One-pot synthesis of isobenzofuran-1(3H)-ones using sulfuric acid immobilized on silica under solvent-free conditions and survey of third-order nonlinear optical properties

Article abstract of DOI:10.4067/S0717-97072015000100011

Solvent-free synthesis of isobenzofuran-1(3H)-ones have been described via reaction of phthalaldehydic acid (2-carboxybenzaldehyde) with methylaryl or cyclic ketones using sulfuric acid immobilized on silica (H₂SO₄-SiO₂) in excellent yields (70-88%). The catalyst can be recovered by simple filtration and reused. Also, some of these compounds has been studied the third-order nonlinear optical properties by laser Gaussian z-scan techniques.

Full text of DOI:10.4067/S0717-97072015000100011

J. Chil. Chem. Soc., 60, Nº 1 (2015)
ONE-POT SYNTHESIS OF ISOBENZOFURAN-1(3H)-ONES USING SULFURIC ACID IMMOBILIZED ON SILICA
UNDER SOLVENT-FREE CONDITIONS AND SURVEY OF THIRD-ORDER NONLINEAR OPTICAL PROPERTIES
BEHROOZ MALEKI1*, EHSAN KOUSHKI2, MEHDI BAGHAYERI1, SAMANEH SEDIGH ASHRAFI1
1Department of Chemistry, Hakim Sabzevari University, Sabzevar, 96179-76487, Iran
2Department of Physics, Hakim Sabzevari University, Sabzevar, 96179-76487, Iran
ABSTRACT
Solvent-free synthesis of isobenzofuran-1(3H)-ones have been described via reaction of phthalaldehydic acid (2-carboxybenzaldehyde) with methylaryl or
cyclic ketones using sulfuric acid immobilized on silica (H2SO4-SiO2) in excellent yields (70–88%). The catalyst can be recovered by simple filtration and reused.
Also, some of these compounds has been studied the third-order nonlinear optical properties by laser Gaussian z-scan techniques.
INTRODUCTION
Isobenzofuran-1(3H)-ones and their derivatives are very important biological compounds that occur widely in natural products. Typical examples are are
fuscinarin (1)1 , typhaphthalide (2)2 , catalpalactone (3)3, alcyopterosin E (4)4 , (+)-spirolaxine (5)5 , vermistatin (6)6 , rubiginone-H (7)7 , (-)-hydrastine (8)8 ,
isopestacin (9)9 , and cryphonectricacid (10) 10
.
Figure 1.
Some members of this family have displayed interesting physiological
activities and found attractive applications in medicinal chemistry, being
used as anti-bacterial, anti-convulsant, anti-HIV, anti-asthmatic, anti-tumor,
anti-plateletactivities, anesthesiaprolongation, and PGF2ainhibitory properties
11,12. 3-Alkylidene phthalide derivatives are known for their anti-spasmodic,
herbicidal, and insecticidal properties and 3-styryl phthalides are used as
color formers for heat and pressure sensitive recording materials 13. Also,
isobenzofuran-1(3H)-ones are valuable intermediates in the synthesis of a
polycyclic compounds 14. Because of importance of these kinds of compounds,
development of a general and efficient synthetic strategy to synthesize those
compounds is still desired.
montmorillonite K-10 24, Ac2O 25, ZrOCl .8H2O 26,are also used in the synthesis
of 3-alkyl phthalides. Some of the abo2ve mentioned methods including, the
use of strong corrosive and harmful acides or bases, low yields, long reactions
times and tedious work up.
Inrecentyears, theuseofsolidacidsasheterogeneouscatalystshasreceived
tremendous interest in different areas of organic synthesis. Heterogeneous solid
acids have advantageous higher than conventional homogeneous acid catalysts.
As Heterogeneous solid acids can be easily recovered from the reaction
mixture by simple filtration, they can be reused after activation or without
activation. The main drawback of the bulk catalyst is its low specific surface
area. Therefore, it is important to increase the surface area or even better to
increase the number of accessible active sites of the catalyst. In order to reach
to this objective, the catalyst is usually deposited on the surface of a solid
support with high surface area and suitable mechanical strength which is able
not only to disperse the catalyst. But it can increase its thermal stability and
Due to the potential of phthalides, a number of methods have been
developed for their synthesis. These methods include cyclization reractions
19
catalyzed by strong bases such as DBU 15,16, NaOH 17, KOH 18, NaOCH3
NaOC2H5 20, (C2H5)2NH 21. Strong acides such as CF3COOH 22, CF3SO3H
,
,
23
e-mail: b.maleki@hsu.ac.ir
2827

J. Chil. Chem. Soc., 60, Nº 1 (2015)
the catalyst life. In supported catalysts, the catalytic behavior of the catalyst
is strongly dependent on support properties. Among the various supported
catalysts, particularly, alumina and silica supported reagents have advantages
Table 1. Screening of the reaction conditions for the synthesis of 3-(2-oxo-
2-phenylethyl) isobenzofuran-1(3H)-ones (3f).
Times
(min)
Yielda
(%)
of low cost, ease of preparation, and catalyst recycling 27-35
.
Entry
Catalysts
AcOH (1 ml)
Conditions
Our new approach is based on the use of a solid acid (H2SO4.SiO2) catalyzed
cyclization of phthaldehydic acid with aryl ketones and 1,3-dicarbonyl
compounds that are all commercially available. Finally, the presence of
multiple π electrons with different structures and conjugation lengths impelled
us to study optical properties associated with these electrons called optical
nonlinearity. The results were interesting from view point of optical application.
1
2
Reflux,1200C
600
Trace
Solvent-
Free,1100C
Solvent-
H2SO4 (18 M, 0.1 ml)
120
Trace
3
4
H2SO4 (0.1 M, 0.1 ml)
120
600
600
180
25
42
Trace
Trace
52
Free,1100C
Solvent-
NH H PO4-SiO2
4(02.04 g)
Free,1100C
Solvent-
RESULTS AND DISCUSSION
5
AlCl3.6H2O (0.05 g)
Free,1100C
Solvent-
P O5-SiO2 (70%
In continuation of our research to develop new and eco-friendly synthetic
methodologies 36-46, we herein present efficient and environmentally benign
protocols for the synthesis of isobenzofuran-1(3H)-one derivatives by
condensation of phthalaldehydic acid (2-carboxy benzaldehyde) with aryl
ketones or 1,3-dicarbonyl compounds catalyzed by H2SO4-SiO2 under solvent-
free conditions at 1200C (Scheme 1).
2w/w,0.05 g)
Free,1100C
Solvent-
6
7
H2SO4-SiO2 (0.05 g)
67
Free,1100C
Solvent-
Poly [AMPS-co-AA]
(0.1 g)
8
360
20
62
Free,1100C
Solvent-
9
H2SO4-SiO2 (0.05 g)
H2SO4-SiO2 (0.05 g)
H2SO4-SiO2 (0.05 g)
H2SO4-SiO2 (0.07 g)
H2SO4-SiO2 (0.03 g)
-
82
Free,1200C
Solvent-
10
11
12
13
14
20
72
Free,1300C
Solvent-
25
54
Free,1000C
Solvent-
20
66
Free,1200C
Solvent-
25
52
Free,1200C
Solvent-
b
120
-
Free,1200C
a Isolated yields. bNo Reaction.
To further explore the scope of this protocol, we decided to investigate the
condensation reaction of phthalaldehydic acid (2-carboxy benzaldehyde) with
another aryl ketones or 1,3-dicarbonyl compounds (Table 2).
Proposed Mechanism for the Synthesis of Isobenzofuran-1(3H)-one
(3a-k)
A plausible mechanism for the formation of isobenzofuran-1(3H)-one
(3a-k) in the presence of H SO -SiO2 is proposed in Scheme 2. The reaction
proceeds in two steps; an a2ldol4 condensation and the subsequent cyclization
(lactonization).
Scheme 1. Synthesis of isobenzofuran-1(3H)-one derivatives by
condensation of phthalaldehydic acid (2-carboxy benzaldehyde) with aryl
ketones or 1,3-dicarbonyl compounds catalyzed by H2SO4-SiO2
The Effect of Temperature andAmount Catalyst on the Rate and Yeild
of the Reaction Phthalaldehydic acid with Acetophenone
To choose optimum conditions, we initially investigated the reaction of
phthalaldehydic acid (1 mmol) with acetophenone (1.2 mmol) in the presence
of acid catalysts such as AcOH, H2SO4, NH4H2PO4-SiO2, AlCl .6H O, P O5-
SiO2, Poly [AMPS-co-AA], and H2SO4-SiO2 in different media (3Tabl2e 1, e2ntry
1-8). Best result was obtained in the presence of catalytic amount of H2SO4-
SiO2 (entry 7). The use of 0.1 ml of H2SO4 (18 M) in reaction condition, the
yield unexpectedly decreased to trace (entry 2). A possible explanation for the
trace product yield is that the starting material or the product may be destroyed
during the reaction when 0.1 ml of H2SO4 (18 M) was used in the reaction and
that H SO -SiO2 was effectively sufficient to catalyze the reaction. Also, the
same r2eact4ion in presence of 0.1 ml of H2SO4 (0.1 M) was carried out. After 2h,
only 42% of expected 3-(2-oxo-2-phenylethyl) isobenzofuran-1(3H)-one (3f)
was obtained (entry 3). Then, the effect of temperature on the rate of the reaction
was studied for the preparation of 3-(2-oxo-2-phenylethyl) isobenzofuran-
1(3H)-ones (3f) using H2SO4-SiO under solvent-free conditions. At 120oC, the
reaction proceeded smoothly and2almost complete conversion of product was
observed (entry 9). Further increase in temperature to 130oC did not increased
the rate and the yield of reaction (entry 10). Therefore, we kept the reaction
temperature as 120oC (giving short reaction time and high yield). Next, the
study set out to determine optimal amount of H2SO -SiO2, the reaction was
carried out by varying amount of the catalyst (entry 412-13). Maximum yield
was obtained with 0.05 g (entry 9). Further increase in amount of H2SO4-SiO2
in the mentioned reaction did not has any significant effect on the product yield
(entry 12). No desired product was detected in the absence of the catalyst (entry
14).
Scheme 2. Mechanism for the formation of isobenzofuran-1(3H)-one (3a-
k) in the presence of H2SO4-SiO2
Studying Reusability of the Catalyst H2SO4-SiO2
The recycling and reuse of H SO4-SiO2 was investigated for the synthesis
of 3-(2-oxo-2-phenylethyl) isoben2zofuran-1(3H)-ones (3f) in three consecutive
runs. The results summarized in Table 3 indicate a gradual decrease in the
isolated yields from 82% to 78%.
2828

J. Chil. Chem. Soc., 60, Nº 1 (2015)
Table 2. The heterogeneous synthesis of isobenzofuran-1(3H)-ones using H2SO4-SiO2
Isobenzofuran-1(3H)-ones 3
Mp (0C)
Ketones
Enty
Time (min)
Yield (%) a
2
Found
Reported
O
O
O
O
3a
3b
40
80
77
7826
OEt
O
O
OEt
O
O
O
O
60
60
72
70
103
10526
O
O
O
O
O
3c
164-166
165-16726
O
HO
O
O
O
O
208-21016
O
3d
25
74
212-214
HO
O
O
O
O
3e
3f
60
20
76
82
oil
Oil24
O
O
O
O
144-145
14526
O
O
O
COCH3
O
3g
3h
40
30
88
86
212-214
142-144
21026
NO2
NO2
O
COCH3
O
O
14626
Cl
Cl
O
COCH3
O
O
3i
20
82
217-219
21926
OMe
OMe
O
COCH3
O
O
3j
30
40
80
76
148
14926
CH3
CH3
O
O
O
3k
212-214
216-21716
O
O
O
aThe yields refer to the isolated pure products which were characterized from their spectral data and were compared with authentic sample.
2829

J. Chil. Chem. Soc., 60, Nº 1 (2015)
Table 3. Reuse of the H SO -SiO2 for synthesis of 3-(2-oxo-2-phenylethyl)
isobenzofuran-1(3H)-ones (32 f). 4
Entry
Times (min)
Yielda (%)
1
2
3
20
20
30
82
80
78
a Isolated yields.
Studying Third-Order Nonlinear Optical Properties
Materials with third-order optical nonlinearities have been investigated
widely for their applications in opto-electronic and all-optical devices such as
eye and sensor protection, optical phase conjugation, high-speed all optical
switches, optical bistability, optical limiting devices, optical modulators and
so on47-49. Organic materials exhibiting strong nonlinear optical properties
have attracted considerable interest in recent years because of their possible
applications in nonlinear optical devices50-51. Conjugated polymers are a
promising class of third-order nonlinear materials because of their potentially
large third-order susceptibilities associated with fast response time in addition
to their variety and processability47.
Fig. 3. Normalized transmittance of close aperture z-scan for 3-(2-oxo-2-
phenylethyl) isobenzofuran-1(3H)-ones (3f)
One of the interesting properties of organic molecules is their nonlinear
optical behavior in laser irradiations. The main origin of these treatments is
the π electrons which gives rise to marked optical nonlinearities. The value
for the nonlinear polarization of the π-electrons is large, even for radiation
frequencies far removed from the electronic resonances involved (in which
a carbon molecule absorbs an incident photon). The absorption spectrum of
such material depends on a large extent on the degree of electron-conjugation
λ
∝ L
Ld
is the conjugation
present within the π-orbital. In particular,
d , where
length 47,52. Also, the conjugation length is proportional to the real part of
third order susceptibility. Nonlinear refraction index 2 is the best measurable
coefficient to evaluate third order nonlinearity 53
max
n
.
The best method to measuring third order nonlinear refractive index is
closed-aperture z-scan method 54. In this technique a laser Gaussian beam
passing through a lens and a thin sample containing the subject material scans
a distance surrounding the focal point of the beam. The transmitted power
Fig. 4. Normalized transmittance of close aperture z-scan for 3-(2-hydroxy-
4,4-dimethyl-6-oxo-cyclohexen-1-yl-3H-isobenzofuran-1-one (3d)
n
through a finite aperture in far field leads to calculate
.
2
CONCLUSION
For determining the nonlinear refractive index, the closed-aperture z-scan
setup shown in Fig.1 was employed initially. The light source was a CW He-
Ne laser beam λ=632.8nm, with 48mW maximum power, 30μm beam waist
radius, and the focal length of convergence lens was 8cm. the irradiation
In conclusion, this paper describes an efficient, heterogeneous, simple
and safe procedure for the preparation of the isobenzofuran-1(3H)-ones
derivatives. Considerable optical nonlinearity due to high polarization of the
π-electrons and also thermal effect is observed in the mentioned components.
It was found that the components could be good candidates for electro-optical
devices and optical modulators. Also, dependency of nonlinear optical indexes
to the conjugation length of the components has been studied.
W
intensity at the beam waist wasI
. 0.1 M concentrations of both the
= 3340
2
0
cm
components in DMSO were prepared and poured into 1mm length quartz cells.
The normalized transmittances of the samples have been shown in Figs. 2 and
3. Using the numerical curve fitting, the values of nonlinear refraction indexes
for
1-one (3d) and 3-(2-oxo-2-phenylethyl) isobenzofuran-1(3H)-ones (3f)
were obtained and , respectively. This could
3-(2-hydroxy-4,4-dimethyl-6-oxo-cyclohexen-1-yl-3H-isobenzofuran-
EXPERIMENTAL
Commercially available materials were purchased from Merck, Fluka
and Aldrich, and were used without additional purification. H2SO4-SiO2 was
prepared according to literature [42]. IR spectra were recorded on a Shimadzu
interpreted simplify using molecular structures where the electron paths have
been drown schematically. As shown in figures, the conjugation length in 3d is
longer than for 3f. Considering these magnitudes of nonlinear refractive index,
these components have good potential in nonlinear optical devices.
1
435-U-04 spectrophotometer (KBr pellets). H and 13C NMR spectra were
obtained using Bruker DRX-300 Advance spectrometer in DMSO-d6 or
CDCl3 using TMS as an internal reference. Melting points were determined in
open capillary tubes in a Stuart BI Branstead Electrothermal Cat No: IA9200
apparatus and uncorrected.
General procedure for the synthesis of isobenzofuran-1(3H)-ones
derivatives
To a mixture of aryl ketones or 1,3-dicarbonyl compounds (1.2 mmol)
and phthalaldehydic acid (2-carboxy benzaldehyde) (1 mmol), H2SO4-SiO2
(0.05 g) was added and the mixture was heated on an oil bath at 1200C for
the reasonable time (Table 2). After completion of the reaction (monitored
by TLC, hexane:ethyl acetate, 8:2), the reaction mixture diluted with EtOH
(96%, 3 ml) and stirred for 5 min in 120°C. The resulting crude product was
poured into crushed ice and the solid product, which separated was filtered and
recrystallized from ethanol to get pure products (3a-k).
Selected spectral data
3-(1,3-Dihydro-3-oxo-1-isobenzofuranyl)-2,4-pentanedione (3b)
FT-IR (KBr, v, cm-1): 3002, 2930, 1770, 1710, 1690 1450, 1400, 1280,
1240, 1080,720, 680. 1H NMR (CDCl , 300 MHz, δ, ppm): 2.21 (s, 3H), 2.34
(s, 3H), 4.04 (d, 1H), 6.13 (d, 1H), 7.341-7.82 (m, 4H). 13C NMR (CDCl3, 75
MHz, δ, ppm): 29.91, 30.43, 72.00, 78.54, 123.34, 125.68, 126.09, 130.21,
Fig. 2. Schematic description of close aperture z-scan setup.
2830

J. Chil. Chem. Soc., 60, Nº 1 (2015)
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3-(2-oxo-2-phenylethyl) isobenzofuran-1(3H)-one (3f)
FT-IR (KBr, v, cm-1): 3020, 2980, 1700, 1660, 1600 1460, 1400, 1280,
1200, 1080,760, 680. 1H NMR (CDCl3, 300 MHz, δ, ppm): 3.41 (d, 1H), 3.86
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43.65, 76.45, 123.98, 124.54, 125.09, 127.12, 128.46, 1293.12, 129.86, 132.43,
134.68, 145.79, 170.64, 198.92 .
3-(2-oxo-2-4-methylphenylethyl) isobenzofuran-1(3H)-one (3j)
FT-IR (KBr, v, cm-1): 3010, 2960, 1750, 1670, 1610 1470, 1410, 1290,
1
1200, 1090,760, 680. H NMR (CDCl3, 300 MHz, δ, ppm): 2.45 (s, 3H),
3.43(d, 1H), 3.86 (d, 1H), 6.32 (t, 1H), 7.56-7.98 (m, 8H); 13C NMR (CDCl3,
75 MHz, δ, ppm): 28.24, 43.05, 77.25, 121.94, 123.14, 124.09, 125.12, 127.26,
128.72, 129.96, 133.43, 135.14, 144.67, 171.94, 196.76.
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ACKNOWLEDGEMENTS
The authors are thankful to research council of Hakim Sabzevari University
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