5096
A. Srivastava, N. Jain / Tetrahedron 69 (2013) 5092e5097
NMR (300 MHz, CDCl
eCH ), 2.45 (3H, s, eC(O)CH
C NMR (75 MHz, CDCl ): 196.13, 165.00, 63.02, 49.17, 26.31,
3.98; MS (ESI): (MþNa ), found 230.9640. C Br requires
3
)
d
4.83 (1H, s, CH), 4.28 (2H, q, J 7.2, 6.9 Hz,
4.6. General procedure for amination of aryl and heterocyclic
halides
2
3
), 1.32 (3H, t, J 7.2 Hz, eCH ).
3
1
3
3
d
þ
1
2
6
H
9
O
3
An oven-dried flask was charged with aryl halide (1.0 mmol),
aqueous NH (28%, 1.5 mmol), CuI nanoparticles (0.02 mmol), 4a
3.0 mmol) and acetonitrile (2 mL). The contents were stirred under
30.969.
3
(
argon atmosphere at rt for 12 h. After completion of the reaction as
monitored by TLC, the product was extracted with diethyl ether
4
.3. Synthesis of 1-ethylacetoacetate-3-methyl imidazolium
hydroxide (4a) and 1-ethylacetoacetate-3-methyl imidazolium
acetate (4b)
(5ꢁ5 mL). The organic layer was washed with brine, dried over
MgSO and concentrated in vacuo. Purification was done on silica
4
gel column, and elution with ethyl acetateehexane mixture affor-
To a stirring solution of N-methylimidazole (2.5 mmol, 1 equiv)
in acetonitrile, 2 was added (2.5 mmol, 1 equiv) and the contents
were stirred for half an hour at rt. Completion of reaction was
monitored by TLC. The product was purified by repeated washing
with hexane and ether alternatively to remove any unreacted re-
actants. The pure product 1-ethylacetoacetate-3-methyl imidazo-
lium bromide (3) was obtained in 85% yield after drying the
sample for 24 h in vacuo. KOH (3.75 mmol, 1.5 equiv) was added to
a solution of 3 (2.5 mmol, 1 equiv) in acetonitrile (5 mL) and the
contents were stirred at rt for 24 h. The reaction mixture was fil-
tered through Celite to remove precipitated KBr and the solvent
evaporated in vacuo to give the title compound 4a as a colourless
oil in 82% yield. The synthesis of 4b was carried out using a similar
ded the aminated products. All products obtained herein are
1
13
known compounds, and were confirmed by H NMR, C NMR and
mass spectroscopic analysis, see Supplementary data for full
details.
4
(
6
CDCl
.6.1. Aniline (Table 2, entries 1, 6, 11). Colourless liquid; 1H NMR
300 MHz, CDCl 7.34 (2H, t, J 7.5 Hz, H ), 6.95 (1H, t, J 7.5 Hz, H ),
.79 (2H, d, J 7.8 Hz, H ), 3.73 (2H, s, eNH
3
)
d
1
3
13
2
2
); C NMR (75 MHz,
þ
3
)
d
146.76, 129.40, 118.46, 115.23; MS (ESI): (MþH ), found
9
4.0715. C
6 7
H N requires 94.0702.
4
.6.2. 4-Aminotoluene (Table 2, entry 2). Yellow liquid; 1H NMR
(
300 MHz, CDCl
3
)
d
7.01 (2H, d, J 7.8 Hz, H ), 6.64 (2H, d, J 7.8 Hz, H ),
1
2
2
procedure as for 4a with NaOAc$3H O (3.75 mmol, 1.5 equiv) as the
1
3
1
3.57 (2H, s, eNH
d
2
), 2.29 (3H, s, eCH
3
); C NMR (75 MHz, CDCl
3
)
salt for anion exchange reaction; H NMR (400 MHz, CD
keto): 9.11 (1H, s, imidazolium C-2H), 7.67e7.63 (2H, m, imi-
dazolium C-4H, C-5H), 5.50 (1H, s, eCOeCHeCOe), 4.28 (2H, q, J
.0 Hz, eCH ), 4.04 (3H, s, NeCH ), 2.58 (3H, s, eCOCH ), 1.22 (3H,
t, J 7 Hz, eCH CH ), 4a (enol): 8.93 (1H, s, imidazolium C-2H), 7.74
1H, d, J 3.36 Hz, imidazolium C-5H), 7.49 (1H, s, imidazolium C-
3
OD): 4a
þ
143.94, 129.80, 127.75, 115.34, 20.50; MS (ESI): (MþH ), found
(
d
1
08.0802. C
7
H
9
N requires 108.0814.
7
2
3
3
4
.6.3. 4-Methoxy-phenylamine (Table 2, entry 3). Dark brown solid;
2
3
1
H NMR (300 MHz, CDCl
3 1 2
) d 6.67 (2H, s, H ), 6.58 (2H, s, H ), 3.67
(
1
3
(3H, s, eOCH
3
), 3.26 (2H, s, NH
2
); C NMR (75 MHz, CDCl
3
)
4
H), 4.19 (2H, q, J 7 Hz, eCH
2
), 3.99 (3H, s, NeCH
3
), 2.01 (3H, s,
þ
13
d
152.79, 139.96, 116.40, 114.81, 55.71; MS (ESI): (MþH ), found
eC(OH)CH
CD
imidazolium C2), 125.44 (imidazolium C5), 124.08 (imidazolium
C4), 65.11 (eCH ), 54.90 (eCOeCHeCOe), 37.14 (NeCH ), 28.65
), 14.41(eCH CH ). Compound 4a (enol): 168.73
eCOOe), 164.47 (CeOH), 139.29 (imidazolium C2), 126.82 (imi-
3
), 1.37 (3H, t, J 7 Hz, eCH
2 3
CH ); C NMR (100 MHz,
124.0767. C
7
H
9
ON requires 124.0850.
3
OD): 4a (keto): d 195.69 (eCOe), 177.78 (eCOOe), 140.41
(
1
4
.6.4. 4-Aminonitrobenzene (Table 2, entry 4). Yellow solid; H NMR
2
3
(
H
1
300 MHz, CDCl
3
)
d
8.04 (2H, d, J 8.4 Hz, H ), 6.60 (2H, d, J 8.7 Hz,
2
(eCOCH
3
2
3
13
1
), 4.36 (2H, s, eNH
2
); C NMR (75 MHz, CDCl
3
)
d
152.63, 128.98,
re-
(
þ
26.36, 113.38; MS (ESI): (MþH ), found 139.0513. C
6 6 2 2
H O N
dazolium C5), 124.92 (imidazolium C4), 101.42 (eCOHeCeCOe),
quires 139.0673.
6
3.49 (eCH
2
), 36.67 (NeCH
3
), 18.27 (eCOCH
3
), 14.59 (eCH
2 3
CH );
þ
HRMS (ESI): (MþNa ), found 211.1077.
C H O N requires
10 15 3 2
4
.6.5. Pentafluorophenylamine (Table 2, entry 5). Colourless
2
11.1077.
.4. Synthesis of CuI nanoparticles
Dimethylglyoxime (dmgH) (0.464 g, 4 mmol) and Cu(OAc)
1
13
liquid; H NMR (300 MHz, CDCl
3 2
) d 4.13 (2H, s, eNH ); C NMR
(
75 MHz, CDCl 148.53e148.38, 145.50e145.24, 137.86e137.64,
3
) d
4
134.66e134.43, 127.13e126.75.
2
$H
2
O
.6.6. 4-Aminoacetophenone (Table 2, entry 7). Brown solid; 1
4
H
(
0.4 g, 2 mmol) were taken in absolute ethanol (50 mL) and stirred
NMR (300 MHz, CDCl
.1 Hz, H ), 4.18 (2H, s, eNH
CDCl 196.78, 151.80, 130.76, 127.11, 113.55, 25.95; MS (ESI):
MþH ), found 136.0759. C ON requires 136.0757.
3 2
) d 7.78 (2H, d, J 8.4 Hz, H ), 6.62 (2H, d, J
ꢀ
at 0 C for 30 min when a brown precipitate of Cu(dmg)
2
was
13
8
1
2 3
), 2.57 (3H, s, eCH ); C NMR (75 MHz,
formed. To this, 4a (1 mL) and potassium iodide (0.664 g, 4 mmol)
3
) d
ꢀ
were added and the contents were heated at 120 C for 2 h under
þ
(
8 9
H
reduced pressure. A black precipitate was obtained, which was
collected by centrifugation and washed with ethanol and deionized
water three times to ensure the removal of residual KI, and other
impurities. The final product was then dried in a vacuum oven at rt
for 12 h and 160 mg solid was obtained.
1
4
(
H
1
.6.7. 4-Aminobenzonitrile (Table 2, entry 8). Yellow liquid; H NMR
300 MHz, CDCl 7.34 (2H, d, J 8.4 Hz, H ), 6.62 (2H, d, J 8.4 Hz,
); C NMR (75 MHz, CDCl 150.99, 133.70,
3
)
d
2
13
1
), 4.40 (2H, s, eNH
2
3
) d
þ
20.50, 114.40, 99.18; MS (ESI): (MþH ), found 119.0608. C
7
H
6
N
2
requires 119.0693.
4
.5. Characterization of CuI nanoparticles
4
.6.8. 4-Fluoro-phenylamine (Table 2, entry 9). Yellow liquid; 1
NMR (300 MHz, CDCl 6.85 (2H, t, J 8.4 Hz, H
4.5 Hz, H ), 6.60 (1H, d, J 4.5 Hz, H ), 3.54 (2H, s, eNH
(M), found 111.0460. C NF requires 111.0524.
H
Characterization of CuI nanoparticles was done by TEM, DLS,
3
)
d
2
), 6.63 (1H, d, J
SEM/EDAX and UV analysis. To prepare the sample for SEM/EDAX,
CuI NPs were redispersed in 4aeacetonitrile mixture and sonicated
for about 1 h. Sample was prepared on a glass slide with the help
of spin coating to get a uniform distribution of particles. For TEM,
sample was prepared by mounting the NPs dispersed in
1
1
2
); MS (ESI):
6 6
H
1
4.6.9. 1H-Indol-5-ylamine (Table 2, entry 10). Light brown solid; H
NMR (300 MHz, CDCl
7.14 (1H, s, H ), 6.96 (1H, s, H
), 3.52 (2H, s, eNH
3
)
d
7.96 (1H, s, eNH), 7.20 (1H, d, J 8.1 Hz, H
), 6.67 (1H, d, J 8.1 Hz, H ), 6.38 (1H, s,
); C NMR (75 MHz, CDCl 139.49, 130.73,
1
),
4
aeacetonitrile mixture on a copper grid. DLS was recorded in
5
3
2
1
3
acetonitrile at a sample concentration of 0.1 mg/mL.
H
4
2
3
) d