Ammonium chloride-catalyzed one-pot synthesis of tetrahydrobenzo[α] xanthen-11-one derivatives under solvent-free conditions

Article abstract of DOI:10.1080/00397911.2010.515340

A one-pot, multicomponent reaction of aldehydes, dimedone, and β-naphthols is described for the preparation of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[α]xanthen- 11-one derivatives using ammonium chloride as a mild, inexpensive, and environmentally

Full text of DOI:10.1080/00397911.2010.515340

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Ammonium Chloride–Catalyzed
One-Pot Synthesis of
Tetrahydrobenzo[α]xanthen-11-
one Derivatives Under Solvent-Free
Conditions
Naser Foroughifar a b , Akbar Mobinikhaledi a , Hassan Moghanian a ,
Reza Mozafari a & Hamid R. M. Esfahani b
a Department of Chemistry, Faculty of Science, Arak University,
Arak, Iran
b Faculty of Chemistry, Islamic Azad University, Tehran, Iran
To cite this article: Naser Foroughifar , Akbar Mobinikhaledi , Hassan Moghanian , Reza
Mozafari & Hamid R. M. Esfahani (2011): Ammonium Chloride–Catalyzed One-Pot Synthesis
of Tetrahydrobenzo[α]xanthen-11-one Derivatives Under Solvent-Free Conditions, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry,
41:18, 2663-2673
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Synthetic Communications1, 41: 2663–2673, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.515340
AMMONIUM CHLORIDE–CATALYZED ONE-POT
SYNTHESIS OF TETRAHYDROBENZO[a]XANTHEN-
11-ONE DERIVATIVES UNDER SOLVENT-FREE
CONDITIONS
Naser Foroughifar,1,2 Akbar Mobinikhaledi,1
Hassan Moghanian,1 Reza Mozafari,1 and
Hamid R. M. Esfahani2
1Department of Chemistry, Faculty of Science, Arak University, Arak, Iran
2Faculty of Chemistry, Islamic Azad University, Tehran, Iran
GRAPHICAL ABSTRACT
Abstract A one-pot, multicomponent reaction of aldehydes, dimedone, and b-naphthols is
described for the preparation of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-
11-one derivatives using ammonium chloride as a mild, inexpensive, and environmentally
benign catalyst under solvent-free conditions. Different types of aldehyde and b-naphthol
derivatives are used in the reaction, and in all cases the products were synthesized
successfully.
Keywords Ammonium chloride; multicomponent; one pot; solvent-free; xanthene
INTRODUCTION
Multicomponent reactions (MCRs), with three or more reactants combining in a
one-pot procedure to give a single product, are a promising and vital field of chemistry
because the synthesis of complicated molecules can be achieved in a very fast, efficient,
and time-saving manner without the isolation of any intermediate.[1–4] As a result, it
requires minimum effort, which minimizes the environmental loading and is accept-
able from a ‘‘green chemistry’’ point of view. There has been tremendous development
in three- or four-component reactions, especially Biginelli,[5,6] Passerini,[7] Ugi,[8,9]
and Mannich[10,11] reactions, which have further led to a renaissance of MCRs.
Nevertheless, great efforts still are being made to find and develop new MCRs.
Received March 28, 2010.
Address correspondence to Naser Foroughifar, Department of Chemistry, Faculty of Science,
Arak University, Arak 38156-879, Iran. E-mail: N_Foroughifar@yahoo.com
2663

2664
N. FOROUGHIFAR ET AL.
The synthesis of xanthenes and benzoxanthenes has gained considerable atten-
tion in organic synthesis because of their wide range of therapeutic and biological
properties, such as use as anti-inflammatory agents[12] and in photodynamic ther-
apy.[13] Xanthene-based compounds have also been investigated for agricultural bac-
tericide activity, and some other benzoxanthenes find applications in industries such
as dyes in laser technology[14,15] and fluorescent materials for visualization of bio-
molecules.[16,17] Xanthene dyes are extracted naturally from soil and plants such as
Indigofera longeracemosa.[18]
Various methods are available for the construction of xanthenes and benzox-
anthenes involving trapping of benzynes by phenols,[19] cyclocondensation reaction
between 2-hydroxyaromatic aldehydes and 2-tetralone,[20] the reaction of aldehydes
with 2-naphthol,[21,22] and intramolecular phenyl carbonyl coupling reactions of
benzaldehydes and acetophenones.[23] Also, the synthesis of tetrahydrobenzo[a]-
xanthen-11-ones has been reported from condensation reaction of aldehydes,
b-naphthol, and cyclic 1,3-dicarbonyl compounds in the presence of different cata-
lysts such as NaHSO4 ꢀ SiO2,[24] Sr(OTf)2,[25] para-toluenesulfonic acid (p-TSA),[26]
ceric ammonium nitrate (CAN),[27] InCl3,[28] H3PW12O40,[29] and sulfamic acid.[30]
However, these methodologies suffer from one or more disadvantages such as pro-
longed reaction time, toxic solvents, special reagents, and often expensive catalysts.
Thus, the need for the development of an alternative route to construct the
tetrahydrobenzo[a]xanthen-11-one derivatives is in high demand.
RESULTS AND DISCUSSION
During the course of our recent studies directed toward the development of
practical, safe, and environmentally friendly procedures for some important trans-
formations,[31–35] we succeeded in preparing tetrahydrobenzo[a]xanthen-11-one deri-
vatives from condensation of aldehydes, dimedone, and b-naphthols in the presence
of ammonium chloride in good to excellent yield without any other by-products
(Scheme 1).
For the primary study and optimization of reaction conditions, first we
chose benzaldehyde and b-naphthol as a simple model for the reaction with dime-
done in the presence of ammonium chloride. After many examinations, we found
that the best conditions for this reaction were solvent-free with 10 mol%
ammonium chloride at 120 ꢁC (Table 1). A slight excess of the dimedone was
found to be advantageous, and hence the molar ratio of b-naphthol to dimedone
was kept as 1:1.1.
To explore the generality of the reaction, we extended our study using
ammonium chloride as catalysts under solvent-free conditions with different aromatic
Scheme 1. Synthesis of tetrahydrobenzo[a]xanthene-11-one derivatives.

TETRAHYDROBENZO[a]XANTHEN-11-ONES
Table 1. Optimization of reaction conditions
2665
Entry
Solvent
CH2Cl2
Ammonium chloride (mol%)
Temperature
Time (min)
Yield (%)a
1
2
3
4
5
6
7
8
10
10
10
10
10
10
10
20
Reflux
Reflux
Reflux
Reflux
Reflux
Rt
120
120
120
120
120
120
15
41
63
70
30
40
<5
86
86
C2H5OH
THF
CH3CN
Toluene
Solvent-free
Solvent-free
Solvent-free
120 ꢁC
120 ꢁC
15
aIsolated yields.
aldehydes as well as aliphatic aldehydes to prepare a series of tetrahydrobenzo[a]-
xanthene-11-one derivatives (Table 2). Various aromatic aldehydes bearing electron-
withdrawing groups (such as nitro, halide) and electron-releasing groups (such as
methyl, methoxy) showed equal ease toward the product formation in good to excel-
lent yields. Interestingly, aliphatic aldehydes such as propanal also gave the expected
xanthene derivatives in good yields.
Encouraged by the successful condensation of aldehydes, 2-naphthol, and
dimedone under solvent-free conditions, we further studied the reaction of aldehydes
and dimedone with 6-bromo-2-naphthol or 2,7-naphthalenediol under similar con-
ditions. It was found that the corresponding tetrahydrobenzo[a]xanthene-11-one
derivatives could also be obtained in good to excellent yields without any difficulties
Table 2. Synthesis of tetrahydrobenzo[a]xanthene-11-one derivatives
Mp (ꢁC)
Entry
Aldehyde
Phenol
2-Naphthol
2-Naphthol
Time (min)
Yield (%)a
Found
Reported[lit.]
1
2
4-MeC6H4
C6H5
15
15
20
15
15
25
40
30
30
25
8
80
86
78
88
83
72
69
71
70
78
93
94
90
88
94
86
—
195–196
152–154
202–203
187–188
180–181
Liquid
196–198[28]
151–153[28]
3
3-MeOC6H4
4-ClC6H4
4-NO2C6H4
Propanal
4-MeC6H4
3-ClC6H4
4-FC6H4
3-BrC6H4
C6H5
2-Naphthol
2-Naphthol
204–205[30]
4
180–182[28]
5
2-Naphthol
2-Naphthol
178–180[28]
6
Liquid[25,27]
7
6-Bromo-2-naphthol
6-Bromo-2-naphthol
6-Bromo-2-naphthol
6-Bromo-2-naphthol
2,7-Naphthalenediol
2,7-Naphthalenediol
2,7-Naphthalenediol
2,7-Naphthalenediol
2,7-Naphthalenediol
2,7-Naphthalenediol
3-Hydroxy-2-naphthoic
238–239
215–217
209–210
219–220
283–284
303–305
282–283
248–250
286–287
272–274
—
—
—
—
—
—
—
—
—
—
—
—
8
9
10
11
12
13
14
15
16
17
4-MeC6H4
2-ClC6H4
propanal
2-OHC6H4
=
C6H5C C-
C6H5
10
15
15
10
15
60
aIsolated yields.

2666
N. FOROUGHIFAR ET AL.
Table 3. Different catalysts for reaction of benzaldehyde, dimedone, and 2-naphthol
Entry
Catalyst
Conditions
Time (min)
Yield (%)a
1
2
3
4
5
6
NH4Cl
Sr(OTf)2
p-TSA
Solvent-free=120 ꢁC
ClCH2CH2Cl=60 ꢁC
Solvent-free=120 ꢁC
Solvent-free=120 ꢁC
Solvent-free=120 ꢁC
Solvent-free=60 ꢁC
15
300
45
86
85[25]
88[26]
94[27]
84[28]
86[29]
CAN
InCl3
H3PW12O40
30
30
70
aIsolated yields.
(Table 2). On the other hand, the reactions with 3-hydroxy-2-naphthoic acid were
also examined under the same conditions, but the reactions were unsuccessful.
On the basis of the results listed in Table 2, b-naphthol and 6-bromo-2-naph-
thol afforded relatively lower yields of the corresponding products. An explanation
for this behavior might be the fact that the electron-releasing groups on the 2-naph-
thol ring increased the electron density at the a -position of 2-naphthol. Thus the
nucleophilic attack at the carbonyl group is favored.
The results obtained with benzaldehyde, dimedone, and 2-naphthol under the
optimized conditions were compared with the best ones published so far for this
reaction using inorganic or organic catalysts; the data are listed in Table 3. It showed
that the ammonium chloride was fairly a good catalyst for this reaction.
CONCLUSION
In summary, we have developed a simple and efficient methodology for the
synthesis of tetrahydrobenzo[a]xanthene-11-one derivatives in the presence of
ammonium chloride under solvent-free conditions. The conditions are mild, and
a wide range of functional groups can be tolerated. In addition to the efficiency
and simplicity provided by this procedure, ease of workup, short reaction time,
excellent yields of products, and environmental friendliness make the method
advantageous.
EXPERIMENTAL
All products were characterized by a comparison of their spectral [infrared
1
(IR), H NMR, 13C NMR, and elemental analysis] data or by comparison of their
physical and spectroscopic data with those reported in the literature. Melting points
were measured by using capillary tubes on an Electrothermal digital apparatus and
are uncorrected. The progress of reactions was monitored by thin-layer chromato-
graphy (TLC) using n-hexane=EtOAc as an eluent. IR spectra were recorded as
KBr disc on a Galaxy series Fourier transform (FT)–IR 5000 spectrometer. NMR
spectra were recorded on a Brucker spectrometer in dimethylsulfoxide (DMSO-d6)
with tetramethylsilane (TMS) as an internal standard. Elemental analyses were per-
formed on Vario EL equipment at Arak University.

TETRAHYDROBENZO[a]XANTHEN-11-ONES
2667
General Procedure for Tetrahydrobenzo[a]xanthen-11-one
Derivatives
Ammonium chloride (0.10 mmol) was added to mixture of aldehyde (1 mmol),
2-naphthol (1 mmol), and dimedone (1.1 mmol). The reaction mixture was stirred
magnetically at 120 ꢁC for the appropriate time as shown in Table 2. The progress
of the reaction was monitored by TLC. After completion of the reaction, a mixtur
of EtOH–H2O (10 mL, 1:1) was added, and the mixture was stirred for 15 min.
The obtained solid product was filtered and recrystallized from ethanol to yield pure
xanthene derivatives. [In the case of condesation of propanal, 2-naphthol, and dime-
done, after completion of the reaction, the residue was purified by column chroma-
tography (silica gel, 3% EtOAc in hexane).]
Characterization Data
3-Bromo-12-(4-methylphenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 7)
1
IR (KBr): nmax ¼ 3022, 2957, 1651, 1589, 1500, 1373, 1222, 1024, 885, 817 cmꢂ1; H
NMR (300 MHz, DMSO-d6): d ¼ 7.93 (s, 1H), 7.88 (d, J ¼ 9.1 Hz, 1H), 7.67 (d,
J ¼ 8.9 Hz, 1H), 7.50 (d, J ¼ 9.0 Hz, 1H), 7.35 (d, J ¼ 8.9 Hz, 1H), 7.21 (d, J ¼ 8.1 Hz,
2H), 6.99 (d, J ¼ 7.9 Hz, 2H), 5.63 (s, 1H), 2.58 (s, 2H), 2.29 (d, J ¼ 6.0 Hz, 2H), 2.22
(s, 3H), 1.14 (s, 3H), 0.99 (s, 3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 196.9, 163.6,
147.8, 141.5, 135.9, 132.6, 130.3, 130.2, 130.0, 129.2, 129.0, 128.2, 127.8, 125.5, 118.9,
118.3, 114.2, 50.9, 41.3, 34.3, 32.3, 29.3, 27.3, 21.0. Anal. calcd. for C26H23BrO2: C,
69.80; H, 5.18. Found: C, 69.67; H, 5.34.
3-Bromo-12-(3-chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 8)
IR (KBr): nmax ¼ 3078, 2960, 1645, 1589, 1500, 1379, 1224, 1167, 1080, 960, 798 cmꢂ1
;
1H NMR (300 MHz, DMSO-d6): d ¼ 8.20 (s, 1H), 7.99 (d, J ¼ 9.1 Hz, 1H), 7.92 (d,

2668
N. FOROUGHIFAR ET AL.
J ¼ 9.0 Hz, 1H), 7.58 (d, J ¼ 8.9 Hz, 1H), 7.51 (d, J ¼ 8.9 Hz, 1H), 7.37 (s, 1H),
7.21–7.12 (m, 3H), 5.58 (s, 1H), 2.66 and 2.58 (AB system, J ¼ 17.5 Hz, 2H), 2.33
and 2.14 (AB system, J ¼ 16.2 Hz, 2H), 1.04 (s, 3H), 0.86 (s, 3H); 13C NMR
(75 MHz, DMSO-d6): d ¼ 196.4, 164.5, 147.9, 147.4, 133.2, 132.9, 131.1, 130.9,
130.6, 129.6, 129.2, 128.4, 127.2, 126.9, 126.1, 119.0, 118.8, 117.3, 113.0, 50.5,
40.7, 34.2, 32.4, 29.2, 26.6. Anal. calcd. for C25H20BrClO2: C, 64.19; H, 4.31. Found:
C, 64.03; H, 4.41.
3-Bromo-12-(4-fluorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 9)
IR (KBr): nmax ¼ 3065, 2939, 2870, 1645, 1589, 1504, 1377, 1195, 1165, 1014, 958,
1
841 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 7.96 (s, 1H), 7.80 (d, J ¼ 9.0 Hz,
1H), 7.69 (d, J ¼ 8.9 Hz, 1H), 7.51 (d, J ¼ 9.0 Hz, 1H), 7.35 (d, J ¼ 8.9 Hz, 1H),
7.28 (t, J ¼ 6.2 Hz, 2H), 6.87 (t, J ¼ 7.7 Hz, 2H), 5.65 (s, 1H), 2.58 (s, 2H), 2.33
and 2.27 (AB system, J ¼ 16.4 Hz, 2H), 1.14 (s, 3H), 0.98 (s, 3H); 13C NMR
(75 MHz, DMSO-d6): d ¼ 196.9, 163.8, 147.9, 140.2, 132.7, 130.5, 130.4, 129.9,
129.8, 128.1, 125.3, 119.0, 118.3, 117.7, 115.3, 115.0, 113.9, 50.8, 41.3, 34.0,
32.3, 29.3, 27.1. Anal. calcd. for C25H20BrFO2: C, 66.53; H, 4.47. Found: C,
66.68; H, 4.55.
3-Bromo-12-(3-bromophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 10)
IR (KBr): nmax ¼ 3057, 2960, 2930, 1645, 1589, 1500, 1421, 1377, 1225, 1167, 1072,
958, 796 cmꢂ1; 1H NMR (300 MHz, DMSO-d6): d ¼ 7.96 (s, 1H), 7.79 (d, J ¼ 9.0 Hz,
Hz, 1H), 7.70 (d, J ¼ 9.0 Hz, 1H), 7.54 (d, J ¼ 8.9 Hz, 1H), 7.40–7.28 (m, 4H), 7.07 (t,
J ¼ 7.8 Hz, 1H), 5.63 (s, 1H), 2.60 (s, 1H), 2.33 and 2.27 (AB system, J ¼ 16.2 Hz,
2H), 1.14 (s, 3H), 1.00 (s, 3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 196.7, 164.0,
147.9, 146.6, 133.3, 132.7, 131.2, 130.5, 129.9, 129.7, 128.3, 127.2, 125.2, 123.2,
122.6, 119.1, 118.3, 117.1, 113.5, 50.8, 41.3, 34.5, 32.3, 29.2, 27.3. Anal. calcd. for
C25H20Br2O2: C, 58.62; H, 3.94. Found: C, 58.75; H, 4.02.

TETRAHYDROBENZO[a]XANTHEN-11-ONES
2669
2-Hydroxy-12-(phenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-
11-one (Table 2, Entry 11)
IR (KBr): nmax ¼ 3177, 3059, 2947, 1628, 1599, 1473, 1450, 1379, 1215, 1028, 835,
1
696 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.92 (s, 1H), 7.74 (d, J ¼ 8.8 Hz,
2H), 7.26–1.16 (m, 6H), 7.08–6.97 (m, 2H), 5.37 (s, 1H), 2.63 and 2.53 (AB system,
J ¼ 17.5 Hz, 2H), 2.31 and 2.10 (AB system, J ¼ 16.2 Hz, 2H), 1.02 (s, 3H), 0.84 (s,
3H); 13C NMR (75 MHz, DMSO-d6): d ¼ 196.3, 164.3, 156.9, 148.1, 145.2, 133.0,
130.7, 129.2, 128.8, 128.6, 126.6, 126.0, 117.6, 116.0, 114.0, 113.8, 105.7, 50.5,
40.7, 34.7, 32.3, 29.3, 26.6. Anal. calcd. for C25H22O3: C, 81.06; H, 5.99. Found:
C, 79.93; H, 6.10.
2-Hydroxy-12-(4-methylphenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 12)
IR (KBr): nmax ¼ 3158, 2959, 2930, 1632, 1597, 1450, 1379, 1232, 1140, 1028, 837,
1
771 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.88 (s, 1H), 7.73 (d, J ¼ 8.9 Hz,
2H), 7.23 (s, 1H), 7.19–7.11 (m, 3H), 6.99 (d, J ¼ 8.0 Hz, 3H), 5.30 (s, 1H), 2.65
and 2.54 (AB system, J ¼ 17.4 Hz, 2H), 2.32 and 2.10 (AB system, J ¼ 16.2 Hz,
2H), 2.16 (s, 3H), 1.04 (s, 3H), 0.86 (s, 3H); 13C NMR (75 MHz, DMSO-d6):
d ¼ 196.4, 164.2, 156.9, 148.0, 142.3, 135.7, 133.0, 132.9, 130.7, 129.1, 128.5, 125.9,
117.6, 116.1, 114.0, 113.8, 105.7, 50.5, 40.7, 34.2, 32.3, 29.3, 26.6, 21.0. Anal. calcd.
for C26H24O3: C, 81.22; H, 6.29. Found: C, 81.11; H, 6.40.
2-Hydroxy-12-(2-chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 13)
IR (KBr): nmax ¼ 3163, 3057, 2955, 1630, 1597, 1446, 1379, 1209, 1134, 1037, 835,
1
750 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.87 (s, 1H), 7.76–7.71 (m, 2H),

2670
N. FOROUGHIFAR ET AL.
7.37 s, 1H), 7.28 (d, J ¼ 7.8 Hz, 2H), 7.20–7.06 (m, 3H), 7.01 (d, J ¼ 8.8 Hz, 1H),
5.63 (s, 1H), 2.66 and 2.53 (AB system, J ¼ 17.4 Hz, 2H), 2.31 and 2.07 (AB sys-
tem, J ¼ 16.1 Hz, 2H), 1.04 (s, 3H), 0.88 (s, 3H); 13C NMR (75 MHz, DMSO-d6):
d ¼ 196.0, 164.6, 157.0, 148.4, 142.1, 133.4, 132.6, 132.5, 130.6, 130.1, 129.5,
128.4, 127.5, 125.9, 117.6, 115.2, 114.0, 112.7, 106.2, 50.6, 40.7, 33.3, 32.1,
29.4, 26.6. Anal. calcd. for C25H21ClO3: C, 74.16; H, 5.23. Found: C, 74.25;
H, 5.14.
2-Hydroxy-12-(ethyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-
11-one (Table 2, Entry 14)
IR (KBr): nmax ¼ 3156, 2960, 2872, 1624, 1593, 1450, 1377, 1232, 1174, 1030, 833,
1
796 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.88 (s, 1H), 7.77 (d, J ¼ 8.8 Hz,
1H), 7.70 (d, J ¼ 8.8 Hz, 1H), 7.25 (s, 1H), 7.04 (t, J ¼ 8.5 Hz, 2H), 4.39 (s, 1H),
2.57 (d, J ¼ 4.4 Hz, 2H), 2.37 and 2.25 (AB system, J ¼ 16.0 Hz, 2H), 1.72–1.67
(m, 2H), 1.11 (s, 3H), 1.08 (s, 3H), 0.53 (t, J ¼ 7.2 Hz, 3H); 13C NMR (75 MHz,
DMSO-d6): d ¼ 197.0, 166.4, 156.9, 149.1, 132.8, 130.8, 128.5, 125.9, 117.6, 115.4,
113.7, 111.4, 104.9, 50.7, 32.2, 29.5, 28.6, 27.1, 26.7, 9.2. Anal. calcd. for
C21H22O3: C, 78.23; H, 6.88. Found: C, 78.37; H, 6.76.
2-Hydroxy-12-(2-hydroxyphenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo-
[a]xanthen-11-one (Table 2, Entry 15)
IR (KBr): nmax ¼ 3258, 3057, 2953, 1649, 1627, 1589, 1485, 1388, 1232, 1031,
1
837, 758 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.79 (s, 1H), 9.55 (s, 1H),
7.70 (d, J ¼ 8.7 Hz, 2H), 7.49 (s, 1H), 7.11 (d, J ¼ 8.8 Hz, 1H), 7.00 (t, J ¼ 7.9 Hz,
Hz, 2H), 6.89 (t, J ¼ 7.7 Hz, 1H), 6.71 (d, J ¼ 8.0 Hz, 1H), 6.62 (t, J ¼ 7.3 Hz,
1H), 5.52 (s, 1H), 2.67 and 2.53 (AB system, J ¼ 17.4 Hz, 2H), 2.33 and 2.10
(AB system, J ¼ 16.1 Hz, 2H), 1.05 (s, 3H), 0.91 (s, 3H); 13C NMR (75 MHz,
DMSO-d6): d ¼ 197.0, 165.1, 156.7, 154.4, 148.3, 133.5, 131.5, 130.6, 130.4,
128.7, 127.7, 125.8, 119.6, 117.4, 116.6, 116.4, 114.0, 113.2, 106.4, 50.6, 40.8,
33.7, 32.3, 29.5, 26.6. Anal. calcd. for C25H22O4: C, 77.70; H, 5.74. Found: C,
77.83; H, 5.69.

TETRAHYDROBENZO[a]XANTHEN-11-ONES
2671
2-Hydroxy-12-(styryl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-
11-one (Table 2, Entry 16)
IR (KBr): nmax ¼ 3165, 3059, 3024, 2957, 1626, 1593, 1448, 1383, 1232, 1172, 1132,
1
1028, 960, 831, 733 cmꢂ1; H NMR (300 MHz, DMSO-d6): d ¼ 9.94 (s, 1H), 7.76
(t, J ¼ 8.2 Hz, 2H), 7.32 (s, 1H), 7.22–7.09 (m, 6H), 7.03 (d, J ¼ 8.8 Hz, 1H),
6.32–6.21 (m, 2H), 4.98 (d, J ¼ 6.2 Hz, 1H), 2.55 (s, 2H), 2.34 and 2.25 (AB system,
J ¼ 16.0 Hz, 2H), 1.04 (s, 6H); 13C NMR (75 MHz, DMSO-d6): d ¼ 196.6, 165.2,
157.0, 148.2, 136.9, 133.3, 131.2, 130.7, 130.3, 129.1, 128.9, 127.8, 126.5, 125.9,
117.8, 114.5, 114.1, 111.5, 105.6, 50.6, 32.3, 31.5, 29.1, 27.1. Anal. calcd. for
C27H24O3: C, 81.79; H, 6.10. Found: C, 81.88; H, 6.05.
ACKNOWLEDGMENT
We gratefully acknowledge the financial support from the Research Council of
Arak University.
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