Nano-TiCl4/SiO2: An efficient and reusable catalyst for the synthesis of tetrahydrobenzo[a]xanthenes-11-ones

Article abstract of DOI:10.2174/157017812801264700

Tetrahydrobenzo[a]xanthen-11-ones have been synthesized using 50% nano-TiCl₄/SiO₂ as a reusable, inexpensive, and efficient Lewis acid catalyst. Short reaction times, high yields, scale up, and easy work-up are the advantages of this

Full text of DOI:10.2174/157017812801264700

338
Letters in Organic Chemistry, 2012, 9, 338-343
Nano-TiCl4/SiO2: An Efficient and Reusable Catalyst for the Synthesis of
Tetrahydrobenzo[a]xanthenes-11-ones
Bi Bi Fatemeh Mirjalili*,a, Abdolhamid Bamonirib and Leila Zamania
aDepartment of Chemistry, College of Science, Yazd University, Yazd, PO Box 89195-741, I. R. Iran
bDepartment of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, I. R. Iran
Received August 04, 2011: Revised February 03, 2012: Accepted February 29, 2012
Abstract: Tetrahydrobenzo[a]xanthen-11-ones have been synthesized using 50% nano-TiCl4/SiO2 as a reusable,
inexpensive, and efficient Lewis acid catalyst. Short reaction times, high yields, scale up, and easy work-up are the
advantages of this protocol.
Keywords: Heterogeneous catalyst, multi component reaction, Nano-TiCl4/SiO2, one-pot reactions, Tetrahydrobenzo
[a]xanthen-11-one, solvent free condition.
INTRODUCTION
the commercial silica gel and synthesized nano-TiCl4/SiO2
were about 16-24 nm and 37-41 nm (Fig. 1), respectively.
Titanium tetrachloride as a powerful Lewis acid is a
liquid which is highly volatile, corrosive and difficult to
handle. It hydrolyses to produce HCl in the presence of
moisture. Silica-supported TiCl4 is a mild solid Lewis acid
that promotes acidic catalyzed organic reactions. This
catalyst does not need special precautions for preparation,
handling, or storage. It can be stored at an ambient
Tetrahydrobenzo[a]xanthen-11-ones have important
biological and pharmaceutical activities such as anti-
bacterial [2] and anti-inflammatory ones [3]. Previously,
these products were catalyzed by indium(III)chloride [4],
proline triflate [5] p-toluene sulfonic acid [6] strontium
triflate [7], tetrabutyl ammonium fluoride [8], NaHSO4/SiO2
(a)
(b)
(a)
(b)
Fig. (1). SEM photograph of (a) nano-SiO2 and (b) nano-TiCl4/SiO2.
temperature for months without losing its catalytic activity.
This catalyst was previously applied for the production of
polymers [1].
[9] and HBF4/SiO2 [10]. Many of these protocols have high
product yields and easy work-up but they have some
disadvantages such as difficult preparation and high price of
catalyst. In this work, we wish to report the application of
nano-TiCl4/SiO2 as catalyst for the synthesis of
tetrahydrobenzo[a]xanthen-11-ones under solvent free
condition. Nano-TiCl4/SiO2 has some advantages such as
easy preparation procedure and low cost.
Nano silica supported titanium chloride (nano-
TiCl4/SiO2) as an efficient acidic catalyst was prepared via a
reaction of nano SiO2 with TiCl4. The dimensions of
nanoparticles were observed with SEM. The particle sizes of
*Address correspondence to this author at the Department of Chemistry,
College of Science, Yazd University, Yazd, PO Box 89195-741, I. R. Iran;
Tel: (+98) 351 8211670-9; Fax: (+98) 351 8210644;
RESULTS AND DISCUSSION
For the identification of the structure of nano-TiCl4/SiO2,
we studied IR spectra of SiO2, nano-TiCl4/SiO2, and TiCl4
E-mail: fmirjalili@gmail.com
1875-6255/12 $58.00+.00
© 2012 Bentham Science Publishers

Nano-TiCl4/SiO2 Catalyzed Synthesis of Tetrahydrobenzo[a]xanthenes-11-ones
Letters in Organic Chemistry, 2012, Vol. 9, No. 5
339
(Fig. 2). In all of the spectra, very broad OH stretching bands
are observed with a strong intermolecular hydrogen bonding.
In FT-IR spectra of nano-TiCl4/SiO2 and SiO2, the
absorption bands for Si-OH and Si-O-Si appears in ~700
cm−1 and ~1100 cm−1, respectively. The absorption band of
Ti-Cl appear in 1600 cm-1 in TiCl4 spectrum. In the FT-IR
spectrum of nano-TiCl4/SiO2, the O-Ti-Cl, Si-OH and Si-O-
Si absorption bands are observed in 900, 700 and 1100 cm-1
respectively [11,12]. We have suggested the following
structure for nano-TiCl4/SiO2 (Scheme 1).
amount of TiCl4 in acetone. Determination of the extracted
Ti was carried out by an atomic absorption spectrometer
with a hollow cathode lamp at a wavelength of 346 nm using
C2H2/N2O flame. The calibration equation for titanium was
found as A=0.012C-0.1895 (R2=0.9998). In this equation, A
and C are the absorbance and concentration (mg L−1) of
titanium, respectively. The calculated loading amount of Ti
in catalyst is 7mg g-1.
In continuation of our investigation on application of
solid acids in organic synthesis [13-15], we wish to apply the
nano-TiCl4/SiO2 for the synthesis of tetrahydrobenzo
[a]xanthenes-11-one derivatives under various conditions.
The reaction of benzaldehyde (1 mmol), dimedone (1.2
mmol) with 2-naphthol (1 mmol) was examined to optimize
the reaction condition (Scheme 2). Reaction in different
conditions in the presence of TiCl4/SiO2 revealed that the
best condition for all the reactions was a solvent-free one at
90°C (entry 21, Table 1).
We have repeated the above-mentioned reaction with
50% nano-TiCl4/SiO2 and found that the 0.05 g of it is
necessary for 1 mmol of substrate (entry 23, Table 1). To
examine the reusability of nano-TiCl4/SiO2 in a solvent-free
condition, after each run, the product was dissolved to CHCl3
and filtered. The catalyst residue was washed with acetone
and reused. Treatment with acetone removes the tar from the
catalyst surface more efficiently (Table 1, entries 24 and 25).
The catalyst was reusable although a gradual decline was
observed in its activity. All of the products were known and
characterized by FT-IR, 1H-NMR, and the physical
properties of those reported in the literature. According to
the best obtained condition, we have applied 2-Naphthol,
dimedone or 1,3-cyclohexadione and various aldehydes were
used as substrates for the synthesis of tetrahydrobenzo
[a]xanthenes-11-one derivatives at 90 °C (Table 2, Scheme
3).
Fig. (2). FT-IR spectrum of: (a) SiO2, (b) nano-TiCl4/SiO2, and (c)
TiCl4.
Ti
O
Si
*
*
O
O
O
According to the literature, two types of mechanisms are
reported for the formation of tetrahydrobenzo[a]xanthenes-
11-one from the condensation of β -naphthol, aldehyde and
1,3-diketone in the presence of an acidic catalyst. In the first
one (a), initially, by the condensation of aldehyde and β -
naphthol, ortho-quinone methide (o-QMs) was formed as an
intermediate [4, 6, 7]. In the second one (b), an intermediate
was formed by the condensation of aldehyde and 1, 3-
diketone [5]. Our investigation has shown that in a one-pot
reaction between β -naphthol, 4-nitrobenzaldehyde and
dimedone in the presence of low-amount TiCl4/SiO2, the side
product (6) could be formed (Scheme 4). Also, the same
n
Scheme 1. Suggested structure for nano-TiCl4/SiO2.
Because the nano-TiCl4/SiO2 produces HCl in water, we
have determined the concentration of the acidic aqueous
solution by titration. We have found that 0.1 g of catalyst
produced
a
0.0064
M
aqueous solution. For the
determination of the loading amount of Ti on 0.1 g of nano-
TiCl4/SiO2, we have extracted Ti from the catalyst using
EDTA solution (0.004 M) at pH of 4. The standard solutions
of titanium (IV) were prepared by dissolving a proper
O
CHO
OH
Catalyst
O
+
+
O
O
Scheme 2. Synthesis of 9,9-dimethyl-12-(phenyl)-8,9,10,12-tetrahydrobenzo-[a]xanthen-11-one.

340 Letters in Organic Chemistry, 2012, Vol. 9, No. 5
Mirjalili et al.
Table 1. Synthesis of 9,9-dimethyl-12-(phenyl)-8,9,10,12-tetrahydrobenzo-[a]xanthen-11-one under Various Conditionsa
Reference
Yield (%)
Time (h)
Condition
Solvent
Catalyst(g)
Entry
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
[4]
[7]
[5]
[9]
[8]
[10]
10
40
10
15
15
30
60
65
69
60
75
70
85
85
84
84
84
95
94
84
76
84
85
85
87
99
92
4
r.t.
Ethanol
n-Hexane
CHCl3
TiCl4/SiO2 (0.2)
TiCl4/SiO2 (0.2)
1
4
r.t.
2
4
r.t.
TiCl4/SiO2 (0.2)
3
4
r.t.
CH2Cl2
TiCl4/SiO2 (0.2)
4
4
r.t
ClCH2CH2Cl
Ethanol
TiCl4/SiO2 (0.2)
5
3
Reflux
Reflux
Reflux
Reflux
Reflux
90 ˚C
90˚C
90˚C
90˚C
90˚C
90˚C
90˚C
90˚C
90˚C
100 °C
120 °C
120 °C
80 °C
Reflux
Reflux
Reflux
80˚C
TiCl4/SiO2 (0.2)
6
3
n-Hexane
CHCl3
TiCl4/SiO2 (0.2)
7
3
TiCl4/SiO2 (0.2)
8
3
CH2Cl2
TiCl4/SiO2 (0.2)
9
3
ClCH2CH2Cl
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
ClCH2CH2Cl
Water
TiCl4/SiO2 (0.2)
10
11
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
3
TiCl4/SiO2 (0.2)
1
30%TiCl4/SiO2 (0.2)
50% TiCl4/SiO2 (0.2)
60% TiCl4/SiO2 (0.2)
50% TiCl4/SiO2 (0.15)
50% TiCl4/SiO2 (0.125)
50% TiCl4/SiO2 (0.1)
50%Nano-TiCl4/SiO2 (0.075)
50%Nano-TiCl4/SiO2 (0.05)
50% nano-TiCl4/SiO2 (0.05), 2nd run
50% nano-TiCl4/SiO2 (0.05), 3rd run
InCl3
1
1
1
1
1
0.5
0.5
0.8
1
30min
5
Sr(OTf)2
3
proline triflate
4
CH2Cl2
NaHSO4/SiO2
9
Water
TBAF
1
Solvent-free
HBF4/SiO2
aThe molar ratio of aldehyde:dimedone:β-naphthol is 1:1.2:1.
O
OH
nano-TiCl4/SiO2
R1CHO
+
R1
O
O
+
R2
R2
Solvent free
90 ˚C
O
R2
1
2
3
4
R2
Scheme 3. Synthesis of tetrahydrobenzo[a]xanthen-11-one in the presence of nano-TiCl4/SiO2 at 90 °C under solvent-free condition.
product was formed in a reaction of 4-nitrobenzaldehyde and
dimedone in the absence of β -naphthol. According to the
obtained data, our proposed mechanism is similar to (b).
methodology, easy work-up and green conditions are
advantages of this protocol.
EXPERIMENTAL SECTION
CONCLUSION
The chemicals were used without any additional
purification. The products were characterized by FT-IR, H-
NMR, and a comparison of their physical properties with
those reported in the literature. FT-IR spectra were run on a
Bruker, Eqinox 55 spectrometer. A Bruker (DRX-400
1
We have demonstrated simple methods for the synthesis
of tetrahydrobenzo-[a]xanthen-11-one with using 50% nano-
TiCl4/SiO2 as eco-friendly and efficient catalyst. Short
reaction times, high yields, a clean process, simple

Nano-TiCl4/SiO2 Catalyzed Synthesis of Tetrahydrobenzo[a]xanthenes-11-ones
Letters in Organic Chemistry, 2012, Vol. 9, No. 5
341
Table 2. Synthesis of Tetrahydrobenzo[a]xanthen-11-one in the Presence of 50% Nano-TiCl4/SiO2 at 90 °C
Mp (°C)
Reference
Yeildb (%)
R2
R1
Entry
Reported.
Found
[4]
[4]
[6]
[5]
[7]
[4]
[3]
[9]
[3]
[6]
[3]
[4]
151-153
186-187
150-151
180-182
183-185
204-205
160-162
175-176
168-170
188-189
205-206
205-206
151-153
184-185
150-151
183-184
181-182
206-207
160-161
174-176
167-168
186-187
200-204
205-208
88
87
86
96
87
84
84
77
70
82
84
79
Me
Me
Me
Me
Me
Me
Me
Me
Me
H
C6H5
4-Br–C6H4
4-OH–C6H4
4-Cl–C6H4
4-O2N–C6H4
4-MeO–C6H4
4-CH(CH3)3C6H4
3-Br-C6H4
3-NO2C6H4
C6H5
1
2
3
4
5
6
7
8
9
10
11
12
H
4-ClC6H4
H
4-MeC6H4
aThe ratio of 2-naphthol(mole): aldehydes (mole):dimedone (mole): nano-TiCl4/SiO2 (g) is 1:1:1.2:0.05.
bIsolated yield.
NO2
NO2
CHO
O
low amount
O
OH
+
O
+
O
TiCl4/SiO2
+
Solvent free
90 ˚C
O
O2N
O
O
OH
6
5
Scheme 4. Reaction between β-naphthol, 4-nitrobenzaldehyde and dimedone in the presence of low-amount TiCl4/SiO2.
1
Avanes) NMR was used to record the H NMR spectra. The
absorption of titanium solutions was determined by an
atomic absorption spectrometer, AVONA AA300. Also the
charged in to isolating funnel and extracted with chloroform
to isolation of product. The chloroform layer was evaporated
carefully and the obtained solid was crystallized in
ethanol:water (80:20) to afford the pure tetrahydrobenzo
[a]xanthenes-11-one derivatives in good to excellent yields.
SEM of nano particles was determined with
VEGA/TESCAN scanning electron microscope.
a
Preparation of 50% Nano-TiCl4/SiO2 and 50% TiCl4/
SiO2
Selected Spectroscopic Data
9,9-Dimethyl-12-phenyl-8,9,10,12-tetrahydrobenzo
[a]xanthen-11-one (Table 2, entry1)
0.5 g (0.29 mL) of TiCl4 was added drop wise to a
mixture of 0.5 g of silica gel or nano silica gel and 5 mL of
chloroform. The mixture was stirred for one hour at room
temperature. The resulted suspension was filtered. The
obtained solid was washed with chloroform and dried at
room temperature.
FT-IR (KBr): υ max: 3053, 2957, 2891,1649,1620, 1596,
1469, 1452, 1372, 1241, 1226, 1184, 1032, 837, 747, 723,
697.
1H NMR (400 MHz, CDCl3): δ = 0.97 (s, 3H), 1.13 (s,
3H), 2.25 (d, J=16 Hz, 1H, COCH2), 2.32 (d, J=16.4 Hz, 1H,
COCH2), 2.58 (s, 2H), 5.71 (s, 1H), 7.06 (t, J=7.6, 1H), 7.18
(t, J=8, 2H), 7.32-7.46 (m, 5H), 7.77 (d, J=8.4 Hz, 1H), 7.79
(d, J=6.4 Hz, 1H), 8.00 (d, J=8.4Hz, 1H) ppm.13C NMR (125
MHz, CDCl3): δ = 27.59, 29.72, 32.69, 35.14, 41.85, 51.34,
114.71, 117.46, 118.14, 124.11, 125.31, 126.65, 127.42,
128.65, 128.80, 128.85, 129.25, 131.85, 131.93, 145.18,
148.19, 164.30, 197.29 ppm.
General Procedure for the Synthesis of Tetrahydrobenzo
[a]xanthen-11-one
A mixture of 2-naphthol (1 mmol), aldehyde (1 mmol),
dimedone (1.2 mmol) and 50% nano-TiCl4/SiO2 (0.05 g) was
heated at 90 °C. The progress of the reaction was monitored
by TLC. After completion of the reaction, the mixture was

342 Letters in Organic Chemistry, 2012, Vol. 9, No. 5
Mirjalili et al.
12-(4-bromophenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-one (Table 2, entry2)
12-(4-methoxyphenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-one, (Table 2, entry 6)
FT-IR (KBr): υmax: 2966, 2876, 1640, 1622, 1593, 1484,
FT-IR (KBr): υmax: 2957, 2898, 1644, 1611, 1594, 1509,
1460, 1371, 1245, 1249, 1223, 1164, 1027, 1025, 833, 812,
747cm-1.
1H NMR (400 MHz, CDCl3): δ = 0.98 (s, 3H), 1.12 (s,
3H), 2.25 (d, J=16 Hz, 1H, COCH2), 2.32 (d, J=16.4 Hz, 1H,
COCH2), 2.57 (s, 2H), 3.69 (s,3H), 5.66 (s,1H), 6.71 (d,
J=8.4 Hz, 2H), 7.20-7.27 (m, 2H), 7.32 (d, J=8.8 Hz, 1H),
7.38 (t, J=8 Hz, 1H), 7.44 (t, J=8 Hz, 1H), 7.76 (d, J=9.2 Hz,
1H), 7.78 (d, J=9.2 Hz, 1H), 7.99 (d, J=8.4 Hz, 1H) ppm.
1372, 1274, 1220, 1174, 1071, 1010, 837, 811, 756 cm-1.
1H NMR (400 MHz, CDCl3): δ = 0.97 (s, 3H), 1.13 (s,
3H), 2.25 (d, J=16.4 Hz, 1H, COCH2), 2.32 (d, J=16 Hz, 1H,
COCH2), 2.58 (s, 2H), 5.67 (s,1H), 7.22 (d, J=7.2 Hz, 2H),
7.29 (d, J=7.2 Hz, 2H), 7.33 (d, J=9.2 Hz, 1H), 7.40 (t, J=7.6
Hz, 1H), 7.45 (t, J=7.6 Hz, 1H), 7.78 (d, J=7.2 Hz, 1H), 7.80
(d, J=6.8 Hz, 1H), 7.91 (d, J=8 Hz, 1H) ppm.
13C NMR (125 MHz, CDCl3): δ = 27.59, 29.72, 32.68,
34.70, 41.83, 51.29, 114.18, 117.41, 117.46, 120.54, 123.88,
125.46, 127.56, 128.92, 129.54, 130.62, 131.64, 131.77,
131.95, 144.19, 148.17, 164.49, 197.27 ppm.
12-(4-isopropylphenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-one, (Table 2, entry 7)
FT-IR (ATR, neat): υmax: 2960, 2873, 1649, 1622, 1596,
1469, 1370, 1241, 1227, 1145, 1016, 833, 818, 745cm-1.1H
NMR (400 MHz, CDCl3): δ = 0.99 (s, 3H), 1.12 (s, 3H), 1.13
(d, J=6.8, 6H), 2.26 (d, J=16 Hz, 1H), 2.31 (d, J=16.4 Hz,
1H), 2.58 (s, 2H), 2.76 (m,1H), 5.68 (s,1H), 7.01 (d, J=8 Hz,
2H), 7.24 (d, J=8.4 Hz, 2H), 7.32 (d, J=8.8 Hz, 1H), 7.38 (t,
J=8.4 Hz, 1H), 7.43 (t, J=8.4 Hz, 1H), 7.76 (d, J=8.8 Hz,
1H), 7.78 (d, J=8.8 Hz, 1H), 8.04 (d, J=8.4 Hz, 1H) ppm.
12-(4-hydroxyphenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-onele 2, (Table 2, entry 3)
FT-IR (KBr): υmax: 3610, 3141-3440, 3029, 2952, 2891,
1649, 1615, 1595, 1510, 1466, 1371, 1234, 1227, 1174,
1014, 837, 818, 747cm-1.
1H NMR (500 MHz, CDCl3): δ = 0.99 (s, 3H), 1.14 (s,
3H), 2.31 (d, J=16.4 Hz, 1H, COCH2), 2.35 (d, J=16 Hz, 1H,
COCH2), 2.48(s,1H), 2.59 (s, 2H), 5.65 (s,1H), 6.62 (d, J=8.5
Hz, 2H), 7.19 (d, J=8.6 Hz, 2H), 7.39 (d, J=6.8 Hz, 1H), 7.45
(t, J=8.4 Hz, 1H), 7.47 (t, J=8.4 Hz, 1H), 7.78 (d, J=8.8 Hz,
1H), 7.80 (d, J=6.9 Hz, 1H), 8.0 (d, J=8.4 Hz, 1H) ppm.
13C NMR (125 MHz, CDCl3): δ = 27.56, 27.76, 29.64,
32.77, 34.31, 41.84, 51.28, 114.90, 115.67, 117.42, 118.28,
124.17, 125.34, 127.39, 128.80, 129.18, 129.95, 131.79,
131.96, 137.18, 148.01, 154.67, 164.82 ppm.
12-(3-bromophenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-one, (Table 2, entry 8)
FT-IR (ATR, neat): υmax: 2958, 2891, 1646, 1622, 1594,
1470, 1432, 1370, 1282, 1218, 1175, 1076, 1024, 805, 879,
775, 692, 744cm-1.1H NMR (400 MHz, CDCl3): δ = 0.99 (s,
3H), 1.13 (s, 3H), 2.26 (d, J=16.4 Hz, 1H), 2.32 (d, J=16 Hz,
1H), 2.59 (s, 2H), 5.68 (s,1H), 7.06 (t, J=8 Hz, 1H), 7.20 (d,
J=8.4 Hz, 1H), 7.34 (d, J=8.4 Hz, 2H), 7.39-7.42 (m, 2H),
7.47 (t, J=8 Hz, 1H), 7.79 (d, J=5.2 Hz, 1H), 7.81 (d, J=6.4
Hz, 1H), 7.92 (d, J=8.4 Hz, 1H) ppm.
12-(4-chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydro-
benzo[a]xanthen-11-one (Table 2, entry 4)
12-(3-nitrophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo
[a]xanthen-11-one, (Table 2, entry 9)
FT-IR (KBr): υmax: 2957, 2884, 1644, 1622, 1596, 1487,
1469, 1372, 1234, 1221, 1141,1088, 1013, 845, 838,
750cm-1.
1H NMR (400 MHz, CDCl3): δ = 0.97 (s, 3H), 1.13 (s,
3H), 2.25 (d, J=16.4 Hz, 1H, COCH2), 2.32 (d, J=16 Hz, 1H,
COCH2), 2.58 (s, 2H), 5.69 (s,1H), 7.14 (d, J=8.4 Hz, 2H),
7.28 (d, J=8.4 Hz, 2H), 7.33 (d, J=8.8 Hz, 1H), 7.40 (td,
J=6.8, 1.2 Hz, 1H), 7.45 (td, J=6.8, 1.2 Hz, 1H), 7.78 (d,
J=8.8 Hz, 1H), 7.8 (d, J=5.6 Hz, 1H), 7.91 (d, J=8.4 Hz, 1H).
FT-IR (KBr): υmax: 2969, 2891, 1645, 1622, 1594, 1465,
1536, 1477, 1371, 1355, 1249, 1218, 1174,1024, 830, 806,
779, 689, 741 cm-1.
1H NMR (400 MHz, CDCl3): δ = 0.96 (s, 3H), 1.14 (s,
3H), 2.25 (d, J=16.4 Hz, 1H, COCH2), 2.34 (d, J=16 Hz, 1H,
COCH2), 2.62 (s, 2H), 5.82 (s,1H), 7.36-7.48 (m, 4H), 7.81-
7.84 (m, 3H), 7.78 (d, J=8.4 Hz, 1H), 7.94 (d, J=8 Hz, 1H),
8.12 (s, 1H) ppm.
12-(4-nitrophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo
[a]xanthen-11-one (Table 2, entry 5)
12-phenyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one
(Table 2, entry 10)
FT-IR (KBr): υmax: 2956, 1643, 1622, 1594, 1477, 1513,
1477, 1376, 1342, 1244, 1221, 1183, 1031, 850, 830, 751
cm-1.
1H NMR (400 MHz, CDCl3): δ = 0.95 (s, 3H), 1.14 (s,
3H), 2.25 (d, J=16.4 Hz, 1H, COCH2), 2.34 (d, J=16 Hz, 1H,
COCH2), 2.61 (s, 2H), 5.82 (s,1H), 7.36 (d, J= 9.2, 1H),
7.39-7.47 (m, 2H), 7.52 (d, J=8.8 Hz, 2H), 7.81-7.85 (m,
3H), 8.05 (d, J=8.4 Hz, 2H) ppm.
13C NMR (125 MHz, CDCl3): δ = 27.50, 29.72, 32.69,
35.30, 41.85, 51.21, 113.42, 116.47, 117.52, 123.54, 124.05,
125.67, 127.81, 129.09, 129.79, 130.06, 131.46, 132.01,
146.78, 148.22, 152.29, 165.05, 197.14.
FT-IR (KBr): υmax: 3059, 2930, 1644, 1616, 1593, 1511,
1453, 1249, 1227, 1189, 1032, 830, 757, 701cm-1.
1H NMR (400 MHz, CDCl3): δ = 1.94-2.06 (m, 2H),
2.35-2.49 (m, 2H), 2.63-2.73 (m, 2H), 5.75 (s, 1H), 7.07 (t,
J=7.6 Hz, 1H), 7.18 (t, J=7.6 Hz, 2H), 7.34 (d, J=8.4 Hz,
2H), 7.39-7.45 (m, 3H), 7.77 (d, J=7.2 Hz, 1H), 7.79 (d,
J=6.8 Hz, 1H), 7.90 (d, J=8.4 Hz, 1H) ppm.
13C NMR (125 MHz, CDCl3): δ = 20.71, 28.17, 35.10,
37.50, 116.01, 117.43, 118.16, 123.12, 124.14, 125.34,
126.71, 127.44, 128.73, 128.83, 128.95, 129.29, 131.85,
145.52, 148.24, 166.03, 197.46 ppm.

Nano-TiCl4/SiO2 Catalyzed Synthesis of Tetrahydrobenzo[a]xanthenes-11-ones
Letters in Organic Chemistry, 2012, Vol. 9, No. 5
343
12-(4-Chlorophenyl)-8,9,10,12-tetrahydrobenzo[a]xanthen-
11-one (Table 2, entry 11)
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FT-IR (KBr): υmax: 3063, 1645, 1622, 1593, 1488, 1458,
1226, 1189, 1089, 1014, 838, 818, 751cm-1.1H NMR (400
MHz, CDCl3): δ = 1.94-2.10 (m, 2H), 2.35-2.50 (m, 2H),
2.63-2.78 (m, 2H), 5.72 (s, 1H), 7.15 (d, J=8 Hz, 2H), 7.28
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12-(4-Methylphenyl)-8,9,10,12-tetrahydrobenzo[a]xanthen-
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FT-IR (KBr): υmax: 2947, 1647, 1622,, 1596, 1509, 1406,
1372, 1253, 1224, 1188, 1032, 838, 808, 742cm-1.1H NMR
(400 MHz, CDCl3): δ = 1.99-2.06 (m, 2H), 2.22 (s, 3H),
2.38-2.46 (m, 2H), 2.67-2.74 (m, 2H), 5.72 (s, 1H), 6.99 (d,
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CONFLICT OF INTEREST
Declared none.
ACKNOWLEDGEMENT
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[15]
The Research Council of Yazd University is gratefully
acknowledged for the financial support of this study.
dihydropyrimidin-2(1H)-ones(thiones)
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ABBREVIATIONS
TBAF
=
tetrabutyl ammonium fluoride