H. Eshghi et al. / Journal of Molecular Catalysis A: Chemical 363–364 (2012) 430–436
431
Ar
O
HN
O
O
Fe(HSO4)3.SiO2
R1
R2
+
ArNH2
R1
R2
Solvent-free. r.t
3
1
2
R1, R2 = alkyl, aryl, cycloalkyl, alkoxy
Scheme 1. Synthesis of -enaminones and -enamino esters in the presence of Fe(HSO4)3·SiO2.
lit. [13] m.p 46–47 ◦C; 1H NMR (CDCl3, 100 MHz) ı: 10.3 (b, 1H),
Table 1
Conditions optimization of the reaction between aniline and acetylacetone.
7.0–7.3 (m, 5H), 4.7 (s, 1H), 3.67 (s, 3H), 2.0 (s, 3H(. IR (KBr, cm−1
)
Entry
Solvent
CH3OH
Catalyst
Mol (%)
Condition
Yield (%)
ꢀ: 3248, 1651, 1606, 1590, 1262, 786.
1
2
Fe(HSO4)3
Fe(HSO4)3
10
10
10
25
50
25
25
25
25
25
Reflux, 1 h
r.t, 1 h
50
50
80
89
89
89
87
85
85
84
m.p = 65–67 ◦C, lit. [13] oil; 1H NMR (CDCl3, 100 MHz) ı:10.2 (b,
1H), 7.0 (AB-q, 4H), 4.8 (s, 1H), 3.75 (s, 3H), 3.06 (s, 3H), 2.0 (s, 3H).
IR (KBr, cm−1) ꢀ: 3264, 1651, 1613, 1513, 1246, 788.
Methyl (Z)-3-(4-toluidino)-2-butenoate (3g): yield 91%;
m.p = 58–60 ◦C, lit. [13] m.p 57–58 ◦C; 1H NMR (CDCl3, 100 MHz)
ı: 10.3 (b, 1H), 7.1 (AB-q, 4H), 4.3 (s, 1H), 3.65 (s, 3H), 2.4 (s,
3H), 1.95 (s, 3H). IR (KBr, cm−1) ꢀ: 3264, 1651, 1598, 1275,
1163.
m.p = 61–62 ◦C, lit. [13] m.p 60–61 ◦C; 1H NMR(CDCl3, 100 MHz) ı:
10.4 (b, 1H), 7.2 (AB-q, 4H), 6.6 (b, 1H), 4.85 (s, 1H), 3.7 (s, 3H), 2.1
(s, 3H). IR (KBr, cm−1) ꢀ: 3374, 1652, 7618, 1271, 1167.
CH3OH
3
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
Fe(HSO4)3/SiO2
r.t, 20 min
r.t, 7 min
r.t, 7 min
r.t, 7 min
r.t, 7 min
r.t, 7 min
r.t, 7 min
r.t, 7 min
4a
5
6b
7c
8d
9e
10f
a
Optimum conditions.
b–f
Reusability of the catalyst in the new runs.
respectively. Chemical shifts are reported in ppm downfield from
TMS as internal standard; coupling constants J are given in Hertz.
Elemental analyses were obtained on a Thermo Finnigan Flash EA
micro-analyzer. Silica supported ferric hydrogensulfate prepared
as we previously reported [19].
(Z)-3-Anilino-1-phenyl-2-buten-1-one
(3i):
yield
93%;
m.p = 108–110 ◦C, lit. [15] m.p 109–111 ◦C; 1H NMR (CDCl3,
100 MHz) ı: 13.1 (b, 1H), 8.0 (m, 2H), 7.1–7.5 (m, 8H), 5.95 (s, 1H),
2.3 (s, 3H). IR (KBr, cm−1) ꢀ: 3435, 1621, 1589, 1547, 1325, 752.
(Z)-3-(4-Methoxyaniline)-1-phenyl-2-buten-1-one (3j): yield
95%; m.p = 103–105 ◦C; 1H NMR (CDCl3, 400 MHz) ı: 13.99 (b, OH,
0.083H), 12.96 (b, NH, 0.917H), 7.95 (d, 2H, J = 6.4 Hz), 7.47 (m, 3H),
7.14 (d, 2H, J = 7.6 Hz), 6.93 (d, 2H, J = 8.0 Hz), 5.90 (s, 1H), 3.85 (s,
3H), 2.10 (s, 3H). 13C NMR (CDCl3, 100 MHz) ı: 188.4, 163.2, 157.9,
140.2, 131.5, 130.8, 128.3, 127.1, 126.6, 93.6, 55.5, 20.3. IR (KBr,
cm−1) ꢀ: 3051, 3010, 2949, 2830, 1623, 1607, 1587, 1508, 1330,
768.
2.2. General procedure for the synthesis of compounds 3a–3t
A mixture of the -dicarbonyl compound (2 mmol), the amine
(2 mmol) and Fe(HSO4)3·SiO2 [0.22 g containing 0.25 mmol of
Fe(HSO4)3] was stirred in solvent free condition at room temper-
ature for the appropriate time (Table 1). After completion of the
reaction as indicated by TLC, the mixture was diluted by ethyl
acetate (20 ml). The insoluble catalyst was separated by filtration
and rinsed with ethyl acetate, dried and re-used. The solvent of
recrystallization from EtOH/H2O (1/1).
(Z)-1-Phenyl-3-(4-toluidino)-2-buten-1-one (3k): yield 91%;
m.p = 90–92 ◦C; 1H NMR (CDCl3, 400 MHz) ı: 13.96 (b, OH, 0.246H),
12.95 (b, NH, 0.754H), 7.96 (m, 2H), 7.47 (m, 3H), 7.20 (m, 2H),
7.11 (m, 2H), 5.91 (s, 1H), 2.34 (s, 3H), 2.15(s, 3H). 13C NMR (CDCl3,
100 MHz) ı: 188.5, 162.6, 140.1, 136.0, 135.7, 130.8, 129.8, 128.3,
127.1, 124.9, 93.9, 21.0, 20.4. IR (KBr, cm−1) ꢀ: 3047, 2912, 1993,
1899, 1821, 1622, 1572, 754, 506.
(Z)-3-(4-Choloroanilino)-1-phenyl-2-buten-1-one (3l): yield 81%;
m.p = 126–128 ◦C; 1H NMR (CDCl3, 400 MHz) ı: 14.05 (b, OH,
0.242H), 13.10 (b, NH, 0.758H), 7.94 (d, 2H, J = 6.8 Hz), 7.47 (m, 3H),
7.37 (d, 2H, J = 7.2 Hz), 7.14 (d, 2H, J = 7.6 Hz), 5.95 (s, 1H), 2.17 (s,
3H). 13C NMR (CDCl3, 100 MHz) ı: 189.0, 161.8, 139.8, 137.3, 131.3,
131.1, 129.4, 128.4, 127.1, 125.9, 94.7, 20.5. IR (KBr, cm−1) ꢀ: 3411,
3080, 3051, 1623, 1588, 1549, 1326, 766.
Spectral data of the prepared compounds:
[15] m.p 47–49 ◦C; 1H NMR (CDCl3, 100 MHz) ı: 12.5 (b, 1H), 6.9–7.3
(m, 5H), 5.15 (s, 1H), 2.1 (s, 3H), 1.95 (s, 3H). IR (KBr, cm−1) ꢀ: 3435,
3051, 2994, 2924, 1614, 1596, 1282, 764, 696.
(Z)-4-(4-Methoxyanilino)-3-penten-2-one (3b): yield 91%;
m.p = 45–47 ◦C, lit. [13] m.p 41–43 ◦C; 1H NMR (CDCl3, 100 MHz)
ı: 12.3 (b, 1H), 6.9 (AB-q, 4H), 5.1 (s, 1H), 3.7 (s, 3H), 2.07 (s, 3H),
1.88 (s, 3H). IR (KBr, cm−1) ꢀ: 3447, 3358, 3219, 2990, 2916, 1617,
1567, 1494, 1277, 1091.
3-Anilino-5,5-dimethyl-2-cyclohexen-1-one (3m): yield 86%;
m.p = 184–185 ◦C, lit. [15] m.p 184–186 ◦C; 1H NMR (CDCl3,
100 MHz) ı: 7.1–7.4 (m, 5H), 6.4 (b, 1H), 5.6 (s, 1H), 2.25 (m, 4H),
2.25 (m, 4H), 1.1(s, 6H). IR (KBr, cm−1) ꢀ: 3231, 1597, 1573, 1244,
705.
(Z)-4-(4-Toluidino)-3-penten-2-one
(3c):
yield
90%;
m.p = 63–65 ◦C, lit. [15] m.p 66–68 ◦C; 1H NMR (CDCl3, 100 MHz) ı:
12.4 (b, 1H), 7.1 (m, 4H), 5.15 (s, 1H), 2.4 (s, 3H) 2.1 (s, 3H), 1.9 (s,
3H). IR (KBr, cm−1) ꢀ: 3440, 3031, 2994, 2921, 2855, 1610, 1567,
1276, 808.
3-(4-Methoxy aniline)-5,5-dimethyl-2-cyclohexen-1-one (3n):
yield 91%; m.p = 193–195 ◦C, lit. [15] m.p 192–194 ◦C; 1H NMR
(CDCl3, 100 MHz) ı: 7.1 (b, 1H), 6.9 (AB-q, 4H), 5.3 (s, 1H), 3.75 (s,
3H), 2.25 (AB-q, 4H), 1.05 (s, 6H). IR (KBr, cm−1) ꢀ: 3206, 1607,
1568, 1536, 1509, 1243.
(Z)-4-(4-Choloroanilino)-3-penten-2-one (3d): yield 85%;
m.p = 59–60 ◦C, lit. [13] m.p 61–62 ◦C; 1H NMR (CDCl3, 100 MHz)
ı: 12.45 (b, 1H), 7.2 (m, 4H), 5.25 (s, 1H), 2.15 (s, 3H), 2.0 (s, 3H).
IR (KBr, cm−1) ꢀ: 3448, 3354, 3219, 3060, 2990, 2921, 1617, 1567,
1494, 1276.