ꢀC; IR (KBr)
nmax (cmꢂ1): 1611, 1569, 1557, 1528, 1495, 1473, 1455, 1437, 1392,
1374, 1296, 1255, 1144, 1058, 773, 760, 749, 731, 725; 1H NMR
421; 1H NMR (300 MHz, DMSO-d6):
d 9.65 (s,1H, NH), 8.69 (s,1H, H-
2), 8.34 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-9), 8.17 (dd, 1H, J1 ¼ 1 Hz,
J2 ¼ 7 Hz, H-6), 7.71 (td, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-8), 7.63 (td, 1H,
J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-7), 7.37 (d, 1H, J ¼ 2 Hz, H-ar), 7.12 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.97 (d, 1H, J ¼ 8 Hz, H-ar), 6.06 (s, 2H, H-
(300 MHz, DMSO-d6):
d
9.84 (s, 1H, NH), 8.85 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 5 Hz, H-7), 8.75 (s, 1H, H-2), 8.68 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-
9), 7.79 (dd, 2H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-ar), 7.66 (td, 1H, J1 ¼ 5 Hz,
J2 ¼ 8 Hz, H-8), 7.42 (td, 2H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-ar), 7.16 (td, 1H,
ar); 13C NMR (75 MHz, DMSO-d6):
d 156.1 (C-4), 155.7 (C-2), 154.4
(C-5a), 147.0 (C-13), 144.0 (C-14), 139.7 (C-4a), 133.6 (C-7), 132.6 (C-
11), 129.7 (C-8), 125.3 (C-9), 123.6 (C-9a), 123.0 (C-6), 116.4 (C-16),
114.6 (C-9b), 107.8 (C-15), 105.4 (C-12), 101.2 (C-18); HRMS calcd for
J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-ar); 13C NMR (75 MHz, DMSO-d6):
d 161.3,
155.2, 154.7, 153.9, 151.8, 138.7, 131.5, 128.6 (2C), 127.5, 124.0, 122.4
(2C), 121.0, 114.3; HRMS calcd for C15H11N4S [M þ H]þ 279.0704
found 279.0708.
C
17H12N3O2S [M þ H]þ 322.0650 found 322.0640.
5.1.4.1.7. N-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)benzo[4,5]
5.1.4.2.2. N-(4-Methoxyphenyl)pyrido[30,20:4,5]thieno[3,2-d]pyr-
imidin-4-amine (4c). Yield: 57%; gold powder; mp 257e258 ꢀC; IR
(KBr) nmax(cmꢂ1): 1559, 1502, 1473, 1451, 1411, 1378, 1245, 1233,
1212, 1179, 1055, 1036, 1023, 832, 823, 814, 770, 748, 739, 721; 1H
thieno[3,2-d]pyrimidin-4-amine (3h). Yield: 84%; grey powder; mp
254e255 ꢀC; IR (KBr) nmax (cmꢂ1): 1573, 1563, 1534, 1495, 1472,
1451, 1435, 1420, 1308, 1283, 1203, 1168, 1068, 1059, 862, 745, 730,
709, 576, 421; 1H NMR (300 MHz, DMSO-d6):
d
9.59 (s, 1H, NH), 8.69
NMR (300 MHz, DMSO-d6): d 9.73 (s, 1H, NH), 8.85 (dd, 1H,
(s, 1H, H-2), 8.34 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-9), 8.17 (dd, 1H,
J1 ¼1 Hz, J2 ¼ 7 Hz, H-6), 7.71 (td, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-8), 7.63
(td, 1H, J1 ¼1 Hz, J2 ¼ 7 Hz, H-7), 7.34 (d, 1H, J ¼ 2 Hz, H-ar), 7.16 (dd,
1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.87 (d, 1H, J ¼ 8 Hz, H-ar), 4.26 (br. s,
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.69 (s, 1H, H-2), 8.67 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-9), 7.66 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.63 (d, 2H,
J ¼ 9 Hz, H-ar), 6.99 (d, 2H, J ¼ 9 Hz, H-ar), 3.79 (s, 3H, OCH3); 13
C
NMR (75 MHz, DMSO-d6):
d 161.4, 156.3, 115.6, 154.9, 153.7, 151.7,
4H, H-ar); 13C NMR (75 MHz, DMSO-d6):
d
156.0 (C-4), 155.5 (C-2),
131.4, 131.1, 127.7, 125.0 (2C), 120.9 (2C), 113.8, 113.6, 55.2; HRMS
154.4 (C-5a), 142.7 (C-13), 140.1 (C-14), 139.7 (C-4a), 133.6 (C-7),
132.0 (C-11), 129.7 (C-8), 125.3 (C-9), 123.6 (C-9a), 123.0 (C-6), 116.6
(C-16), 116.2 (C-15), 114.6 (C-9b), 112.1 (C-12), 64.1 (C-18), 64.2 (C-
19); HRMS calcd for C18H14N3O2S [M þ H]þ 336.0807 found
336.0801.
calcd for C16H13N4OS [M þ H]þ 309.0810 found 309.0821.
5.1.4.2.3. N-(3,4-Dimethoxyphenyl)pyrido[30,20:4,5]thieno[3,2-d]
pyrimidin-4-amine (4d). Yield: 58%; gold powder; mp 237e238 ꢀC;
IR (KBr) nmax (cmꢂ1): 1574, 1559, 1505, 1456, 1417, 1374, 1279, 1252,
1226, 1200, 1145, 1023, 981, 863, 807, 774, 765, 751, 739, 722; 1H
5.1.4.1.8. N-(4-bromo-2-fluorophenyl)benzo[b]thieno[3,2-d]pyr-
imidin-4-amine (3i). Yield: 76%; yellow powder; mp 201e202 ꢀC;
IR (KBr) nmax (cmꢂ1): 3417, 1683, 1597, 1562, 1524, 1508, 1469,
1444, 1429, 1411, 1273, 1249, 1180, 1105, 1053, 959, 862, 855, 818,
NMR (300 MHz, DMSO-d6): d 9.72 (s, 1H, NH), 8.84 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.72 (s, 1H, H-2), 8.67 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-9), 7.65 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.34e7.31 (m,
2H, H-ar), 6.99 (dd, 1H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 3.79 (s, 3H, OCH3),
740, 726, 708; 1H NMR (300 MHz, DMSO-d6):
d
9.81 (s,1H, NH), 8.66
3.78 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d 161.4, 155.6,
(s, 1H, H-2), 8.37 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-9), 8.20 (dd, 1H,
154.8, 153.7, 151.7, 148.4, 145.9, 131.5, 131.4, 127.4, 120.9, 115.5, 113.7,
111.6, 108.3, 55.7, 55.5; HRMS calcd for C17H15N4O2S [M þ H]þ
339.0916 found 339.0914.
J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-6), 7.75e7.47 (m, 5H, H-ar, H-8 and H-7), 13
C
NMR (75 MHz, DMSO-d6):
d 155.8 (C-4), 154.5 (C-2), 152.3 (C-5a),
148.3 (C-12), 146.2 (C-15), 142.6 (C-11), 139.9 (C-4a), 133.4 (C-7),
129.8 (C-8), 127.7 (C-13), 125.5 (C-9), 123.8 (C-9a), 123.2 (C-6), 119.7
(C-16), 119.1 (C-14), 114.7 (C-9b); HRMS calcd for C16H10N3SBrF
[M þ H]þ 373.9763 found 373.9773.
5.1.4.2.4. N-(3,5-Dimethoxyphenyl)pyrido[30,20:4,5]thieno[3,2-d]
pyrimidin-4-amine (4e). Yield: 73%; white powder; mp 214e
215 ꢀC; IR (KBr) nmax (cmꢂ1): 1617, 1581, 1557, 1528, 1483, 1468,
1457, 1422, 1373, 1158, 1148, 1139, 1076, 1061, 833, 818, 812, 770,
5.1.4.1.9. 4-(Benzo[4,5]thieno[3,2-d]pyrimidin-4-ylamino)-2-
nitrophenol (3j). Yield: 66%; red powder; mp 256e257 ꢀC; IR (KBr)
nmax (cmꢂ1): 3360, 1529, 1503, 1473, 1449, 1434, 1328, 1312, 1235,
1216, 1171, 1135, 1056, 969, 825, 753, 708, 684, 576, 555, 425; 1H
731; 1H NMR (300 MHz, DMSO-d6):
d 9.76 (s, 1H, NH), 8.86 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.72 (s, 1H, H-2), 8.69 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-9), 7.68 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.14 (d, 2H,
J ¼ 1 Hz, H-ar), 6.30 (t, 1H, J ¼ 1 Hz, H-ar), 3.71 (s, 6H, (OCH3)2); 13
C
NMR (300 MHz, DMSO-d6):
d
10.86 (s,1H, OH), 9.87 (s, 1H, NH), 8.75
NMR (75 MHz, DMSO-d6): d 161.3, 160.3 (2C), 155.1, 154.6, 154.0,
(s, 1H, H-2), 8.44 (d, 1H, J ¼ 2 Hz, H-ar), 8.37 (dd, 1H, J1 ¼ 1 Hz,
J2 ¼ 7 Hz, H-9), 8.21 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-6), 7.97 (d, 1H,
J ¼ 8 Hz, H-15), 7.72 (td, 1H, J1 ¼ 1 Hz, J2 ¼ 7 Hz, H-8), 7.64 (td, 1H,
151.9, 140.5, 131.5, 127.4, 121.0, 114.5, 100.3 (2C), 95.7, 55.2 (2C);
HRMS calcd for C17H15N4O2S [M þ H]þ 339.0916 found 339.0914.
5.1.4.2.5. N-(3,4,5-Trimethoxyphenyl)pyrido[30,20:4,5]thieno[3,2-
d]pyrimidin-4-amine (4f). Yield: 79%; yellow powder; mp 200e
201 ꢀC; IR (KBr) nmax (cmꢂ1): 1577, 1502, 1457, 1430, 1411, 1182,
1118, 1082, 1009, 990, 840, 823, 746, 729; 1H NMR (300 MHz,
J1 ¼1 Hz, J2 ¼ 7 Hz, H-7), 7.18 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar); 13
C
NMR (75 MHz, DMSO-d6):
d 156.1 (C-4), 155.2 (C-2), 154.3 (C-5a),
139.7 (C-4a), 139.7 (C-14), 135.7 (C-13), 133.6 (C-7), 131.8 (C-11),
130.5 (C-16), 129.9 (C-8), 125.4 (C-9), 123.7 (C-9a), 123.0 (C-6), 119.3
(C-15), 118.2 (C-12), 114.6 (C-9b); HRMS calcd for C16H11N4O3S
[M þ H]þ 339.0552 found 339.0547.
DMSO-d6):
d
9.76 (s, 1H, NH), 8.86 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7),
8.78 (s, 1H, H-2), 8.69 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-9), 7.67 (td, 1H,
J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.22 (s, 2H, H-ar), 3.80 (s, 6H, (OCH3)2),
3.68 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d 161.3, 155.3,
5.1.4.2. Synthesis of N-arylpyrido[30,20:4,5]thieno[3,2-d]pyrimidin-4-
amines (4bej). A mixture of (E)-N0-(2-cyanothieno[2,3-b]pyridin-
3-yl)-N,N-dimethylformimidamide (2b, 0.1 g, 0.43 mmol) and
appropriate aniline (1.0 equiv) in acetic acid (2 mL) was irradiated
at 118 ꢀC (400 W). On completion (followed by thin-layer
154.7, 153.8, 152.5 (2C), 151.8, 134.6, 134.1, 131.5, 127.4, 121.0, 114.1,
100.5 (2C), 60.1, 55.8 (2C); HRMS calcd for C18H17N4O3S [M þ H]þ
369.1021 found 369.1007.
5.1.4.2.6. N-(Benzo[d][1,3]dioxol-5-yl)pyrido[30,20:4,5]thieno[3,2-
d]pyrimidin-4-amine (4g). Yield: 67%; brown powder; mp 292e

180
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
293 ꢀC; IR (KBr) nmax (cmꢂ1): 1590, 1533, 1520, 1498, 1486, 1470,
138.7, 134.9, 132.3, 128.5 (2C), 124.0, 123.5, 122.6 (2C), 117.3; HRMS
calcd for C15H11N4S [M þ H]þ 279.0704 found 279.0709.
1454, 1376, 1234, 1203, 1034, 937, 833, 812, 798, 780, 768, 744, 729;
1H NMR (300 MHz, DMSO-d6):
d
9.74 (s, 1H, NH), 8.84 (dd, 1H,
5.1.4.3.2. N-(4-Methoxyphenyl)pyrido[20,30:4,5]thieno[3,2-d]pyr-
imidin-4-amine (5c). Yield: 66%; white powder; mp 272e273 ꢀC; IR
(KBr) nmax(cmꢂ1): 1569, 1548, 1512, 1497, 1435, 1388, 1251, 1217,
1186, 1173, 1055, 1028, 830, 818, 808, 779, 756, 719; 1H NMR
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.71 (s, 1H, H-2), 8.66 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-9), 7.66 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.38 (d, 1H,
J ¼ 2 Hz, H-ar), 7.13 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.95 (d, 1H,
J ¼ 8 Hz, H-ar), 6.06 (s, 2H, H-ar); 13C NMR (75 MHz, DMSO-d6):
(300 MHz, DMSO-d6):
d
9.77 (s, 1H, NH), 8.87 (dd, 1H, J1 ¼ 2 Hz,
d
161.3, 155.5, 154.8, 153.8, 151.7, 147.0, 144.1, 132.4, 131.4, 127.4,
J2 ¼ 5 Hz, H-8), 8.72 (s, 1H, H-2), 8.66 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-
6), 7.66 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.63 (d, 2H, J ¼ 9 Hz H-ar),
6.99 (d, 2H, J ¼ 9 Hz, H-ar), 3.78 (s, 3H, OCH3); 13C NMR (75 MHz,
121.0, 116.4, 113.7, 107.8, 105.3, 101.2; HRMS calcd for C16H11N4O2S
[M þ H]þ 323.0603 found 323.0588.
5.1.4.2.7. N-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)pyrido
[30,20:4,5]thieno[3,2-d]pyrimidin-4-amine (4h). Yield: 84%; silver
powder; mp 294e295 ꢀC; IR (KBr) nmax (cmꢂ1): 1574, 1557, 1530,
1495, 1472, 1452, 1421, 1391, 1374, 1310, 1248, 1235, 1203, 1140,
1069, 1058, 864, 812, 772, 739; 1H NMR (300 MHz, DMSO-d6):
DMSO-d6): d 156.4,156.1,154.9,154.6,149.1,148.1,134.8,132.2,131.1,
125.2 (2C), 123.4,116.6, 113.8 (2C), 55.2; HRMS calcd for C16H13N4OS
[M þ H]þ 309.0810 found 309.0803.
5.1.4.3.3. N-(3,4-Dimethoxyphenyl)pyrido[20,30:4,5]thieno[3,2-d]
pyrimidin-4-amine (5d). Yield: 75%; white powder; mp 217e
218 ꢀC; IR (KBr) nmax (cmꢂ1): 1608, 1580, 1536, 1511, 1449, 1420,
1394, 1270, 1234, 1205, 1167, 1126, 1063, 1024, 988, 808, 789, 775,
d
9.68 (s, 1H, NH), 8.85 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.72 (s, 1H,
H-2), 8.67 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-9), 7.65 (td, 1H, J1 ¼ 5 Hz,
J2 ¼ 8 Hz, H-8), 7.35 (d, 1H, J ¼ 2 Hz, H-ar), 7.17 (dd, 1H, J1 ¼ 2 Hz,
748; 1H NMR (300 MHz, DMSO-d6):
d 9.78 (s, 1H, NH), 8.86 (dd, 1H,
J2 ¼ 8 Hz, H-ar), 6.88 (d, 1H, J ¼ 8 Hz, H-ar), 4.27 (br. s, 4H, H-ar); 13
C
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8), 8.74 (s, 1H, H-2), 8.67 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-6), 7.66 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.32e7.29 (m,
2H, H-ar), 6.98 (dd, 1H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 3.78 (s, 3H, OCH3),
NMR (75 MHz, DMSO-d6):
d 161.3, 155.3, 154.8, 153.7, 151.7, 142.8,
140.3, 131.9, 131.4, 127.5, 121.0, 116.6, 116.2, 113.8, 112.1, 64.1, 64.0;
HRMS calcd for C17H13N4O2S [M þ H]þ 337.0759 found 337.0746.
5.1.4.2.8. N-(4-Bromo-2-fluorophenyl)pyrido[30,20:4,5]thieno[3,2-
d]pyrimidin-4-amine (4i). Yield: 60%; white powder; mp 259e
260 ꢀC; IR (KBr) nmax (cmꢂ1): 1620, 1596, 1590, 1570, 1558, 1526,
1507, 1483, 1471, 1444, 1412, 1386, 1373, 1280, 1192, 1117, 1057, 873,
3.77 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d 156.1, 154.9,
154.6,149.1, 148.4, 148.1, 146.0,134.9,132.2,131.4,123.4,116.6,115.8,
111.6, 108.5, 55.7, 55.5; HRMS calcd for C17H15N4O2S [M þ H]þ
339.0916 found 339.0918.
5.1.4.3.4. N-(3,5-Dimethoxyphenyl)pyrido[20,30:4,5]thieno[3,2-d]
pyrimidin-4-amine (5e). Yield: 65%; yellow powder; mp 283e
284 ꢀC; IR (KBr) nmax (cmꢂ1): 1609, 1574, 1529, 1472, 1458, 1437,
1418, 1389, 1200, 1148, 1061, 1052, 815, 786, 766, 758, 748, 727; 1H
849, 770; 1H NMR (300 MHz, DMSO-d6):
d 9.92 (s,1H, NH), 8.87 (dd,
1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.72 (s,1H, H-2), 8.70 (dd,1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-9), 7.71e7.66 (m, 2H, H-8 and H-ar), 7.57e7.48 (m, 2H,
H-ar); 13C NMR (75 MHz, DMSO-d6):
d
161.4, 158.5, 155.7, 154.9,
NMR (300 MHz, DMSO-d6): d 9.88 (s, 1H, NH), 8.91 (dd, 1H,
154.2, 152.0, 131.7, 129.8, 127.7, 127.3, 125.3, 121.1, 119.6, 118.5, 113.8;
HRMS calcd for C15H9N4SBrF [M þ H]þ 374.9715 found 374.9716.
5.1.4.2.9. 2-Nitro-4-(pyrido[30,20:4,5]thieno[3,2-d]pyrimidin-4-
ylamino)phenol (4j). Yield: 71%; orange powder; mp 267e268 ꢀC;
IR (KBr) nmax (cmꢂ1): 3202, 1613, 1560, 1533, 1514, 1490, 1475,
1456, 1350,1324,1256,1230,1164, 1149,1066, 817, 773, 760, 729; 1H
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8), 8.75 (s, 1H, H-2), 8.72 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-6), 7.72 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.13 (d, 2H,
J ¼ 1 Hz, H-ar), 6.33 (t, 1H, J ¼ 1 Hz, H-ar), 3.77 (s, 6H, O(CH3)2); 13
C
NMR (75 MHz, DMSO-d6):
d 160.3 (2C), 155.7, 154.7, 149.0, 148.2,
140.4, 134.9, 132.3, 130.0, 123.6, 117.4, 100.5 (2C), 95.8, 55.2 (2C);
HRMS calcd for C17H15N4O2S [M þ H]þ 339.0916 found 339.0910.
5.1.4.3.5. N-(3,4,5-Trimethoxyphenyl)pyrido[20,30:4,5]thieno[3,2-
d]pyrimidin-4-amine (5f). Yield: 78%; white powder; mp 249e
250 ꢀC; IR (KBr) nmax (cmꢂ1): 1532, 1503, 1459, 1452, 1444, 1414,
1400, 1119, 1014, 992, 824, 781, 748, 732, 671; 1H NMR (300 MHz,
NMR (300 MHz, DMSO-d6): d 10.87 (s, 1H, OH), 9.94 (s, 1H, NH), 8.86
(dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-7), 8.77 (s, 1H, H-2), 8.68 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-9), 8.45 (d, 1H, J ¼ 2 Hz, H-ar), 7.98 (d, 1H,
J ¼ 8 Hz, H-ar), 7.68 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-8), 7.19 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar); 13C NMR (75 MHz, DMSO-d6):
d
161.3,
DMSO-d6):
d
9.82 (s, 1H, NH), 8.89 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8),
154.9,154.6,153.8,151.8,148.7,135.6,131.5,130.6,129.9,127.4,121.0,
119.2, 117.9, 114.2; HRMS calcd for C15H10N5O3S [M þ H]þ 340.0504
found 340.0492.
8.79 (s, 1H, H-2), 8.68 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 7.68 (td, 1H,
J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.20 (s, 2H, H-ar), 3.80 (s, 6H, (OCH3)2),
3.68 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d 155.8, 154.8,
154.6, 152.6 (2C), 149.0, 148.2, 134.8, 134.4, 134.2, 132.3, 123.5, 117.0,
100.7 (2C), 60.1, 55.8 (2C); HRMS calcd for C18H17N4O3S [M þ H]þ
369.1021 found 369.1011.
5.1.4.3. Synthesis of N-arylpyrido[20,30:4,5]thieno[3,2-d]pyrimidin-4-
amines (5bej). A mixture of (E)-N0-(2-cyanothieno[3,2-b]pyridin-
3-yl)-N,N-dimethylformimidamide (2c, 0.1 g, 0.43 mmol) and
appropriate aniline (1.0 equiv) in acetic acid (2 mL) was irradiated
at 118 ꢀC (400 W). On completion (followed by thin-layer
chromatography), the reaction was cooled to room temperature
and water was added. The solid was filtered off, washed with
water and dried. The crude solid was purified by column
chromatography over silica gel using a gradient of petroleum
ether/ethyl acetate (100:0e0:100, v/v) as the eluent to give the
desired compounds (5bej).
5.1.4.3.6. N-(Benzo[d][1,3]dioxol-5-yl)pyrido[20,30:4,5]thieno[3,2-
d]pyrimidin-4-amine (5g). Yield: 31%; brown powder; mp 256e
257 ꢀC; IR (KBr) nmax (cmꢂ1): 1532, 1499, 1485, 1456, 1392, 1333,
1264, 1237, 1182, 1140, 1058, 1033, 919, 800, 788, 750; 1H NMR
(300 MHz, DMSO-d6):
d
9.82 (s, 1H, NH), 8.87 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 5 Hz, H-8), 8.74 (s, 1H, H-2), 8.69 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-
6), 7.67 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.39 (d, 1H, J ¼ 2 Hz, H-ar),
7.15 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.96 (d, 1H, J ¼ 8 Hz, H-ar),
6.09 (s, 2H, H-18); 13C NMR (75 MHz, DMSO-d6):
d 156.0, 154.9,
5.1.4.3.1. N-Phenylpyrido[20,30:4,5]thieno[3,2-d]pyrimidin-4-
amine (5b). Yield: 87%; yellow powder; mp 285e286 ꢀC; IR (KBr)
nmax (cmꢂ1): 1613, 1527, 1511, 1494, 1475, 1452, 1444, 1435, 1394,
1382, 1284, 1217, 1059, 755, 748, 740, 725; 1H NMR (300 MHz,
154.6, 149.1, 148.1, 147.0, 144.1, 134.9, 132.4, 132.3, 123.4, 116.8, 116.6,
107.8, 105.5, 101.2; HRMS calcd for C16H11N4O2S [M þ H]þ 323.0603
found 323.0587.
5.1.4.3.7. N-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)pyrido
[20,30:4,5]thieno[3,2-d]pyrimidin-4-amine (5h). Yield: 59%; yellow
powder; mp 299e300 ꢀC; IR (KBr) nmax (cmꢂ1): 1628, 1573, 1498,
1475, 1456, 1447, 1422, 1394, 1311, 1279, 1265, 1199, 1163, 1059, 885,
DMSO-d6):
d
9.91 (s, 1H, NH), 8.90 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8),
8.79 (s, 1H, H-2), 8.72 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 7.80 (dd, 2H,
J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 7.69 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.41
(td, 2H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-ar), 7.15 (td, 1H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-
807, 779, 750, 740; 1H NMR (300 MHz, DMSO-d6):
d
9.95 (s,1H, NH),
ar); 13C NMR (75 MHz, DMSO-d6):
d 155.7, 154.8, 154.7, 149.1, 148.2,
8.90 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8), 8.76 (s, 1H, H-2), 8.72 (dd, 1H,

Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
181
J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 7.69 (td, 1H, J1 ¼ 5 Hz, J2 ¼ 8 Hz, H-7), 7.36
(d,1H, J ¼ 2 Hz, H-ar), 7.18 (dd,1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.88 (d,
1H, J ¼ 8 Hz, H-ar), 4.27 (br s, 4H, H-ar); 13C NMR (75 MHz, DMSO-
7.33 (m, 2H, H-ar), 6.99 (dd, 1H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-ar), 3.79 (s,
3H, OCH3), 3.78 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
d
156.4, 155.8, 155.4, 152.2, 148.4, 146.1, 145.2, 143.5, 143.2, 131.2,
d6):
d
156.0, 154.1, 153.0, 148.1, 142.8 (2C), 140.5, 135.3, 132.4, 131.6,
116.2, 115.6, 111.6, 108.4, 55.7, 55.5; HRMS calcd for C16H14N5O2S
123.8, 117.1, 116.6 (2C), 112.5, 64.1, 64.0; HRMS calcd for
[M þ H]þ 340.0868 found 340.0858.
C
17H13N4O2S [M þ H]þ 337.0759 found 337.0766.
5.1.4.4.4. N-(3,5-Dimethoxyphenyl)pyrazino[20,30:4,5]thieno[3,2-
d]pyrimidin-4-amine (6e). Yield: 96%; yellow powder; mp 249e
250 ꢀC; IR (KBr) nmax (cmꢂ1): 1575, 1527, 1458, 1444, 1415, 1357,
1334, 1200, 1145, 1056, 815, 762, 749, 733; 1H NMR (300 MHz,
5.1.4.3.8. N-(4-Bromo-2-fluorophenyl)pyrido[20,30:4,5]thieno[3,2-
d]pyrimidin-4-amine (5i). Yield: 55%; white powder; mp 250e
251 ꢀC; IR (KBr) nmax(cmꢂ1): 1620, 1529, 1505, 1490, 1475, 1442,
1397, 1384, 1345, 1288, 1263, 1190, 1116, 1058, 873, 814, 786, 752,
DMSO-d6):
d
9.86 (s, 1H, NH), 8.97 (d, 1H, J ¼ 2 Hz, H-7), 8.87 (d, 1H,
728; 1H NMR (300 MHz, DMSO-d6):
d
9.96 (s, 1H, NH), 8.90 (dd, 1H,
J ¼ 2 Hz, H-8), 8.84 (s, 1H, H-2), 7.13 (d, 2H, J ¼ 1 Hz, H-ar), 6.31 (t,
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8), 8.74 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-6), 8.71
1H, J ¼ 1 Hz, H-ar), 3.77 (s, 6H, (OCH3)2); 13C NMR (75 MHz, DMSO-
(s, 1H, H-2), 7.73e7.70 (m, 2H, H-7 and H-ar), 7.59e7.48 (m, 2H, H-
d6): d 160.3 (2C), 156.4, 155.4, 155.1, 152.3, 145.3, 143.5, 143.2, 140.2,
ar); 13C NMR (75 MHz, DMSO-d6):
d
156.2, 155.0, 148.9, 148.3, 135.0,
116.9, 100.4 (2C), 95.9, 55.2 (2C); HRMS calcd for C16H14N5O2S
132.4, 129.9, 127.7, 125.5, 125.3, 123.7, 119.6, 119.3, 118.6, 116.8;
HRMS calcd for C15H9N4SBrF [M þ H]þ 374.9715 found 374.9712.
5.1.4.3.9. 2-Nitro-4-(pyrido[20,30:4,5]thieno[3,2-d]pyrimidin-4-
ylamino)phenol (5j). Yield: 62%; brown powder; mp 280e281 ꢀC; IR
(KBr) nmax (cmꢂ1): 1628, 1582, 1536, 1516, 1478, 1456, 1395, 1328,
1300, 1284, 1260, 829, 805, 791, 762, 749, 727; 1H NMR (300 MHz,
[M þ H]þ 340.0868 found 340.0860.
5.1.4.4.5. N-(3,4,5-Trimethoxyphenyl)pyrazino[20,30:4,5]thieno
[3,2-d]pyrimidin-4-amine (6f). Yield: 99%; yellow powder; mp
245e246 ꢀC; IR (KBr) nmax (cmꢂ1): 1634, 1584, 1504, 1454, 1444,
1431, 1410, 1117, 1085, 983, 840, 825, 761; 1H NMR (300 MHz,
DMSO-d6):
J ¼ 2 Hz, H-8), 8.84 (s, 1H, H-2), 7.22 (s, 2H, H-ar), 3.81 (s, 6H,
(OCH3)2), 3.68 (s, 3H, OCH3); 13C NMR (75 MHz, DMSO-d6):
156.4,
d
9.93 (s, 1H, NH), 8.99 (d, 1H, J ¼ 2 Hz, H-7), 8.91 (d, 1H,
DMSO-d6):
d 10.93 (s, 1H, OH), 10.04 (s, 1H, NH), 8.90 (dd, 1H,
J1 ¼ 2 Hz, J2 ¼ 5 Hz, H-8), 8.81 (s, 1H, H-2), 8.74 (dd, 1H, J1 ¼ 2 Hz,
J2 ¼ 8 Hz, H-6), 8.44 (d,1H, J ¼ 2 Hz, H-ar), 8.00 (d,1H, J ¼ 8 Hz, H-ar),
7.71 (td,1H, J1 ¼5 Hz, J2 ¼ 8 Hz, H-7), 7.20 (dd,1H, J1 ¼2 Hz, J2 ¼ 8 Hz,
d
155.6, 155.3, 152.6 (2C), 152.3, 145.4, 143.5, 143.3, 134.3, 133.3, 116.5,
100.6 (2C), 60.1, 55.8 (2C); HRMS calcd for C17H16N5O3S [M þ H]þ
370.0980 found 370.0977.
H-ar); 13C NMR (75 MHz, DMSO-d6):
d 155.6, 154.6, 154.2, 148.8,
148.25,135.7,134.9,132.4,130.4,130.2,123.6,119.2 (2C),118.3,117.2;
5.1.4.4.6. N-(Benzo[d][1,3]dioxol-5-yl)pyrazino[20,30:4,5]thieno
[3,2-d]pyrimidin-4-amine (6g). Yield: 79%; orange powder; mp
293e294 ꢀC; IR (KBr) nmax (cmꢂ1): 1595, 1530, 1501, 1486, 1458,
1444, 1267, 1223, 1192, 1159, 1037, 923, 854, 798, 785, 763, 748; 1H
HRMS calcd for C15H10N5O3S [M þ H]þ 340.0504 found 340.0501.
5.1.4.4. Synthesis of N-arylpyrazino[20,30:4,5]thieno[3,2-d]pyrimidin-
4-amines (6bej). A mixture of (E)-N0-(6-cyanothieno[2,3-b]
pyrazin-7-yl)-N,N-dimethylformimidamide (2d, 0.1 g, 0.43 mmol)
and appropriate aniline (1.0 equiv) in acetic acid (2 mL) was
irradiated at 118 ꢀC (400 W). On completion (followed by thin-
layer chromatography), the reaction was cooled to room
temperature and water was added. The solid was filtered off,
washed with water and dried. The crude solid was purified by
NMR (300 MHz, DMSO-d6):
d
9.93 (s, 1H, NH), 8.99 (d, 1H, J ¼ 2 Hz,
H-7), 8.90 (d, 1H, J ¼ 2 Hz, H-8), 8.79 (s, 1H, H-2), 7.39 (d, 1H,
J ¼ 2 Hz, H-ar), 7.15 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.97 (d, 1H,
J ¼ 8 Hz, H-ar), 6.07 (s, 2H, H-ar); 13C NMR (75 MHz, DMSO-d6):
d
156.4, 155.9, 155.1, 151.8, 147.1, 145.4, 144.4, 143.3, 135.8, 132.0,
116.7, 116.2, 107.9, 105.5, 101.3; HRMS calcd for C15H10N5O2S
[M þ H]þ 324.0555 found 324.0554.
column chromatography over silica gel using
a
gradient of
5.1.4.4.7. N-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)pyrazino
[20,30:4,5]thieno[3,2-d]pyrimidin-4-amine (6h). Yield: 76%; yellow
powder; mp 255e256 ꢀC; IR (KBr) nmax (cmꢂ1): 1615, 1528, 1495,
1477, 1459, 1450, 1359, 1297, 1244, 1223, 1201, 1065, 1048, 863, 805,
petroleum ether/ethyl acetate (100:0e0:100, v/v) as the eluent to
give the desired compounds (6bej).
5.1.4.4.1. N-Phenylpyrazino[20,30:4,5]thieno[3,2-d]pyrimidin-4-
amine (6b). Yield: 88%; yellow powder; mp 292e293 ꢀC; IR (KBr)
nmax (cmꢂ1): 1623, 1525, 1500, 1488, 1479, 1454, 1438, 1364, 1339,
1253, 1158, 1046, 766, 760, 745, 733, 715; 1H NMR (300 MHz,
764; 1H NMR (300 MHz, DMSO-d6):
d 9.84 (s, 1H, NH), 8.98 (d, 1H,
J ¼ 2 Hz, H-7), 8.89 (d, 1H, J ¼ 2 Hz, H-8), 8.78 (s, 1H, H-2), 7.36 (d,
1H, J ¼ 2 Hz, H-ar), 7.17 (dd, 1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-ar), 6.88 (d,
1H, J ¼ 8 Hz, H-ar), 4.27 (br s, 4H, H-ar); 13C NMR (75 MHz, DMSO-
DMSO-d6):
d
10.01 (s, 1H, NH), 9.00 (d,1H, J ¼ 2 Hz, H-7), 8.91 (d,1H,
J ¼ 2 Hz, H-8), 8.83 (s, 1H, H-2), 7.80 (dd, 2H, J1 ¼1 Hz, J2 ¼ 8 Hz, H-
d6): d 156.4, 155.6, 155.3, 152.2, 145.2, 143.5, 143.2, 142.8, 140.5,
ar), 7.43 (td, 2H, J1 ¼ 1 Hz, J2 ¼ 8 Hz, H-ar), 7.18 (td, 1H, J1 ¼ 1 Hz,
131.6, 116.7, 116.3 (2C), 112.2, 64.1, 64.0; HRMS calcd for
J2 ¼ 8 Hz, H-ar); 13C NMR (75 MHz, DMSO-d6):
d
156.5, 155.5, 155.3,
C
16H12N5O2S [M þ H]þ 338.0712 found 338.0706.
152.3, 145.4, 143.6, 143.3, 138.4, 128.6 (2C), 124.2, 122.6 (2C), 116.7;
HRMS calcd for C14H10N5S [M þ H]þ 280.0657 found 280.0654.
5.1.4.4.2. N-(4-Methoxyphenyl)pyrazino[20,30:4,5]thieno[3,2-d]
pyrimidin-4-amine (6c). Yield: 99%; yellow powder; mp 191e
192 ꢀC; IR (KBr) nmax (cmꢂ1): 1606, 1571, 1505, 1478, 1451, 1439,
1362, 1244, 1227, 1176, 1156, 1081, 1047, 1023, 830, 763, 748, 724; 1H
5.1.4.4.8. N-(4-Bromo-2-fluorophenyl)pyrazino[20,30:4,5]thieno
[3,2-d]pyrimidin-4-amine (6i). Yield: 78%; yellow powder; mp
262e263 ꢀC; IR (KBr) nmax (cmꢂ1): 1631, 1596, 1530, 1511, 1481,
1449, 1411, 1362, 1337, 1186, 1115, 1046, 869, 854, 838, 763; 1H NMR
(300 MHz, DMSO-d6):
d
10.11 (s, 1H, NH), 9.02 (d, 1H, J ¼ 2 Hz, H-7),
8.92 (d, 1H, J ¼ 2 Hz, H-8), 8.77 (s, 1H, H-2), 7.72 (ddd, 1H, J1 ¼1 Hz,
NMR (300 MHz, DMSO-d6):
d
9.92 (s, 1H, NH), 8.99 (d, 1H, J ¼ 2 Hz,
J2 ¼ 2 Hz, J3 ¼ 8 Hz, H-ar), 7.59e7.49 (m, 2H, H-ar); 13C NMR
H-7), 8.89 (d,1H, J ¼ 2 Hz, H-8), 8.76 (s,1H, H-2), 7.63 (d, 2H, J ¼ 9 Hz
(75 MHz, DMSO-d6): d 156.6, 156.0, 155.4, 152.6, 145.5, 143.4, 143.4,
H-ar), 6.99 (d, 2H, J ¼ 9 Hz, H-ar), 3.79 (s, 3H, OCH3); 13C NMR
129.8, 127.8, 125.2, 119.7, 119.3, 118.7, 116.2; HRMS calcd for
(75 MHz, DMSO-d6):
d
156.4, 155.9, 155.4, 152.1, 145.2, 143.6, 143.2,
C
14H8N5SBrF [M þ H]þ 375.9668 found 375.9666.
130.9, 128.0, 125.1, 120.5, 116.2, 113.8 (2C), 55.2; HRMS calcd for
5.1.4.4.9. 2-Nitro-4-(pyrazino[20,30:4,5]thieno[3,2-d]pyrimidin-4-
C
15H12N5OS [M þ H]þ 310.0763 found 310.0755.
ylamino)phenol (6j). Yield: 68%; yellow powder; mp 261e262 ꢀC; IR
(KBr) nmax (cmꢂ1): 3205, 1604, 1523, 1505, 1485, 1447, 1359, 1244,
1226, 1154, 1133, 1077, 1050, 835, 801, 763, 752; 1H NMR (300 MHz,
5.1.4.4.3. N-(3,4-Dimethoxyphenyl)pyrazino[20,30:4,5]thieno[3,2-
d]pyrimidin-4-amine (6d). Yield: 96%; gold powder; mp 212e
213 ꢀC; IR (KBr) nmax (cmꢂ1): 1661, 1623, 1579, 1519, 1511, 1436,
1263, 1239, 1157, 1139, 1084, 1049, 1028, 996, 855, 786, 771, 745,
DMSO-d6):
d
10.99 (s, 1H, OH), 10.11 (s, 1H, NH), 9.01 (d, 1H, J ¼ 2 Hz,
H-7), 8.91 (d,1H, J ¼ 2 Hz, H-8), 8.85 (s,1H, H-2), 8.45 (d,1H, J ¼ 2 Hz,
H-ar), 8.00 (d,1H, J ¼ 8 Hz, H-ar), 7.19 (dd,1H, J1 ¼ 2 Hz, J2 ¼ 8 Hz, H-
729, 704; 1H NMR (300 MHz, DMSO-d6):
d
9.88 (s, 1H, NH), 8.98 (d,
1H, J ¼ 2 Hz, H-7), 8.88 (d, 1H, J ¼ 2 Hz, H-8), 8.78 (s, 1H, H-2), 7.35e
ar); 13C NMR (75 MHz, DMSO-d6):
d 156.4, 155.3, 155.2, 152.3, 148.9,

182
Y. Loidreau et al. / European Journal of Medicinal Chemistry 58 (2012) 171e183
145.4,143.5,143.3,135.7,130.2,130.0,119.3,118.3,116.7; HRMS calcd
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This work was supported by a PhD grant from the Région Haute-
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from the “Fonds Unique Interministériel” (FUI) PHARMASEA
project (LM), the “Association France-Alzheimer (Finistère)” (LM)
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