A novel synthetic route for the synthesis of 4,6-diaryl-2-methyl-1,3- benzoxazoles

Article abstract of DOI:10.1002/jhet.5570420711

A new synthetic route was developed for the synthesis of 4,6-diaryl-2-methyl-1,3-benzoxazoles and their hydrogenated derivatives. The target compounds were obtained via the Neber rearrangement from 3,5-diaryl-2-cyclohexen-1-ones. The formation of the isom

Full text of DOI:10.1002/jhet.5570420711

Nov-Dec 2005
1321
A Novel Synthetic Route for the Synthesis of
4,6-Diaryl-2-methyl-1,3-benzoxazoles
V. Sridharan, S. Muthusubramanian* and S. Sivasubramanian
Department of Organic Chemistry, Madurai Kamaraj University, Madurai-625 021, India
* Corresponding author, E mail: muthumanian2001@yahoo.com
Received April 25, 2005
A new synthetic route was developed for the synthesis of 4,6-diaryl-2-methyl-1,3-benzoxazoles and their
hydrogenated derivatives. The target compounds were obtained via the Neber rearrangement from 3,5-
diaryl-2-cyclohexen-1-ones. The formation of the isomers in the dihydro derivatives was explained by the
[1,5] sigmatropic shift of hydrogen under thermal condition. DDQ was employed for the dehydrogenation of
the dihydro benzoxazoles.
J. Heterocyclic Chem., 42, 1321 (2005).
azoles employing the Neber rearrangement. The Neber
rearrangement, which describes the formation of α-
aminoketones by the treatment of sulfonic esters of
ketoximes with potassium ethoxide, has been extensively
reviewed [13,14]. It is a key step in the synthesis of several
aminoacids [15], aminoalcohols [16], leucoanthocyanins
[17], and 3-aminopiperidines [18]. The asymmetric syn-
thesis of 2H-azirine-2-phosphates involving Neber
rearrangement has also been recently reported [19].
Introduction.
The chemistry and pharmacology of suitably substituted
benzoxazoles have attracted the attention of organic
chemists and biochemists. A large number of benzoxa-
zoles and their derivatives have been shown to possess
interesting biological activities [1-6] and photophysical
properties [7,8]. A variety of methods are available to syn-
thesize such benzoxazoles [9-12]. Here we report a new
facile route to synthesize 4,6-diaryl-2-methyl-1,3-benzox-
Scheme 1

1322
V. Sridharan, S. Muthusubramanian and S. Sivasubramanian
Vol. 42
The key chiral intermediate for the synthesis of a β
3
agonist was prepared via an improved Neber rearrange-
ment [20]. The intermediate 1-aminoindolo[2,3-a]quino-
lizidine for the synthesis of E-azaeburamine type com-
pounds has been successfully prepared employing this
rearrangement [21].
Results and Discussion.
Figure 1
We planned to synthesize the target compounds 8 from
3,5-diarylcyclohex-2-en-1-ones, 1 involving the base- cat-
alyzed Neber rearrangement (Scheme 1). The 3,5-diarylcy-
clohex-2-en-1-ones 1 were prepared from the corresponding
chalcones and ethyl acetoacetate by the reported method
[22]. The enones were converted to their oximes 2 by reflux-
Since the isomers 6 and 7 have the same R value under
f
identical conditions, these compounds could not be sepa-
rated. The aromatized product was separated from the mix-
ture through silica column chromatography. It should be
mentioned that the acetates 5g and 5i, in which the 2-furyl
group is at 5 position, upon treatment with phosphorous
oxychloride gave entirely the aromatized product 8g and 8i
respectively with no trace of 6 or 7.
ing the alcoholic solution of the enones with an excess of
13
hydroxylamine hydrochloride and sodium acetate. The
C
NMR spectrum of the crude oxime 2 showed the formation
of a major amount of E-isomer and a trace amount of the Z-
isomer. In the case of 2a, the C-2 olefinic carbon appears at
119.9 ppm for the E-isomer and at 112.4 ppm for the Z-iso-
Table 1
1
Yields of 6,7 and 8 Obtained from POCl Cyclisation of 5
3
mer but in the H NMR spectrum, the olefinic hydrogen of
the E-isomer appears at 6.67 ppm and that of the Z-isomer
gets deshielded and merged with the other aromatic protons.
The major E-isomer was isolated by a careful recrystalliza-
tion of the mixture from ethanol and characterized by NMR.
The E-oximes 2 were converted to their corresponding tosy-
lates 3 by treating the oximes with a large excess of p-tolue-
nesulfonyl chloride in pyridine at 0 °C.
The key step of our synthetic route is the conversion of
oxime tosylate 3 to the amine hydrochloride 4 by a Neber
rearrangement. When the oxime tosylate 3 was treated
with sodium ethoxide in absolute ethanol, it was converted
to the corresponding α-amino ketone, which was then con-
verted to amine hydrochloride 4 by treatment with
hydrochloric acid.
Starting acetate Overall yield of
Percentage yield*
6, 7 and 8 %
6
7
8
5a
5b
5c
5d
5e
5f
5g
5h
5i
93
90
94
92
95
89
80
91
65
93
77
75
86
31
80
60
0
29
0
39
8
15
3
54
8
30
0
59
0
15
10
11
15
12
10
100
12
100
13
5j
48
1
* calculated from H NMR based on the 2-methyl signal intensity.
In the case of compound 6a (Scheme 2), the proton H-7
appeared at 6.75 ppm as a broad singlet as it has two pro-
tons in the allylic position. The protons H-5a and H-5b
appeared as two different doublets of doublets of doublets
(ddd) at 3.10 ppm (J = 17.1, 8.7, 0.9 Hz) and 3.33 ppm (J =
17.1, 9.0, 1.8 Hz) respectively and H-4 appeared as dou-
blet of doublets with coupling constants 9.0 and 8.7 Hz.
For compound 7a, the proton H-7' appeared as a doublet of
triplets at 6.26 ppm with coupling constants 3.6 and 1.8 Hz
and H-6' appeared as another doublet of triplets with cou-
pling constants 7.2 and 3.6 Hz. The geminal hydrogens H-
5'a and H-5'b appeared as a multiplet in between 3.69 ppm
It should be mentioned that the formation of the azirine
intermediate in a Neber rearrangement was independent of
the configuration of the oxime tosylate. The crude oxime
mixture containing both E and Z isomers was also con-
verted into the corresponding mixture of oxime tosylates
(characterized by NMR) which on treatment with sodium
ethoxide was converted to the amine with the same percent-
age yield as in the case of pure E-isomer of the tosylate.
The N-(2-oxo-4,6-diaryl-3-cyclohexyl) acetamides 5
have been obtained by acetylating the hydrochlorides of
α-amino ketones 4 with acetic anhydride and sodium
acetate in good yield. Although we had planned to cyclise
the acetates 5 with phosphoryl chloride to get 6, there is a
possibility for the formation of phenanthridone derivative
9 [23] (Figure 1). But the expected product 6 was isolated
along with its isomer 7 and the aromatized product 8. The
overall yield of this reaction was excellent and the percent-
age yields of the hydrogenated products 6, 7 and the arom-
1
13
and 3.87 ppm. The selected H and C NMR signals of 6
and 7 are given in Tables 2 and 3 respectively.
The formation of 7 can be explained by the [1,5] sigma-
tropic rearrangement (Scheme 2) of 6, which is a symme-
try allowed process under thermal condition. The percent-
age of 7, in some cases, is high even though the oxazole
ring loses its aromatic sextet. The aromatized product 8
1
atized product 8 were calculated from H NMR (Table 1).

Nov-Dec 2005
A Novel Synthetic Route for the Synthesis of 4,6-Diaryl-2-methyl-1,3-benzoxazoles
1323
Scheme 2
dicyano-1,4-benzoquinone (DDQ) was employed for dehy-
drogenation in dioxane and the reaction was completed
within ten hours. The yields and reaction times of the DDQ
dehydrogenation of 6/7 are given in the experimental section.
All the benzoxazoles 8 are solids and were fully character-
ized by 1D and 2D NMR experiments and all the compounds
gave satisfactory C, H and N analytical data.
The configuration of the acetate 5 may play a role in the
cyclisation step with the possibility for the formation of
Table 2
1H NMR* data of 6 and 7
Compd.
2-Me
s
H-4
dd
H-5a
ddd
H-5b
ddd
H-7
bs
2'-Me
s
H-5'a &
5'b m
H-6'
dt
H-7'
td
Others
6,7a
6,7b
6,7c
6,7d
6,7e
6,7f
6,7h
6,7j
2.45
2.45
2.46
2.45
2.41
2.42
2.43
2.45
4.28 (J =
9.0, 8.7 Hz)
4.27 (J =
3.10 (J = 17.1, 3.33 (J = 17.1,
8.7, 0.9 Hz) 9.0, 1.8 Hz)
3.04 (J = 17.1, 3.28 (J = 17.1,
8.7, 0.9 Hz) 9.0, 1.5 Hz)
3.02 (J = 16.8, 3.26 (J = 16.8,
8.7, 0.9 Hz) 9.0, 1.5 Hz)
3.21 (J = 17.1, 3.42 (J = 17.1,
9.0, 1.2 Hz) 9.0, 1.5 Hz)
3.06 (J = 17.1, 3.27 (J = 17.1,
8.7, 0.9 Hz) 9.0, 1.5 Hz)
3.05 (J = 17.1, 3.27 (J = 17.1,
8.7, 1.2 Hz) 9.0, 1.8 Hz)
3.07 (J = 17.1, 3.28 (J = 17.1,
8.7, 1.2 Hz) 9.3, 1.5 Hz)
3.16 (J = 16.8, 3.31 (J = 16.8,
8.7, 0.9 Hz) 8.7, 1.8 Hz)
6.75
6.73
6.73
6.89
6.72
6.73
6.76
6.69
2.42
2.42
2.43
2.43
2.39
2.39
2.41
2.43
3.69-
3.87
3.65-
3.83
3.70-
3.90
3.79-
3.97
3.65-
3.82
3.67-
3.85
3.68-
3.87
3.62-
3.78
4.70 (J =
6.26 (J =
7.18-7.45, m
7.19-7.39, m
7.2, 3.6 Hz) 3.6, 1.5 Hz)
4.69 (J = 6.24 (J =
6.9, 3.6 Hz) 3.6, 1.8 Hz)
4.65 (J = 6.23 (J =
6.9, 3.6 Hz) 3.6, 1.8 Hz)
4.73 (J = 6.41 (J =
7.2, 3.6 Hz) 3.6, 1.5 Hz)
4.64 (J = 6.24 (J =
7.2, 3.6 Hz) 3.6, 1.8 Hz)
4.63 (J = 6.23 (J =
7.2, 3.9 Hz) 3.9, 1.8 Hz)
4.63 (J = 6.31 (J =
6.9, 3.6 Hz) 3.6, 1.5 Hz)
4.99 (J = 6.28 (J =
7.2, 3.6 Hz) 3.6, 1.8 Hz)
9.0, 8.7 Hz)
4.23 (J =
3.76, s, 3.80, s
6.82-7.37, m
7.20-7.85, m
9.0, 8.7 Hz)
4.31 (J =
9.0, 9.0 Hz)
4.21 (J =
2.27, s, 2.28, s
7.06-7.42
9.0, 8.7 Hz)
4.21 (J =
9.0, 8.7 Hz)
4.23 (J =
9.3, 8.7 Hz)
4.53 (J =
8.7, 8.7 Hz)
3.72, s, 3.73, s
6.80-7.46, m
2.29, s, 2.30, s
6.95-7.20, m
2.33, s, 2.34, s
6.89-7.54, m
*chemical shifts in ppm and coupling constants in Hz.
was obtained from either 6 or 7, probably by air oxidation.
Though 7 has been assigned a structure as shown in
Scheme 2, it could have an alternate structure 7'
(Scheme 1) with double bonds between 3a/7a and 4/5 in
the central ring. This structure 7', which may result due to
a subsequent [1,5] sigmatropic shift on 7, also accounts for
the available NMR data.
phenanthridone derivative 9 (Figure 1). The coupling con-
stant of protons H-1 and H-6 are very high (around 13 Hz)
suggesting that they are perfectly anti to each other. This
has also been confirmed from the NOESY spectrum. The
proton H-1 made very strong nOe contact with the NH pro-
ton but it showed a very weak correlation with H-6. The
preferable geometry of the acetate 5 is shown in Figure 1.
Although this diequatorial like arrangement of the
acetamido group and the aryl ring is not unfavorable for
cyclisation to yield 9, the easy enolisation at carbonyl dri-
ven by the presence of conjugation makes the other cycli-
sation to yield 6 easier.
Although the dihydrobenzoxazoles are easily air oxidized,
to achieve complete conversion of 6/7 to 8, 2,3-dichloro-5,6-
Table 3
13
Selected C NMR* Data of 6 and 7
Compd.
6,7a
6,7b
6c
6,7d
6,7e
6,7f
C-4
40.0
39.9
39.1
40.1
39.6
39.1
39.5
35.1
C-5
37.8
37.6
37.8
37.6
37.7
37.8
37.6
37.9
C-7
C-5'
26.5
26.4
**
26.5
26.5
26.4
26.7
26.5
C-6'
43.5
43.5
**
43.6
43.1
42.6
42.8
37.9
EXPERIMENTAL
111.9
112.2
112.2
112.2
111.8
111.8
110.0
111.0
1
13
All melting points are uncorrected. H, C and the related 2D
NMR spectra were recorded on a Bruker 300 MHz instrument in
CDCl using TMS as internal standard. Chemical shifts are given
3
in parts per million (δ-scale) while coupling constants are in
Hertz. IR spectra were recorded on a Jasco FT-IR instrument
(KBr). Elemental analyses were carried out on a Vario EL III
instrument. Column chromatography was carried out on silica gel
(60-120 mesh) using petroleum ether-ethyl acetate as eluent.
6,7h
6,7j
* Chemical shifts in ppm; ** The concentration of 7c is so small in the
mixture to get recognizable signals.

1324
V. Sridharan, S. Muthusubramanian and S. Sivasubramanian
Vol. 42
Preparation of 3,5-diaryl-2-cyclohexen-1-one (1).
This compound was obtained as colorless crystals (alcohol),
yield: 70%, mp 106-107 ºC (107-108 ºC) [22].
General Procedure.
5-(2-Furyl)-3-(2-thienyl)-2-cyclohexen-1-one (1g).
To a mixture of 1,3-diaryl-2-propen-1-one (20 mmol) and
ethyl acetoacetate (2.60 g, 20 mmol) in dry ether (60 mL), a
solution of sodium ethoxide (0.276 g, 4 mmol) in ethanol (20
mL) was added. The reaction mixture was stirred for 20 h, acid-
ified with acetic acid (4 mL) and the organic layer was washed
with water. The ethereal solution was dried (Na SO ) and evapo-
rated to get the β-ketoester, which was refluxed with 10% sodium
hydroxide solution (100 mL) for 6 h. After completion of the
reaction, the mixture was extracted with chloroform and dried.
The pure product of 1 was obtained either by recrystallization
from alcohol or by running through silica column.
This compound was obtained as colorless crystals (alcohol),
yield 69%, mp 87-88 ºC; ir (KBr) 3052, 2911, 1650, 1592, 1417,
-1
1
1319, 1257, 1090, 1010 cm ; H nmr (300 MHz, CDCl ) δ 2.63-
3
2.99 (m, 3 H), 3.21 (dd, J = 17.7, 4.5 Hz, 1 H), 3.53-3.61 (m, 1
H), 6.12 (d, J = 3.0 Hz, 1 H), 6.33 (dd, J = 3.0, 1.8 Hz, 1 H), 6.48
(d, J = 2.1 Hz, 1 H), 7.12 (dd, J = 4.5, 4.2 Hz, 1 H), 7.37-7.47 (m,
2
4
13
3 H); C nmr (75 MHz, CDCl ) δ 33.3, 34.3, 41.8, 105.3, 110.6,
3
122.8, 128.2, 128.8, 129.6, 142.1, 142.7, 151.2, 156.5, 198.2.
Anal. Calcd for C H O S: C, 68.83; H, 4.95%. Found: C,
14 12
2
68.9; H, 4.9%.
3,5-Diphenyl-2-cyclohexen-1-one (1a).
5-(4-Methylphenyl)-3-(2-thienyl)-2-cyclohexen-1-one (1h).
This compound was obtained as colorless crystals (alcohol),
yield 75%, mp 89-90 ºC (89-90 ºC) [22].
This compound was obtained as colorless crystals (alcohol),
yield: 70%, mp 116-117 ºC; ir (KBr): 3043, 2915, 1655, 1594,
-1 1
1470, 1310, 1255, 1094, 1016 cm ; H nmr (300 MHz, CDCl ) δ
3
3-(4-Chlorophenyl)-5-phenyl-2-cyclohexen-1-one (1b).
2.35 (s, 3 H), 2.64-2.70 (m, 2 H), 2.84 (ddd, J = 17.4, 11.1, 2.1
Hz, 1 H), 3.07 (dd, J = 17.4, 4.2 Hz, 1 H), 3.33-3.43 (m, 1 H),
6.50 (d, J = 2.1 Hz, 1 H), 7.07 (dd, J = 5.1, 3.9 Hz, 1 H), 7.17-
7.19 (m, 4 H), 7.36 (d, J = 3.9 Hz, 1 H), 7.42 (dd, J = 5.1, 0.6 Hz,
This compound was obtained as colorless crystals (alcohol),
yield 72%, mp 104-105 ºC; ir (KBr) 3031, 2938, 1654, 1594,
-1 1
1488, 1402, 1261, 1093, 1014 cm ; H nmr (300 MHz, CDCl ) δ
3
13
2.65-2.81 (m, 2 H), 2.84-3.04 (m, 2 H), 3.39-3.50 (m, 1 H), 6.48
1 H); C nmr (75 MHz, CDCl ) δ 21.5, 36.6, 40.7, 44.6, 122.8,
3
(d, J = 2.1 Hz, 1 H), 7.25-7.40 (m, 7 H), 7.48 (d, J = 8.4 Hz, 2 H);
127.1, 128.1, 128.8, 129.5, 130.0, 137.2, 140.5, 142.8, 152.0,
199.2.
13
C nmr (75 MHz, CDCl ) δ 36.1, 40.9, 43.8, 125.3, 126.7,
3
127.1, 127.4, 128.8, 129.0, 136.2, 136.7, 142.9, 157.2, 199.0.
Anal. Calcd for C H OS: C, 76.08; H, 6.01%. Found: C,
17 16
Anal. Calcd for C H ClO: C, 76.46; H, 5.35%. Found: C,
76.2; H, 5.9%.
18 15
76.5; H, 5.3%.
5-(2-Furyl)-3-phenyl-2-cyclohexen-1-one (1i).
3-(4-Chlorophenyl)-5-(4-methoxyphenyl)-2-cyclohexen-1-one
(1c).
This compound was obtained as colorless crystals (alcohol),
yield: 73%, mp 44-45 ºC; ir (KBr) 3030, 2937, 1651, 1596, 1488,
-1
1
This compound was obtained as colorless crystals (alcohol),
yield: 76%, mp 129-130 ºC. ir (KBr) 3048, 2940, 1652, 1590,
1405, 1261, 1094, 1010 cm ; H nmr (300 MHz, CDCl ) δ 2.68
3
(dd, J = 16.5, 11.4 Hz, 1 H), 2.84 (dd, J = 16.5, 4.2 Hz, 1 H), 2.96
(ddd, J = 17.7, 9.9, 2.1 Hz, 1 H), 3.16 (dd, J = 17.7, 4.8 Hz, 1 H),
3.52-3.62 (m, 1 H), 6.11 (m, 1 H), 6.32 (dd, J = 3.0, 1.8 Hz, 1 H),
6.47 (d, J = 1.8Hz, 1 H), 7.36 (dd, J = 1.8, 0.9 Hz, 1 H), 7.40-7.43
-1 1
1486, 1400, 1270, 1099, 1015 cm ; H nmr (300 MHz, CDCl ) δ
3
2.62-2.80 (m, 2 H), 2.84-3.02 (m, 2 H), 3.34-3.45 (m, 1 H), 3.81
(s, 3 H), 6.47 (d, J = 2.4 Hz, 1 H), 6.91 (d, J = 8.7 Hz, 2 H), 7.21
(d, J = 8.7 Hz, 2 H), 7.37 (d, J = 8.4 Hz, 2 H), 7.48 (d, J = 8.4 Hz,
13
(m, 3 H), 7.54-7.58 (m, 2 H); C nmr (75 MHz, CDCl ) δ 33.6,
3
13
2 H); C nmr (75 MHz, CDCl ) δ 36.9, 40.6, 44.6, 55.7, 114.6,
34.7, 41.8, 105.2, 110.6, 125.6, 126.6, 129.3, 130.6, 138.7, 142.0,
156.7, 158.5, 198.8.
3
125.7, 127.9, 128.2, 129.5, 135.6, 136.6, 137.2, 157.8, 159.0,
199.6.
Anal. Calcd for C H O : C, 80.65; H, 5.92%. Found: C,
16 14
2
Anal. Calcd for C H ClO : C, 72.96; H, 5.48%. Found: C,
80.7; H, 6.0%.
19 17
2
73.0; H, 5.5%.
3-(4-Methylphenyl)-5-(2-thienyl)-2-cyclohexen-1-one (1j).
3-(2-Naphthyl)-5-phenyl-2-cyclohexen-1-one (1d).
This compound was obtained as colorless crystals (alcohol),
yield 74%, mp 72-73 ºC; ir (KBr) 3073, 2927, 1650, 1596, 1413,
This compound was obtained as colorless crystals (alcohol),
yield: 78%, mp 157-158 ºC; ir (KBr) 3033, 2938, 1650, 1594,
-1
1
1359, 1268, 1085, 1015 cm ; H nmr (300 MHz, CDCl ) δ 2.37
3
-1 1
1480, 1404, 1275, 1080, 1021 cm ; H nmr (300 MHz, CDCl ) δ
(s, 3 H), 2.68 (dd, J = 16.5, 11.4 Hz, 1 H), 2.86-2.97 (m, 2 H),
3.18 (dd, J = 17.7, 4.2 Hz, 1 H), 3.67-3.74 (m, 1 H), 6.49 (d, J =
3
2.70-2.85 (m, 2 H), 2.96-3.24 (m, 2 H), 3.44-3.53 (m, 1 H), 6.67
(d, J = 2.1 Hz, 1 H), 7.28-7.44 (m, 5 H), 7.50-7.53 (m, 2 H), 7.66
(d, J = 8.4 Hz, 1 H), 7.82-7.87 (m, 3 H), 8.01 (s, 1 H); C nmr
2.1 Hz, 1 H), 6.92 (m, 1 H), 6.97 (dd, J = 5.1, 3.3 Hz, 1 H), 7.18-
13
13
7.24 (m, 3 H), 7.45 (d, J = 8.4 H, 2 H); C nmr (75 MHz, CDCl )
3
(75 MHz, CDCl ) δ 36.7, 41.5, 44.4, 123.7, 125.8, 126.8, 127.2,
δ 21.8, 36.7, 37.3, 45.4, 123.9, 124.0, 124.9, 126.6, 127.3, 130.0,
3
127.3, 127.6, 127.8, 128.1, 129.0, 129.1, 129.3, 133.5, 134.4,
135.8, 143.7, 158.8, 199.7.
135.6, 141.2, 147.7, 158.6, 198.23.
Anal. Calcd for C H OS: C, 76.08; H, 6.01%. Found: C,
17 16
Anal. Calcd for C H O: C, 88.56; H, 6.08%. Found: C, 88.6;
76.1; H, 6.0%.
22 18
H, 6.2%.
Preparation of 3,5-Diaryl-2-cyclohexen-1-one Oxime (2).
General Procedure.
5-(4-Methylphenyl)-3-phenyl-2-cyclohexen-1-one (1e).
This compound was obtained as colorless crystals (alcohol),
yield 74%, mp 105-106 ºC (106.5-107.5 ºC) [22].
To a solution of 3,5-diaryl-2-cyclohexen-1-one 1 (3.0 g) in
minimum amount of alcohol, a saturated solution of 6 g of
hydroxylamine hydrochloride and 9 g of sodium acetate was
5-(4-Methoxyphenyl)-3-phenyl-2-cyclohexen-1-one (1f).

Nov-Dec 2005
A Novel Synthetic Route for the Synthesis of 4,6-Diaryl-2-methyl-1,3-benzoxazoles
1325
-1
1
added. The reaction mixture was refluxed for an hour on a water
bath and poured into crushed ice, filtered and dried. The major E
isomer was crystallized out in alcohol from the crude mixture of
E and Z isomers.
1430, 1370, 1326, 960 cm ; H nmr (300 MHz, CDCl ) δ 2.41
3
(dd, J = 16.8, 12.9 Hz, 1 H), 2.62-2.91 (m, 2 H), 3.04-3.16 (m, 1
H), 3.38 (dd, J = 17.1, 3.6 Hz, 1 H), 3.81 (s, 3 H), 6.65 (d, J = 1.2
Hz, 1 H), 6.89 (d, J = 8.7 Hz, 2 H), 7.22-7.37 (m, 5 H), 7.49 (dd,
J = 8.4, 1.5 Hz, 2 H), 9.20 (bs, 1 H).
(E)-3,5-Diphenyl-2-cyclohexen-1-one Oxime (2a).
Anal. Calcd for C H NO : C, 77.79; H, 6.53; N, 4.77%.
19 19
2
This compound was obtained as colorless solid (alcohol), yield
91%, mp 165-66 ºC (167-170 ºC) [24].
Found: C, 77.8; H, 6.6; N, 4.7%.
(E) 5-(2-Furyl)-3-(2-thienyl)-2-cyclohexen-1-one Oxime (2g).
(E) 3-(4-Chlorophenyl)-5-phenyl-2-cyclohexen-1-one Oxime
(2b).
This compound was obtained as colorless solid (alcohol), yield
89%, mp 134-135 ºC; ir (KBr): 3270, 3045, 2905, 1600, 1495,
1436, 1370, 1326, 1175, 1140, 970 cm ; H nmr (300 MHz,
CDCl ) δ 2.55 (dd, J = 16.5, 11.4 Hz, 1 H), 2.65-3.06 (m, 2 H),
3.23-3.32 (m, 1 H) 3.38 (dd, J = 16.8, 4.2 Hz, 1 H), 6.12 (d, J =
This compound was obtained as colorless solid (alcohol), yield
93%, mp 154-155 ºC; ir (KBr) 3260, 3030, 2890, 1605, 1515,
-1
1
3
-1
1
1430, 1370, 1320, 980 cm ; H nmr (300 MHz, CDCl ) δ 2.44
3
(dd, J = 16.8, 12.9 Hz, 1 H), 2.65-2.94 (m, 2 H), 3.07-3.23 (m, 1
H), 3.41 (dd, J = 17.1, 3.9 Hz, 1 H), 6.64 (s, 1 H), 7.24-7.49 (m, 9
H), 9.30 (bs, 1 H); C nmr (75 MHz, CDCl ) δ 29.3, 36.0, 39.7,
121.1, 127.1, 127.3, 127.4, 127.6, 129.1, 134.5, 138.7, 144.1,
144.7, 157.8.
2.1 Hz, 1 H), 6.31 (bs, 1 H), 6.66 (bs, 1 H), 7.00-7.35 (m, 4 H),
13
10.10 (bs, 1 H); C nmr (75 MHz, CDCl ) δ 26.9, 32.7, 33.0,
104.9, 110.6, 119.0, 124.8, 126.2, 128.2, 138.1, 141.8, 144.6,
156.6, 157.7.
3
13
3
Anal. Calcd for C H NO S: C, 64.84; H, 5.05; N, 5.40%.
14 13
2
Anal. Calcd for C H ClNO: C, 72.60; H, 5.42; N, 4.70%.
18 16
Found: C, 64.8; H, 5.1; N, 5.3%.
Found: C, 72.7; H, 5.5; N, 4.7%.
(E) 5-(4-Methylphenyl)-3-(2-thienyl)-2-cyclohexen-1-one
Oxime (2h).
(E) 3-(4-Chlorophenyl)-5-(4-methoxyphenyl)-2-cyclohexen-1-
one Oxime (2c).
This compound was obtained as colorless solid (alcohol), yield
92%, mp 155-156 ºC; ir (KBr): 3265, 3025, 2898, 1600, 1513,
This compound was obtained as colorless solid (alcohol), yield
85%, mp 188-189 ºC; ir (KBr) 3265, 3045, 2892, 1601, 1498,
-1
1
1427, 1375, 1320, 983 cm ; H nmr (300 MHz, CDCl ) δ 2.35
3
-1
1
1433, 1372, 1325, 975 cm ; H nmr (300 MHz, CDCl ) δ 2.40
3
(s, 3 H) 2.41 (dd, J = 17.1, 12.9 Hz, 1 H), 2.61-2.95 (m, 2 H),
3.05-3.16 (m, 1 H), 3.39 (dd, J = 16.8, 4.2 Hz, 1 H), 6.66 (s, 1 H),
(dd, J = 16.8, 12.9 Hz, 1 H), 2.61-2.86 (m, 2 H), 3.04-3.14 (m, 1
H), 3.37 (dd, J = 17.1, 4.2 Hz, 1 H), 3.82 (s, 3 H), 6.61 (d, J = 1.5
Hz, 1 H), 6.90 (d, J = 8.7 Hz, 2 H), 7.24 (d, J = 8.7 Hz, 2 H), 7.32
(d, J = 8.7 Hz, 2 H), 7.42 (d, J = 8.7 Hz, 2 H), 8.50 (bs, 1 H).
13
6.98-7.34 (m, 7 H), 9.20 (bs, 1 H); C nmr (75 MHz, CDCl ) δ
3
21.5, 29.4, 36.3, 39.0, 119.0, 124.6, 126.1, 127.2, 127.3, 129.8,
136.9, 139.1, 141.7, 144.8, 157.8.
Anal. Calcd for C H ClNO : C, 69.62; H, 5.53; N, 4.27%.
19 18
2
Anal. Calcd for C H NOS: C, 72.05; H, 6.05; N, 4.94%.
17 17
Found: C, 69.7; H, 5.5; N, 4.3%.
Found: C, 72.0; H, 6.1; N, 5.0%.
(E) 3-(2-Naphthyl)-5-phenyl-2-cyclohexen-1-one Oxime (2d).
5-(2-Furyl)-3-phenyl-2-cyclohexen-1-one Oxime (2i).
This compound was obtained as colorless solid (alcohol), yield
96%, mp 180-181 ºC; ir (KBr) 3262, 3052, 2896, 1600, 1496,
This compound was obtained as colorless solid (alcohol), yield
86%, mp 148-149 ºC; ir (KBr): 3270, 3056, 2904, 1602, 1496,
-1
1
1427, 1373, 1317, 968 cm ; H nmr (300 MHz, CDCl ) δ 2.50
3
-1
1
1436, 1369, 1326, 1180, 1145, 966 cm ; H nmr (300 MHz,
(dd, J = 16.8, 12.9 Hz, 1 H), 2.76-3.09 (m, 2 H), 3.15-3.24 (m, 1
H), 3.45 (dd, J = 16.2, 3.6 Hz, 1 H), 6.83 (s, 1 H), 7.29-7.98 (m,
12 H), 9.50 (bs, 1 H).
CDCl ) δ 2.57 (dd, J = 16.8, 11.4 Hz, 1 H), 2.77 (ddd, J = 17.1,
3
9.9, 1.5 Hz, 1 H), 3.01 (dd, J = 17.1, 4.2 Hz, 1 H), 3.22-3.32 (m,
1 H), 3.40 (dd, J = 16.8, 4.2 Hz, 1 H), 6.20 (dd, J = 3.0, 0.6 Hz, 1
Anal. Calcd for C
H NO: C, 84.31; H, 6.11; N, 4.47%.
22 19
H), 6.31 (dd, J = 3.3, 3.0 Hz, 1 H), 6.65 (d, J = 1.5 Hz, 1 H), 7.30-
7.38 (m, 4 H), 7.50 (dd, J = 7.8, 1.2 Hz, 2 H), 9.80 (bs, 1 H);
Found: C, 84.4; H, 6.2; N, 4.4%.
13
C
(E) 5-(4-Methylphenyl)-3-phenyl-2-cyclohexen-1-one Oxime
(2e).
nmr (75 MHz, CDCl ): δ = 26.9, 32.9, 33.0, 104.81, 110.6, 120.8,
3
125.9, 128.8, 129.0, 140.3, 141.8, 144.5, 157.0, 157.9.
Anal. Calcd for C H NO : C, 75.87; H, 5.97; N, 5.53%.
Found: C, 75.8; H, 5.9; N, 5.4%.
This compound was obtained as colorless solid (alcohol), yield
93%, mp 162-163 ºC; ir (KBr) 3266, 3043, 2895, 1608, 1510,
16 15
2
-1
1
1425, 1375, 1319, 976 cm ; H nmr (300 MHz, CDCl ) δ 2.35
3
(E) 3-(4-Methylphenyl)-5-(2-thienyl)-2-cyclohexen-1-one
Oxime (2j).
(s, 3 H), 2.43 (dd, J = 17.1, 12.9 Hz, 1 H), 2.68-2.91 (m, 2 H),
3.04-3.17 (m, 1 H), 3.40 (dd, J = 16.8, 4.2 Hz, 1 H), 6.66 (s, 1 H),
13
This compound was obtained as colorless solid (alcohol), yield
90%, mp 66-67 ºC; ir (KBr): 3266, 3052, 2895, 1599, 1492,
7.15-7.36 (m, 7 H), 7.49 (d, J = 8.1 Hz, 2 H), 9.80 (bs, 1 H);
C
nmr (75 MHz, CDCl ) δ 21.5, 29.4, 36.3, 39.3, 120.8, 125.8,
3
-1
1
1430, 1370, 1320, 970 cm ; H nmr (300 MHz, CDCl ) δ 2.34
127.3, 128.7, 129.0, 129.8, 136.8, 140.3, 141.9, 145.4, 158.1.
3
(s, 3 H), 2.51 (dd, J = 16.2, 11.4 Hz, 1 H), 2.69-3.04 (m, 2 H),
Anal. Calcd for C
H NO: C, 82.28; H, 6.90; N, 5.05%.
19 19
3.38-3.52 (m, 2 H), 6.64 (d, J = 1.8 Hz, 1 H), 6.92-6.96 (m, 2 H),
Found: C, 82.2; H, 6.9; N, 5.0%.
13
7.13-7.18 (m, 3 H), 7.39 (d, J = 8.1 Hz, 2 H), 9.80 (bs, 1 H);
C
(E) 5-(4-Methoxyphenyl)-3-phenyl-2-cyclohexen-1-one Oxime
(2f).
nmr (75 MHz, CDCl ) δ 21.6, 30.5, 35.0, 36.9, 120.2, 123.7,
3
125.8, 126.3, 127.2, 129.7, 137.3, 138.8, 144.6, 149.0, 157.3.
Anal. Calcd for C H NOS: C, 72.05; H, 6.05; N, 4.94%.
Found: C, 72.2; H, 6.0; N, 5.0%.
This compound was obtained as colorless solid (alcohol), yield
88%, mp 164-165 ºC; ir (KBr) 3275, 3055, 2900, 1602, 1497,
17 17

1326
V. Sridharan, S. Muthusubramanian and S. Sivasubramanian
Vol. 42
Preparation of 3,5-diaryl-2-cyclohexen-1-one Oxime Tosylate (3).
7.28-7.81 (m, 14 H), 7.91 (d, J = 8.4 Hz, 2 H).
Anal. Calcd for C H NO S: C, 74.49; H, 5.39; N, 3.00%.
Found: C, 74.6; H, 5.5; N, 3.1%.
29 25
3
General Procedure.
To a cold solution of E-3,5-diaryl-2-cyclohexen-1-one oxime 2
(8 mmol) in dry pyridine (28 mL), a solution of p-toluenesulfonyl
chloride (6.0 g, 32 mmol) in dry pyridine (14 mL) was added
slowly, maintaining the temperature at 0-2 °C. The stirring was
continued at 0 ºC for 2 h and the reaction mixture was poured into
crushed ice with vigorous stirring. The product was filtered,
washed with water, dried and recrystallised from alcohol.
(E) 5-(4-Methylphenyl)-3-phenyl-2-cyclohexen-1-one Oxime
Tosylate (3e).
This compound was obtained as colorless solid (alcohol), yield
88%, mp 70-71 ºC; ir (KBr) 3050, 2935, 2850, 1613, 1494, 1373,
-1
1
1188, 1179, 1094 cm ; H nmr (300 MHz, CDCl ) δ 2.34 (s, 3
3
H), 2.44 (s, 3 H), 2.49 (dd, J = 17.4, 13.2 Hz, 1 H), 2.72 (ddd, J =
17.4, 11.1, 2.1 Hz, 1 H), 2.89 (dd, J = 17.4, 4.2 Hz, 1 H), 3.01-
3.13 (m, 1 H), 3.33 (dd, J = 17.4, 4.2 Hz, 1 H), 6.59 (d, J = 2.1
Hz, 1 H), 7.13-7.15 (m, 4 H), 7.33-7.47 (m, 7 H), 7.89 (d, J = 8.1
(E)-3,5-Diphenyl-2-cyclohexen-1-one Oxime Tosylate (3a).
This compound was obtained as colorless solid (alcohol), yield
95%, mp 136-137 ºC; ir (KBr) 3048, 2923, 2854, 1610, 1494,
13
Hz, 2 H); C nmr (75 MHz, CDCl ) δ 21.0, 21.7, 30.4, 35.6,
3
-1
1
1373, 1189, 1180, 1095 cm ; H nmr (300 MHz, CDCl ) δ 2.45
38.7, 118.0, 125.4, 126.7, 128.6, 128.7, 129.2, 129.5, 129.6,
132.7, 136.8, 139.0, 140.1, 145.0, 150.6, 164.3.
3
(s, 3 H), 2.52 (dd, J = 17.1, 12.9 Hz, 1 H), 2.74 (ddd, J = 17.1,
11.1, 2.4 Hz, 1 H), 2.92 (dd, J = 17.1, 3.9 Hz, 1 H), 3.05-3.17 (m,
1 H), 3.36 (dd, J = 17.1, 3.9 Hz, 1 H), 6.60 (d, J = 2.4 Hz, 1 H),
7.23-7.54 (m, 12 H), 7.89 (d, J = 8.4 Hz, 2 H).
Anal. Calcd for C H NO S: C, 72.36; H, 5.84; N, 3.25%.
26 25
3
Found: C, 72.4; H, 5.8; N, 3.2%.
(E) 5-(4-Methoxyphenyl)-3-phenyl-2-cyclohexen-1-one Oxime
Tosylate (3f).
Anal. Calcd for C H NO S: C, 71.92; H, 5.55; N, 3.35%.
25 23
3
Found: C, 71.8; H, 5.5; N, 3.4%.
This compound was obtained as colorless solid (alcohol), yield
86%, mp 119-120 ºC; ir (KBr) 3046, 2925, 2858, 1610, 1489, 1368,
(E) 3-(4-Chlorophenyl)-5-phenyl-2-cyclohexen-1-one Oxime
Tosylate (3b).
-1 1
1185, 1176, 1090 cm ; H nmr (300 MHz, CDCl ) δ 2.44 (s, 3 H),
3
This compound was obtained as colorless solid (alcohol), yield
92%, mp 85-86 ºC; ir (KBr) 3042, 2930, 2845, 1615, 1490, 1375,
2.47 (dd, J = 17.1, 10.2 Hz, 1 H), 2.69 (ddd, J = 17.1, 11.1, 2.1 Hz,
1 H), 2.88 (dd, J = 17.1, 3.9 Hz, 1 H), 2.96-3.10 (m, 1 H), 3.31 (dd,
J = 17.1, 3.9 Hz, 1 H), 3.81 (s, 3 H), 6.58 (d, J = 2.1 Hz, 1 H), 6.88
(d, J = 8.7 Hz, 2 H), 7.17 (d, J = 8.7 Hz, 2 H), 7.33-7.45 (m, 7 H),
-1
1
1180, 1173, 1098 cm ; H nmr (300 MHz, CDCl ) δ 2.44 (s, 3
3
H), 2.50 (dd, J = 17.4, 13.2 Hz, 1 H), 2.71 (ddd, J = 17.4, 11.4,
2.4 Hz, 1 H), 2.86 (dd, J = 17.4, 4.2 Hz, 1 H), 3.04-3.20 (m, 1 H),
3.35 (dd, J = 17.4, 4.2 Hz, 1 H), 6.57 (d, J = 2.4 Hz, 1 H), 7.24-
13
7.89 (d, J = 8.4 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 21.7, 30.6,
3
35.7, 38.2, 55.3, 114.1, 117.9, 125.6, 127.8, 128.7, 128.8, 129.2,
129.6, 132.7, 135.2, 139.0, 145.0, 150.6, 158.6, 164.3.
13
7.40 (m, 11 H), 7.88 (d, J = 8.1 Hz, 2 H); C nmr (75 MHz,
CDCl ) δ 21.7, 30.3, 35.3, 39.0, 118.4, 126.8, 126.9, 127.3,
Anal. Calcd for C H NO S: C, 69.78; H, 5.63; N, 3.13%.
Found: C, 69.9; H, 5.6; N, 3.2%.
3
26 25
4
128.8*, 128.9, 129.6, 132.6, 135.1, 137.4, 142.9, 145.1, 149.1,
163.9 (*two carbon signals are merged together).
(E) 5-(2-Furyl)-3-(2-thienyl)-2-cyclohexen-1-one Oxime
Tosylate (3g).
Anal. Calcd for C H ClNO S: C, 66.44; H, 4.91; N, 3.10%.
25 22
3
Found: C, 66.4; H, 4.8; N, 3.1%.
This compound was obtained as colorless solid (alcohol), yield
90%, mp 82-83 ºC; ir (KBr) 3042, 2930, 2856, 1616, 1490, 1370,
(E) 3-(4-Chlorophenyl)-5-(4-methoxyphenyl)-2-cyclohexen-1-
one Oxime Tosylate (3c).
-1 1
1178, 1170, 1085 cm ; H nmr (300 MHz, CDCl ) δ 2.44 (s, 3 H),
3
This compound was obtained as colorless solid (alcohol), yield
94%, mp 89-90 ºC; ir (KBr) 3035, 2927, 2840, 1612, 1513, 1371,
2.53 (dd, J = 17.4, 11.4 Hz, 1 H), 2.72 (ddd, J = 17.4, 10.2, 1.8 Hz,
1 H), 3.03 (dd, J = 17.4, 4.2 Hz, 1 H), 3.17-3.25 (m, 1 H), 3.28 (dd,
J = 17.1, 4.2 Hz, 1 H), 6.06 (d, J = 3.0 Hz, 1 H), 6.30 (dd, J = 3.3,
3.0 Hz, 1 H), 6.54 (d, J = 1.8 Hz, 1 H), 7.00-7.08 (m, 2 H), 7.22-7.47
-1
1
1191, 1178, 1093 cm ; H nmr (300 MHz, CDCl ) δ 2.44 (s, 3
3
H), 2.47 (dd, J = 17.1, 13.2 Hz, 1 H), 2.66 (ddd, J = 17.1, 11.4,
2.4 Hz, 1 H), 2.83 (dd, J = 17.1, 4.2 Hz, 1 H), 2.99-3.10 (m, 1 H),
3.32 (dd, J = 17.1, 3.9 Hz, 1 H), 3.81 (s, 3 H), 6.56 (d, J = 2.4 Hz,
1 H), 6.89 (d, J = 8.7 Hz, 2 H), 7.16 (d, J = 8.7 Hz, 2 H), 7.30-
13
(m, 4 H), 7.89 (d, J = 8.7 Hz, 2 H); C nmr (75 MHz, CDCl ) δ
3
22.1, 28.3, 32.4, 32.7, 105.3, 110.6, 116.2, 126.2, 127.7, 128.4,
129.3, 130.1, 133.0, 142.1, 143.2, 143.5, 145.5, 156.3, 163.5.
13
7.39 (m, 6 H), 7.89 (d, J = 8.4 Hz, 2 H); C nmr (75 MHz,
Anal. Calcd for C H NO S : C, 61.00; H, 4.63; N, 3.39%.
21 19
4 2
CDCl ) δ 21.7, 30.5, 35.6, 38.2, 55.3, 114.2, 118.4, 126.9, 127.8,
Found: C, 61.1; H, 4.7; N, 3.5%.
3
128.9*, 129.6, 132.6, 135.0, 135.1, 137.4, 145.0, 149.2, 158.7,
164.1 (*two carbon signals are merged together).
(E) 5-(4-Methylphenyl)-3-(2-thienyl)-2-cyclohexen-1-one
Oxime Tosylate (3h).
Anal. Calcd for C H ClNO S: C, 64.79; H, 5.02; N, 2.91%.
26 24
4
Found: C, 64.7%; H, 4.9; N, 3.0%.
This compound was obtained as colorless crystals (alcohol),
yield 89%, mp 143-144 ºC; ir (KBr) 3045, 2928, 2850, 1610,
(E) 3-(2-Naphthyl)-5-phenyl-2-cyclohexen-1-one Oxime
Tosylate (3d).
-1 1
1490, 1373, 1187, 1179, 1093 cm ; H nmr (300 MHz, CDCl ) δ
3
2.35 (s, 3 H), 2.44 (s, 3 H), 2.45 (dd, J = 17.1, 13.2 Hz, 1 H), 2.68
(ddd, J = 17.1, 12.3, 1.8 Hz, 1 H), 2.92 (dd, J = 17.1, 3.9 Hz, 1
H), 2.99-3.09 (m, 1 H), 3.29 (dd, J = 17.1, 3.9 Hz, 1 H), 6.57 (d,
J = 1.8 Hz, 1 H), 7.00 (t, J = 3.9 Hz, 1 H), 7.12-7.46 (m, 8 H),
This compound was obtained as colorless solid (alcohol), yield
96%, mp 164-165 ºC; ir (KBr) 3045, 2928, 2860, 1605, 1498,
-1
1
1365, 1180, 1175, 1080 cm ; H nmr (300 MHz, CDCl ) δ 2.45
3
13
(s, 3 H), 2.55 (dd, J = 17.1, 12.9 Hz, 1 H), 2.84 (ddd, J = 17.1,
11.4, 2.4 Hz, 1 H), 3.06 (dd, J = 17.4, 3.9 Hz, 1 H), 3.13-3.22 (m,
1 H), 3.39 (dd, J = 17.4, 3.9 Hz, 1 H), 6.76 (d, J = 2.4 Hz, 1 H),
7.89 (d, J = 8.4 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 21.5, 22.2,
3
30.9, 35.9, 38.7, 116.2, 127.0, 127.2, 127.6, 128.4, 129.3, 129.9,
130.1, 133.1, 137.3, 140.3, 143.6, 144.3, 145.4, 164.6.

Nov-Dec 2005
A Novel Synthetic Route for the Synthesis of 4,6-Diaryl-2-methyl-1,3-benzoxazoles
1327
Anal. Calcd for C H NO S : C, 65.88; H, 5.30; N, 3.20%.
N-(2-Oxo-4,6-diphenyl-3-cyclohexenyl)acetamide (5a).
24 23
3 2
Found: C, 65.8; H, 5.2; N, 3.1%.
This compound was obtained as pale yellow crystals (alcohol),
yield 61%, mp 149-150 ºC; ir (KBr) 3276, 3058, 2927, 1671,
1646, 1540, 1423, 1371, 1243, 1141 cm ; H nmr (300 MHz,
5-(2-Furyl)-3-phenyl-2-cyclohexen-1-one Oxime Tosylate (3i).
-1
1
This compound was obtained as colorless crystals (alcohol),
yield 91%, mp 128-129 ºC; ir (KBr) 3048, 2925, 2854, 1616,
1485, 1365, 1189, 1182, 1094 cm ; H nmr (300 MHz, CDCl ) δ
2.44 (s, 3 H), 2.63 (dd, J = 17.1, 10.8 Hz, 1 H), 2.76 (ddd, J =
17.1, 9.6, 1.8 Hz, 1 H), 2.99 (dd, J = 17.1 4.2 Hz, 1 H), 3.18-3.28
(m, 1 H), 3.32 (dd, J = 17.1, 4.2 Hz, 1 H), 6.06 (d, J = 3.0 Hz, 1
H), 6.29 (t, J = 3.0 Hz, 1 H), 6.55 (d, J = 1.8 Hz, 1 H), 7.34-7.46
CDCl ) δ 1.86 (s, 3 H), 3.09-3.23 (m, 2 H), 3.32-3.46 (m, 1 H),
3
5.12 (dd, J = 13.2, 9.0 Hz, 1 H), 5.74 (d, J = 8.1 Hz, 1 H), 6.57 (s,
-1 1
13
3
1 H), 7.26-7.54 (m, 10 H); C nmr (75 MHz, CDCl ) δ 24.2,
3
39.0, 48.8, 59.4, 124.9, 127.3, 128.7, 128.9, 129.9, 130.0, 131.6,
138.6, 141.3, 159.3, 171.8, 197.5.
Anal. Calcd for C H NO : C, 78.66; H, 6.27; N, 4.59%.
20 19
2
Found: C, 78.6; H, 6.3; N, 4.7%.
13
(m, 8 H), 7.90 (d, J = 8.1 Hz, 2 H); C nmr (75 MHz, CDCl ) δ
3
N-[4-(4-Chlorophenyl)-2-oxo-6-phenyl-3-cyclohexenyl]-
acetamide (5b).
22.1, 28.3, 32.7, 32.8, 105.3, 110.6, 118.5, 126.0, 129.1, 129.2,
129.7, 130.1, 133.1, 139.3, 142.0, 145.5, 150.0, 156.5, 163.7.
Anal. Calcd for C H NO S: C, 67.79; H, 5.19; N, 3.44%.
This compound was obtained as pale yellow crystals (alcohol),
yield 60%, mp 88-89 ºC; ir (KBr) 3280, 3051, 2925, 1669, 1645,
23 21
4
Found: C, 67.9; H, 5.3; N, 3.4%.
-1 1
1535, 1418, 1368, 1240, 1140 cm ; H nmr (300 MHz, CDCl ) δ
3
(E) 3-(4-Methylphenyl)-5-(2-thienyl)-2-cyclohexen-1-one
Oxime Tosylate (3j).
1.86 (s, 3 H), 3.03-3.07 (m, 2 H), 3.36-3.42 (m, 1 H), 5.04 (dd, J
= 13.5, 8.7 Hz, 1 H), 5.85 (d, J = 8.7 Hz, 1 H), 6.49 (d, J = 1.5 Hz,
1 H), 7.27-7.59 (m, 9 H). C NMR (75 MHz, CDCl ) δ 23.0,
37.6, 47.3, 58.2, 123.9, 127.4, 127.7, 128.7, 128.8, 129.1, 135.8,
136.6, 139.9, 156.6, 170.7, 196.0.
13
This compound was obtained as colorless crystals (alcohol),
yield 92%, mp 92-93 ºC; ir (KBr) 3039, 2930, 2860, 1615, 1499,
3
-1
1
1378, 1180, 1168, 1090 cm ; H nmr (300 MHz, CDCl ) δ 2.36
3
Anal. Calcd for C H ClNO : C, 70.69; H, 5.34; N, 4.12%.
(s, 3 H), 2.44 (s, 3 H), 2.57 (dd, J = 18.0, 12.9 Hz, 1 H), 2.75
(ddd, J = 17.4, 9.9, 2.1 Hz, 1 H), 3.03 (dd, J = 17.4, 4.2 Hz, 1 H),
3.36-3.44 (m, 2 H), 6.56 (d, J = 2.1 Hz, 1 H), 6.89 (d, J = 3.0 Hz,
1 H), 6.95 (dd, J = 4.8, 5.1 Hz, 1 H), 7.15-7.37 (m, 7 H), 7.89 (d,
20 18
2
Found: C, 70.8; H, 5.4; N, 4.2%.
N-[4-(4-Chlorophenyl)-6-(4-methoxyphenyl)-2-oxo-3-cyclo-
hexenyl]acetamide (5c).
13
J = 8.1 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 21.6, 22.1, 31.7,
3
This compound was obtained as pale yellow crystals (alcohol),
yield 65%, mp 90-91 ºC; ir (KBr) 3295, 3058, 2918, 1675, 1670,
34.8, 36.6, 117.7, 124.0, 125.9, 127.3, 129.3, 129.8, 129.9, 130.0,
133.1, 136.3, 139.9, 145.4, 147.4, 150.2, 163.9.
-1
1
1530, 1423, 1375, 1245, 1144 cm ; H nmr (300 MHz, CDCl ) δ
3
Anal. Calcd for C H NO S : C, 65.88; H, 5.30; N, 3.20%.
24 23
3 2
1.88 (s, 3 H), 2.97-3.13 (m, 2 H), 3.29-3.38 (m, 1 H), 3.79 (s, 3 H),
Found: C, 65.8; H, 5.4; N, 3.3%.
5.03 (dd, J = 12.6, 8.7 Hz, 1 H), 5.71 (d. J = 8.7 Hz, 1 H), 6.52 (s,
13
Preparation of 6-amino-3,5-diaryl-2-cyclohexen-1-one
1 H), 6.87 (d, J = 8.1 Hz, 2 H), 7.22-7.55 (m, 6 H); C nmr (75
Hydrochloride (4).
MHz, CDCl ) δ 23.4, 38.4, 47.2, 55.7, 58.9, 114.5, 124.3, 127.9,
3
129.1, 129.5, 132.4, 136.3, 137.0, 157.1, 159.3, 171.1, 196.6.
General Procedure.
Anal. Calcd for C H ClNO : C, 68.20; H, 5.45; N, 3.79%.
21 20
3
A suspension of 3,5-diaryl cyclohexen-1-one oxime tosylate 3
(8 mmol) in absolute alcohol (50 mL) was stirred with 0.3 g (13
mmol) of sodium in absolute alcohol (20 mL) for 8 h. After com-
pletion of the reaction, the mixture was diluted with water, acidi-
fied with acetic acid (2 mL) and extracted with ether. The ethe-
real solution was washed with water. The amine hydrochloride
was isolated by extracting the ether solution several times with
10% hydrochloric acid followed by evaporating the acid solution
under reduced pressure and the solid obtained was washed with
alcohol. All the amine hydrochlorides have their melting points
above 250 ºC.
Found: C, 68.1; H, 5.4; N, 3.9%.
N-[4-(2-Naphthyl)-2-oxo-6-phenyl-3-cyclohexenyl]acetamide
(5d).
This compound was obtained as pale yellow crystals (alcohol),
yield 62%, mp 90-91ºC; ir (KBr) 3298, 3040, 2928, 1664, 1660,
-1
1
1535, 1420, 1380, 1251, 1149 cm ; H nmr (300 MHz, CDCl ) δ
3
1.88 (s, 3 H), 3.18-3.28 (m, 2 H), 3.37-3.49 (m, 1 H), 5.16 (dd, J =
13.2, 9.0 Hz, 1 H), 5.71 (d, J = 9.0 Hz, 1 H), 6.72 (s, 1 H), 7.11-
13
7.91 (m, 12 H); C nmr (75 MHz, CDCl ) δ 23.1, 37.8, 47.7, 58.3,
3
123.1, 123.9, 126.5, 126.9, 127.5, 127.6, 127.7, 127.8, 128.6,
128.7, 128.8, 133.0, 134.1, 134.5, 140.2, 157.6, 170.6, 196.3.
Preparation of N-(2-oxo-4,6-diaryl-3-cyclohexenyl)acetamide (5).
Anal. Calcd for C H NO : C, 81.10; H, 5.96; N, 3.94%.
24 21
2
Found: C, 81.2; H, 6.0; N, 3.9%.
General Procedure.
N-[6-(4-Methylphenyl)-2-oxo-4-phenyl-3-cyclohexenyl]-
acetamide (5e).
To a solution of amine hydrochloride (4) taken as such from
the previous stage in water (50 mL) was added sodium acetate (3
g) in water (10 mL) and warmed on a water bath at 70 ºC. To this
suspension about 3 mL of acetic anhydride was added with con-
stant stirring and the stirring was continued for further 30 min.
The separated acetate was filtered, washed with water and dried.
The unreacted amine hydrochloride was removed by dissolving
the acetate in chloroform and filtering off the suspended
hydrochloride. The filtrate was evaporated and recrystallised
from alcohol to get 5.
This compound was obtained as pale yellow crystals (alcohol),
yield 61%, mp 97-98 ºC; ir (KBr) 3295, 3056, 2921, 1654, 1610,
-1 1
1545, 1446, 1371, 1250, 1141 cm ; H nmr (300 MHz, CDCl ) δ
3
1.86 (s, 3 H), 2.33 (s, 3 H), 3.00-3.17 (m, 2 H), 3.30-3.41 (m, 1
H), 5.08 (dd, J = 11.7, 8.1 Hz, 1 H), 5.85 (d, J = 8.1 Hz, 1 H), 6.54
13
(s, 1 H), 7.00-7.58 (m, 9 H); C nmr (75 MHz, CDCl ) δ 22.7,
3
24.6, 39.6, 48.8, 59.9, 125.3, 127.8, 129.2, 130.5, 131.0, 132.1,
138.7, 138.8, 139.1, 159.9, 172.4, 198.1.

1328
V. Sridharan, S. Muthusubramanian and S. Sivasubramanian
Vol. 42
Anal. Calcd for C H NO : C, 78.97; H, 6.63; N, 4.39%.
Found: C, 78.9; H, 6.6; N, 4.5%.
of 6 and 7 are given in Tables 2 and 3 respectively. The 4,6-
diaryl-2-methyl-1,3-benzoxazole 8 was separated from the mix-
ture by silica column using pet ether- ethyl acetate as eluent.
21 21
2
N-[6-(4-Methoxyphenyl)-2-oxo-4-phenyl-3-cyclohexenyl]-
acetamide (5f).
Dehydrogenation of 6 and 7 by DDQ to 4,6-diaryl-2-methyl-1,3-
benzoxazole (8).
This compound was obtained as pale yellow crystals (alcohol),
yield, 65%, mp 95-96 ºC; ir (KBr) 3282, 3048, 2919, 1663, 1640,
General Procedure.
-1 1
1530, 1420, 1362, 1235, 1142 cm ; H nmr (300 MHz, CDCl ) δ
3
To a solution of 1 mmol of 6/7 in anhydrous dioxane (1.5 mL)
was added 0.227 g (1 mmol) of 2,3-dichloro-5,6-dicyano-1,4-
benzoquinone dissolved in 1.5 mL of anhydrous dioxane. The
mixture was heated in an oil bath at 105 ºC for time periods spec-
ified below. The mixture was cooled, diluted with water and
extracted with ether. The ether solution was washed well with
water, dried, evaporated and recrystallised from alcohol to yield
pure 8.
1.86 (s, 3 H) 3.07-3.16 (m, 2 H) 3.28-3.38 (m, 1 H), 3.78 (s, 3 H),
5.05 (dd, J = 13.2, 8.7 Hz, 1 H), 5.92 (d, J = 8.7 Hz, 1 H), 6.53 (s,
13
1 H), 6.86 (d, J = 8.4 Hz, 2 H), 7.22-7.57 (m, 7 H); C nmr (75
MHz, CDCl ) δ 23.4, 38.4, 47.3, 55.6, 58.9, 114.4, 124.1, 126.6,
3
129.2, 129.3, 130.8, 132.7, 138.0, 158.7, 159.2, 171.1, 196.9.
Anal. Calcd for C H NO : C, 75.20; H, 6.31; N, 4.18%.
21 21
3
Found: C, 75.3; H, 6.4; N, 4.3%.
N-[6-(2-Furyl)-2-oxo-4-(2-thienyl)-3-cyclohexenyl]acetamide
(5g) with its Fully Aromatized Compound.
2-Methyl-4,6-diphenyl-1,3-benzoxazole (8a).
This compound was obtained as pale yellow crystals (alcohol),
reaction time 8 h, yield 85%, mp 141-142 ºC; ir (KBr) 3056,
2919, 2854, 1610, 1579, 1382, 1257, 1116 cm ; H nmr (300
This mixture was obtained as viscous liquid, yield 59%.
-1
1
N-[6-(4-Methylphenyl)-2-oxo-4-(2-thienyl)-3-cyclohexenyl]-
acetamide (5h).
MHz, CDCl ) δ 2.68 (s, 3 H), 7.35-7.53 (m, 6 H), 7.64-7.69 (m, 4
3
13
H), 7.95 (dd, J = 8.4, 1.2 Hz, 2 H); C nmr (75 MHz, CDCl ) δ
3
This compound was obtained as pale yellow crystals (alcohol),
yield 60%, mp 76-77 ºC; ir (KBr) 3280, 3052, 2910, 1661, 1642,
15.1, 108.1, 123.4, 127.9*, 128.3, 129.1, 129.2, 129.3, 133.1,
137.8, 138.8, 139.1, 141.4, 152.5, 164.6 (*two carbon signals are
merged together).
-1 1
1533, 1424, 1366, 1238, 1143 cm ; H nmr (300 MHz, CDCl ) δ
3
1.85 (s, 3 H), 2.34 (s, 3 H), 3.02-3.22 (m, 2 H), 3.32-3.41 (m, 1
Anal. Calcd for C
H NO: C, 84.19; H, 5.30; N, 4.91%.
20 15
H), 5.04 (dd, J = 12.9, 8.7 Hz, 1 H), 5.82 (d, J = 8.7 Hz, 1 H),
Found: C, 84.3; H, 5.2; N, 4.8%.
13
6.53 (s, 1 H), 6.99-7.51 (m, 7 H); C nmr (75 MHz, CDCl ) δ
3
21.5, 22.4, 38.0, 47.2, 58.7, 121.5, 128.0, 128.5, 128.9, 129.8,
130.0, 137.4, 137.6, 142.0, 151.5, 171.1, 196.3.
6-(4-Chlorophenyl)-2-methyl-4-phenyl-1,3-benzoxazole (8b).
This compound was obtained as pale yellow crystals (alcohol),
reaction time 9 h, yield 82%, mp 119-120 ºC; ir (KBr) 3048,
2915, 2855, 1614, 1467, 1386, 1249, 1093 cm ; H nmr (300
Anal. Calcd for C H NO S: C, 70.12; H, 5.88; N, 4.30%.
19 19
2
Found: C, 70.0; H, 6.0; N, 4.2%.
-1
1
MHz, CDCl ) δ 2.69 (s, 3 H), 7.41-7.66 (m, 9 H), 7.93 (dd, J =
N-[6-(2-furyl)-2-oxo-4-phenyl-3-cyclohexenyl]acetamide (5i)
with its Fully Aromatized Compound.
3
13
8.4, 1.2 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 15.1, 107.9,
3
123.2, 128.4, 129.1, 129.1, 129.2, 129.5, 133.2, 134.0, 137.5,
137.6, 139.3, 139.8, 152.5, 64.8.
This mixture was obtained as viscous liquid, yield: 58%.
Anal. Calcd for C H ClNO: C, 75.12; H, 4.41; N, 4.38%.
Found: C, 75.2; H, 4.4; N, 4.5%.
N-[4-(4-Methylphenyl)-2-oxo-6-(2-thienyl)-3-cyclohexenyl]-
acetamide (5j).
20 14
This compound was obtained as pale yellow crystals (alcohol),
yield 62%, mp 105-106 ºC; ir (KBr) 3300, 3056, 2925, 1662,
1658, 1525, 1420, 1365, 1243, 1142 cm ; H nmr (300 MHz,
6-(4-Chlorophenyl)-4-(4-methoxyphenyl)-2-methyl-1,3-benzox-
azole (8c).
-1
1
This compound was obtained as pale yellow crystals (alcohol),
reaction time 8 h, yield 79%, mp 135-136 ºC; ir (KBr) 3050,
CDCl ) δ 2.05 (s, 3 H), 2.39 (s, 3 H), 3.16-3.28 (m, 2 H), 3.67-
3
3.77 (m, 1 H), 4.79 (dd, J = 12.9, 8.7 Hz, 1 H), 6.13 (d, J = 8.7
Hz, 1 H), 6.55 (d, J = 2.7 Hz, 1 H), 6.76 (d, J = 3.3 Hz, 1 H), 6.84
-1
1
2925, 2854, 1610, 1519, 1467, 1376, 1243, 1186, 1033 cm ; H
nmr (300 MHz, CDCl ) δ 2.68 (s, 3 H), 3.87 (s, 3 H), 7.05 (d, J =
3
13
(dd, J = 3.6, 3.3 Hz, 1 H), 7.18-7.49 (m, 5 H); C nmr (75 MHz,
8.7 Hz, 2 H), 7.43 (d, J = 8.7 Hz, 2 H), 7.55-7.60 (m, 4 H), 7.90
CDCl ) δ 21.8, 23.7, 35.3, 40.4, 59.3, 123.8, 125.0, 126.7, 126.8,
3
13
(d, J = 8.7 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 15.1, 55.8,
3
126.9, 130.1, 135.3, 141.2, 141.6, 158.1, 170.9, 194.8.
107.4, 114.6, 122.6, 129.1, 129.4, 130.1, 130.4, 132.9, 133.9,
137.5, 139.1, 139.9, 152.5, 159.9, 164.6.
Anal. Calcd for C H NO S: C, 70.12; H, 5.88; N, 4.30%.
19 19
2
Found: C, 70.1; H, 5.9; N, 4.4%.
Anal. Calcd for C H ClNO : C, 72.10; H, 4.61; N, 4.00%.
21 16
2
Found: C, 72.2; H, 4.7; N, 3.9%.
Reaction of N-(2-Oxo-4,6-diaryl-3-cyclohexenyl)acetamide (5)
with POCl .
3
2-Methyl-6-(2-naphthyl)-4-phenyl-1,3-benzoxazole (8d).
General Procedure.
This compound was obtained as pale yellow crystals (alcohol),
reaction time 7 h, yield: 87%, mp 160-161 ºC; ir (KBr) 3048,
2915, 2850, 1606, 1577, 1384, 1257, 1114 cm . H NMR (300
N-(2-Oxo-4,6-diaryl-3-cyclohexenyl)acetamide (5) (0.5 g)
was refluxed with 3 mL of POCl for about 3 h. After completion
-1
1
3
of the reaction, the excess POCl was carefully destroyed with
MHz, CDCl ) δ 2.68 (s, 3 H), 7.37-7.55 (m, 4 H), 7.74-7.99 (m,
3
3
13
water and the product was extracted with chloroform. The chlo-
roform layer was washed with water, dried and evaporated. The
9 H), 8.09 (s, 1 H); C nmr (75 MHz, CDCl ) δ 15.1, 108.3,
3
123.6, 126.2, 126.5, 126.6, 126.9, 128.1, 128.3, 128.6, 129.0,
129.1, 129.3, 133.1, 133.2, 134.1, 137.8, 138.6, 138.7, 139.2,
152.6, 164.7.
1
ratios of 6, 7 and 8 were calculated from the H NMR spectra of
1
13
the crude mixture (Table 1). The selected H and C NMR data

Nov-Dec 2005
A Novel Synthetic Route for the Synthesis of 4,6-Diaryl-2-methyl-1,3-benzoxazoles
1329
Anal. Calcd for C
H
NO: C, 85.94; H, 5.11; N, 4.18%.
Anal. Calcd for C H NO : C, 78.53; H, 4.76; N, 5.09%.
18 13 2
24 17
Found: C, 85.8; H, 5.2; N, 4.3.
Found: C, 78.4; H, 4.8; N, 5.0%.
2-Methyl-4-(4-methylphenyl)-6-phenyl-1,3-benzoxazole (8e).
2-Methyl-6-(4-methylphenyl)-4-(2-thienyl)-1,3-benzoxazole
(8j).
This compound was obtained as pale yellow crystals (alcohol),
reaction time 9 h, yield 86%, mp 131-132 ºC; ir (KBr) 3044,
2923, 2845, 1604, 1575, 1469, 1378, 1253, 1112 cm ; H nmr
This compound was obtained as pale yellow crystals (alcohol),
reaction time 8 h, yield 86%, mp 175-176 ºC; ir (KBr) 3045,
-1
1
-
2921, 2840, 1606, 1571, 1475, 1434, 1396, 1261, 1112, 1043 cm
(300 MHz, CDCl ) δ 2.41 (s, 3 H), 2.67 (s, 3 H), 7.32 (d, J = 8.1
3
1
1
; H nmr (300 MHz, CDCl ) δ 2.42 (s, 3 H), 2.71 (s, 3 H), 7.17
Hz, 2 H), 7.36-7.49 (m, 3 H), 7.61-7.68 (m, 4 H), 7.84 (d, J = 8.1
3
13
(dd, J = 5.1, 3.6 Hz, 1 H), 7.29 (d, J = 7.8 Hz, 2 H), 7.38 (dd, J =
5.1, 0.9 Hz, 1 H), 7.53-7.56 (m, 3 H), 7.76 (d, J = 1.2 Hz, 1 H),
Hz, 2 H); C nmr (75 MHz, CDCl ) δ 15.1, 21.7, 107.8, 123.1,
3
127.8, 127.9, 129.1, 129.3, 129.8, 133.1, 134.9, 138.1, 138.8,
139.0, 141.5, 152.5, 164.5.
13
7.98 (dd, J = 3.6, 0.9 Hz, 1 H); C nmr (75 MHz, CDCl ) δ 15.2,
21.5, 107.7, 121.4, 126.2, 127.3, 127.7, 128.4, 130.0, 137.6,
137.8, 137.9, 138.3, 138.9, 140.0, 152.6, 164.5.
3
Anal. Calcd for C
H NO: C, 84.25; H, 5.72; N, 4.68%.
21 17
Found: C, 84.1; H, 5.6; N, 4.8%.
Anal. Calcd for C H NOS: C, 74.72; H, 4.95; N, 4.59%.
Found: C, 74.6; H, 5.1; N, 4.4%.
19 15
4-(4-Methoxyphenyl)-2-methyl-6-phenyl-1,3-benzoxazole (8f).
This compound was obtained as pale yellow crystals (alcohol),
reaction time 10 h, yield 84%, mp 85-86 ºC; ir (KBr) 3049, 2933,
2848, 1606, 1519, 1469, 1382, 1253, 1182, 1035 cm ; H nmr
Acknowledgement.
-1
1
The authors thank DST, New Delhi for assistance under
IRHPA program for the very generous support by providing the
NMR facility. One of the authors (V.S.) thanks CSIR, New Delhi
for a Senior Research Fellowship.
(300 MHz, CDCl ) δ 2.66 (s, 3 H), 3.85 (s, 3 H), 7.04 (d, J = 8.7
3
Hz, 2 H), 7.36 (td, J = 7.5, 2.1 Hz, 1 H), 7.46 (dd, J = 7.8, 7.5 Hz,
2 H), 7.58 (d, J = 1.8 Hz, 1 H), 7.63-7.66 (m, 3 H), 7.91 (d, J =
13
8.7 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 15.1, 55.8, 107.5,
3
114.6, 122.8, 127.8, 127.9, 129.3, 130.3, 130.4, 132.7, 138.8,
138.9, 141.5, 152.5, 159.9, 164.4.
REFERENCES AND NOTES
Anal. Calcd for C H NO : C, 79.98; H, 5.43; N, 4.44%.
Found: C, 80.1; H, 5.2; N, 4.5%.
21 17
2
[1] I. Yildiz-Oran, I. Yalcin, E. Aki-Sener and N. Ucarturk, Eur. J.
Med. Chem., 39, 291 (2004).
[2] T. Mouri, J. Tokumura, S. Kochi, H. Fukui, J. Nakano, T. Ando
and M. Hori, J. Pesticide Science, 27, 353 (2002).
[3] R. Paramashivappa, P. Phani Kumar, P. V. Subba Rao and A.
Srinivasa Rao, Bioorg. Med. Chem. Lett., 13, 657 (2003).
[4] E. Aki-Sener, K. K. Bingoel, O. Temiz-Arpaci, I. Yalacin and
N. Altanlar, Farmaco. 57, 451 (2002).
[5] M. A. Weidner-Wells, K. A. Ohemeng, V. N. Nguyen, S.
Fraga-Spano, M. J. Macielag, H. M. Werblood, B. D. Foleno, G. C. Webb,
J. F. Barrett and D. J. Halast, Bioorg. Med. Chem. Lett., 11, 1545 (2001).
[6] O. Temiz, I. Oren, E. Sener, I. Yalcin and N. Ucarturk,
Farmaco. 53, 337 (1998).
[7] G. Yang, F. Morlet-Savary, Z. Peng, S. Wu and J. Fouassier,
Chem. Phys. Lett., 256, 536 (1996).
[8] A. Rzeska, J. Malicka, K. Guzow, M. Szabelski and W. Wiczk,
J. Photochem. Photobiol. A. 146, 9 (2001).
[9] A. S. Kiselyov, Tetrahedron Lett., 40, 4119 (1999).
[10] C. Saitz, H. Rodriguez, A. Marquez, A. Canete, C. Jullian and
A. Zanocco, Synth. Commun., 31, 135 (2001).
[11] A. Hari, C. Karan, W. C. Rodrigues and B. L. Miller, J. Org.
Chem., 66, 991 (2001).
4-(2-Furyl)-2-methyl-6-(2-thienyl)-1,3-benzoxazole (8g).**
This compound was obtained as pale yellow crystals (alcohol),
mp 79-80 ºC; ir (KBr) 3048, 2928, 2840, 1610, 1575, 1473, 1375,
-1
1
1228, 1110, 1008 cm ; H nmr (300 MHz, CDCl ) δ 2.67 (s, 3
3
H), 6.57 (dd, J = 3.6, 1.8 Hz, 1 H), 7.09 (dd, J = 5.1, 3.6 Hz, 1 H),
7.30 (dd, J = 5.1, 1.2 Hz, 1 H), 7.37 (dd, J = 3.6, 1.2 Hz, 1 H),
7.41 (dd, J = 3.3, 0.6 Hz, 1 H), 7.55-7.57 (m, 2 H), 7.95 (d, J =
13
1.5 Hz, 1 H); C nmr (75 MHz, CDCl ) δ 15.1, 106.4, 111.1,
3
112.5, 117.9, 122.7, 124.0, 125.5, 128.5, 131.9, 136.8, 142.8,
144.4, 150.5, 152.4, 164.7 (** obtained directly from 5).
Anal. Calcd for C H NO S: C, 68.31; H, 3.94; N, 4.98%.
16 11
2
Found: C, 68.2; H, 3.8; N, 4.8%.
2-Methyl-4-(4-methylphenyl)-6-(2-thienyl)-1,3-benzoxazole
(8h).
This compound was obtained as pale yellow crystals (alcohol),
reaction time 7 h, yield 80%, mp 84-85 ºC; ir (KBr) 3051, 2923,
-1
1
2835, 1604, 1515, 1421, 1384, 1249, 1228, 1110, 1025 cm ; H
[12] V. Sridharan, S. Muthusubramanian and S. Sivasubramanian,
Magn. Reson. Chem., 41, 291 (2003).
nmr (300 MHz, CDCl ) δ 2.42 (s, 3 H), 2.67 (s, 3 H), 7.11 (dd, J
3
= 5.1, 3.6 Hz, 1 H), 7.30-7.34 (m, 3 H), 7.36 (dd, J = 3.6, 1.2 Hz,
1 H), 7.65 (d, J = 1.5 Hz, 1 H), 7.70 (d, J = 1.5 Hz, 1 H), 7.82 (d,
[13] C. O’Brien, Chem. Rev., 64, 81 (1964).
[14] R. T. Conley, S. Ghosh, Mechanisms of Molecular Migrations,
vol. 4, ed by B. S. Thyagarajan, Wiley-Interscience, New York (1971),
pp.289.
[15] K. O. Hallinan, D. H. G. Crout and W. Errington, J. Chem.
Soc., Perkin Trans. 1, 24, 3537 (1994).
13
J = 8.1 Hz, 2 H); C nmr (75 MHz, CDCl ) δ 15.1, 21.7, 106.6,
3
122.1, 123.9, 125.4, 128.5, 129.1, 129.8, 131.8, 133.3, 134.5,
138.3, 139.2, 144.6, 152.4, 164.6.
Anal. Calcd for C H NOS: C, 74.72; H, 4.95; N, 4.59%.
19 15
[16] B. Wuensch, M. Zott and G. Hoefner, Liebigs Ann. Chem., 12,
1225 (1992).
Found: C, 74.8; H, 5.0; N, 4.7%.
4-(2-Furyl)-2-methyl-6-phenyl-1,3-benzoxazole (8i).**
[17] C. O’Brien, E. M. Philbin, S. Ushioda and T. S. Wheeler,
Tetrahedron. 19, 373 (1963).
[18] A. Diez, A. Voldoire, I. Lopez, M. R. V. Segarra, L. Pages and
J. M. Palacios, Tetrahedron. 51, 5143 (1995).
[19] F. Palacios, D. Aparicio, A. M. Ochoa de Retana, J. M. de los
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(2003).
This compound was obtained as pale yellow crystals (alcohol),
mp 76-77 ºC; ir (KBr) 3047, 2920, 2850, 1666, 1593, 1492, 1359,
-1
1
1126 cm ; H nmr (300 MHz, CDCl ) δ 2.71 (s, 3 H), 6.59 (dd,
3
J = 3.6, 1.8 Hz, 1 H), 7.36-7.56 (m, 6 H), 7.68 (dd, J = 7.2, 1.5
Hz, 2 H), 7.95 (d, J = 1.5 Hz, 1 H) (** obtained directly from 5).

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V. Sridharan, S. Muthusubramanian and S. Sivasubramanian
Vol. 42
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