A novel method for the synthesis of tetrahydrobenzo[a]-xanthen-11-one derivatives using cerium(III) chloride as a highly efficient catalyst

Article abstract of DOI:10.1016/j.crci.2012.01.002

Cerium(III) chloride is found to be an highly efficient catalyst for the addition of aldehydes, β-naphthol and cyclic 1,3-dicarbonyl compounds/Meldrum's acid via a multicomponent reaction. The easy availability of starting materials, novel and eco-friendl

Full text of DOI:10.1016/j.crci.2012.01.002

C. R. Chimie 15 (2012) 324–330
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Full paper/Memoire
A novel method for the synthesis of tetrahydrobenzo[a]-xanthen-11-one
derivatives using cerium(III) chloride as a highly efficient catalyst
Mazaahir Kidwai 1, , Anwar Jahan, Neeraj Kumar Mishra
*
Green Chemistry Research Laboratory, Department of Chemistry, University of Delhi, Delhi 110007, India
A R T I C L E I N F O
A B S T R A C T
Article history:
Cerium(III) chloride is found to be an highly efficient catalyst for the addition of aldehydes,
Received 9 May 2011
b
-naphthol and cyclic 1,3-dicarbonyl compounds/Meldrum’s acid via a multicomponent
Accepted after revision 3 January 2012
Available online 8 February 2012
reaction. The easy availability of starting materials, novel and eco-friendly procedure
makes this strategy more useful for the preparation of tetrahydrobenzo[a]-xanthen-11-
one, and benzo[f]chromen-3-one derivatives.
Keywords:
CeCl3.7H2O
MCRs
ß 2012 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
b-naphthol
Aldehydes
1,3-dicarbonyl Compounds
Tetrahydrobenzo[a]-xanthen-11-ones
Benzo[f]chromen-3-ones
1. Introduction
[10]. However, with carbon nucleophiles, only limited
works have been reported [11]. It is difficult to create the
The development of highly efficient and sustainable
procedures has become a major driving force to assemble
the biologically active compounds in the field of academia
and industry [1]. A multicomponent reaction (MCR) is a
process in which three or more components are combined
together in a single reaction vessel to produce a final
product [2]. The versatility and effectiveness as potential
multicomponent substrate has been used in various MCRs
such as Hantzsch reaction [3], Biginelli reaction [4],
Schopfs tropinone synthesis [5], Tietze’s reaction [6], Ugi
[7] and Mannich type reactions [8].
reaction conditions for proper exploitation of O-QMs in
reactions with carbon nucleophiles for organic synthesis
[9].
Xanthene and its derivatives are known as an important
class of heterocyclic compounds, widely used as lecodyes
[12], pH-sensitive fluorescent materials for visualization of
biomolecules [13] and are utilized in laser technologies
due to their photochemical and photophysical properties.
They possess diverse biological and therapeutic properties
such as anti-inflammatory [14], antiviral [15] and antibac-
terial activities [16]. These compounds are being utilized as
antagonists for paralyzing action of zoxazolamine [17] and
in photodynamic therapy [18]. Among the molecules of
this class, benzoxanthen is a prominent structural motif
found in various natural products [19] and synthetic
compounds with important biological activities [20].
Several methods have been used for the synthesis of
tetrahydrobenzo[a]-xanthen-11-one and benzo[f]chro-
men-3-one derivatives [21]. These procedures have
limitations of long reaction time, harsh reaction conditions
and often required expensive catalysts. As a consequence,
Nevertheless, the development of MCRs is still in
demand. In this context, ortho-quinone methides (O-QMS)
intermediate were utilized in many tandem processes [9]
and [4+2] cycloaddition with a wide range of dienophiles
* Corresponding author.
E-mail address: kidwai.chemistry@gmail.com (M. Kidwai).
1
Presently Vice-Chancellor, Jiwaji University, Gwalior (MP), India (on
deputation from Department of Chemistry, University of Delhi, Delhi-
110007, India).
1631-0748/$ – see front matter ß 2012 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.crci.2012.01.002

M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
325
O
O
O
3
O
O
R
5 (a-j)
CeCl3.7H2O
OH
O
(3 mol%)
+
MeOH, 50 oC
H
R
O
2
1
O
R
6 (a-c)
O
4
Scheme 1. CeCl3.7H2O catalyzed condensation of
b-naphthol, aldehydes and cyclic 1,3-dicarbonyl compounds.
Table 1
the development of a mild and practical procedure for
accessing these benzoxanthen derivatives remains an
elusive goal. Recently, lanthanide compounds have be-
come attractive candidates for use as Lewis acid catalysts
in organic chemistry with numerous applications as
promoters [22]. The introduction of electronegative
ligands such as chloride enhances the activity by increas-
ing the Lewis acidity of the metal [23]. These catalysts offer
several advantages including mild reaction conditions,
cleaner reactions, shorter reaction times, lower catalyst
loading and simple experimental procedures with high
yields.
Optimization of the concentration of CeCl3.7H2O for the synthesis of
tetrahydrobenzo[a]-xanthen-11-ones.a
Entry
CeCl3.7H2O (mol%)
Time (h)
Yield (%)b
1
2
3
4
0
1
2
3
8
5
2
2
10
25
60
90
a
Reaction conditions: benzaldehyde
1
(1.0 mmol),
b
-naphthol 2
(1.0 mmol), 5,5-dimethyl-1,3-cyclohexanedione 3 (1.2 mmol), catalyst
CeCl3.7H2O, solvent CH3OH (5 mL), temp. 50 8C.
b
Isolated yields.
In this context, cerium(III) chloride has been received as
an inexpensive, non-toxic, water tolerant and potentially
useful Lewis acid catalyst [24] for several organic reactions
[25]. The activity of cerium(III) chloride was increased in
combination with NaI [26]. As a part of our ongoing
program on the development of new synthetic methods
[27] and to examine the behaviour of cerium(III) chloride
as catalyst [28] in the synthesis of organic compounds [29]
herein, we wish to report a mild and efficient protocol for
the synthesis of tetrahydrobenzo[a]-xanthen-11-one deri-
vatives via one-pot, three-component reaction of alde-
yield from 25 to 90% (entry 4, Table 1). In a search for an
even higher yield, we decided to employ NaI as an additive
with CeCl3.7H2O (CeCl3.7H2O-NaI system). In this context,
the effect of the amounts of the NaI and CeCl3.7H2O was
evaluated. When the reaction was carried out by using
CeCl3.7H2O-NaI (3 mol%) in methanol (5 mL), the product
yield was nearly the same (entry 3, Table 2) as the yield
obtained with CeCl3.7H2O (3 mol%) (entry 2, Table 2). The
rate of this reaction was slightly improved by adding
5 mol% of CeCl3.7H2O-NaI, and the desired product was
obtained in 2 h. Thus we found that 3 mol% CeCl3.7H2O is
better suited than the CeCl3.7H2O-NaI system for the
optimum yield of tetrahydrobenzo[a]-xanthen-11-one
derivatives (Table 2).
hydes,
b-naphthol and cyclic 1,3-dicarbonyl compounds
using cerium(III) chloride as catalyst in methanol at 50 8C
(Scheme 1).
2. Results and discussion
Table 2
Evaluation of catalytic activity of various catalysts for the synthesis of
tetrahydrobenzo[a]-xanthen-11-ones.a
To find the optimum reaction conditions, a mixture of
-naphthol (1 mmol), benzaldehyde (1 mmol) and 5,5-
b
Entry
Catalyst
Mol %
Time (h)
Yield (%)b
dimethyl-1,3-cyclohexanedione (1.2 mmol) in methanol
(5 mL) were stirred at 50 8C under various reaction
conditions (Table 1). The reaction was completed within
8 h in the absence of catalyst. However, under the same
reaction conditions, by employing 1 mol% of CeCl3.7H2O,
the reaction afforded expected product up to 25% yield
within 5 h of reaction time (entry 2, Table 1).
With this optimistic result in hand, we further
investigated the best reaction conditions by using different
amounts of CeCl3.7H2O. An increase in the quantity of
CeCl3.7H2O from 1 to 3 mol% not only decreases the
reaction time from 5 to 2 h but also increased the product
1
2
3
4
5
6
7
8
CuSO4
10
3
8
2
2
2
5
5
5
5
25
90
91
93
35
45
30
85
CeCl3.7H2O
CeCl3.7H2O-NaI
CeCl3.7H2O-NaI
Y(OTf)3
3
5
10
10
10
10
AlCl3
ZnCl2
Sr(OTf)2
a
Reaction conditions: Benzaldehyde
1
(1.0 mmol),
b
-naphthol 2
(1.0 mmol), 5,5-dimethyl-1,3-cyclohexanedione 3 (1.2 mmol), different
catalysts, solvent CH3OH (5 mL), temp. 50 8C.
b
Isolated yields.

326
M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
Table 3
Table 4
Solvent effect on reaction of
1,3-cyclohexanedione.a
b
-naphthol, benzaldehyde and 5,5-dimethyl-
Synthesis of tetrahydrobenzo[a]-xanthen-11-one derivatives using
CeCl3.7H2O.a
Entry
Solvent
Yield (%)b
Entry
Aldehydes
1,3-dicarbonyl
compounds
Product
Time
(h)
Yield
(%)b
(R)
1
2
3
4
5
Acetonitrile
THF
42
25
12
90
30
1
C6H5
3
3
3
3
3
3
3
3
3
3
4
4
4
5a
5b
5c
5d
5e
5f
2
90
95
95
89
87
90
83
89
76
78
87
94
91
Toluene
2
4-ClC6H4
4-BrC6H4
4-H3CC6H4
4-CH3OC6H4
4-O2NC6H4
4-HOC6H4
2-Naphthyl
Piperonyl
2-Thienyl
C6H5
2.5
2.5
3
Methanol
Dichloromethane
3
4
5
3.5
2
a
Reaction conditions: Benzaldehyde
1
(1.0 mmol),
b
-naphthol 2
6
(1.0 mmol), 5,5-dimethyl-1,3-cyclohexanedione
3 (1.2 mmol) catalyst
7
5g
5h
5i
2.5
2
CeCl3.7H2O (3 mol%), different solvent (5 mL), time (2 h), temp. 50 8C.
8
b
Isolated yields.
9
2
10
11
12
13
5j
2
6a
6b
6c
3
4-ClC6H4
4-O2NC6H4
2.5
2
Further, we have also scrutinized this reaction by using
various Lewis acid catalysts such as CuSO4, CeCl3.7H2O,
Y(OTf)3, AlCl3, ZnCl2, and Sr(OTf)2. Comparative studies
show that CeCl3.7H2O is a more effective catalyst for this
condensation reaction (entry 2, Table 2).
a
Reaction conditions: Benzaldehyde
1
(1.0 mmol), b-naphthol 2
3 & 4 (1.2 mmol), catalyst
(1.0 mmol), 1, 3-dicarbonyl compounds
CeCl3.7H2O (3 mol%), solvent CH3OH (5 mL), temp. 50 8C.
b
Isolated yields.
It is well known that the reaction medium plays an
important role in the catalytic reaction. To study the
influence of the nature of solvent for this reaction using
CeCl3.7H2O as a catalyst was carried out at a temperature
(508 C) in different solvents, such as acetonitrile, THF,
toluene, methanol and dichloromethane (Table 3). The
highest reaction activity was achieved in the system using
methanol as a solvent in comparision to other solvents
under similar reaction conditions (entry 4, Table 3). The
results show that the catalytic performance is strongly
affected by the type of solvent but a direct correlation
between solvent properties and their efficiency could not
be established in any case.
Encouraged by these remarkable results, we screened a
variety of aromatic and heterocyclic aldehydes with
b-
naphthol and 5,5-dimethyl-1,3-cyclohexanedione to ob-
tain the corresponding products. The results are summa-
rized in Table 4. In all cases, various aromatic aldehydes
with electron-donating and electron-withdrawing substi-
tuents were reacted successfully giving the products in
good to excellent yields. It was observed that substituents
in the aromatic ring of aldehydes have a delicate effect on
the reaction process. Aromatic aldehydes with electron-
withdrawing groups reacted faster than those with
R
O
CeCl3
O
H
R
H
O
OH
R
1
-H
2
H
O
O
5 (a-j)
CeCl3
R
H
O
-H2O
R
O
9
H
O
-CeCl3
-H2O
O
O H
R
12
R
3
H
O
OH
O
CeCl3
O
O
H
CeCl3
10
11
Scheme 2. Proposed mechanism for the condensation reaction of aldehydes,
b-naphthol and 5,5-dimethyl-1,3-cyclohexanedione.

M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
327
O
O
O
OH
O
O
CeCl3 (3 mol%)
MeOH, 50 oC
+
+
R
H
R
O
O
8 (a-e)
1
2
7
Scheme 3. Synthesis of benzo[f]chromen-3-one derivatives using Meldrum’s acid.
Table 5
A tentative mechanism for the formation of tetrahy-
drobenzo[a]xanthen-11-ones 5 (a-j) is proposed in Scheme
2. By following the literature [30], we suppose that the
reaction might have proceeded via ortho-quinone
methides intermediate (9), which was formed by the
Synthesis of benzo[f]chromen-3-one derivatives catalyzed by
CeCl3.7H2O.a
Entry
R
Product
Time (h)
Yield (%)b
1
2
3
4
5
C6H5
8a
8b
8c
8d
8e
3.5
2
89
92
94
70
80
4-ClC6H4
4-FC6H4
4-CH3OC6H4
2-Thienyl
nucleophilic addition of
b-naphthol (2) to aldehydes (1)
2.5
6
catalyzed by CeCl3. Subsequent substitution of the oxygen
atom, coordinated by CeCl3 with 5,5-dimethyl-1,3-cyclo-
hexanedione (3), afforded 11 and 12. The compound 12
eliminated one molecule of H2O and afforded desired
product 5 (a-j).
3
a
Reaction conditions: Aldehydes
1
(1.0 mmol),
b
-naphthol 2
(1.0mmol), Meldrum’s Acid 7 (1.2 mmol), catalyst CeCl3.7H2O (3 mol%),
solvent CH3OH (5 mL), temp. 50 8C.
b
Further, to realize the generality and versatility of the
catalyst, this novel protocol was extended for the
Isolated yields.
condensation of aromatic aldehydes,
b-naphthol and
Meldrum’s acid. During the experiments, it was observed
that different aromatic aldehydes bearing electron-with-
drawing groups reacted smoothly in the presence of
3 mol% of CeCl3.7H2O at 50 8C in methanol to afford the
high yield of benzo[f]chromen-3-ones (Scheme 3, Entries 2
and 3, Table 5).
electron-donating groups. In order to broaden the scope of
the present method, the replacement of 5,5-dimethyl-1,3-
cyclohexanedione with 1,3-cyclohexanedione was also
examined. Under similar conditions, the reactions pro-
ceeded steadily to afford a series of 12-phenyl-8,9,10,12-
tetrahydrobenzo[a]-xanthen-11-one derivatives with
good yields (Entries 11–13, Table 4).
Mechanistically, to clarify Scheme 3 for the synthesis of
benzo[f]chromen-3-one derivatives, a mechanism was
R
O
CeCl3
CeCl3
O
H
R
H
OH
1
R
2
-H
H
O
CeCl3
O
8 (a-e)
O
R
H
-Acetone
-CO2
O
R
O
O
O
9
O
O
O
O
-CeCl3
-H2O
H
13
O
O H
R
7
O
CeCl3
10
Scheme 4. Proposed mechanism for the condensation reaction of aldehydes,
b-naphthol and Meldrum’s acid.

328
M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
proposed [31]. The reaction may be rationalized by the
condensation of -naphthol (2) with aldehydes (1)
organic layer was dried over anhydrous Na2SO4 and
evaporated. The crude product was purified by column
chromatography (hexane/ethyl acetate, 80:20) to provide
the pure products. All the products were synthesized by
novel route and elucidated comparing with authentic
literature [21d,30,32].
b
catalyzed by CeCl3 and the initial formation of ortho-
quinone methides intermediate (9) takes place which may
be attacked by enol tautomer of Meldrum’s acid (7) leading
to the intermediate 13. The intermediate 13 may undergo
formation of benzochromen-3-one derivatives as product
8 (a-e) followed by the removal of acetone and carbon
dioxide molecules (Scheme 4).
4.3. Spectral dataof synthesized compounds (5a–j, 6a–c, 8a–e)
9,9-Dimethyl-12-phenyl-8,9,10,12-tetrahydroben-
zo[a]-xanthen-11-one (5a). White solid; mp 152–153 8C;
IR (KBr): 3059, 2960, 2874, 1632, 1379, 1223, 1169, 1075,
3. Conclusions
812 cmÀ1; 1H NMR (400 MHz, CDCl3):
d = 7.98 (d, J = 8.0 Hz,
We have developed
methodology for the synthesis of tetrahydrobenzo[a]-
xanthen-11-one and benzo[f]chromen-3-one derivatives
a novel and highly efficient
1H), 7.70–7.76 (m, 2H), 7.40–7.42 (m, 1H), 7.29–7.38 (m,
4H), 7.14 (t, J = 7.5 Hz, 1H), 7.08 (t, J = 7.4 Hz, 2H), 4.77 (s,
1H), 2.45 (s, 2H), 2.27 (d, J = 17.1 Hz, 1H), 2.21 (d,
J = 17.1 Hz, 1H), 1.10 (s, 3H), 0.97 (s, 3H); 13C NMR
from aldehydes,
b-naphthol and cyclic 1,3-dicarbonyl
compounds or Meldrum’s acid. This process is based on the
Lewis acid catalytic activity of cerium(III) chloride
represents an eco-friendly benign alternative to current
chemical processes. We believe that this economically
viable procedure could be successfully applied to a variety
of cyclic 1,3-dicarbonyl compounds as well as Meldrum’s
acid to synthesize a variety of one-pot synthesis of
xanthene derivatives in excellent yields.
(100 MHz, CDCl3):
d = 196.1, 165.2, 147.9, 144.8, 130.5,
130.7, 129.1, 128.6, 128.5, 128.3, 127.1, 126.4, 124.7, 123.8,
116.7, 116.1, 113.3, 51.1, 40.6, 34.9, 32.4, 29.5, 27.4; m/z
(ESI-MS, HRMS) 355.1653 (M+1, C25H22O2 requires
354.1620).
12-(4-Chlorophenyl)-9,9-dimethyl-8,9,10,12-tetra-
hydrobenzo[a]-xanthen-11-one (5b). White solid; mp
183–184 8C; IR (KBr): 3056, 2960, 1602, 1513, 1381, 1217,
1168, 1019, 960, 847, 748 cmÀ1
;
1H NMR (400 MHz,
4. Experimental
CDCl3): d = 7.97 (d, J = 8.4 Hz, 1H), 7.77 (d, J = 6.1 Hz, 1H),
7.75 (d, J = 8.4 Hz, 1H), 7.39–7.43 (m, 1H), 7.30–7.33 (m,
1H), 7.29 (d, J = 8.7 Hz, 1H) 7.27 (s, 2H), 7.14 (d, J = 8.2 Hz,
2H), 4.73 (s, 1H) 2.55 (s, 2H), 2.56 (s, 2H), 2.45 (d,
J = 16.1 Hz, 1H), 2.27 (d, J = 16.1 Hz, 1H), 1.08 (s, 3H), 0.98 (s,
4.1. General considerations
IR spectra were recorded on Perkin Elmer FTIR-1710
n
spectrophotometer using KBr pellets. IR frequency, max
3H); 13C NMR (100 MHz, CDCl3):
d = 196.4, 164.2, 147.4,
is measured in cmÀ1
.
1H NMR and 13C NMR (400 and
143.5, 131.7, 131.4, 130.1, 129.3, 128.7, 128.8, 127.2, 125.3,
123.7, 117.2, 114.1, 51.6, 41.2, 34.4, 32.5, 29.2, 27.3; m/z
(ESI-MS, HRMS) 390.1201 (M+1, C25H21ClO2 requires
388.1230).
100 MHz, respectively) spectra were recorded on Jeol JNM
ECX-400P Spectrometer using TMS as an internal stan-
dard. The chemical shift values are recorded on dscale and
the coupling constants (J) are in hertz. Mass spectral data
was recorded on Water micromass LCT Mass Spectrome-
ter. The temperature of the reaction mixture was
measured through AZ, Mini Gun type, non-contact IR
thermometer, model no. 8868. The melting points were
determined on Thomas Hoover melting point apparatus.
The purity of the compounds was checked on TLC (silica
gel coated aluminium sheets, Silica gel 60 F254, E. Merck
(Germany).
12-(4-Bromophenyl)-9,9-dimethyl-8,9,10,12-tetra-
hydro-benzo[a]-xanthen-11-one (5c). White solid; mp
184–186 8C; IR (KBr): 2959, 2861, 1643, 1591, 1482, 1401,
1373, 1221, 1173, 1144, 1006, 960, 845, 745 cmÀ1; 1H NMR
(400 MHz, CDCl3):
d = 7.86 (d, J = 8.3 Hz, 1H), 7.78 (d,
J = 6.2 Hz, 1H), 7.74 (d, J = 8.3 Hz, 1H), 7.37–7.42 (m, 1H),
7.29–7.32 (m, 1H), 7.28 (d, J = 8.6 Hz, 1H), 7.26 (s, 2H), 7.13
(d, J = 8.1 Hz, 2H), 4.72 (s, 1H), 2.57 (s, 2H), 2.47 (d,
J = 16.3 Hz, 1H), 2.25 (d, J = 16.3 Hz, 1H), 1.05 (s, 3H), 0.96 (s,
3H); 13C NMR (100 MHz, CDCl3):
d = 196.2, 164.3, 147.4,
4.2. General procedure for the synthesis of
tetrahydrobenzo[a]-xanthen-11-one, and benzo[f]chromen-
3-one derivatives
143.4, 132.1, 131.7, 131.4, 130.1, 129.3, 128.7, 128.6, 127.2,
125.2, 123.6, 117.3, 117.2, 114.1, 51.1, 41.5, 32.4, 29.5,
27.3; m/z (ESI-MS, HRMS) 434.0704 (M+1, C25H21BrO2
requires 432.0725).
Aldehydes (1.0 mmol),
b
-naphthol (1.0 mmol) and 5 mL
9,9-Dimethyl-12-p-tolyl-8,9,10,12-tetrahydroben-
zo[a]-xanthen-11-one (5d). White solid; mp 178–179 8C;
IR (KBr): 3044, 2959, 2865, 1610, 1513, 1383, 1219, 1019,
of methanol were placed in a 50 mL round bottom flask
over a magnetic stirrer. Cerium(III) chloride (3 mol%)/
(0.03 mmol, 11.12 mg) was added to the mixture and the
contents were stirred at 50 8C for an appropriate time. To
this stirred mixture, cyclic 1,3-dicarbonyl compounds/
Meldrum’s acid (1.2 mmol) were added. The progress of
the reaction was monitored by TLC. After completion of the
reaction, the reaction mixture was allowed to cool at room
temperature and water was added to the reaction mixture
and then extracted with ethyl acetate (3 Â 10 mL). The
846 cmÀ1; 1H NMR (400 MHz, CDCl3):
d = 7.99 (d, J = 8.4 Hz,
1H), 7.65–7.79 (m, 2H), 7.39–7.41 (m, 1H), 7.30–7.33 (m,
2H), 7.14–7.25 (m, 2H), 7.02 (d, J = 8.0 Hz, 2H), 4.73 (s, 1H),
2.56 (s, 2H), 2.45 (d, J = 16.3 Hz, 1H), 2.22 (d, J = 16.3 Hz,
1H), 2.15 (s, 3H), 1.09 (s, 3H), 0.98 (s, 3H); 13C NMR
(100 MHz, CDCl3):
d = 196.1, 163.2, 153.2, 146.4, 140.6,
134.7, 133.7, 130.4, 128.5, 127.8, 127.1, 126.5, 125.8, 123.9,
122.5, 117.1, 116.5, 115.8, 113.1, 49.6, 40.2, 33.1, 31.1,

M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
329
28.3, 26.1, 19.4; m/z (ESI-MS, HRMS) 369.1810 (M+1,
1.2 Hz, 1H), 7.39 (td, J = 7.9, 0.9 Hz, 1H), 7.34 (d, J = 8.9 Hz,
1H), 6.86 (dd, J = 8.0, 1.7 Hz, 1H), 6.77 (d, J = 1.6 Hz, 1H),
6.62 (d, J = 8.0 Hz, 1H), 5.80 (s, 2H), 4.72 (s, 1H), 2.42 (s, 2H),
2.31 (d, J = 16.4 Hz, 1H), 2.23 (d, J = 16.4 Hz, 1H), 1.06 (s,
C26H24O2 requires 368.1776).
12-(4-Methoxyphenyl)-9,9-dimethyl-8,9,10,12-tetra-
hydrobenzo[a]-xanthen-11-one (5e). White solid; mp
206–208 8C; IR (KBr): 3018, 2963, 2843, 1677, 12.18, 1161,
3H), 0.98 (s, 3H); 13C NMR (100 MHz, CDCl3):
d = 197.5,
1028, 960, 847, 756 cmÀ1
;
1H NMR (400 MHz, CDCl3):
164.1, 147.9, 147.7, 146.3, 138.2, 131.7, 131.6, 129.3, 128.6,
127.5, 125.4, 123.9, 121.9, 117.9, 117.3, 114.5, 109.2, 108.3,
101.5, 51.2, 41.6, 34.5, 32.6; m/z (ESI-MS, HRMS) 399.1552
(M+1, C26H22O4 requires 398.1518).
d
= 7.85 (d, J = 8.4 Hz, 1H), 7.74 (t, J = 9.3 Hz, 2H), 7.41 (t,
J = 7.3 Hz, 1H), 7.39 (t, J = 7.2 Hz, 1H), 7.30 (d, J = 8.9 Hz, 1H),
7.25 (d, J = 8.7 Hz, 2H), 6.69 (d, J = 8.6 Hz, 2H), 5.40 (s, 1H),
3.68 (s, 3H), 2.45 (s, 2H), 2.27 (d, J = 16.2 Hz, 1H), 2.21 (d,
J = 16.2 Hz, 1H), 1.07 (s, 3H), 0.96 (s, 3H); 13C NMR
9,9-Dimethyl-12-(thiophen-2-yl)-8,9,10,12-tetrahy-
drobenzo[a]-xanthen-11-one (5j). White solid; mp 183–
184 8C; IR (KBr): 3124, 2926, 1629, 1513, 1388, 1215, 1171,
(100 MHz, CDCl3):
d = 197.1, 163.8, 157.9, 147.8, 137.3,
131.6, 129.5, 128.8, 128.5, 127.1, 125.1, 123.9, 118.1, 117.3,
114.7, 113.7, 55.2, 51.3, 41.5, 33.9, 32.4, 29.4, 27.3; m/z
(ESI-MS, HRMS) 385.1759 (M+1, C26H24O3 requires
384.1725).
1148, 1010, 811, 746 cmÀ1 1H NMR (400 MHz, CDCl3):
;
d
= 7.78–7.73 (m, 2H), 7.68 (d, J = 8.5 Hz, 1H), 7.29–7.43 (m,
3H), 7.20–7.25 (m, 1H), 7.09–7.16 (m, 2H), 5.57 (s, 1H),
3.68 (s, 2H), 2.45 (s, 2H), 1.25 (s, 3H), 1.07 (s, 3H); 13C NMR
9,9-Dimethyl-12-(4-nitrophenyl)-8,9,10,12-tetrahy-
drobenzo-[a]-xanthen-11-one (5f). White solid; mp 174–
176 8C; IR (KBr): 3075, 2960, 1668, 1652, 1596, 1519, 1347,
1313, 1224, 1165, 960, 832, 756 cmÀ1; 1H NMR (400 MHz,
(100 MHz, CDCl3): d = 196.7, 164.5, 148.4, 147.9, 131.5,
129.2, 128.3, 127.1, 126.2, 125.2, 125.1, 124.2, 123.3, 117.3,
117.2, 113.7, 50.8, 41.2, 32.1, 29.3, 29.2, 27.1; m/z (ESI-MS,
HRMS) 361.1218 (M+1, C23H20O2S requires 360.1186).
12-Phenyl-8,9,10,12-tetrahydrobenzo[a]-xanthen-
11-one (6a). White solid; mp 191–192 8C; IR (KBr): 3131,
3053, 2956, 1647, 1593, 1453, 1372, 1228, 1190, 998, 956,
CDCl3):
7.53 (m, 5H), 4.82 (s, 1H), 2.59 (s, 2H), 2.36 (d, J = 16.5 Hz,
1H), 2.22 (d, J = 16.5 Hz, 1H), 1.11 (s, 3H), 0.98 (s, 3H); 13
NMR (100 MHz, CDCl3): = 196.5, 165.2, 147.6, 143.9,
d = 8.04 (d, J = 8.8 Hz, 2H), 7.79–7.84 (m, 3H), 7.34–
C
d
817, 759, 702, 532 cmÀ1
;
1H NMR (400 MHz, CDCl3):
132.1, 131.8, 131.5, 130.0, 129.3, 128.7, 128.6, 127.3, 125.2,
123.7, 117.13, 117.2, 114.1, 51.2, 41.6, 34.4, 32.5, 29.5,
27.3; m/z (ESI-MS, HRMS) 400.1504 (M+1, C25H21NO4
requires 399.1471).
d
= 7.95 (d, J = 8.5 Hz, 1H), 7.76–7.77 (m, 2H), 7.30–7.45 (m,
5H), 7.14–7.17 (m, 2H), 7.03–7.09 (m, 1H), 4.72 (s, 1H),
2.65–2.76 (m, 2H), 2.33–2.48 (m, 2H), 1.95–2.07 (m, 2H);
13C NMR (100 MHz, CDCl3):
d = 197.2, 165.4, 147.9, 145.2,
12-(4-Hydroxyphenyl)-9,9-dimethyl-8,9,10,12-tetra-
hydrobenzo[a]-xanthen-11-one (5 g). White solid; mp
152–153 8C; IR (KBr): 3312, 2956, 1636, 1599, 1381, 1216,
131.4, 131.5, 128.8, 128.4, 128.5, 128.3, 127.1, 126.2, 124.8,
123.6, 117.8, 117.1, 115.5, 37.2, 34.6, 27.7, 20.2; m/z (ESI-
MS, HRMS) 327.1340 (M+1, C23H18O2 requires 326.1307).
12-(4-Chlorophenyl)-8,9,10,12-tetrahydrobenzo[a]-
xanthen-11-one (6b). White solid; mp 208–209 8C; IR
(KBr): 3132, 3051, 2960, 1648, 1592, 1487, 1367, 1229,
1190, 1141, 1088, 1008, 955, 817, 754, 531 cmÀ1; 1H NMR
1160, 959, 841, 742 cmÀ1 1H NMR (400 MHz, CDCl3):
;
d
= 7.77 (d, J = 8.3 Hz, 1H), 7.64–7.66 (m, 2H), 7.42 (t,
J = 8.0 Hz, 1H), 7.32 (t, J = 7.4 Hz, 1H), 7.28 (d, J = 8.8 Hz, 1H),
7.14 (d, J = 8.4 Hz, 2H), 6.89 (s, 1H), 6.62 (d, J = 8.4 Hz, 2H),
5.01 (s, 1H), 4.69 (s, 1H), 2.45 (s, 1H), 2.26 (d, J = 16.4 Hz,
(400 MHz, CDCl3):
d = 7.89 (d, J = 8.5 Hz, 1H), 7.77–7.78 (m,
1H), 2.22 (d, J = 16.4 Hz, 1H), 1.08 (s, 3H), 0.96 (s, 3H); 13
C
2H), 7.24–7.43 (m, 5H), 7.13–7.15 (m, 2H), 4.71 (s, 1H),
2.62–2.75 (m, 2H), 2.34–2.47 (m, 2H), 1.92–2.07 (m, 2H);
13C NMR (100 MHz, CDCl3):
d = 197.2, 165.7, 147.5, 143.7,
132.1, 131.2, 129.6, 129.3, 128.4, 127.4, 125.6, 123.3, 117.2,
117.1, 115.2, 37.3, 34.3, 27.7, 20.2; m/z (ESI-MS, HRMS)
362.0888 (M+1, C23H17ClO2 requires 360.0917).
NMR (100 MHz, CDCl3):
d = 198.4, 164.4, 154.2, 147.8,
136.2, 131.6, 131.5, 129.4, 128.9, 128.8, 126.1, 125.2, 123.9,
118.9, 117.2, 115.6, 114.3, 51.2, 41.3, 33.4, 32.6, 29.4, 27.3;
m/z (ESI-MS, HRMS) 371.1602 (M+1, C25H22O3 requires
370.1569).
9,9-Dimethyl-12-(naphthalen-2-yl)-8,9,10,12-tetra-
hydrobenzo[a]-xanthen-11-one (5 h). White solid; mp
234–235 8C; IR (KBr): 3057, 2959, 1693, 1513, 1380, 1218,
12-(4-Nitrophenyl)-8,9,10,12-tetrahydrobenzo[a]-
xanthen-11-one (6c). White solid; mp 237–238 8C; IR
(KBr): 3076, 2932, 1644, 1596, 1515, 1376, 1342, 1224,
1168, 960 cmÀ1
;
1H NMR (400 MHz, CDCl3):
d
= 8.03 (d,
1176, 1025, 961, 847, 752 cmÀ1
;
1H NMR (400 MHz,
d = 8.04 (d, J = 8.4 Hz, 2H), 7.79–7.83 (m, 3H),
J = 8.3 Hz, 1H), 7.62 (s, 1H), 7.70–7.81 (m, 3H), 7.57 (d,
J = 7.7 Hz, 1H), 7.63 (d, J = 8.8 Hz, 1H), 7.42 (d, J = 8.3 Hz,
1H), 7.31–7.40 (m, 5H), 5.78 (s, 1 H), 2.54 (s, 2H), 2.26 (q,
J = 16.1 Hz, 2H), 1.12 (s, 3H), 0.94 (s, 3H); 13C NMR
CDCl3):
7.52 (d, J = 8.9 Hz, 2H), 7.35–7.46 (m, 3H), 4.75 (s, 1H),
2.71–2.80 (m, 2H), 2.37–2.49 (m, 2H), 2.06–2.12 (m, 1H),
1.95–2.01 (m, 1H); 13C NMR (100 MHz, CDCl3):
d = 197.5,
(100 MHz, CDCl3):
d
= 198.2, 163.2, 147.1, 141.3, 133.5,
166.3, 152.4, 147.8, 146.3, 131.6, 131.3, 129.9, 129.6, 128.4,
127.6, 125.5, 123.7, 123.3, 117.2, 116.3, 114.4, 37.1, 35.1,
27.9, 20.4; m/z (ESI-MS, HRMS) 372.1191 (M+1, C23H17NO4
requires 371.1158).
132.3, 131.7, 131.6, 129.1, 128.6, 128.3, 128.2, 127.6, 127.4,
127.3, 126.9, 125.9, 125.7, 125.1, 123.9, 117.8, 117.3,
114.23, 51.2, 40.6, 34.1, 32.4, 29.5, 27.4; m/z (ESI-MS,
HRMS) 405.1810 (M+1, C29H24O2 requires 404.1776).
12-{Benzo[d][1,3]dioxol-5-yl}-9,9-dimethyl-
1-Phenyl-1H-benzo[f]chromen-3(2H)-one (8a).
White solid; mp 117–119 8C; IR (KBr): 3058, 2983, 1735,
8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one
(5i).
1629, 1454, 1212, 1029, 960 cmÀ1 1H NMR (400 MHz,
;
White solid; mp 214–215 8C; IR (KBr): 3210, 2960, 1667,
CDCl3): d = 7.87 (d, J = 8.5 Hz, 2H), 7.67 (d, J = 8.0 Hz, 1H),
1503, 1361, 1230, 1138, 1039, 960, 847, 748, 621 cmÀ1; 1H
7.39–7.45 (m, 2H), 7.31 (d, J = 6.8 Hz, 1H), 7.24–7.30 (m,
3H), 7.15 (d, J = 7.5 Hz, 2H), 4.92 (dd, J = 7.3, 3.4 Hz, 1H),
NMR (400 MHz, CDCl3):
d = 7.98 (d, J = 8.4 Hz, 1H), 7.79 (d,
J = 8.5 Hz, 1H), 7.72 (d, J = 9.0 Hz, 1H), 7.40 (td, J = 7.0,
3.35–3.40 (m, 2H); 13C NMR (100 MHz, CDCl3):
d = 169.3,

330
M. Kidwai et al. / C. R. Chimie 15 (2012) 324–330
References
150.1, 140.4, 132.8, 131.2, 130.6, 129.6, 127.9, 127.7, 127.5,
126.9, 124.3, 123.5, 116.7, 116.4, 37.2, 36.8; m/z (ESI-MS,
HRMS) 275.1027 (M+1, C19H14O2 requires 274.0994).
1-(4-Chlorophenyl)-1H-benzo[f]chromen-3(2H)-one
(8b). Colourless oil; IR (Film): 3058, 2955, 1738, 1630,
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1H), 7.39–7.43 (m, 2H), 7.32 (d, J = 8.6 Hz, 1H), 7.22 (d,
J = 8.3 Hz, 2H), 7.10 (d, J = 7.8 Hz, 2H), 4.91 (d, J = 5.8 Hz,
1H), 3.76 (dd, J = 10.8, 2.4 Hz, 1H), 3.53 (dd, J = 12.5, 3.0 Hz,
1H); 13C NMR (100 MHz, CDCl3):
d = 167.2, 150.9, 140.2,
134.7, 132.2, 130.2, 129.7, 128.9, 128.5, 127.3, 126.1, 124.2,
117.8, 116.9, 37.5, 36.8; m/z (ESI-MS, HRMS) 309.1865
(M+1, C19H13ClO2 requires 308.0604).
1-(4-Fluorophenyl)-1H-benzo[f]chromen-3(2H)-one
(8c). White solid; mp 136–138 8C; IR (KBr): 3061, 2955,
1733, 1654, 1516, 1347, 1270, 1173, 1072, 960, 851,
748 cmÀ1 1H NMR (400 MHz, CDCl3)
; d = 8.30 (d, 8.5 Hz,
1H), 7.61 (d, J = 8.0 Hz, 1H), 7.51 (d, J = 8.0 Hz, 1H), 7.34–
7.37 (m, 2H), 7.31 (d, 8.0 Hz, 1H), 7.24–7.27 (m, 2H), 7.05–
7.10 (m, 2H), 4.80 (d, J = 5.9 Hz, 1H), 3.77 (dd, J = 14.6,
3.4 Hz, 1H), 3.16 (dd, J = 14.2, 2.5 Hz, 1H); 13C NMR
(100 MHz, CDCl3):
d = 169.2, 161.0, 148.7, 137.3, 136.9,
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132.4, 130.2, 129.3, 128.6, 127.4, 127.0, 125.8, 122.1, 118.6,
117.5, 116.3, 116.2, 37.5, 36.7; m/z (ESI-MS, HRMS)
293.6101 (M+1, C19H13FO2 requires 292.0900).
1-(4-Methoxyphenyl)-1H-benzo[f]chromen-3(2H)-
one (8d). Yellowish solid; mp 135–136 8C; IR (KBr): 3060,
2920, 1727, 1635, 1438, 1213, 1138, 1014, 958, 843,
742 cmÀ1; 1H NMR (400 MHz, CDCl3):
d = 7.79 (d, J = 8.2 Hz,
2H), 7.77 (d, J = 8.2 Hz, 1H), 7.64–7.71 (m, 2H), 7.24 (d,
J = 8.6 Hz, 1H), 7.09 (d, J = 7.8 Hz, 2H), 6.94 (d, J = 8.7 Hz,
2H), 4.78 (dd, J = 6.6, 3.2 Hz, 1H), 3.70 (s, 3H), 3.23 (dd,
J = 12.6, 2.8 Hz, 1H), 3.08 (dd, J = 12.7, 3.4 Hz, 1H); 13C NMR
(100 MHz, CDCl3):
d = 168.3, 157.0, 148.2, 134.8, 132.6,
131.3, 129.2, 128.4, 127.8, 127.6, 126.8, 125.4, 123.5,
1119.0 117.30, 115.2, 114.1, 56.3, 37.9, 35.8; m/z (ESI-MS,
HRMS) 305.1133 (M+1, C20H16O3 requires 304.1099).
1-(Thiophen-2-yl)-1H-benzo[f]chromen-3(2H)-one
(8e). Sticky; IR (Film): 2954, 1716, 1602, 1436, 1208, 1120,
(c) G.C. Nandi, S. Samai, R. Kumar, M.S. Singh, Tetrahedron 65 (2009)
7129;
1070, 960, 845, 745 cmÀ1
;
1H NMR (400 MHz CDCl3):
(d) S. Gao, C.H. Tsai, C.F. Yao, Synlett (2009) 949.
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d
= 7.74 (d, J = 7.8 Hz, 1H), 7.64–7.71 (m, 2H), 7.38–7.52 (m,
3H), 7.20–7.30 (m, 1H), 7.08–7.14 (m, 2H), 4.01 (s, 1H),
3.92 (dd, J = 12.6, 2.2 Hz, 1H), 3.79 (dd, J = 12.6, 2.5 Hz, 1H);
13C NMR (100 MHz, CDCl3):
d = 169.1 147.3, 144.2, 134.6,
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128.6, 127.8, 127.0, 126.7, 126.3, 125.5 125.3, 125.1, 123.3,
122.4, 37.6, 35.7; m/z (ESI-MS, HRMS) 281.0592 (M+1,
C17H12O2S requires 280.0558).
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Acknowledgements
A. Jahan thanks to University Grants Commission (UGC)
for the grant of Junior Research Fellowship and N. K. Mishra
is grateful to CSIR, New Delhi, India for the award of
Research Associateship. The authors also would like to
acknowledge the University Science Instrumentation
Centre (USIC), University of Delhi for providing the
instrumental facilities to characterize the synthesize
compounds.