Synthesis of sterically congested 1,3,4-oxadiazole derivatives from aromatic carboxylic acids, acenaphthoquinone, and (N-isocyanimino) triphenylphosphorane

Article abstract of DOI:10.1007/s00706-011-0488-4

Reactions of (N-isocyanimino)triphenylphosphorane with acenaphthoquinone in the presence of aromatic carboxylic acids proceed smoothly at room temperature and under neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yie

Full text of DOI:10.1007/s00706-011-0488-4

Monatsh Chem (2011) 142:625–630
DOI 10.1007/s00706-011-0488-4
ORIGINAL PAPER
Synthesis of sterically congested 1,3,4-oxadiazole derivatives
from aromatic carboxylic acids, acenaphthoquinone,
and (N-isocyanimino)triphenylphosphorane
•
Ali Ramazani Fatemeh Zeinali Nasrabadi
•
•
Asemeh Mashhadi Malekzadeh Yavar Ahmadi
Received: 29 October 2010 / Accepted: 20 March 2011 / Published online: 20 April 2011
Ó Springer-Verlag 2011
Abstract Reactions of (N-isocyanimino)triphenylphos-
phorane with acenaphthoquinone in the presence of
aromatic carboxylic acids proceed smoothly at room tem-
perature and under neutral conditions to afford sterically
congested 1,3,4-oxadiazole derivatives in high yields. The
reaction proceeds smoothly and cleanly under mild con-
ditions and no side reactions are observed.
interesting heterocyclic scaffolds are particularly useful for
the construction of diverse chemical libraries of drug-like
molecules. The isocyanide-based MCRs are of special
importance in this context [7–9].
The intramolecular version of the aza-Wittig-type reac-
tion has attracted considerable attention recently because of
its high potential for the synthesis of a wide variety of
nitrogen heterocycles, which can be attributed, in good
measure, to the rapid progress in the preparation of func-
tionalized iminophosphoranes. Several interesting hetero-
cyclization reactions involving iminophosphoranes have
been reported [10–16]. These compounds can easily be
converted through aza-Wittig reaction with isocyanates,
carbon dioxide, or carbon disulfide into functionalized het-
ero-cumulenes which exhibit a rich chemistry of unusual
synthetic promise [10–16]. The nucleophilicity at the nitro-
gen is a factor of essential mechanistic importance in the use
of these iminophosphoranes as aza-Wittig reagents. Imino-
phosphoranes are important reagents in synthetic organic
chemistry, especially in the synthesis of naturally occurring
products, compounds with biological and pharmacological
activity [10–16]. (N-Isocyanimino)triphenylphosphorane
(3) is expected to have synthetic potential because it provides
a reaction system in which the iminophosphorane group can
react with a reagent having a carbonyl functionality [17, 18].
In recent years, several synthetic methods have been
reported for the preparation of (N-isocyanimino)triphenyl-
phosphorane (CNNPPh3, 3) (Scheme 1) [17, 18]. There are
several reports on the use of (N-isocyanimino)triphenyl-
phosphorane in the synthesis of metal complexes [17, 18].
However, application of 3 in the synthesis of organic
compounds is rare [19–29]. As part of our ongoing pro-
gram to develop efficient and robust methods for the
preparation of heterocyclic compounds [19–33], we sought
to develop a convenient preparation of sterically congested
Keywords (N-Isocyanimino)triphenylphosphorane Á
Acenaphthoquinone Á Aromatic carboxylic acid Á
1,3,4-Oxadiazole Á Aza-Wittig reaction
Introduction
Multicomponent reactions are capable of achieving high
levels of brevity and diversity, as they allow more than two
simple and flexible building blocks to be combined in
practical, time-saving one-pot operations. Owing to their
valued features such as atom economy, inherent simple
experimental procedures, and their one-pot character, they
are perfectly suited for automated synthesis. Thus, MCRs
have attracted considerable interest owing to their excep-
tional synthetic efficiency [1–4]. Typically, the purification
of products resulting from MCRs is also simple because all
the organic reagents employed are consumed and incor-
porated into the target compound [5, 6]. MCRs leading to
A. Ramazani (&) Á F. Zeinali Nasrabadi Á
A. Mashhadi Malekzadeh
Chemistry Department, Zanjan University, Zanjan, Iran
e-mail: aliramazani@gmail.com
Y. Ahmadi
Islamic Azad University, Zanjan Branch, Young Researchers
Club, Zanjan, Iran
123

626
A. Ramazani et al.
1,3,4-oxadiazole derivatives 4a–4p. Herein, we report a
hitherto unknown, one-pot three-component reaction,
which, starting from readily available acenaphthoquinone
(2), affords disubstituted 1,3,4-oxadiazole derivatives
4a–4p (Scheme 1).
In summary, we believe that the reported method offers
a mild, simple, and efficient route for the preparation of
1,3,4-oxadiazole derivatives 4. Its ease of work-up, high
yields, and fairly mild reaction conditions make it a useful
addition to modern synthetic methodologies. Other aspects
of this process are under investigation.
1,3,4-Oxadiazoles have attracted interest in medicinal
chemistry as surrogates of carboxylic acids, esters, and
carboxamides. 1,3,4-Oxadiazoles are an important class
of heterocyclic compounds that have a wide range of
pharmaceutical and biological activities including anti-
microbial, antifungal, anti-inflammatory, and antihyper-
tensive [34–38]. Several methods have been reported in the
literature for the synthesis of 1,3,4-oxadiazoles. These pro-
tocols are multi-step in nature [39–45]. The most general
method involves the cyclization of diacylhydrazides with a
variety of reagents, such as SOCl2, POCl3, or H2SO4, usually
under harsh reaction conditions. Few reliable and opera-
tionally simple examples have been reported for the
one-pot synthesis of 1,3,4-oxadiazoles, especially from
readily available carboxylic acids and acid hydrazides
[46–50].
Experimental
(N-Isocyanimino)triphenylphosphorane (3) was prepared
based on reported procedures [17, 18]. Other starting
materials and solvents were obtained from Merck
(Germany) and Fluka (Switzerland) and were used without
further purification. The methods used to monitor the
reactions are TLC and NMR. Melting points were mea-
sured on an Electrothermal 9100 apparatus. IR spectra were
measured on a Jasco 6300 FTIR spectrometer. H and 13C
1
NMR spectra (CDCl3) were recorded on a Bruker DRX-
250 Avance spectrometer at 250.0 and 62.5 MHz, respec-
tively. Elemental analyses were performed using a Heraeus
CHN-O-Rapid analyzer. Mass spectra were recorded on a
Finnigan MAT-8430 mass spectrometer operating at an
ionization potential of 70 eV. Preparative layer chroma-
tography (PLC) plates were prepared from Merck silica gel
(F254) powder.
Results and discussion
The carboxylic acid derivatives 1 with acenaphthoquinone
(2) and (N-isocyanimino)triphenylphosphorane (3) in
CH3CN react together in a 1:1:1 ratio at room temperature
to produce sterically congested 1,3,4-oxadiazole deriva-
tives 4 and triphenylphosphine oxide (5) (Scheme 1,
Table 1). The reaction proceeds smoothly and cleanly
under mild conditions and no side reactions are observed.
The suggested mechanism for the formation of products
4a–4p is illustrated in Scheme 2. On the basis of the
chemistry of isocyanides, it is reasonable to assume that the
first step may involve nucleophilic addition of (N-isocy-
animino)triphenylphosphorane (3) to acenaphthoquinone
(2), which is facilitated by its protonation with the acid 1,
leading to nitrilium intermediate 6. This intermediate may
be attacked by the conjugate base of acid 1 to form 1:1:1
adduct 7. This adduct may undergo intramolecular aza-
Wittig reaction of the iminophosphorane moiety with the
ester carbonyl to afford the isolated sterically congested
1,3,4-oxadiazole derivatives 4 by elimination of triphen-
ylphosphine oxide (5) from intermediate 8.
General procedure for the preparation of compounds
4a–4p
A mixture of (N-isocyanimino)triphenylphosphorane (1.0
mmol), acenaphthoquinone (1.0 mmol), and aromatic car-
boxylic acid (1.0 mmol) in 5 cm3 CH3CN was stirred at room
temperature for 24 h. The solvent was removedunder reduced
pressure, and the viscous residue was purified by PLC [silica
gel (F254) powder; petroleum ether/ethyl acetate 4:1].
2-Hydroxy-2-(5-phenyl-1,3,4-oxadiazol-2-yl)-1(2H)-
acenaphthylenone (4a, C20H12N2O3)
Yellow powder; yield 80%; Rf = 0.36 (petroleum ether/
ethyl acetate 4:1); m.p.: 162–164 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.59 (br s, OH), 7.40–8.30
(m, 11CHarom) ppm; 13C NMR (62.53 MHz, CDCl3):
d = 87.74 (C–OH), 122.56, 123.88, 126.97, 127.13,
128.79, 128.96, 129.07, 132.02, 132.85 (11CH of arom),
Scheme 1
N
N
HO
O
O
O
Ar
O
CH3CN
ArCO2H
+
Ph3P
N
N
C
+
Ph3PO
+
r.t., 24 h
1
2
3
4
5
123

Synthesis of sterically congested 1,3,4-oxadiazole derivatives
627
Table 1 continued
Table 1 Synthesis of sterically congested 1,3,4-oxadiazole deriva-
tives 4a–4p from carboxylic acids 1 and acenaphthoquinone (2) in the
presence of (N-isocyanimino)triphenylphosphorane (3)
4
Ar
Product
Yield (%)a
4
Ar
Product
Yield (%)a
H3CO
N
N
n
3,5-diMeOC6H3
2-MeC6H4
67
72
70
O
HO
O
H3CO
N
N
a
C6H5
80
O
HO
O
CH3
N
N
o
O
HO
O
N
N
b
4-BrC6H4
78
O
HO
Br
O
N
O
p
3,4-diMeC6H3
N
H3C
H3C
HO
N
O
N
c
d
e
4-CNC6H4
3-MeC6H4
4-t-BuC6H4
73
83
85
a Yield of isolated 4
O
HO
O
NC
123.22, 127.80, 129.60, 135.12, 142.96 (5C of arom),
161.05, 166.13 (2C=N of oxadiazole), 198.51 (C=O) ppm;
N
N
H3C
O
HO
O
ꢀ
IR (KBr): m = 3,366, 3,073, 1,718, 1,603, 1,448,
1,012 cm-1; MS (EI, 20 eV): m/z (%) = 328 (M?), 198
(16), 182 (34), 154 (83), 126 (100), 98 (28), 85 (28), 76
(39), 62 (38), 43 (45).
N
N
O
H3C
H3C
HO
O
CH3
2-[5-(4-Bromophenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxy-
1(2H)-acenaphthylenone (4b, C20H11BrN2O3)
N
N
f
3-ClC6H4
76
72
Cl
O
HO
N
Yellow powder; yield 78%; Rf = 0.33 (petroleum ether/
ethyl acetate 4:1); m.p.: 151–153 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.57 (br s, OH), 7.57 (d,
O
g
3-PhOC6H4
N
PhO
3
3JHH = 8.3 Hz, 2CHarom), 8.03 (d, JHH = 8.3 Hz,
O
HO
O
2CHarom), 7.69–7.86, 8.09–8.30 (m, 6CHarom) ppm; 13C
NMR (62.53 MHz, CDCl3): d = 86.50 (C–OH), 122.59,
123.96, 127.03, 128.51, 128.83, 129.08, 132.33, 132.94
(10CH of arom), 122.12, 126.80, 129.50, 130.98, 134.22,
140.25 (6C of arom), 164.02, 165.03 (2C=N of oxadiaz-
N
BrH2C
N
h
i
4-BrCH2C6H4
82
75
O
HO
O
N
C10H7
N
ꢀ
ole), 202.02 (C=O) ppm; IR (KBr): m = 3,204, 3,077,
1,733, 1,600, 1,481, 1,007 cm-1; MS (EI, 20 eV): m/z
(%) = 407 (M?), 198 (8), 182 (37), 154 (78), 126 (100), 98
(22), 85 (22), 75 (55), 62 (45), 50 (18).
O
HO
O
N
O
N
Cl
j
k
l
4-ClC6H4
4-FC6H4
72
75
80
HO
4-[5-(1,2-Dihydro-1-hydroxy-2-oxo-1-acenaphthylenyl)-
1,3,4-oxadiazol-2-yl]benzonitrile (4c, C21H11N3O3)
O
N
F
N
Yellow powder; yield 73%; Rf = 0.30 (petroleum ether/ethyl
acetate 4:1); m.p.: 161–163 °C; 1H NMR (250.13 MHz,
CDCl3): d = 3.63 (s, OH), 7.71–8.33 (m, 10CHarom) ppm;
13C NMR (62.53 MHz, CDCl3): d = 77.31 (C–OH), 122.07,
127.13, 127.60, 128.45, 129.09, 132.62, 132.75 (10CH of
arom), 109.98, 115.51, 124.00, 128.90, 133.02, 135.05,
143.03 (7C of arom), 161.03, 165.13 (2C=N of oxadiazole),
O
HO
O
Me
N
N
4-MeC6H4
O
HO
O
MeO
ꢀ
192.21 (C=O) ppm; IR (KBr): m = 3,439, 3,209, 1,729,
N
N
1,604, 1,495, 1,014 cm-1; MS (EI, 20 eV): m/z (%) = 353
(M?), 197 (17), 182 (32), 154 (73), 130 (100), 126 (85), 101
(90), 75 (86), 62 (47), 50 (48), 42 (30).
m
4-MeOC6H4
68
O
HO
O
123

628
A. Ramazani et al.
O
HO
O
Ar
HO
O
1
O
N N C
(Ph)3P
O
N
N
C
(Ph)3P
Ar
O
3
2
6
(Ph)3P
O
N
(Ph)3P
O
N
HO
N
O
N
N
OH
OH
N
O
O
Ar
O
O
O
+
Ar
Ph3PO
Ar
5
7
4
8
Scheme 2
2-Hydroxy-2-[5-(3-methylphenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4d, C21H14N2O3)
MS (EI, 20 eV): m/z (%) = 384 (M?), 182 (11), 163 (25),
148 (14), 120 (38), 103 (17), 91 (73), 76 (35), 57 (18), 43
(100).
Yellow powder; yield 83%; Rf = 0.36 (petroleum ether/
ethyl acetate 4:1); m.p.: 169–171 °C; 1H NMR
(250.13 MHz, CDCl3): d = 2.37 (s, CH3), 4.50 (br s,
2-[5-(3-Chlorophenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxy-
1(2H)-acenaphthylenone (4f, C20H11ClN2O3)
OH), 7.26–8.30 (m, 10CHarom
)
ppm; 13C NMR
Yellow powder; yield 76%; Rf = 0.30 (petroleum ether/
ethyl acetate 4:1); m.p.: 174–176 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.06 (br s, OH), 7.33–8.29
(m, 10CHarom) ppm; 13C NMR (62.53 MHz, CDCl3):
d = 77.25 (C–OH), 122.06, 123.98, 125.24, 127.02,
128.44, 129.09, 130.34, 132.09, 132.62, 132.94 (10CH of
arom), 122.59, 128.83, 129.50, 133.82, 135.12, 148.62 (6C
of arom), 158.50, 164.82 (2C=N of oxadiazole), 198.27
(C=O) ppm; IR (KBr): ꢀm = 3,379, 3,080, 1,718, 1,602,
1,551, 1,068 cm-1; MS (EI, 20 eV): m/z (%) = 362 (M?),
197 (18), 182 (44), 154 (95), 126 (100), 98 (23), 85 (19), 75
(47), 62 (34), 50 (17).
(62.53 MHz, CDCl3): d = 21.21 (CH3), 76.57 (C–OH),
122.06, 122.55, 124.29, 126.84, 127.58, 128.44, 128.78,
129.07, 132.60, 132.86 (10CH of arom),123.82, 128.81,
129.10, 130.91, 134.80, 143.35 (6C of arom), 164.18,
166.75 (2C=N of oxadiazole), 198.87 (C=O) ppm; IR
-1
ꢀ
(KBr): m = 3,399, 3,073, 1,723, 1,603, 1,490, 1,073 cm
;
MS (EI, 20 eV): m/z (%) = 342 (M?), 198 (6), 182 (24),
154 (54), 126 (60), 105 (100), 91 (18), 76 (54), 62 (23), 50
(24).
2-[5-(4-tert-Butylphenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxy-
1(2H)-acenaphthylenone (4e, C24H20N2O3)
Yellow powder; yield 85%; Rf = 0.33 (petroleum ether/
ethyl acetate 4:1); m.p.: 176–178 °C; 1H NMR (250.13
MHz, CDCl3): d = 1.30 (s, 3CH3), 5.30 (br s, OH), 7.41
(d, JHH = 8.3 Hz, 2CHarom), 7.98 (d, JHH = 8.3 Hz,
2CHarom), 7.71–7.86, 8.05–8.20 (m, 6CHarom) ppm; 13C
NMR (62.53 MHz, CDCl3): d = 31.03 (3CH3), 35.03 (C),
76.60 (C–OH), 122.53, 123.74, 125.89, 126.79, 126.98,
128.70, 129.03, 132.73 (10CH of arom), 122.04, 128.43,
129.75, 130.88, 135.51, 142.33 (6C of arom), 164.28,
2-Hydroxy-2-[5-(3-phenoxyphenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4g, C26H16N2O4)
Yellow powder; yield 72%; Rf = 0.26 (petroleum ether/
ethyl acetate 4:1); m.p.: 153–155 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.81 (br s, OH), 6.96–8.29
(m, 15CHarom) ppm; 13C NMR (62.53 MHz, CDCl3):
d = 85.02 (C–OH), 117.19, 119.14, 121.80, 122.05,
123.88, 123.97, 126.95, 128.77, 129.04, 129.95, 130.45,
130.92, 132.84 (15CH of arom), 122.52, 128.44, 129.62,
135.22, 145.30, 156.20, 157.85 (7C of arom), 165.45,
164.71 (2C=N of oxadiazole), 198.17 (C=O) ppm; IR
3
3
166.00 (2C=N of oxadiazole), 198.17 (C=O) ppm; IR
-1
ꢀ
(KBr): m = 3,209, 2,965, 1,738, 1,614, 1,495, 1,010 cm
;
123

Synthesis of sterically congested 1,3,4-oxadiazole derivatives
629
3
(KBr): ꢀm = 3,307, 3,082, 1,743, 1,563, 1,485, 1,225 cm-1
;
arom), 129.53 (d, JCF = 12.5 Hz, 2CH of arom), 123.93,
127.00, 128.94, 135.02, 140.74 (5C of arom), 160.52 (d,
1JCF = 252.0 Hz, C of arom), 164.48, 166.53 (2C=N of
oxadiazole), 189.51 (C=O) ppm; IR (KBr): ꢀm = 3,375,
MS (EI, 20 eV): m/z (%) = 420 (M?), 214 (27), 197 (29),
182 (80), 154 (80), 126 (100), 98 (21), 85 (15), 76 (29), 62
(29), 50 (22).
3,082, 1,725, 1,606, 1,497, 1,013 cm-1
.
2-[5-[4-(Bromomethyl)phenyl]-1,3,4-oxadiazol-2-yl]-2-
hydroxy-1(2H)-acenaphthylenone (4h, C21H13BrN2O3)
Yellow powder; yield 82%; Rf = 0.33 (petroleum ether/
ethyl acetate 4:1); m.p.: 163–165 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.46 (s, CH2), 4.98 (br s,
2-Hydroxy-2-[5-(4-methylphenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4l, C21H14N2O3)
Yellow powder; yield 80%; Rf = 0.36 (petroleum ether/
ethyl acetate 4:1); m.p.: 170–172 °C; 1H NMR
(250.13 MHz, CDCl3): d = 2.37 (s, CH3), 4.30 (br s,
3
OH), 7.43 (d, JHH = 8.3 Hz, 2CHarom), 7.90 (d,
3JHH = 8.3 Hz, 2CHarom), 7.70–7.86, 7.99–8.29 (m,
OH), 7.20–8.29 (m, 10CHarom
)
ppm; 13C NMR
6CHarom
)
ppm; 13C NMR (62.53 MHz, CDCl3):
(62.53 MHz, CDCl3): d = 21.61 (CH3), 76.64 (C–OH),
122.05, 123.81, 127.07, 128.44, 129.05, 129.64, 132.61,
132.80 (10CH of arom), 122.52, 128.60, 128.75, 126.89,
135.22, 142.85 (6C of arom), 162.08, 164.13 (2C=N of
d = 32.09 (CH2), 76.77 (C–OH), 122.56, 123.89, 126.95,
127.55, 129.07, 129.61, 132.62, 132.87 (10CH of arom),
123.10, 128.44, 128.79, 130.92, 135.24, 141.80 (6C of
arom), 165.12, 166.22 (2C=N of oxadiazole), 198.15
ꢀ
oxadiazole), 198.10 (C=O) ppm; IR (KBr): m = 3,355,
ꢀ
(C=O) ppm; IR (KBr): m = 3,343, 3,072, 1,717, 1,603,
3,068, 1,725, 1,603, 1,498, 1,012 cm-1
.
1,486, 1,012 cm-1
.
2-Hydroxy-2-[5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4m, C21H14N2O4)
2-Hydroxy-2-[5-(1-naphthalenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4i, C24H14N2O3)
Yellow powder; yield 68%; Rf = 0.26 (petroleum ether/
ethyl acetate 4:1); m.p.: 195–197 °C; 1H NMR
(250.13 MHz, CDCl3): d = 3.84 (s, CH3), 4.33 (s, OH),
6.85–8.31 (m, 10CHarom) ppm; 13C NMR (62.53 MHz,
CDCl3): d = 55.55 (OCH3), 77.55 (C–OH), 114.40,
122.54, 123.92, 126.92, 128.93, 128.95, 132.50, 132.89
(10CH of arom), 122.54, 128.86, 131.04, 135.22, 140.04,
158.82 (6C of arom), 164.08, 166.53 (2C=N of oxadiaz-
Yellow powder; yield 75%; Rf = 0.36 (petroleum ether/
ethyl acetate 4:1); m.p.: 154–156 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.84 (br s, OH), 7.42–9.07
(m, 13CHarom) ppm; 13C NMR (62.53 MHz, CDCl3):
d = 76.39 (C–OH), 122.60, 124.67, 125.95, 126.71,
126.96, 128.22, 128.59, 128.75, 128.79, 129.08, 132.88
(13CH of arom), 123.91, 128.35, 129.90, 131.92, 133.80,
135.22, 142.26 (7C of arom), 162.32, 166.25 (2C=N of
ꢀ
ole), 194.51 (C=O) ppm; IR (KBr): m = 3,244, 3,083,
ꢀ
oxadiazole), 198.17 (C=O) ppm; IR (KBr): m = 3,433,
1,739, 1,614, 1,500, 1,185 cm-1
.
3,186, 1,741, 1,604, 1,538, 1,089 cm-1
.
2-[5-(3,5-Dimethoxyphenyl)-1,3,4-oxadiazol-2-yl]-2-
hydroxy-1(2H)-acenaphthylenone (4n, C22H16N2O5)
Yellow powder; yield 67%; Rf = 0.20 (petroleum ether/
ethyl acetate 4:1); m.p.: 168–170 °C; 1H NMR
(250.13 MHz, CDCl3): d = 3.80 (s, 2OCH3), 4.43 (s,
OH), 6.56–8.30 (m, 9CHarom) ppm; 13C NMR (62.53 MHz,
CDCl3): d = 55.64 (2OCH3), 87.00 (C–OH), 105.00,
107.05, 122.04, 123.94, 128.43, 132.59, 132.84 (9CH of
arom), 124.75, 127.00, 131.04, 135.03, 142.10, 162.15 (7C
of arom), 164.02, 166.43 (2C=N of oxadiazole), 189.51
2-[5-(4-Chlorophenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxy-
1(2H)-acenaphthylenone (4j, C20H11ClN2O3)
Yellow powder; yield 72%; Rf = 0.30 (petroleum ether/
ethyl acetate 4:1); m.p.: 169–171 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.58 (br s, OH), 7.77 (d,
3
3JHH = 8.3 Hz, 2CHarom), 8.24 (d, JHH = 8.3 Hz,
2CHarom), 7.40–7.73, 7.83–8.13 (m, 6CHarom) ppm; 13C
NMR (62.53 MHz, CDCl3): d = 83.23 (C–OH), 122.07,
122.58, 128.40, 128.45, 129.09, 129.37, 132.63, 132.94
(10CH of arom), 123.95, 127.02, 128.83, 135.02, 137.52,
138.45 (6C of arom), 164.12, 165.23 (2C=N of oxadiaz-
ꢀ
(C=O) ppm; IR (KBr): m = 3,380, 3,094, 1,725, 1,604,
1,463, 1,162 cm-1
.
ꢀ
ole), 202.12 (C=O) ppm; IR (KBr): m = 3,227, 3,022,
2-Hydroxy-2-[5-(2-methylphenyl)-1,3,4-oxadiazol-2-yl]-
1(2H)-acenaphthylenone (4o, C21H14N2O3)
1,732, 1,604, 1,486, 1,078 cm-1
.
2-[5-(4-Fluorophenyl)-1,3,4-oxadiazol-2-yl]-2-hydroxy-
1(2H)-acenaphthylenone (4k, C20H11FN2O3)
Yellow powder; yield 72%; Rf = 0.34 (petroleum ether/
ethyl acetate 4:1); m.p.: 154–156 °C; 1H NMR
(250.13 MHz, CDCl3): d = 2.57 (s, CH3), 4.09 (br s,
Yellow powder; yield 75%; Rf = 0.33 (petroleum ether/
ethyl acetate 4:1); m.p.: 156–158 °C; 1H NMR
(250.13 MHz, CDCl3): d = 4.40 (s, OH), 7.10–8.31 (m,
OH), 7.06–8.64 (m, 10CHarom
)
ppm; 13C NMR
(62.53 MHz, CDCl3): d = 22.32 (CH3), 77.70 (C–OH),
122.06, 126.06, 126.98, 128.44, 129.09, 129.13, 131.50,
132.61, 132.80 (10CH of arom), 123.82, 128.60, 131.65,
132.00, 138.62, 140.35 (6C of arom), 164.18, 166.73
10CHarom
)
ppm; 13C NMR (62.53 MHz, CDCl3):
2
d = 82.65 (C–OH), 116.38 (d, JCF = 20.1 Hz, 2CH of
arom), 122.06, 122.55, 128.44, 129.09, 132.62 (6CH of
123

630
A. Ramazani et al.
18. Chiu TW, Liu YH, Chi KM, Wen YS, Lu KL (2005) Inorg Chem
44:6425
19. Souldozi A, Ramazani A, Bouslimani N, Welter R (2007) Tet-
rahedron Lett 48:2617
20. Souldozi A, Ramazani A (2007) Tetrahedron Lett 48:1549
21. Souldozi A, Ramazani A (2009) Phosphorus Sulfur Silicon Relat
Elem 184:3191
22. Souldozi A, Ramazani A (2009) Phosphorus Sulfur Silicon Relat
Elem 184:2344
(2C=N of oxadiazole), 198.03 (C=O) ppm; IR (KBr):
-1
ꢀ
m = 3,416, 3,072, 1,725, 1,604, 1,491, 1,014 cm
.
2-[5-(3,4-Dimethylphenyl)-1,3,4-oxadiazol-2-yl]-2-
hydroxy-1(2H)-acenaphthylenone (4p, C22H16N2O3)
Yellow powder; yield 70%; Rf = 0.32 (petroleum ether/
ethyl acetate 4:1); m.p.: 167–169 °C; 1H NMR
(250.13 MHz, CDCl3): d = 2.26, 2.28 (s, 2CH3), 4.42
(br s, OH), 7.07–8.75 (m, 9CHarom) ppm; 13C NMR
(62.53 MHz, CDCl3): d = 19.65, 19.93 (2CH3), 80.00
(C–OH), 122.05, 122.54, 126.89, 128.43, 128.59, 128.85,
130.16, 132.61, 132.75 (9CH of arom), 122.05, 123.92,
127.50, 128.05, 129.02, 135.32, 145.90 (7C of arom),
164.18, 166.33 (2C=N of oxadiazole), 188.07 (C=O) ppm;
23. Souldozi A, Ramazani A (2008) Arkivoc (xvi):235
24. Ramazani A, Salmanpour S, Souldozi A (2010) Phosphorus
Sulfur Silicon Relat Elem 185:97
´
25. Souldozi A, Slepokura K, Lis T, Ramazani A (2007) Z Natur-
forsch 62b:835
26. Ramazani A, Morsali A, Ganjeie B, Kazemizadeh AR, Ahmadi
E, Kempe R, Hertle I (2005) Z Naturforsch 60b:569
27. Ramazani A, Rezaei A (2010) Org Lett 12:2852
28. Ramazani A, Ahmadi Y, Rouhani M, Shajari N, Souldozi A
(2010) Heteroat Chem 21:368
29. Ramazani A, Shajari N, Mahyari A, Ahmadi Y (2010) Mol
Divers 14. doi:10.1007/s11030-010-9275-0
30. Ramazani A, Rezaei A, Mahyari TA, Rouhani M, Khoobi M
(2010) Helv Chim Acta 93:2033
ꢀ
IR (KBr): m = 3,376, 3,083, 1,721, 1,603, 1,494,
1,184 cm-1
.
Acknowledgments The authors are thankful to the Zanjan Uni-
versity for partial support of this work.
´
31. Mahyari TA, Shajari N, Kazemizadeh AR, Slepokura K, Lis T,
Ramazani A (2007) Z Naturforsch 62b:829
32. Adib M, Riazati Kesheh M, Ansari S, Bijanzadeh HR (2009)
Synlett 1575
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