An Efficient Synthesis of 2-Substituted Quinazolin-4(3 H)-ones Catalyzed by Iron(III) Chloride

Article abstract of DOI:10.1055/s-0033-1340786

A simple and highly efficient synthesis of 2-substituted quinazolin-4(3H)-ones by the iron(III) chloride catalyzed reaction of isatoic anhydride with various amidoxime derivatives was developed. Several aryl and alkyl amidoximes were screened to demonstra

Full text of DOI:10.1055/s-0033-1340786

LETTER
▌821
lAettner Efficient Synthesis of 2-Substituted Quinazolin-4(3H)-ones Catalyzed by
Iron(III) Chloride
2-Substituted Quinazolin-4(3H)-ones
Ramamohan Mekala,a,b Raghunadh Akula,a Raghavendra Rao Kamaraju,a Chandrasekhar Kothapalli Bannoth,b
Sridhar Regati,a Jayaprakash Sarva*a
a
Technology Development Centre, Custom Pharmaceutical Services, Dr. Reddy's Laboratories Ltd, Bollaram Road, Miyapur, Hyderabad,
500049, India
Fax +91(40)44658699; E-mail: sarvaj@drreddys.com
b
Department of Chemistry, Jawaharlal Nehru Technological University, Anantapur, Andhra Pradesh 515002, India
Received: 22.10.2013; Accepted after revision: 15.01.2014
O
Abstract: A simple and highly efficient synthesis of 2-substituted
quinazolin-4(3H)-ones by the iron(III) chloride catalyzed reaction
of isatoic anhydride with various amidoxime derivatives was devel-
oped. Several aryl and alkyl amidoximes were screened to demon-
strate the scope of the methodology.
O
N
N
N
N
OH
O
N
L-vasicinone (1)
methaqualone (2)
Key words: heterocycles, polycycles, ketones, catalysis, iron,
quinazolinones
N
N
Quinazolinones are fused heterocyclic compounds that
form building blocks of various natural products and syn-
thetic analogues possessing an extensive array of biologi-
cal activities.1 The quinazolinone moiety is an important
pharmacophore, and compounds that contain it show a di-
verse range of pharmacological activities, including anti-
luotonin A (3)
O
N
N
O
N
O
N
Me
inflammatory,
antihypertensive,
anticancer,
N
anticonvulsant, and antibacterial activities. For example,
vasicinone (1, Figure 1) is a pyrrolo[2,1-b]quinazoline al-
kaloid, isolated from the aerial parts of adhatoda (Justica
adhatoda, also known as Adhatoda vasica Nees), a plant
used extensively in indigenous medicine for treating
colds, coughs, bronchitis, and asthma.2 Methaqualone (2)
is a hypnotic/sedative that was used for the treatment of
insomnia until it was banned and listed as an addictive
drug in 1985.3 Luotonin A (3), commonly found in the
Chinese plant Peganum nigellastrum, is a human DNA
topoisomerase I inhibitor and displays cytotoxicity to-
wards the murine leukemia P388 cell line (IC50 = 1.8
μg/mL) by stabilizing the topoisomerase I–DNA com-
plex.4 Benzomalvin A (4) is an inhibitor of human neuro-
kinin-1, isolated from a fungal culture of a Penicillium
species.5 Rutaecarpine (5) is the major alkaloid compo-
nent of the traditional Chinese herbal drug Wu-chu-yu
(evodia fruit; Evodia rutaecarpa), used extensively as a
remedy for headaches, cholera, and dysentery.6
HN
benzomalvin A (4)
rutaecarpine (5)
Figure 1 Examples of biologically active quinazolinones
of 2-aminobenzamide with an aliphatic or aromatic alde-
hyde, and subsequent oxidation with a reagent such as
copper(II) chloride, 2,3-dichloro-5,6-dicyano-1,4-benzo-
quinone, potassium permanganate, or manganese diox-
ide.7 A one-pot synthesis of quinazolinones from primary
alcohols and o-aminobenzamides by an iridium-catalyzed
dehydrogenation has also been recently reported.8
Isatoic anhydride [6; 2H-3,1-benzoxazine-2,4(1H)-dione]
has been widely used in syntheses of 2-substituted quinaz-
olinones by condensation with amines and aldehydes in
the presence of iodine, silica sulfuric acid, Nafion-H, ion-
ic liquids, or Lewis acids such as gallium(III) triflate.
However, these reactions give the corresponding 2,3-di-
hydroquinazolin-4(1H)-ones as major byproducts.9 As a
part of our efforts in the area of total synthesis of quinaz-
olinone-based biologically active molecules, we report a
simple, efficient, and high-yielding preparation of 2-sub-
stituted quinazolinones 8 by the iron(III) chloride cata-
lyzed reaction of isatoic anhydride (6) with amidoxime
derivatives 7 (Scheme 1).
Because of their diverse range of pharmacological activi-
ties, 2-substituted quinazolin-4(3H)-ones have attracted
interest from the synthesis community. The common syn-
thetic approach for the preparation of 2-aryl- and 2-alkyl-
quinazolin-4(3H)-ones involves two stages: condensation
SYNLETT 2014, 25, 0821–0826
Advanced online publication: 10.02.2014
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
DOI: 10.1055/s-0033-1340786; Art ID: ST-2013-D0990-L
© Georg Thieme Verlag Stuttgart · New York

822
R. Mekala et al.
LETTER
water because of the poor solubility of isatoic anhydride
(6) and amidoxime 7a in these solvents. However, the re-
action in 1,4-dioxane showed a clean conversion in
around four hours, and the isolated yield was improved to
85% (entry 6). From these studies, the optimal conditions
were established for the selective formation of 2-aryl
quinazolinone derivatives. A plausible mechanism for the
formation of the quinazolinones is shown in Scheme 2.
O
O
OH
FeCl3 (10 mol%)
solvent, heat
N
O
NH
+
R
NH2
N
H
O
N
R
R = alkyl, aryl
6
7
8
Scheme 1 Iron(III) chloride catalyzed synthesis of quinazolinones
Table 2 Solvent Screening for the Synthesis of Quinazolinone 8a in
the Presence of Iron(III) Chloride (10 mol%)
We intended to couple isatoic anhydride (6) with amidox-
imes 7 to give the corresponding quinazolinones 8 selec-
tively under mild conditions in the presence of a Lewis
acid. Initially, we examined the reaction of isatoic anhy-
dride (6) with N′-hydroxybenzenecarboximidamide (7a)
in the presence of various Lewis acids, and the results are
summarized in Table 1.
Entrya
Solvent
Temp (°C) Time (h)
Yieldb (%)
1
2
3
4
5
6
H2O
100
110
150
65
12
12
6
0
0
toluene
NMP
35
38
61
85
As shown in Table 1, when the reaction was conducted in
the absence of a catalyst, a mixture of products was ob-
tained; the desired quinazolinone 8a was formed as the
minor product (28%), with the 1,2,4-oxadiazole deriva-
tive 9 as the major product (52%; Table1, entry 1). The
base-catalyzed synthesis of 1,2,4-oxadiazole 9 from isato-
ic anhydride (6) and amidoxime 7a is a known reaction.10
Because no selectivity was observed in the absence of a
catalyst, we carried out reactions in the presence of vari-
ous Lewis acids (entries 2−6). Among these, the iron(III)
chloride catalyzed reaction showed an enhanced selectiv-
ity towards the desired product, giving quinazolinone 8a
in 66% yield.
MeOH
EtOH
30
26
4
80
1,4-dioxane
80
a Reaction conditions: 6 (1 mmol), 7a (1.1 mmol), FeCl3 (10 mol%),
solvent (2 mL).
b Yield of isolated product
The scope of the method was evaluated by using a variety
of substituted aryl amidoximes11 under the optimized con-
ditions, and the results are shown in Table 3.12 Gratifying-
ly, the desired products 8a–j were obtained in high yields
in all cases, regardless of the nature of the substituents on
the amidoxime. Interestingly, neither electron-donating
(methyl, 4-hydroxy, 4-methoxy, 4-amino, or 4-methylsul-
fanyl) nor electron-withdrawing groups (4-bromo or 4-ni-
tro) on the amidoxime had any effect on the reaction
profile and yield (Table 3, entries 1−8). Heteroaromatic
Encouraged by these results, we focused our attention on
screening various solvents in an attempt to improve the
yield (Table 2). Solvents such as water, N-methylpyrro-
lidin-2-one, methanol, and ethanol were examined, but all
were found to be less effective solvents than tetrahydrofu-
ran (entries 1−5). No reaction was observed in toluene or
Table 1 Catalyst Screening for the Synthesis of Quinazolinone 8a
Ph
O
OH
O
N
N
N
O
NH
catalyst (10 mol%)
+
NH2
O
+
THF
60 °C
N
H
O
N
Ph
NH2
6
7a
8a
9
Entrya
Catalyst
Time (h)
Yieldb (%) of 8a
Yieldb (%) of 9
1
2
3
4
5
6
no catalyst
12
6
28
66
61
52
65
48
52
–
FeCl3
FeF3
6
5
ZnCl2
14
10
13
15
–
c
FeCl3
TiCl4
20
a Reaction conditions: 6 (1 mmol), 7a (1.1 mmol), catalyst (10 mol%), THF (2 mL), 60 °C.
b Yield of isolated product.
c Reaction conducted using 5.0 mol% catalyst.
Synlett 2014, 25, 821–826
© Georg Thieme Verlag Stuttgart · New York

LETTER
2-Substituted Quinazolin-4(3H)-ones
823
O
O
O
R
O
OH
R
OH
FeCl3 (10 mol%)
– CO2
N
NH
O
N
N
NH
NHOH
H
+
H2N
N
R
N
H
O
– NH2OH
NH2
10
N
R
H
R = alkyl, aryl
6
7
11
8
Scheme 2 A plausible mechanism for the formation of quinazolinones 8
aldoximes also gave the corresponding quinazolinones in participated in the reaction as expected and gave the cor-
good yields (entries 9 and 10).
responding quinazolinones 8k–m in excellent yields (en-
tries 1−3). It therefore appears that this method provides
scope for widespread application in the synthesis of vari-
ous 2-substituted quinazolin-4(3H)-ones.
To check the generality of this process, we also screened
several alkyl amidoximes, and the results are shown in
Table 4. 2-Cyclopropylethanimidamide, 2,2-dimethylpro-
panimidamide, and 2-(4-nitrophenyl)ethanimidamide all
Table 3 Synthesis of 2-Arylquinazolinone Derivatives 8a–j under the Optimized Conditions
Entrya
Amidoxime
Product
Time (h)
Yieldb (%)
O
N
OH
N
NH
NH2
1
6.0
84.6
7a
8a
O
N
OH
N
NH
NH2
2
3
4
8.0
6.0
9.0
80.4
83.2
80.0
Br
Br
7b
8b
8c
O
N
OH
N
NH
NH2
7c
O
N
OH
N
NH
NH2
HO
OH
7d
8d
O
N
OH
N
NH
NH2
5
8.0
78.2
H2N
NH2
7e
8e
© Georg Thieme Verlag Stuttgart · New York
Synlett 2014, 25, 821–826

824
R. Mekala et al.
LETTER
Table 3 Synthesis of 2-Arylquinazolinone Derivatives 8a–j under the Optimized Conditions (continued)
Entrya
Amidoxime
Product
Time (h)
Yieldb (%)
O
N
OH
N
NH
NH2
6
2.0
90.1
93.2
84.0
MeO
OMe
7f
8f
O
N
OH
N
NH
NH2
7
8
3.0
5.0
MeS
SMe
7g
8g
O
N
OH
N
NH
NH2
O2N
NO2
7h
8h
O
N
OH
N
NH
NH2
N
9
6.0
7.0
79.2
80.2
N
7i
8i
O
N
OH
N
NH
NH2
N
10
N
F
F
7j
8j
a Reaction conditions: 6 (1 mmol), 7 (1.1 mmol), FeCl3 (10 mol%), 1,4-dioxane (10 mL), 80 °C.
b Yield of isolated product.
Table 4 Synthesis of 2-Alkylquinazolinone Derivatives 8k–m Under the Optimized Conditions
Entrya
Amidoxime 7
Product
Time (h)
Yieldb (%)
91.0
O
OH
N
NH
NH
1
4.0
3.0
NH2
N
O
7k
7l
8k
OH
N
NH2
2
89.0
N
8l
Synlett 2014, 25, 821–826
© Georg Thieme Verlag Stuttgart · New York

LETTER
2-Substituted Quinazolin-4(3H)-ones
825
Table 4 Synthesis of 2-Alkylquinazolinone Derivatives 8k–m Under the Optimized Conditions (continued)
Entrya
Amidoxime 7
Product
Time (h)
4.0
Yieldb (%)
O
N
O2N
OH
N
NO2
NH
3
89.0
NH2
7m
8m
a Reaction conditions: 6 (1 mmol), amidoxime 7 (1.1 mmol), FeCl3 (10 mol%), 1,4-dioxane (10 mL), 80 °C.
b Yield of isolated product.
(c) Deng, P.-Y.; Ye, F.; Cai, W.-J.; Tan, G.-S.; Hu, C.-P.;
Deng, H.-W.; Li, Y.-J. J. Hypertens. 2004, 22, 1819.
(7) (a) Hisano, T.; Ichikawa, M.; Nakagawa, A.; Tsuji, M.
Chem. Pharm. Bull. 1975, 23, 1910. (b) Mitobe, Y.; Ito, S.;
Mizutani, T.; Nagase, T.; Sato, N.; Tokita, S. Bioorg. Med.
Chem. Lett. 2009, 19, 4075. (c) Balakumar, C.; Lamba, P.;
Kishore, D. P.; Narayana, B. L.; Rao, K. V.; Rajwinder, K.;
Rao, A. R.; Shireesha, B.; Narsaiah, B. Eur. J. Med. Chem.
2010, 45, 4904. (d) Abdel-Jalil, R. J.; Aldoqum, H. M.;
Ayoub, M. T.; Voelter, W. Heterocycles 2005, 65, 2061.
(8) Zhou, J.; Fang, J. J. Org. Chem. 2011, 76, 7730.
(9) (a) Lingaiah, B. V.; Ezikiela, G.; Yakaiaha, T.; Reddy, G.
V.; Rao, P. S. Synlett 2006, 2507. (b) Chen, J.; Wu, D.; He,
F.; Liu, M.; Wu, H.; Ding, J.; Su, W. Tetrahedron Lett. 2008,
49, 3814. (c) Zeng, L.-Y.; Cai, C. J. Heterocycl. Chem.
2010, 47, 1035. (d) Wang, X.-S.; Yang, K.; Zhang, M.-M.;
Yao, C.-S. Synth. Commun. 2010, 40, 2633. (e) Salehi, P.;
Dabiri, M.; Zolfigolc, M. A.; Baghbanzadeh, M.
In conclusion, we have developed an efficient iron(III)
chloride catalyzed synthesis of 2-substituted quinazoli-
nones from isatoic anhydride (6) and various amidoximes
7 in good to excellent yields. The reaction proceeds under
mild conditions without needing an expensive catalyst,
and it provides the desired quinazolinones with high se-
lectivity. Extension of this method to the synthesis of var-
ious biologically active quinazolinone derivatives is in
progress and will be reported in due course.
Acknowledgment
The authors are grateful to Dr. Upadhya Timmanna and Dr. Vilas
H. Dahanukar for their constant encouragement, support, and useful
discussions. We also thank the analytical department of Dr. Reddy’s
Laboratories for providing timely support.
Tetrahedron Lett. 2005, 46, 7051.
(10) Draghici, B.; El-Gendy, B. El-D. M.; Katritzky, A. R.
Synthesis 2012, 44, 547.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synlett.SuppInigfor
m
o
ti
(11) (a) Agirbas, H.; Sumengen, D.; Durust, Y.; Durust, N. Synth.
Commun. 1992, 22, 209. (b) Durust, Y.; Akcan, M.;
Martiskainen, O.; Siirola, E.; Pihlaja, K. Polyhedron 2008,
27, 999. (c) Hussein, A. Q. Heterocycles 1987, 26, 163.
(d) Rai, N. P.; Narayanaswamy, V. K.; Govender, T.;
Manuprasad, B. K.; Shashikanth, S.; Arunachalam, P. N.
Eur. J. Med. Chem. 2010, 45, 2677.
References and Notes
(1) (a) Mhaske, S. B.; Argade, N. P. Tetrahedron 2006, 62,
9787. (b) Sharma, P. C.; Kaur, G.; Pahza, R.; Sharma, A.;
Rajak, H. Curr. Med. Chem. 2011, 18, 4786. (c) Arora, R.;
Kapoor, A.; Gill, N. S.; Rana, A. C. Int. Res. J. Pharm. 2011,
2, 22. (d) Reisch, J.; Kamal, G. M.; Gunaherath, G. J. Nat.
Prod. 1989, 52, 404. (e) Liu, J.-F.; Wilson, C. J.; Ye, P.;
Sprague, K.; Sargent, K.; Si, Y.; Beletsky, G.; Yohannes, D.;
Ng, S.-C. Bioorg. Med. Chem. Lett. 2006, 16, 686. (f) Liu, J.-
F.; Kaselj, M.; Isome, Y.; Ye, P.; Sargent, K.; Sprague, K.;
Cherrak, D.; Wilson, C. J.; Si, Y.; Yohannes, D.; Ng, S.-C.
J. Comb. Chem. 2006, 8, 7. (g) Ma, C.; Li, Y.; Niu, S.;
Zhang, H.; Liu, X.; Che, Y. J. Nat. Prod. 2011, 74, 32.
(h) Nett, M.; Hertweck, C. J. Nat. Prod. 2011, 74, 2265.
(2) Liu, J.-F.; Ye, P.; Sprague, K.; Sargent, K.; Yohannes, D.;
Baldino, C. M.; Wilson, C. J. Org. Lett. 2005, 7, 3363.
(3) (a) Chenard, B. L.; Menniti, F. S.; Pagnozzi, M. J.; Shenk, K.
D.; Ewing, F. E.; Welch, W. M. Bioorg. Med. Chem. Lett.
2000, 10, 1203. (b) Bhogal, N.; Balls, M. Curr. Drug
Discovery Technol. 2008, 5, 250.
(12) 2-Substituted Quinazolin-4(3H)-ones 8a–m; General
Procedure
The appropriate amidoxime 7 (1.1 mmol) and FeCl3 (10
mol%) were added sequentially to a solution of isatoic
anhydride (6; 1 mmol.) in 1,4-dioxane (10 mL), and the
mixture was stirred at 80 °C for 2–9 h until the reaction was
complete (TLC). The mixture was then diluted with EtOAc
(10 mL) and washed with H2O (2 × 5 mL). The organic layer
was dried (Na2SO4), filtered, and concentrated under
reduced pressure to give a crude product that was purified by
column chromatography (silica gel, 30% EtOAc–hexanes).
All new compounds gave satisfactory analytical and
spectroscopic results.
2-(4-Aminophenyl)quinazolin-4(3H)-one (8e)
Yellow solid; yield: 284 mg (78%); mp 250–254 °C; 1H
NMR (400 MHz, DMSO-d6): δ = 5.83 (s, 2 H, NH2), 6.62 (d,
J = 8.8 Hz, 2 H, ArH), 7.40 (t, J = 6.9 Hz, 1 H, ArH), 7.61
(d, J = 8.3 Hz, 1 H, ArH), 7.76 (t, J = 6.8 Hz, 1 H, ArH), 7.95
(d, J = 8.8 Hz, 2 H, ArH), 8.08 (dd, J = 6.9, 1 Hz, 1 H, ArH),
12.06 (br s, 1 H, NH); 13C NMR (100 MHz, DMSO-d6): δ =
113.0, 121.5, 125.3, 125.8, 126.9, 128.7, 129.1, 134.4,
149.6, 152.2, 152.4, 162.4; MS: m/z = 238.1 [M + H];
HRMS (ESI): m/z [M + H] calcd for C14H12 N3O: 238.0980;
found: 238.0969.
(4) (a) Ma, Z. Z.; Hano, Y.; Nomura, T.; Chen, Y. J.
Heterocycles 1997, 46, 541. (b) Cagir, A.; Jones, S. H.; Gao,
R.; Eisenhauer, B. M.; Hecht, S. M. J. Am. Chem. Soc. 2003,
125, 13628.
(5) Sun, H. H.; Barrow, C. J.; Sedlock, D. M.; Gillum, A. M.;
Copper, R. J. Antibiot. 1994, 47, 515.
(6) (a) Chen, A. L.; Chen, K. K. J. Am. Pharm. Assoc. 1933, 22,
716. (b) Hibino, S.; Choshi, T. Nat. Prod. Rep. 2001, 18, 66.
© Georg Thieme Verlag Stuttgart · New York
Synlett 2014, 25, 821–826

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R. Mekala et al.
LETTER
2-(Cyclopropylmethyl)quinazolin-4(3H)-one (8k)
2-[4-(Methylsulfanyl)phenyl]quinazolin-4(3H)-one (8g)
White solid; yield: 383 mg (93%); mp 237–239 °C; 1H NMR
(400 MHz, DMSO-d6): δ = 2.55 (s, 3 H, SCH3), 7.40 (d, J =
8.4 Hz, 2 H, ArH), 7.50 (t, J = 7.2 Hz, 1 H, ArH), 7.72 (d, J
= 7.6 Hz, 1 H, ArH), 7.83 (t, J = 7.6 Hz, 1 H, ArH), 8.13–
8.16 (m, 3 H, ArH), 12.48 (br s, 1 H, NH); 13C NMR (400
MHz, DMSO-d6): δ = 14.1, 120.8, 125.1, 125.8, 126.4,
127.4, 128.0, 128.6, 134.6, 143.0, 148.7, 151.78, 162.2; MS:
m/z = 269.0 [M + H]; HRMS (ESI): m/z [M + H] calcd for
C15H13N2OS: 269.07486; found: 269.07446.
White solid; yield: 279 mg (91%); mp 210–213 °C; 1H NMR
(400 MHz,, CDCl3): δ = 0.38–0.42 (m, 2 H, CH2), 0.70–0.73
(m, 2 H, CH2), 1.14–1.21 (m, 1 H, CH), 2.70 (d, J = 7.6 Hz,
2 H, CH2), 7.26–7.49 (m, 1 H, ArH), 7.68 (d, J = 7.6 Hz, 1
H, ArH), 7.74–7.79 (m, 1 H, ArH), 8.28 (dd, J = 6.8, 1.2 Hz,
1 H, ArH), 10.20 (br s, 1 H, NH); 13C NMR (100 MHz,
DMSO-d6): δ = 4.2, 9.2, 39.2, 120.8, 125.7, 126.0, 126.8,
134.3, 149.0, 157.2, 161.8; MS: m/z = 201.1 [M + H];
HRMS (ESI): m/z [M + H] calcd for C12H13 N2O: 201.1028;
found: 201.1037.
2-(5-Fluoropyridin-2-yl)quinazolin-4(3H)-one (8j)
Brown solid; yield: 296 mg (80%); mp 180–183 °C; 1H
NMR (400 MHz, CDCl3): δ = 7.51–7.56 (m, 1 H, ArH),
7.61–7.65 (m, 1 H, ArH), 7.77–7.80 (m, 2 H, ArH), 8.35 (d,
J = 7.4 Hz, 1 H, ArH), 8.51 (d, J = 2.9 Hz, 1 H, ArH), 8.63
2-(4-Nitrobenzyl)quinazolin-4(3H)-one (8m)
Light-brown solid; yield: 383 mg (89%); mp >300 °C; 1H
NMR (400 MHz, DMSO-d6): δ = 4.11 (s, 2 H, PhCH2), 7.48
(t, J = 7.4 Hz, 1 H, ArH), 7.58 (d, J = 8.4 Hz, 1 H, ArH), 7.65
(d, J = 8.4 Hz, 2 H, ArH), 7.75–7.79 (m, 1 H, ArH), 8.08 (d,
J = 6.9 Hz, 1 H, ArH), 8.20 (d, J = 8.8 Hz, 2 H, ArH), 12.49
(br s, 1 H, NH); 13C NMR (100 MHz, DMSO-d6): δ = 40.7,
121.3, 123.6, 125.7, 126.4, 126.9, 128.3, 128.6, 130.4,
134.4, 144.4, 154.9, 161.7; MS: m/z = 282.0 [M + H];
HRMS (ESI): m/z [M + H] calcd for C15H12 N3O3: 282.0879;
found: 282.0877.
(dd, J = 8.8, 4.8 Hz, 1 H, ArH), 10.76 (br s, 1 H, NH); 13
C
NMR (100 MHz, CDCl3): δ = 122.2, 123.7 (d, J = 5.4 Hz),
124.4 (d, J = 18.4 Hz), 126.7, 127.4, 127.9, 134.6, 137.2 (d,
J = 25.2 Hz), 144.7, 147.9, 148.9, 161.1 (d, J = 260.0 Hz),
161.3; MS: m/z = 242.1 [M + H]; HRMS (ESI): m/z [M + H]
calcd for C13H9N3OF: 242.0730; found: 242.0722.
Synlett 2014, 25, 821–826
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