Synthesis of fused tetracyclic benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-ones derivatives containing thiadiazole/oxazolidine/triazole/triazinanone moieties

Article abstract of DOI:10.1002/jhet.4160

In an attempt to design and synthesize new heterocycles with improved their biological properties, some of fused tetracyclic benzo[4,5]furo[3,2-d]pyrimidin- 4(3H)-ones bearing 1,2,4-triazole, 1,3,4-thiadiazole, 1,2,4-triazinanone, and oxazolidine systems

Full text of DOI:10.1002/jhet.4160

Received: 14 August 2020
DOI: 10.1002/jhet.4160
Revised: 16 September 2020
Accepted: 21 September 2020
A R T I C L E
Synthesis of fused tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones derivatives containing thiadiazole/
oxazolidine/triazole/triazinanone moieties
1
,2
1,2
1,2
1,2
Shengjie He
| Junkai Ma
| Fei Li
| Yanggen Hu
1
School of Pharmaceutical Sciences,
Hubei University of Medicine, Shiyan,
China
Abstract
In an attempt to design and synthesize new heterocycles with improved their
biological properties, some of fused tetracyclic benzo[4,5]furo[3,2-d]pyrimidin-
2
Hubei Key Laboratory of Wudang Local
Chinese Medicine Research and Institute
of Medicinal Chemistry, Hubei University
of Medicine, Shiyan, China
4(3H)-ones bearing 1,2,4-triazole, 1,3,4-thiadiazole, 1,2,4-triazinanone, and
oxazolidine systems have been prepared by the aza-Wittig reactions from
readily available starting material under mild conditions. The structure of
Correspondence
1
13
synthesized compounds was elucidated by H NMR, C NMR, MS, IR, and
elemental analysis.
Yanggen Hu, School of Pharmaceutical
Sciences, Hubei University of Medicine,
Shiyan, China.
Email: huyg@hbmu.edu.cn
Fei Li, School of Pharmaceutical Sciences,
Hubei University of Medicine, Shiyan,
China.
Email: piaopodexinlifei@163.com
Funding information
Hubei Provincial students’ platform for
innovation and entrepreneurship training
program, Grant/Award Numbers:
S201910929016, S201910929033; the
Natural Science Foundation of Hubei
Province of China, Grant/Award Number:
2019CFC838; the Open Project of Hubei
Key Laboratory of Wudang Local Chinese
Medicine Research, Grant/Award
Number: WDCM2018001
1
| INTRODUCTION
triazole have a wide range of medicinal properties,
for example, insecticidal, bactericidal, fungicidal, anti-
[
6–10]
As it is known, fused pyrimidinone rings, which display a
variety of pharmacological properties,
attracted considerable attention. Some of them show
anti-inflammatory, good analgesic, and anti-microbial
activities.
with other heterocyclic moieties show prime antitumor
activity through inhibition of EGFR tyrosine kinase
enzyme. On the other hand, several heterocycle con-
taining triazinanone, thiadiazole, oxazolidine, and
inflammatory, and antitumor agents.
To introduce
[1,2]
have recently
these hetercyclic ring in the fused furopyrimidinone sys-
tem is expected to improve the biological activities. So
far, the known methods could not be used to generate
diversified fused tetracyclic pyrimidinone derivatives.
Over the past 10 years, considerable interest has
been focused on the strategy to design and synthesize
new N-heterocycle via aza-Wittig reaction with mild
[3,4]
In addition, furopyrimidine as a fused ring
[5]
[
11–15]
reaction conditions.
Herein, we report our efforts
J Heterocyclic Chem. 2020;1–6.
wileyonlinelibrary.com/journal/jhet
© 2020 Wiley Periodicals LLC.
1

2
HE ET AL.
aiming to the preparation of fused tetracyclic benzo
2.2 | Preparation of fused tetracyclic
[
4,5]furo[3,2-d]pyrimidin-4(3H)-one derivatives con-
benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-ones
containing triazole/triazinanone 7, 9a-9b,
and 11
taining 1,3,4-thiadiazole/1,2,4-triazole/1,2,4-triazinanone/
oxazolidine moieties via aza-Wittig reactions.
Carbodiimides 6a, formed by reaction of 2 with phenyl
isocyanate, reacts with butyrohydrazide to provide guani-
dine intermediates 6s, and then 6s was easily converted
to fused tetracyclic benzo[4,5]furo[3,2-d]pyrimidin-4
(3H)-ones containing 1,2,4-triazole moieties 7 with cata-
lytic EtONa (Scheme 3).
2
2
| RESULTS AND DISCUSSION
.1 | Preparation of fused tetracyclic
benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-ones
containing 1,3,4- thiadiazole/oxazolidine
moieties 5a and 5b
In order to obtain various fused tetracyclic
pyrimidinone derivatives, the reaction of carbodiimides 6a
and 6b with hydrazine hydrate gives intermediate 8a and
8b. And then 8a and 8b with ethyl bromoacetate in the
presence of anhydrous K CO provided only fused tetra-
As shown in Scheme 1, the preparation of
[
16]
iminophosphorane 2 has been reported earlier.
reacted first with excess carbon disulfide to give 3 in
2
2
3
satisfactory yields. 3 further reacts with hydrazine
hydrate and amino ethanol, respectively, to produce 4a
and 4b, which were no need to purify and used directly.
The methods and strategies used here provide highly effi-
cient synthesis of 3 and 4a, 4b without using the highly
toxic thiophosgene.
cyclic benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-one deriva-
tives containing 1,2,4-triazinanone moieties 9a and 9b,
respectively. Most worthy of mention is that, from the
reaction system after recrystallization, we obtained only 9a
and 9b, one of the possible regioisomers; the other isomers
9a and 9b were not found by H NMR analysis of the
reaction mixture (Scheme 4). The result may be due to the
differences of diversity and nucleophilicity of three differ-
ent amino groups, which shows that the ammonolysis
reaction of intramolecular ester group was easier.
0
0
1
4a reacted with triphenylphosphine and hexachloroeth-
ane, Et N, and butyl isocyanates to give fused tetracyclic
3
pyrimidinone derivative containing 1,3,4-thiadiazole 5a. In
the presence of K CO , unexpectedly, when the reaction of
2
3
S-alkylation of 4b with methyl 3-(2-(bromomethyl)
To further extend the method for preparation of
phenyl)-3-methoxyacrylate generated fused tetracyclic
diverse
tetracyclic
pyrimidinones,
functionalized
pyrimidinone containing oxazolidine moiety 5b at
iminophosphoranes 10, converted using compounds 8b
ꢀ
5
0 C. The direct reaction of 4b did not cyclize using a
reaction with triphenylphosphine, C Cl , and N(C H ) ,
2
6
2
5 3
ꢀ
ꢀ
catalytic amount of sodium ethoxide at 20 C-25 C, or
in dry N,N-dimethy-formamide even temperature
exceed 100 C, 4b did not produce 5b under the same
reacted with phenyl isocyanate to produce carbodiimide
intermediate, and then intramolecular cyclization easily
gives new fused tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones containing 1,2,4-triazole moieties
11 in good yields. The protocols are shown in Scheme 5.
The structures of all the products were confirmed by
NMR, IR, MS, and elemental analysis. And the proposed
structures are consistent with all the data.
ꢀ
catalytic conditions. The reaction mechanism of 5b can
be explained by an initial S-alkylation of 4b to give 5s,
which undergoes further intramolecular nucleophilic
substitution reaction more quickly to yield 5b
(
Scheme 2).
N
PPh3
N
O
C S
NH NH H O
2
2. 2
N
O
SH
NH
CS2 (10mL)
CH CN:CH Cl
(80%, 1mL)
OC H
2 5
OC H
2
5
O
O
N
C
2
5
H OH
3
2
2
O
2
O
(1:1, 20 mL)
(10mL)
2
(10mmol)
3
4
a (3mmol)
C
2
H
5
OH
H
3
CO
0.8g ethanol amine
6mmol(PPh (1),
3
(
10mL)
COOCH3
O
C
2
Cl
6 3
(1), NEt (3))
CH Br
N
SH
O
2
3 mmol n-C H NCO
O
4
9
N
SCHEME 1 Preparation of fused
tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones containing
thiadiazole/oxazolidine moieties 5a
and 5b
N
O
O
N
K
2
CO
3
, CH
3
CN
O
N
S
N
O
5
b (67%)
OH
N
H
4
b(3mmol)
N
5
a (85%)

HE ET AL.
3
SCHEME 2
OCH3
H CO
3
COOCH3
H COOC
3
O
N
N
O
SH
CH Br
2
O
N
N
S
N
N
O
K CO , CH CN
OH
O
2
3
3
4b
O
OH
5b
O
5
s
SCHEME 3 Preparation of fused
tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-one containing
N
PPh3
N
C N
PhNCO
CH Cl
2 5
OC H
1
,2,4-triazole moieties 7
O
OC
2
H
5
2
2
O
O
2
(3 mmol)
O
6
a
n-C
3
H
7
2
CONHNH (3mmol)
O
O
NH
NH
N
N
HN
C
N
C
N
NHPh
C H ONa
N
O
HN
NHPh
2 5
C
2
H
5
OH
N
2 5
OC H
OC
2
H
5
O
O
O
O
O
7(75%)
6s
SCHEME 4 Preparation of fused
tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones containing
triazinanone moieties 9a, 9b
N
C
N R
O
OC H
2
5
BrCH CO C H
H
O
2
2
2
5
O
N
H
N
O
N
O
(
3mmol)
O
N
O
6a: R = Ph;
b: R = n-C H
N
6
0.42g K CO
2 3
DMF (5mL)
4
9.
N
N
N
O
O
hydrazine hydrate
R
9a'
9a (73%)
N
NH
O
O
O
H
N
H
N
O
NH2
O
N
BrCH CO C H
2 2 5
2
N
N
(
3mmol)
O
8
8
a:R = Ph (3 mmol);
N
N
O
0
.42g K CO
N
N
2
3
b: R = n-C H (3 mmol)
4
9
DMF (5mL)
9
b (78%)
9b'
SCHEME 5 Preparation of fused
tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones containing
H
N
O
NH
N
O
N
PPh , C Cl
6
3
2
1
,2,4-triazole moieties 11
N
N
O
NH2 NEt /CH CN
O
N PPh
3
3
3
8b
10 (1mmol)
PhNCO
(
1mmol)
CH Cl2
H
N
2
O
N
O
N
N
N
NH
N
O
N C N
N
O
11 (85%)

4
HE ET AL.
3
3
| EXPERIMENTAL
.1 | General
100); Anal. calcd for C H N O S (314.0): C, 57.31; H,
15
14 4 2
4.49; N, 17.82; found: C, 57.24; H, 4.41; N, 17.70.
Compound 5b white solid, yield: 0.31 g, 67%, m. p.
ꢀ
1
>
250 C. H NMR (600 MHz, DMSO-d6) δ: 7.96-7.94(m,
All chemicals were commercially available and analyti-
cally pure, and used without further purification. Melting
points were recorded using an uncorrected X-4 digital
melting point apparatus. MS were measured by using a
Finnigan Trace MS spectrometer. IR were recorded on
a PE-983 infrared spectrometer as KBr pellets with
1H, Ar-H), 7.78-7.76(m, 1H, Ar-H), 7.66-7.62(m, 1H, Ar-
H), 7.47-7.43(m, 1H, Ar-H), 4.85-4.81(m, 2H, CH ),
2
13
4.34-4.29(m, 2H, CH2); C NMR (100 MHz, DMSO-d6)
δ: 157.8, 156.5, 151.0, 143.9, 134.7, 129.7, 124.0, 122.1,
121.2, 112.9, 67.9, 42.8. IR (KBr) 1714(C=O), 1598, 1402,
−
1
+
1255 cm . MS (70 eV) m/z (%): 228(M , 100), 186(97),
173(16), 130(69), 102(70), 88(9), 75(27). Anal. calcd for
C H N O (228.0): C, 63.16; H, 3.53; N, 12.28; found: C,
−
1
absorptions in cm . NMR were recorded in CDCl
3
(
or DMSO-d ) using a Varian Mercury 400 spectrometer
6
12
8 2 3
with resonances relative to tetramethylsilane (TMS) as an
internal standard. Elemental analyses were recorded on a
PerkinElmer CHN 2400 instrument. TLC analysis was
carried out on silica gel plates GF254 (Wuhan, Geao Co.).
63.07; H, 3.48; N, 12.15.
3.2.1 | Preparation of fused tetracyclic
benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-one
derivative 7
3
.2 | General method for the synthesis of
fused tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones 5a and 5b
Carbodiimide 6, daminozide (3 mmol), and 15 mL dic-
hloromethane were added into 50 mL round bottom
ꢀ
ꢀ
flasks in turn and stirred for 4 hours at 20 C-25 C, and
several drops of EtONa (10%) in EtOH (5 mL) was added.
The reaction was followed by TLC, after completion of
the reaction, the solvent was evaporated, and the residual
was recrystallized to give compound 7 as white solid
The intermediates 4a and 4b can be obtained
[
3]
according to a published method. To a solution of
iminophosphorane (4.65 g) and carbon disulfide (10 mL)
in anhydrous CH Cl and CH CN (20 mL, v/v = 1:1) was
refluxed for 30 hours at 40 C-45 C, and then removed
triphenylphosphine sulfide, further reaction with equimo-
lar hydrazine hydrate or amino-ethanol in 20 mL ethanol
to give 4a and 4b, respectively, which was used directly
without further purification.
2
2
3
ꢀ
ꢀ
ꢀ
1
0.75 g, 75%, m. p. > 250 C; H NMR (400 MHz, DMSO-
d6) δ: 7.96-7.94(m, 1H, Ar-H), 7.82-7.80(m, 1H, Ar-H),
7.74-7.65(m, 7H, Ar-H), 7.43-7.40(m, 1H, Ar-H), 2.69-2.67
(m, 2H, CH ), 1.72-1.66(m, 2H, CH ), 0.93(t, J = 8.0, 3H,
2
2
13
CH3); C NMR (100 MHz, DMSO-d6) δ: 169.0, 157.2,
154.6, 148.9, 147.5, 144.4, 133.8, 132.3, 130.8, 130.5, 128.7,
124.3, 122.6, 122.1, 113.4, 27.6, 19.0, 13.9. MS (70 eV)
To a mixture of 4a (2 mmol) 5 mmol Ph P (1.31 g)
3
and 5 mmol C Cl (1.20 g) in dry CH CN (15 mL) was
added dropwise N(C H ) (1.4 mL, 10 mmol), after the
2
6
3
+
m/z (%): 344(M , 100); Anal. calcd for C H N O
2
5 3
29 16
4
2
reaction was over (monitored with TLC), n-C H NCO
(344.13): C, 69.76; H, 4.68; N, 16.27; found: C, 69.65; H,
4.57; N, 16.16.
4
9
ꢀ
(
3
2 mmol) was added, and then stirred 4 hours at 25 C-
0 C to give fused tetracyclic pyrimidinone containing
,3,4-thia- diazole 5a.
ꢀ
1
A mixture of compound 4b (2 mmol), methyl
-(2-(bromomethyl)phenyl)-3- methoxyacrylate (2 mmol),
3.2.2 | Preparation of fused tetracyclic
benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-ones
containing 1,2,4-triazinanone moieties 9a
and 9b
3
and K CO (0.2 g) in dry 5 mL DMF was stirred for
2
3
ꢀ
5
hours at 50 C to give fused tetracyclic pyrimidinone
containing dihydrooxazole moieties 5b, and the purity
was recrystallized from dichloromethane/alcohol.
Compound 5a white solid, yield: 0.53 g, 85%, m. p.
A mixture of 3 mmol 8 (8a: 0.87 g, 8b: 0.81 g) and
3 mmol ethyl 2-bromoacetate (0.50 g) in N,N-dimethyl
formamide (5 mL), anhydrous potassium carbonate
ꢀ
1
>
250 C. H NMR (400 MHz, DMSO-d6) δ: 8.22(s, 1H,
Ar-H), 8.02-8.00(s, 1H, Ar-H), 7.82-7.80(s, 1H, Ar-H),
.68-7.66(s, 1H, Ar-H), 7.50-7.47(s, 1H, Ar-H), 3.33-3.31
m, 2H, CH ), 1.63-1.37(m, 4H, CH CH ) 0.93(t, J = 8.0,
ꢀ
ꢀ
(0.41 g) were stirred at 50 C-60 C for 6-8 hours. The
mixture was poured into ice water and recrystallized
from CH Cl /C H OH (v/v = 1:1) to give fused tetra-
7
(
2
1
2
2
2
2
2
5
3
3
1
1
H, CH3); C NMR (100 MHz, DMSO-d6) δ: 156.5,
cyclic benzo[4,5]furo[3,2-d]pyrimidin-4(3H)-ones con-
taining 1,2,4-triazinanone moieties 9a and 9b,
respectively.
56.3, 156.2, 147.8, 141.4, 136.0, 129.7, 124.2, 121.7, 121.1,
+
12.9, 43.2, 30.2, 19.5, 13.6. MS (70 eV) m/z (%):314(M ,

HE ET AL.
5
ꢀ
1
Compound 9a yield: 0.72 g (73%) m. p. > 250 C. H
NMR δ: (400 MHz, DMSO-d6) 9.46(s, 1H), 8.01-7.95(m,
3
from easily available starting materials under mild
reaction conditions. This versatile approach is
expected to be a new technology for the synthesis of
pharmacologically important fused tetracyclic benzo
[4,5]furo[3,2-d]pyrimidin-4(3H)-one derivatives con-
taining 1,3,4-thiadiazole/ 1,3,4-triazinanone/oxazolidine/
1,2,4-triazole/ moieties.
H, Ar-H), 7.77-7.76(m, 1H, Ar-H), 7.65-7.63(m, 1H, Ar-
H), 7.47-7.38(m, 3H, Ar-H and N-H), 7.12-7.10(m, 1H),
.85(s, 2H, CH2); C NMR (100 MHz, DMSO-d6) δ:
56.9, 153.3, 150.7, 142.1, 139.0, 132.2, 130.0, 129.1, 124.2,
1
3
5
1
1
23.5, 122.9, 121.8, 121.0, 113.3, 110.0, 40.5. MS (70 eV)
+
m/z (%) = 332(M , 100); Anal. calcd for C H N O
18
12
4
3
(
3
322.1): C, 65.06; H, 3.64; N, 16.86; found: C, 64.92; H,
.48; N, 16.75.
Compound 9b yield: 0.70 g, 78%; m. p. > 250 C. H
NMR δ: (400 MHz, DMSO-d6) 7.92-7.91(m, 1H, Ar-H),
.70-7.69(m, 1H, Ar-H), 7.61-7.58(m, 1H, Ar-H), 7.42-7.39
m, 2H, Ar-H and N-H), 5.57(s, 2H, CH ), 3.47-3.44(m, 2H,
ACKNOWLEDGEMENTS
We gratefully acknowledge financial support from the
Natural Science Foundation of Hubei Province of China
(Grant No. 2019CFC838), the Open Project of Hubei
Key Laboratory of Wudang Local Chinese Medicine
Research (Hubei University of Medicine) (Grant
No. WDCM2018001), Hubei Provincial students' plat-
form for innovation and entrepreneurship training pro-
gram (Grant Nos. S201910929016 and S201910929033).
ꢀ
1
7
(
2
CH ), 1.63-1.60(m, 2H, CH ), 1.39-1.36(m, 2H, CH ), 0.94
2
2
2
13
(t, J = 8.0, 3H, CH3); C NMR (100 MHz, DMSO-d6) δ:
1
56.8, 153.9, 153.4, 142.2, 131.9, 129.7, 123.8, 123.2, 121.7,
1
13.2, 110.0, 40.9, 40.5, 31.4, 20.0, 14.2. MS (70 eV) m/z
+
(%): 312(M , 100); Anal. calcd for C H N O (312.3): C,
16 16 4 3
ORCID
6
1.53; H, 5.16; N, 17.94; found: C, 61.40; H, 5.02; N, 17.76.
Yanggen Hu https://orcid.org/0000-0001-7704-4632
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.2.3 | Preparation of fused tetracyclic
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ꢀ
ꢀ
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ꢀ
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NMR (100 MHz, DMSO-d6) δ: 156.9, 152.3, 148.4, 146.9,
1
1
42.9, 139.3, 134.0, 131.5, 130.0, 129.4, 124.2, 123.3, 121.7,
19.6, 113.3, 42.0, 30.1, 19.7, 14.1. IR (KBr, cm ): 3286
−1
(
NH), 1702 (C=O), 1576, 1397. MS (70 eV) m/z (%): 373
[12] N. Hou, J.-H. Man, X.-Y. Wang, S.-J. He, Q. Li, Y.-G. Hu, Che-
mistrySelect 2019, 4, 4901.
+
(M , 100). Anal. calcd for C H N O (373.15): C,
21 19 5 2
[
[
[
13] H.-M. Wang, S.-B. Guo, Y.-G. Hu, X.-H. Zeng, G.-Y. Yang,
Chin. J. Org. Chem. 2015, 35, 1075.
14] Y.-G. Hu, A.-H. Zheng, G.-J. Li, M.-Z. Dong, F. Sun, Z.-Y. Liu,
W. Li, J. Heterocyclic Chem. 2014, S1, 84.
15] Y.-G. Hu, H.-T. Gao, G. Wang, Y. Wang, Y.-N. Qu, J. Xu, Chin.
J. Org. Chem. 2012, 32, 1468.
6
7.55; H, 5.13; N, 18.76; found: C, 67.36; H, 5.25; N, 18.61.
4
| CONCLUSION
In summary, we have developed a diversity-oriented syn-
thesis of fused tetracyclic system via aza-Wittig reaction
[16] Y.-G. Hu, M.-G. Liu, M.-W. Ding, Helvetica Chimica Acta
2008, 91, 862.

6
HE ET AL.
[
[
17] Y.-G. Hu, M. Liu, M.-W. Ding, Chin. J. Chem. 2010, 28, 309.
18] Y.-G. Hu, L. Li, Q.-Y. Zhang, A.-N. Zhang, C. Feng, P. He, Het-
erocycl. Commun. 2015, 21, 345.
How to cite this article: He S, Ma J, Li F, Hu Y.
Synthesis of fused tetracyclic benzo[4,5]furo[3,2-d]
pyrimidin-4(3H)-ones derivatives containing
thiadiazole/oxazolidine/triazole/triazinanone
moieties. J Heterocyclic Chem. 2020;1–6. https://
doi.org/10.1002/jhet.4160
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