Pd(OAc)2-catalyzed carbonylative coupling of aryl iodide with ortho-haloamines in water

Article abstract of DOI:10.1080/00397911.2010.523155

The carbonylative cross coupling of aryl iodide with ortho-haloaniline to ortho-haloanilide using phosphine-free Pd(OAc)₂ catalyst in water as a reaction medium has been studied. The present protocol facilitated the reaction of o-haloanilines with a wide variety of hindered and functionalized aryl iodides, affording good yields of the desired products. The protocol was also extended for the synthesis of benzoxazoles through cyclization of ortho-haloanilide using Cu(acac)₂ catalyst. Taylor & Francis Group, LLC.

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Pd(OAc)2-Catalyzed Carbonylative
Coupling of Aryl Iodide with Ortho-
Haloamines in Water
Pawan J. Tambade a , Yogesh P. Patil a , Ziyauddin S. Qureshi a
Kishor P. Dhake a & Bhalchandra M. Bhanage a
,
a Department of Chemistry, Institute of Chemical Technology
(Autonomous), Mumbai, India
Accepted author version posted online: 22 Jul 2011.Version of
record first published: 14 Sep 2011.
To cite this article: Pawan J. Tambade, Yogesh P. Patil, Ziyauddin S. Qureshi, Kishor P. Dhake &
Bhalchandra M. Bhanage (2012): Pd(OAc)2-Catalyzed Carbonylative Coupling of Aryl Iodide with Ortho-
Haloamines in Water, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 42:2, 176-185
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Synthetic Communications1, 42: 176–185, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.523155
Pd(OAc)2-CATALYZED CARBONYLATIVE COUPLING
OF ARYL IODIDE WITH ORTHO-HALOAMINES
IN WATER
Pawan J. Tambade, Yogesh P. Patil, Ziyauddin S. Qureshi,
Kishor P. Dhake, and Bhalchandra M. Bhanage
Department of Chemistry, Institute of Chemical Technology (Autonomous),
Mumbai, India
GRAPHICAL ABSTRACT
Abstract The carbonylative cross coupling of aryl iodide with ortho-haloaniline to
ortho-haloanilide using phosphine-free Pd(OAc)2 catalyst in water as a reaction medium
has been studied. The present protocol facilitated the reaction of o-haloanilines with a wide
variety of hindered and functionalized aryl iodides, affording good yields of the desired pro-
ducts. The protocol was also extended for the synthesis of benzoxazoles through cyclization
of ortho-haloanilide using Cu(acac)2 catalyst.
Keywords Aryl iodides; carbonylation; cyclization; halo amines; oxazoles
INTRODUCTION
Palladium-catalyzed carbonylation of aryl halides affords different benzoic
acid derivatives, and depending upon the nucleophile employed, aromatic acids,[1]
amides,[2] esters,[3] aldehydes,[4] or ketones[5] are obtained. The transition-metal-
catalyzed three-component cross-coupling reaction of amine, carbon monoxide,
and organic halides is now considered a useful tool for amide=anilide synthesis
(aminocarbonylation).[6] This method is advantageous because of the broad
availability of substrates and high tolerance of the palladium catalysts to a variety
Received June 15, 2010.
Address correspondence to Bhalchandra M. Bhanage, Department of Chemistry, Institute of
chemical Technology (Autonomas), N. M. Parekh Marg, Matunga, Mumbai 400 019, India. E-mail:
bhalchandra_bhanage@yahoo.com; bm.bhanage@ictmumbai.edu.in
176

AMINOCARBONYLATION REACTIONS IN WATER
177
Scheme 1. Aminocarbonylation of aryl iodides with ortho-haloamines.
of functional groups. Therefore, this route has become a useful tool for the
preparation of substituted amides, as these amides are difficult to synthesize using
conventional synthetic methods.
Several groups have reported a variety of palladium-based catalytic systems,
such as Pd(PhCN)2Cl2=dppf,[7] PdBr2(PPh3)2=PdCl2(PPh3)2,[8] Pd(OAc)2=PPh3 in
ionic liquid,[9] Pd(dppp)Cl2,[10] palladium-1,3-bis(dicyclohexylphosphino) propane
2HBF4,[11] silica-supported bidentate arsine palladium complex,[12] and silica-supported
bidentate sulfur and phosphine mixed palladium complex,[13] for aminocarbonylation
reactions.
[14]
Previously we had reported aminocarbonylation reactions using Pd(OAc)2
and Pd(TMHD)2[15] as a catalyst, in continuation of our previous work on the devel-
opment of phosphine-free aminocarbonylation reactions. Herein, we report a facile
protocol for the aminocarbonylation of aryl iodides with ortho-haloamines using
Pd(OAc)2 as a catalyst in water as a reaction medium (Scheme 1).
To with best of our knowledge, there is no report on carbonylation of ortho-
haloamines with a variety of aryl iodides, as they are difficult substrates for
carbonylation reactions, and it is also difficult to synthesize such anilides using con-
ventional synthetic methods. In this work, excellent yields of the desired anilides
were obtained using 1 mol% of the Pd catalyst under optimized reaction conditions.
The scope of the present methodology was further extended for the synthesis of
oxazoles through cyclization of o-haloanilides using Cu catalyst.
RESULTS AND DISCUSSION
Initially, the reaction of iodobenzene with o-bromoaniline was optimized with
respect to various reaction parameters. The optimum reaction conditions for carbo-
nylation of iodobenzene with o-bromoaniline are catalyst, Pd(OAc)2 (1 mol %);
solvent, water; temperature, 100 ꢀC; carbon monoxide pressure, 200 psi; and time,
8 h. After optimizing the reaction conditions for the aminocarbonylation of iodoben-
zene and o-bromoaniline, several different aryl iodides and ortho-substituted amines
were tried to extend the scope of the present protocol (Table 1).
Formation of the o-bromoanilides from iodobenzene and o-bromoaniline
proceeded in 97% yield (entry 1). The reaction of o-bromoaniline with aryl iodide
containing electron-donating substituents (-Me and -OMe) at para or ortho posi-
tions gives excellent yield of the product (entries 2–5). Furthermore, the reaction
of o-bromoaniline and aryl iodide bearing electron-withdrawing groups such

178
P. J. TAMBADE ET AL.
Table 1. Aminocarbonylation of aryl iodides with ortho-haloaminesa
Entry
1
Aryl iodide
Amine
Product
Yield (%)b
97
2
3
94
92
4
5
92
88
6
7
78
86
8
9
88
91
10
72
(Continued )

AMINOCARBONYLATION REACTIONS IN WATER
179
Table 1. Continued
Entry
11
Aryl iodide
Amine
Product
Yield (%)b
96
12
13
90
87
14
15
16
84
98
87
17
82
aReactions conditons: aryl iodide (1.0 mmol), o-haloamine (2.0 mmol), pd(OAc)2 (1.0 mol%, Et3N
(2.0 mmol), water (10 mL), CO (200 psi), 100ꢀC, 8 h.
bYield of isolated product.
as -NO2 and -COMe gives corresponding products in good yield (entries 6 and 7).
The reaction of o-bromoaniline and 2-iodothiophene (entry 8) results in 88% yield
of the carbonylative product. The carbonylation of bulky 1-iodonaphthalene gives
91% yield of the desired product (entry 9). The reaction of o-iodoaniline with iodo-
benzene was selective toward o-iodoanilide with 72% yield (entry 10).
As expected, the reactions of o-chloro and o-fluoro anilines with aryl iodide pro-
vided excellent yields of the products (entries 11 and 15). The reactions of aryl iodide

180
P. J. TAMBADE ET AL.
Scheme 2. Cyclization of o-haloanilides using Cu(acac)2 as a catalyst.
with electron-donating and electron-withdrawing groups like -Me, -OMe, and -COMe
and o-chloro aniline were well tolerated to give the desired anilides with reasonable
yields (entries 12–14). Also, the reactions of o-fluoroaniline with p-iodoacetophenone
and p-iodonitrobenzene furnishes excellent yields of the products (entries 16 and 17).
Benzoxazole belongs to an important class of molecules and is a common
heterocyclic scaffold in biologically active and pharmaceutically significant
compounds.[16] Benzoxazoles are found in a variety of natural products and are
important scaffolds in drug design. Cyclization of o-haloanilides is one of the
promising methods for the synthesis of benzoxazoles. Recently, the cyclization of
o-haloanilides to benzoxazoles has been reported with various copper-based catalysts
such as CuI=1,10-phenanthroline or dimethylethylenediamine (DMEDA),[17] Cu(I)
or (II)=tetramethylethylenediamine (TMEDA),[18] and CuO nanoparticles.[19] To
show relevance of the carbonylative product, cyclization of the carbonylative product
to benzoxazole was carried out.
We attempted cyclization of o-bromoanilide using various copper catalysts such
as Cu(OAc)2 (12%), CuI (15%), CuI=proline (trace of product), CuI=1,4-diazobicy-
clo[2.2.2]octane (DABCO) (22%), CuI=PPh3 (10%), Cu(acac)2 (88%), and Cu
(TMHD)2 (60%). It was observed that reaction gave better yield using Cu(acac)2 as
a catalyst in the presence of Cs2CO3 as a base in acetonitrile at 80 ꢀC in 24 h.
The cyclization of o-iodo and chloro products provided 2-phenyl-benzoxazole
in 92 and 33% yields respectively (Scheme 2).
A similar catalytic system could be used for the library synthesis of benzoxazole
derivatives.
CONCLUSION
In summary, the present work showed a mild and simple protocol for aminocar-
bonylation, which enables an efficient cross-coupling of o-substituted amines with a
wide range of substituted aryl iodides with the help of the commercially available
Pd(OAc)2 as catalyst without ligand in water. The system was applicable for the coup-
ling of a variety of aryl iodides with o-haloanilines. The cyclization of carbonylated
product to benzoxazole using Cu(acac)2 as a efficient catalyst was also shown.
EXPERIMENTAL
All the chemicals were obtained from either Lancaster (Alfa-Aesar) or Sigma-
Aldrich and used as received. Optimized yields were based on gas chromatographic

AMINOCARBONYLATION REACTIONS IN WATER
181
(GC) analysis (Chemito 1000) and GC–mass spectrometric (MS) analysis
(Shimadzu, QP-2010). The products were characterized by 13C NMR (Varian
100 MHz), 1H NMR (Varian 400 MHz), GC-MS (Shimadzu), infrared (IR)
(Perkin-Elmer), and physical constant.
General Experimental Procedure for Aminocarbonylation Reaction
In a 100-mL autoclave, aryl iodide (1.0 mmol), o-haloamine (2.0 mmol),
Pd(OAc)2 (0.01 mmol), water (10 mL), and Et3N (2.0 mmol) were added. The
mixture was stirred for 10 min, then 200 psi of CO was taken, and the reaction the mix-
ture was heated at 100 ꢀC for 8 h. After completion of the reaction, the reaction
mixture was filtered, the solid residue was washed with ether to remove excess amine,
and the remaining solid was recrystallized using a suitable solvent. All the compounds
are well known and their references are cited in the reference list.[17,20]
Data
N-(2-Bromo-phenyl)-benzamide (Table 1, Entry 1). Yield: 97% (266 mg);
1
mp: 107–109 ꢀC; IR (KBr): n ¼ 1651 cmꢁ1; H NMR (300 MHz CDC13) d ¼ 7.01
(1H, td), 7.35 (1H, td), 7.48–7.59 (4H, m), 7.92–7.95 (2H, m), 8.46 (1H, br s),
8.54–8.57 (1H, dd, J ¼ 8.0 Hz); 13C NMR (75 MHz CDC13) d ¼ 165.4, 135.7,
134.6, 132.3, 132.3, 129.0, 128.4, 127.2, 125.5, 121.8, 113.7 ppm; GC-MS (70 eV,
EI): m=z (%) ¼ 275 (10) (Mþ), 196 (60), 105 (100), 77 (65), 51 (15).
N-(2-Bromo-phenyl)-4-methyl-benzamide (Table 1, Entry 2). Yield: 94%
;
1H NMR (400 MHz CDC13)
(271 mg); mp: 69–71 ꢀC; IR (KBr): n ¼ 1652 cmꢁ1
d ¼ 2.44 (3H, s), 7.02 (1H, td), 7.38 (3H, m), 7.57 (1H, dd, J ¼ 7.9, 7.9 Hz), 7.82
(2H, d, J ¼ 7.9 Hz), 8.45 (1H, br s), 8.56 (1H, dd, J ¼ 8.3, 8.3 Hz); 13C NMR
(100 MHz CDC13) d ¼ 165.3, 142.9, 136.0, 132.4, 131.9, 129.7, 128.7, 127.3, 127.2,
125.2, 121.9, 121.8, 113.8, 21.7 ppm; GC-MS (70 eV, EI): m=z (%) ¼ 289 (10)
(Mþ), 210 (10), 119 (100), 91 (40), 65 (25).
N-(2-Bromo-phenyl)-4-methoxy-benzamide (Taꢁb1le 1, Entry 3). Yield:
;
1H NMR (300 MHz
92% (281 mg); mp: 147–149 ꢀC; IR (KBr): n ¼ 1649 cm
CDC13) d ¼ 3.88 (3H, s), 6.92–7.02 (3H, m), 7.34 (1H, td), 7.57 (1H, dd, J ¼ 8.0,
8.0 Hz), 7.88–7.93 (2H, m), 8.52 (1H, br s), 8.54 (1H, dd, J ¼ 8.4, 8.0 Hz); 13C
NMR (75 MHz CDC13) d ¼ 164.8, 162.8, 136.0, 132.4, 132.3, 129.0, 128.6, 126.8,
125.0, 121.7, 114.2, 113.8, 113.7, 55.6 ppm; MS-MS (ESIꢁ): m=z calcd. for
(M þ 1): 306.15; found (M þ 1): 306.10.
N-(2-Bromo-phenyl)-2-methyl-benzamide (Table 1, Entry 4). Yield: 92%
1
(265 mg); mp: 121–123 ꢀC; IR (KBr): n ¼ 1654 cmꢁ1; H NMR (300 MHz CDC13)
d ¼ 2.56 (3H, s), 7.0 (1H, td), 7.25–7.42 (5H, m), 7.57 (1H, dd, J ¼ 8.0, 7.6 Hz), 8.0
(1H, br s), 8.52 (1H, d, J ¼ 8.0 Hz); 13C NMR (75 MHz CDC13) d ¼ 167.9, 136.9,
136.0, 132.4, 131.6, 130.7, 128.5, 126.9, 126.2, 125.5, 122.0, 113.7, 14.2 ppm; GC-MS
(70 eV, EI): m=z (%) ¼ 289 (10) (Mþ), 210 (30), 119 (100), 91 (50), 65 (20).
N-(2-Bromo-phenyl)-2-methoxy-benzamide (Taꢁb1le 1, Entry 5). Yield:
88% (270 mg); mp: 115–117 ꢀC; IR (KBr): n ¼ 1670 cm
;
1H NMR (300 MHz

182
P. J. TAMBADE ET AL.
CDC13) d ¼ 4.10 (3H, s), 6.96–7.14 (3H, m), 7.35 (1H, m), 7.50–7.59 (2H, m), 8.30
(1H, d, J ¼ 7.8 Hz), 8.67 (1H, d, J ¼ 8.2 Hz) 10.6 (1H, br s); 13C NMR (75 MHz
CDC13) d ¼ 163.5, 157.5, 137.3, 133.7, 132.9, 132.8, 132.5, 128.5, 124.9, 122.6,
121.6, 113.5, 111.6, 56.4 ppm; MS-MS (ESIꢁ): m=z calcd. for (M þ 1): 306.15; found
(M þ 1): 306.20.
N-(2-Bromo-phenyl)-4-nitro-benzamide (Table 1, Entry 6). Yield: 78%
1
(250 mg); mp: 117–119 ꢀC; IR (KBr): n ¼ 1659 cmꢁ1; H NMR (300 MHz CDC13)
d ¼ 7.10 (1H, m), 7.39–7.42 (1H, m), 7.60 (1H, d, J ¼ 7.9 Hz), 7.8 (1H, d, J ¼ 8.8 Hz),
8.10 (2H, d, J ¼ 8.5 Hz), 8.38 (2H, d, J ¼ 8.5 Hz); 13C NMR (75 MHz CDC13)
d ¼ 163.3, 150.1, 145.1, 140.2, 135.3, 132.6, 128.8, 128.5, 126.2, 124.5, 124.4, 122.1,
114.2 ppm; MS-MS (ESIꢁ): m=z calcd. for (M þ 1): 320.98; found (M þ 1): 320.29.
4-Acetyl-N-(2-bromo-phenyl)-benzamide (Table ꢁ11, Entry 7). Yield: 86%
(272 mg); mp: 107–110 ꢀC; IR (KBr): n ¼ 1697, 1654 cm
;
1H NMR (400 MHz
CDC13) d ¼ 2.67 (3H, s), 7.07 (1H, m), 7.39 (1H, t, J ¼ 7.8 Hz), 7.60 (1H, d,
J ¼ 7.6 Hz), 8.05 (4H, m), 8.49 (1H, br s), 8.54 (1H, d, J ¼ 8.0 Hz); 13C NMR
(100 MHz CDC13) d ¼ 197.4, 164.4, 139.8, 138.5, 135.6, 132.5, 129.1, 128.9, 127.7,
125.8, 122.0, 121.9, 114.0, 27.0 ppm; MS-MS (ESIꢁ): m=z calcd. for (M þ 1):
318.17; found (M þ 1): 318.20.
Thiophene-2-carboxylic acid (2-bromo-phenyl)-amide (Table 1, Entry
;
1H NMR
8). Yield: 88% (247 mg); mp: 115–117 ꢀC; IR (KBr): n ¼ 1635 cmꢁ1
(400 MHz CDC13) d ¼ 7.01 (1H, td), 7.16 (1H, dd, J ¼ 5.15, 4.75 Hz), 7.35 (1H,
m), 7.58 (2H, m), 7.67 (1H, dd, J ¼ 3.9, 3.5 Hz), 8.34 (1H, br s), 8.48 (1H, dd,
J ¼ 8.3, 8.3 Hz); 13C NMR (100 MHz CDC13) d ¼ 159.8, 139.2, 135.7, 132.4, 131.5,
131.4, 128.8, 128.1, 125.4, 121.8, 121.7, 113.6 ppm; MS-MS (ESIꢁ): m=z calcd. for
(M ꢁ 1): 280.13; found (M ꢁ 1): 280.13.
Naphthalene-1-carboxylic acid (2-bromo-phenyl)-amide (Tꢁa1ble 1, Entry
9). Yield: 91% (296 mg); mp: 147–150 ꢀC; IR (KBr): n ¼ 1650 cm
;
1H NMR
(300 MHz CDC13) d ¼ 7.06 (1H, td), 7.40 (1H, td), 7.51–7.63 (2H, m), 7.82–8.01
(4H, m), 8.24 (1H, br s), 8.47 (1H, d, J ¼ 8.0 Hz), 8.64 (1H, d, J ¼ 7.6 Hz), 9.03
(1H, d, J ¼ 8.8 Hz); 13C NMR (75 MHz CDC13) d ¼ 167.4, 136.0, 134.0, 133.9,
132.4, 131.6, 130.2, 128.6, 128.5, 127.6, 126.8, 125.6, 125.5, 125.4, 124.9, 122,
113.9 ppm; MS-MS (ESIꢁ): m=z calcd. for (M þ 1): 326.19; found (M þ 1): 326.13.
N-(2-Iodo-phenyl)-benzamide (Table 1, Entry 10). Yield: 72% (232 mg);
1
mp: 132–133 ꢀC; IR (KBr): n ¼ 1649 cmꢁ1; H NMR (300 MHz CDC13) d ¼ 6.80
(1H, m), 7.38–7.59 (3H, m), 7.80 (2H, dd, J ¼ 7.9 Hz), 7.95 (1H, d, J ¼ 7 Hz), 8.30
(1H, br s), 8.42–8.45 (2H, dd, J ¼ 7.9 Hz); GC-MS (70 eV, EI): m=z (%) ¼ 323 (20)
(Mþ), 196 (70), 105 (100), 77 (25).
N-(2-Chloro-phenyl)-benzamide (Table 1, Entry 11). Yield: 96% (221 mg);
mp: 99–101 ꢀC; IR (KBr): n ¼ 1651 cmꢁ1; GC-MS (70 eV, EI): m=z (%) ¼ 231 (10)
(Mþ), 196 (25), 105 (100), 77 (50), 51 (15).
N-(2-Chloro-phenyl)-4-methyl-benzamide (Tabꢁle1 1, Entry 12). Yield:
;
1H NMR (400 MHz
90% (220 mg); mp: 79–81 ꢀC; IR (KBr): n ¼ 1651 cm
CDC13) d ¼ 2.44 (3H, s), 7.08 (1H, td), 7.30 (4H, m), 7.82 (2H, d, J ¼ 8.30 Hz),

AMINOCARBONYLATION REACTIONS IN WATER
183
8.43 (1H, br s), 8.57 (1H, dd, J ¼ 8.30, 8.30 Hz); 13C NMR (100 MHz CDC13)
d ¼ 165.4, 142.9, 135.0, 131.9, 129.8, 129.2, 128.0, 127.4, 127.3, 124.8, 123.2, 121.7,
121.6, 21.7 ppm; GC-MS (70 eV, EI): m=z (%) ¼ 245 (10) (Mþ), 210 (30), 119
(100), 91 (45), 65 (20).
N-(2-Chloro-phenyl)-4-methoxy-benzamide (Table 1, Entry 13). Yield:
87% (227 mg); mp: 128–130 ꢀC; IR (KBr): n ¼ 1648 cmꢁ1; GC-MS (70 eV, EI): m=z
(%) ¼ 261 (10) (Mþ), 226 (15), 135 (100).
4-Acetyl-N-(2-chloro-phenyl)-benzamide (Table 1, Entry 14). Yield: 84%
(230 mg); mp: 112–115 ꢀC; IR (KBr): n ¼ 1687, 1655 cmꢁ1; NMR (400 MHz CDC13)
d ¼ 2.66 (3H, s), 7.11 (1H, d, J ¼ 7.6 Hz), 7.32–7.43 (3H, m), 7.70 (1H, d, J ¼ 8.0 Hz),
7.99–8.09 (2H, dd, J ¼ 8.2, 8.2 Hz), 8.47 (1H, br s), 8.52 (1H, d, J ¼ 8.24 Hz); 13C
NMR (100 MHz CDC13) d ¼ 197.3, 164.3, 139.8, 138.5, 134.5, 129.2, 126.1, 128.9,
128.0, 127.5, 125.3, 123.3, 121.8, 29.9 ppm; MS-MS (ESIꢁ): m=z calcd. for
(M þ 1): 274.06; found (M þ 1): 274.16.
N-(2-Fluoro-phenyl)-benzamide (Table 1, Entry 15). Yield: 98% (210 mg);
IR (KBr): n ¼ 1651 cmꢁ1; GC-MS (70 eV, EI): m=z (%) ¼ 215 (20) (Mþ), 196 (40),
105 (100), 77 (65), 51 (15).
4-Acetyl-N-(2-fluoro-phenyl)-benzamide (Table 1, Entry 16). Yield: 87%
(223 mg); mp: 132–134 ꢀC; IR (KBr): n ¼ 1682, 1654 cmꢁ1; NMR (400 MHz
CDC13) d ¼ 2.66 (3H, s), 7.11–7.22 (3H, m), 7.72 (1H, d, J ¼ 8.2 Hz), 7.96–8.14
(3H, m), 8.14 (1H, br s), 8.43 (1H, t, J ¼ 7.8, 7.8 Hz); 13C NMR (100 MHz
CDC13) d ¼ 197.4, 164.6, 139.8, 138.5, 136.7, 129.1, 128.9, 127.6, 126.4, 126.3,
125.1, 124.9, 122.1, 115.2, 27.0 ppm; MS-MS (ESIꢁ): m=z calcd. for (M þ 1):
258.09; found (M þ 1): 258.27.
N-(2-Fluoro-phenyl)-4-nitro-benzamide (Table 1, Entry 17). Yield: 82%
1
(213 mg); mp: 158–160 ꢀC; IR (KBr): n ¼ 1658 cmꢁ1; H NMR (300 MHz CDC13)
d ¼ 7.11–7018 (3H, m), 7.80 (1H, d, J ¼ 8.8 Hz), 8.08 (2H, d, J ¼ 8.5 Hz), 8.38 (2H,
dd, J ¼ 8.5 Hz); 13C NMR (75 MHz CDC13) d ¼ 163.5, 151.7, 148.1, 145.1, 140.0,
128.5, 128.4, 127.4, 125.9, 125.5, 124.9, 124.5, 122.2, 115.2 ppm; MS-MS (ESIꢁ):
m=z calcd. for (M ꢁ 1): 259.06; found (M ꢁ 1): 259.07.
General Experimental Procedure for Synthesis of Benzoxazoles
The ortho-haloanilide (1 mmol), Cu(acac)2 (5 mol%), and Cs2CO3 (1.5 mmol)
were stirred at 80 ꢀC in acetonitrile (3 mL) for the 24 h. After completion of the reac-
tion, the reaction mixture was cooled to room temperature and diluted with ethyl
acetate. The organic layer was washed successively with brine and water and then
dried over Na2SO4. Solvent was removed under reduced pressure. The residue
obtained was purified by column chromatography (silica gel, 60–120 mesh) using
petroleum ether (60=80)=ethyl acetate as eluent to afford the desired product.

184
P. J. TAMBADE ET AL.
2-Phenyl-benzooxazole
Mp: 100–102 ꢀC; 1H NMR (300 MHz CDC13) d ¼ 7.32–73.7 (2H, m), 7.49–7.58
(4H, m), 7.61–7.80 (1H, m), 8.26 (2H, dd, J ¼ 5.4, 2.2 Hz); 13C NMR (75 MHz
CDC13) d ¼ 163.1, 150.8, 142.2, 131.6, 129.0, 127.7, 127.2, 125.2, 124.6, 120.0,
110.6 ppm; GC-MS (70 eV, EI): m=z (%) ¼ 195 (100) (Mþ), 167 (25), 139 (10), 92
(15), 77 (20).
ACKNOWLEDGMENT
Financial assistance from the Council of Scientific and Industrial Research
(CSIR), New Delhi, India, is kindly acknowledged.
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