Succinimide-N-sulfonic acid: An efficient catalyst for the synthesis of xanthene derivatives under solvent-free conditions

Article abstract of DOI:10.1016/j.dyepig.2012.06.022

A mild, simple and convenient procedure for the synthesis of xanthene derivatives is described via three component condensation of aldehydes with 2-naphthol, 1,3-cyclohexanedione and/or a mixture of 2-naphthol and 1,3-cyclohexanediones using succinimide-N

Full text of DOI:10.1016/j.dyepig.2012.06.022

Dyes and Pigments 95 (2012) 789e794
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Short communication
Succinimide-N-sulfonic acid: An efficient catalyst for the synthesis of xanthene
derivatives under solvent-free conditions
*
Farhad Shirini , Nader Ghaffari Khaligh
Department of Chemistry, College of Science, University of Guilan, Rasht 41335-19141, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A mild, simple and convenient procedure for the synthesis of xanthene derivatives is described via three
component condensation of aldehydes with 2-naphthol, 1,3-cyclohexanedione and/or a mixture of
2-naphthol and 1,3-cyclohexanediones using succinimide-N-sulfonic acid as an efficient, cheap and
readily synthesis catalyst under solvent-free conditions. The structures of the products were charac-
terized by their physical constants, comparison with authentic samples and IR, 1H NMR and 13C NMR
spectroscopy. The present methodology offers several advantages such as high yields, simple procedure,
low cost, short reaction times, solvent-free and mild reaction conditions and use of a reusable catalyst.
Ó 2012 Elsevier Ltd. All rights reserved.
Received 21 April 2012
Accepted 29 June 2012
Available online 7 July 2012
Keywords:
Succinimide-N-sulfonic acid
Multicomponent reactions
Xanthene derivatives
Solvent-free conditions
2-Naphthol
Aldehydes
1. Introduction
In continuation of our ongoing research program on the devel-
opment of new catalysts and methods for organic transformations
The synthesis of xanthene derivatives, especially benzox-
anthenes, has emerged as a powerful tool in organic synthesis due
to their wide range of biological and therapeutic properties such as
antibacterial [1], antiviral [2] and anti-inflammatory activities [3] as
well as in photodynamic therapy [4] and for antagonism of the
paralyzing action of zoxazolamine [5]. Furthermore, due to their
useful spectroscopic properties, they were used as dyes [6], in laser
technologies [7], and in fluorescent materials for visualization of
biomolecules [8]. Many procedures describe the synthesis of
xanthenes and benzoxanthenes including cyclodehydrations [9],
[18], earlier report from our laboratory described the synthesis of
succinimide-N-sulfonic acid [SuSA] and its application in the che-
moselective trimethylsilylation of alcohols and phenols [19] and
N-Boc protection of amines [20]. In this paper we were interested to
investigate the applicability of this reagent in the promotion of the
synthesis of xanthenes derivatives under solvent-free conditions
(Scheme 1).
2. Experimental section
alkylations
g to the heteroatoms [10], trapping of benzynes by
2.1. Material
phenols [11], cyclocondensation between 2-hydroxyaromatic
aldehydes and 2-tetralone [12], the reaction of 2-naphthol with
aldehydes or acetals under acidic conditions and intramolecular
phenyl carbonyl coupling reactions of benzaldehydes and aceto-
phenones [13]. In addition, 14H-dibenzo[a,j]xanthenes and related
products were prepared by reaction of 2-naphthol with formamide
[14], 2-naphthol-1-methanol [15], carbon monoxide [16] and sul-
fomic acid [17]. Even though various procedures were reported,
disadvantages including low yields, prolonged reaction times, use
of an excess of reagents/catalysts and use of toxic organic solvents
necessitate the development of an alternative route for the
synthesis of xanthene derivatives.
All chemicals were purchased from Merck, Aldrich and Fluka
Chemical Companies and used without further purification. Prod-
ucts were characterized by their physical constant and comparison
with authentic samples. The purity determination of the substrates
and reaction monitoring were accompanied by TLC using silica gel
SIL G/UV 254 plates.
2.2. Instrumentation
The MS were measured under GC (70 eV) conditions. The IR
spectra were recorded on a Perkin Elmer 781 Spectrophotometer. In
all the cases the 1H NMR spectra were recorded with Bruker Avance
400 or 300 MHz instrument. The 13C NMR data were collected on
Bruker Avance 100 or 75 MHz instrument. All chemical shifts are
* Corresponding author. Tel./fax: þ98 1313233262.
E-mail addresses: shirini@guilan.ac.ir, fshirini@gmail.com (F. Shirini).
0143-7208/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.dyepig.2012.06.022

790
F. Shirini, N.G. Khaligh / Dyes and Pigments 95 (2012) 789e794
Dyes and Pigments
R
(Table 1, entries 1-6)
(Table 1, entries 7-15)
2A
2B
O
O
O
R
O
O
R
SuSA
Solvent free, 80 o
+
R1
R1
O
H
C
R1
R1
R
O
R1
A + B
(Table 1, entries 16-21)
R1
O
HO
R= Aryl
R1= H or CH3
R1
O
R1
A
B
Scheme 1. Synthesis of xanthene derivatives in the presence of SuSA under solvent-free conditions.
quoted in parts per million (ppm) relative to TMS using deuterated
solvent. Microanalyses were performed on a PerkineElmer 240-B
microanalyzer. Melting points were recorded on a Büchi B-545
apparatus in open capillary tubes.
(m, 2H), 2.26e2.39 (m, 4H), 1.9e2.05 (m, 4H) ppm; 13C NMR
(100 MHz, CDCl3):
127.5,127.1,127.0,125.7,125.4,116.8, 37.0, 31.9, 27.2, 20.3 ppm; Anal.
Calcd for C23H20O3: C, 80.23; H, 5.81. Found: C, 80.20; H, 5.78.
d
¼ 196.7, 164.2, 142.1, 133.4, 132.4, 128.0, 127.7,
2.3. General procedure for the synthesis of xanthene derivatives
2.4.3. 9-(3-Bromophenyl)-1,8-dioxo-octahydroxanthene (Table 1,
entry 8)
A mixture of SuSA (10 mg, 5.6% mol) and the desired substrate
(1, mmol, according to Scheme 1) was heated at 80 ꢀC under
solvent-free conditions. The progress of the reaction was followed
by TLC. After completion of the reaction, the reaction mixture was
diluted with Et2O (10 mL) and stirred for 10 min. The catalyst was
decanted and the crude product was recrystallized from EtOH. The
product was found to be pure and no further purification was
necessary. The products were characterized by IR, NMR spectro-
scopic data and elemental analysis and the melting point of known
compounds are compared with reported values.
White solid, m.p. 281e283 ꢀC; IR (KBr):
n
¼ 3070, 2910, 2890,
1660, 1619, 1560, 1480, 1420, 1200, 1170, 1122 cmꢁ1 1H NMR
(400 MHz, CDCl3):
¼ 7.26e7.36 (m, 3H), 7.11 (t, J ¼ 7.6 Hz,1H), 4.79
(s, 1H), 2.66e2.73 (m, 2H), 2.55e2.63 (m, 2H), 2.30e2.44 (m, 4H),
1.95e2.1 (m, 4H) ppm; 13C NMR (100 MHz, CDCl3):
;
d
d
¼ 196.4, 164.3,
146.6, 131.0, 129.6, 127.7, 122.3, 116.3, 36.9, 31.6, 27.2, 20.3 ppm;
Anal. Calcd for C19H17O3Br: C, 61.12; H, 4.55. Found: C, 61.09; H, 4.51.
2.4.4. 9-(3-Mehtoxyphenyl)-1,8-dioxo-octahydroxanthene (Table 1,
entry 9)
White solid, m.p. 192e194 ꢀC; IR (KBr):
n
¼ 3020, 2950, 2900,
1650, 1618, 1495, 1459, 1235, 1200, 1025 cmꢁ1; 1H NMR (400 MHz,
CDCl3):
2.4. Spectral data for selected and new compounds
d
¼ 7.17 (t, J ¼ 8.0 Hz,1H), 6.89e6.95 (m, 2H), 6.69e6.71 (dd,
2.4.1. 14-Furfuryl-14H-dibenzo[a,j]xanthene (Table 1, entry 6)
J ¼ 8.0 Hz, J ¼ 1.6 Hz, 1H), 4.83 (s, 1H), 3.81 (s, 3H), 2.54e2.71 (m,
White solid, m.p. 198e200 ꢀC; IR (KBr):
n
¼ 3042, 2956, 2868,
1668,1625,1608,1510,1464, 1358,1204,1162, 1145, 1109, 848 cmꢁ1
1H NMR (400 MHz, CDCl3):
4H), 2.30e2.45 (m, 4H),1.99e2.10 (m, 4H) ppm; 13C NMR (100 MHz,
;
CDCl3):
d
¼ 196.5, 164.0, 159.4, 146.0, 129.0, 121.0, 116.8, 114.5, 111.5,
d
¼ 8.35 (d, J ¼ 8.4 Hz, J ¼ 1.6 Hz, 2H),
55.2, 37.0, 31.5, 27.2, 20.3 ppm; Anal. Calcd for C20H20O4: C, 74.04;
H, 6.17. Found: C, 74.01; H, 6.15.
7.83e7.88 (m, 4H), 7.62e7.65 (m, 2H), 7.44e7.54 (m, 2H), 7.15e7.22
(m, 2H), 7.03e7.07 (dd, J ¼ 7.6 and 8.0 Hz, 2H), 6.23 (dd, J ¼ 2.0 and
2.0 Hz, 1H), 6.01 (d, J ¼ 2.8 Hz, 1H), 5.31 (s, 1H) ppm. 13C NMR
2.4.5. 9-(4-Cyanophenyl)-1,8-dioxo-octahydroxanthene (Table 1,
entry 10)
(100 MHz, CDCl3):
d
¼ 158.2, 152.2, 142.1, 135.5, 133.4, 132.4, 127.9,
126.9, 125.7, 122.1, 119.8, 118.5, 115.4, 112.2, 109.8, 42.9 ppm; Anal.
Calcd for C25H16O2: C, 86.21; H, 4.59. Found: C, 86.17; H, 4.55.
White solid, m.p. 273e275 ꢀC; IR (KBr):
n
¼ 3070, 2950, 2900,
2250, 1657, 1619, 1500, 1417, 1200, 1173, 1125 cmꢁ1 1H NMR
(400 MHz, CDCl3):
¼ 7.53 (d, J ¼ 8.0 Hz, 2H), 7.44 (d, J ¼ 8.0 Hz,
2H), 4.84 (s, 1H), 2.57e2.73 (m, 4H), 2.30e2.41 (m, 4H), 1.95e2.11
(m, 4H) ppm; 13C NMR (100 MHz, CDCl3):
;
d
2.4.2. 9-Naphthyl-1,8-dioxo-octahydroxanthene (Table 1, entry 7)
White solid, m.p. 197e199 ꢀC; IR (KBr):
n
¼ 3050, 2900, 2880,
1660, 1620, 1502, 1435, 1200, 1165, 1007 cmꢁ1; 1H NMR (400 MHz,
CDCl3):
¼ 7.74e7.83 (m, 4H), 7.53e7.56 (dd, J ¼ 9.6 Hz, J ¼ 1.6 Hz,
1H), 7.29e7.45 (m, 2H), 5.03 (s, 1H), 2.67e2.74 (m, 2H), 2.55e2.63
d
¼ 196.5, 164.5, 149.7,
132.0, 129.4, 119.19, 115.8, 110.2, 36.8, 32.3, 27.1, 20.2 ppm; Anal.
Calcd for C20H17NO3: C, 75.24; H, 5.33; N, 4.39. Found: C, 75.21; H,
5.32; N, 4.35.
d

F. Shirini, N.G. Khaligh / Dyes and Pigments 95 (2012) 789e794
791
Table 1
Table 1 (continued)
SuSA catalyzed synthesis of xanthene derivatives.a
Entry Arylaldehyde
Time Yield Mp ꢀC
Time Yield Mp ꢀC
(min) (%)b
(min) (%)b
Entry Arylaldehyde
Found
Reported
[Ref.]
Found
Reported
[Ref.]
CHO
CHO
11
25
94
210e212 188e190
1
35
30
92
90
185e186 183e185
[24]
[9c,21]
OCH3
CHO
CHO
2
240e242 238e240
[9c,21]
12
27
92
212e214 184e186
F
[25]
H3CO
CHO
CHO
CHO
OCH3
CHO
3
25
25
15
92
93
91
210e213 209e211
[21,22]
Cl
13
18
96
251e253 230
[26]
NC
4
195e197 192e194
CHO
[23]
14
15
20
18
94
92
259e262 223e225
Br
[25]
F
CHO
5
209e211 210e212
230e231 230e232
[9c,21]
[24]
Cl
NO2
CHO
CHO
6
30
15
94
94
198e200
197e199
e
e
O
16
48
90
220e222 e
CHO
OCH3
7
CHO
CHO
CHO
CHO
17
42
96
216e217 e
H3C
8
17
93
281e283
e
CH3
Br
18
19
32
40
82
78
219e221
215e217
e
9
18
16
88
96
192e194 e
OCH3
CHO
CHO
e
10
273e25
e
NC
(continued on next page)

792
F. Shirini, N.G. Khaligh / Dyes and Pigments 95 (2012) 789e794
Table 1 (continued)
d
¼ 8.04 (d, J ¼ 8 Hz, 1H), 7.80 (t, J ¼ 8.4 Hz, 2H), 7.36e7.48 (m, 3H),
7.28 (d, J ¼ 8.4 Hz, 2H), 7.06 (d, J ¼ 8 Hz, 2H), 5.76 (s, 1H), 2.05e2.84
Entry Arylaldehyde
Time Yield Mp ꢀC
(m, 7H), 1.18 (d, J ¼ 5.2 Hz, 6H) ppm; 13C NMR (100 MHz, CDCl3):
(min) (%)b
Found
Reported
[Ref.]
d
¼ 197.2, 165.6, 147.8, 146.5, 142.4, 131.5, 128.7, 128.4, 128.3, 126.9,
126.4, 124.9, 123.8, 118.1, 117.0, 115.8, 37.1, 34.2, 33.6, 27.8, 23.9,
20.3 ppm; Anal. Calcd for C26H24O2: C, 84.78; H, 6.52. Found: C,
84.73; H, 6.49.
CHO
20
35
30
90
91
203e204
150e152
e
e
2.4.11. 12-(2-Fluorenyl)-9,9-dimethyl-8,9,10,12-octahydrobenzo[a]
xanthenes-11-one (Table 1, entry 18)
NC
CHO
White solid, m.p. 219e221 ꢀC; IR (KBr): nmax ¼ 3050, 2950, 2870,
1640, 1619, 1590, 1475, 1220, 1180 cmꢁ1; 1H NMR (400 MHz, CDCl3):
d
21
H3C
¼ 8.07 (d, J ¼ 7.2 Hz,1H), 7.80 (d, J ¼ 7.6 Hz, 2H), 7.38e7.66 (m, 7H),
7.31e7.24 (m, 3H), 5.81 (s, 1H), 3.79 (s, 2H), 2.52 (s, 1H), 2.22e2.36
(m, 3H), 1.14 (s, 3H), 0.98 (s, 3H) ppm; 13C NMR (100 MHz, CDCl3):
CH3
d
¼ 197.0, 163.8, 147.0, 143.6, 143.3, 141.5, 139.9, 131.5, 131.4, 128.8,
a
Products were characterized by 1H NMR, IR and melting point and also by
128.4, 127.2, 127.0, 126.6, 126.3, 125.1, 124.9, 123.7, 120.0, 119.6, 117.1,
114.4, 50.9, 41.5, 36.9, 34.8, 32.3, 29.3, 27.2 ppm; Anal. Calcd for
C32H26O2: C, 86.87; H, 5.88. Found: C, 86.84; H, 5.85.
comparison with those reported in the literature.
b
Isolated yields.
2.4.6. 9-(2-Mehtoxyphenyl)-3,3,6,6-tetramethyl-1,8-dioxo-
octahydroxanthene (Table 1, entry 11)
2.4.12. 12-(2-Naphthyl)-9,9-dimethyl-8,9,10,12-octahydrobenzo[a]
xanthenes-11-one (Table 1, entry 19)
White solid, m.p. 210e212 ꢀC; IR (KBr):
n
¼ 3010, 2950, 2870,
1650, 1620, 1590, 1490, 1460, 1360, 1250, 1020, 1200, 1000, 1160,
1140, 1118, 750 cmꢁ1 1H NMR (400 MHz, CDCl3):
White solid, m.p. 215e217 ꢀC; IR (KBr):
n
¼ 3050, 2950, 2870,
1640, 1590, 1505, 1460, 1365, 1220 cmꢁ1
;
1H NMR (400 MHz,
;
d
¼ 7.43 (dd,
CDCl3):
d
¼ 8.08 (d, J ¼ 8 Hz,1H), 7.67e7.82 (m, 6H), 7.50 (d, J ¼ 8 Hz,
J ¼ 7.4 Hz, J ¼ 1.6 Hz, 1H), 7.12 (m, 1H), 6.89 (dt, J ¼ 7.4 Hz, J ¼ 1.2 Hz,
1H), 6.77 (d, J ¼ 8 Hz, 1H), 4.87 (s, 1H), 3.79 (s, 3H), 2.39 and 2.48 (d,
J ¼ 17.4 Hz, 2H), 2.14 and 2.23 (d, J ¼ 16.4 Hz, 2H),1.11 (s, 6H), 0.97 (s,
6H) ppm; Anal. Calcd for C24H28O4: C, 75.79; H, 7.37. Found: C,
75.73; H, 7.34.
1H), 7.28e7.44 (m, 5H), 5.92 (s, 1H), 2.61 (s, 2H), 2.32 and 2.36 (AB
system, J ¼ 16.4 Hz, 2H), 1.14 (s, 3H), 0.96 (s, 3H) ppm; 13C NMR
(100 MHz, CDCl3):
d
¼ 196.9, 164.0, 147.8, 142.1, 133.3, 132.1, 131.5,
131.4,129.0,128.4,128.0, 127.4,127.2,127.1,126.7,125.7,125.4,124.9,
123.7, 117.6, 117.1, 114.1, 50.9, 41.5, 34.9, 32.3, 29.3, 27.2 ppm; Anal.
Calcd for C29H24O2: C, 86.14; H, 5.94. Found: C, 86.12; H, 5.91.
2.4.7. 9-(3,4-Dimehtoxyphenyl)-3,3,6,6-tetramethyl-1,8-dioxo-
octahydroxanthene (Table 1, entry 12)
2.4.13. 12-(4-Cyanophenyl)-9,9-dimethyl-8,9,10,12-octahydrobenzo
[a]xanthenes-11-one (Table 1, entry 20)
Yellow solid, m.p. 212e214 ꢀC; IR (KBr):
n
¼ 3020, 2950, 2860,
1660, 1620, 1585, 1510, 1460, 1360, 1260, 1020, 1200, 1000, 1160,
1140, 1100, 850, 818, 750, 685 cmꢁ1; 1H NMR (500 MHz, CDCl3):
White solid, m.p. ¼ 203e204 ꢀC; IR (KBr):
n
¼ 3050, 2950, 2870,
d;
2300, 1640, 1620, 1597, 1520, 1460, 1360, 1220 cmꢁ1 1H NMR
;
6.94 (d, J ¼ 1.7 Hz, 1H), 6.8 (dd, J ¼ 8.3 Hz, J ¼ 1.8 Hz, 2H), 6.75 (d,
J ¼ 8.3 Hz, 2H), 4.74 (s, 1H), 3.89 (s, 3H), 3.84 (s, 3H), 2.49 (s, 4H),
2.22 and 2.27 (d, J ¼ 16.3 Hz, 2H), 1.15 (s, 6H), 1.05 (s, 6H) ppm; Anal.
Calcd for C25H30O5: C, 73.17; H, 7.31. Found: C, 73.15; H, 7.27.
(400 MHz, CDCl3):
d
¼ 7.82e7.86 (m, 3H), 7.41e7.49 (m, 6H), 7.37 (d,
J ¼ 8.8 Hz, 1H), 5.78 (s, 1H), 2.61 (s, 2H), AB system 2.267 (d,
J ¼ 16.0 Hz, 1H), 2.35 (d, J ¼ 16 Hz, 1H), 1.15 (s, 3H), 0.97 (s, 3H) ppm;
13C NMR (100 MHz, CDCl3):
d
¼ 196.8,164.6,149.9,147.8,132.2,131.6,
131.1, 129.5, 129.3, 128.6, 127.4, 125.2, 123.2, 118.9, 117.1, 116.1, 113.1,
110.1, 50.8, 41.4, 35.0, 32.3, 29.3, 27.1 ppm; Anal. Calcd for C26H21NO2:
C, 82.32; H, 5.54; N, 3.69. Found: C, 82.29; H, 5.50; N, 3.65.
2.4.8. 9-(4-Cyanophenyl)-3,3,6,6-tetramethyl-1,8-dioxo-
octahydroxanthene (Table 1, entry 13)
White solid, m.p. 251e253 ꢀC; IR (KBr):
n
¼ 3050, 2950, 2870,
2210, 1660, 1620, 1600, 1500, 1460, 1360, 1200, 1160, 1140, 1105,
850 cmꢁ1 1H NMR (400 MHz, CDCl3):
2.4.14. 12-(4-Isopropylphenyl)-9,9-dimethyl-8,9,10,12-
octahydrobenzo[a]xanthenes-11-one (Table 1, entry 21)
;
d
¼ 7.54 (dd, J ¼ 6.6 Hz,
J ¼ 1.6 Hz, 2H), 7.43 (dd, J ¼ 9.6 Hz, J ¼ 1.6 Hz, 2H), 4.78 (s, 1H), 2.5
(d, J ¼ 1.2 Hz, 2H), 2.17 and 2.26 (d, J ¼ 16.4 Hz, 2H), 1.13 (s, 6H), 0.99
(s, 6H) ppm; Anal. Calcd for C24H25NO3: C, 76.80; H, 6.67. Found: C,
76.75; H, 6.63.
White solid, m.p. ¼ 150e152 ꢀC; IR (KBr):
n
¼ 3050 (w), 2950
(m), 2870 (w), 1642 (s), 1619 (w), 1590 (w), 1460 (s), 1364 (s), 1222
(m) cmꢁ1
34.2, 33.5, 32.3, 32.2, 29.2, 27.5, 23.9, 23.8 ppm; Anal. Calcd for
C28H28O2: C, 84.85; H, 7.07. l3):
;
1H NMR (400 MHz, CDC.8, 118.0, 50.9, 50.8, 41.4, 34.2,
d
¼ 8.05 (d, J ¼ 8 Hz, 1H), 7.78 (t,
2.4.9. 12-(3-Methoxyphenyl)-8,9,10,12-octahydrobenzo[a]
xanthenes-11-one (Table 1, entry 16)
J ¼ 10 Hz, 2H), 7.03e7.46 (m, 7H), 5.70 (s, 1H), 2.76e2.79 (m, 1H),
2.59 (s, 2H), 2.22e2.35 (m, 2H), 1.16 (s, 3H), 1.14 (d, 6H), 1.01 (s, 3H)
White solid, m.p. 220e222 ꢀC; IR (KBr):
n
¼ 3020, 2880, 2850,
1640,1602,1590,1480,1220,1180 cmꢁ1; 1H NMR (400 MHz, CDCl3):
¼ 6.66e8.02 (m, 10H), 5.78 (s, 1H), 3.75 (s, 3H), 2.05e2.74 (m, 6H)
ppm; 13C NMR (100 MHz, CDCl3):
d
Table 2
d
¼ 197.0,165.7,159.5,147.8,146.7,
The recycling of SuSA in the synthesis of 14-(phenyl)-14H-dibenzo[a,j]xanthene
under solvent-free conditions.
131.5, 129.2, 128.9, 128.4, 127.0, 124.9, 123.7, 121.1, 117.6, 117.0, 115.5,
114.8, 111.2, 111.08, 55.1, 37.1, 34.6, 27.8, 20.3 ppm; Anal. Calcd for
C24H20O3: C, 80.89; H, 5.62. Found: C, 80.86; H, 5.60.
Entry
Time min
Yield%a
1
2
3
4
5
35
35
36
38
38
94
92
90
88
88
2.4.10. 12-(4-Isopropylphenyl)-8,9,10,12-octahydrobenzo[a]
xanthenes-11-one (Table 1, entry 17)
White solid, m.p. 216e217 ꢀC; IR (KBr): nmax ¼ 3050, 2950, 2870,
1640, 1619, 1590, 1475, 1220, 1180 cmꢁ1; 1H NMR (400 MHz, CDCl3):
Isolated yields.
a

F. Shirini, N.G. Khaligh / Dyes and Pigments 95 (2012) 789e794
793
Table 3
in high purity with excellent yields. The reactions required
15e35 min with conventional heating at 80 ꢀC (Table 1, entries
1e6). The nature of the functional group on the aromatic ring of the
aldehyde exerted a slightly influence on the reaction time. The
presence of a halogen atom (such as eF, eCl or eBr) (Table 1, entries
2e4) relatively decreases the rate of the reaction. A decrease in the
reaction time was also observed with arylaldehyde bearing
electron-withdrawing groups such as eNO2, in the meta-position
(Table 1, entry 5), in comparison to the unsubstituted arylaldehyde.
Comparison of our results with the results obtained by other groups in the synthesis
of 14-(phenyl)-14H-dibenzo[a,j] xanthene under solvent-free conditions.
Catalyst
Conditions
Time (h)
Yield (%)
Reference
p-TsOH
Sulfamic acid
K5CoW12
I2
Neat/125 ꢀC
Neat/125 ꢀC
Neat/125 ꢀC
Neat/90 ꢀC
Neat/130 ꢀC
Neat/125 ꢀC
Neat/110 ꢀC
Neat/100 ꢀC
Neat/80 ꢀC
Neat/80 ꢀC
4
8
2
2.5
1
2
1.5
1.5
89
93
91
90
82
94
81
78
89
94
[9]
[17]
[22]
[23]
[27]
[28]
[29]
[30]
O
40$3H2O
LiBr
Amberlyst-15
Cellulose sulfuric acid
Dowex-50W
Silica sulfuric acid
SuSA
After successful synthesis of
a series of 14H-dibenzo[a,j]
xanthenes in good yields, we turned our attention toward the
synthesis of 1,8-dioxo-octahydroxanthene derivatives by replacing
of 2-naphthol with 1,3-cyclohexanedione and/or 5,5-dimethyl-1,3-
cyclohexadione (dimedone) under the same conditions (Scheme 1).
As expected, these substrates underwent smooth, one-pot
conversion to give the corresponding 1,8-dioxo-octahydrox-
anthene derivatives in good yields (Table 1, entries 7e15).
Finally, we have developed this synthetic method for the one
pot efficient synthesis of 12-aryl-tetrahydrobenzo[a]xanthene-11-
ones by condensation of aldehydes with 2-naphthol and 1,3-
cyclohexanedione and/or dimedone. The obtained results showed
the efficiency of this method in the synthesis of 12-aryl-tetrahy-
drobenzo[a]xanthene-11-ones (Table 1, entries 16e21).
We have also decided to study the catalytic activity of recycled
Brönsted acid SuSA for the synthesis of 14-(Phenyl)-14H-dibenzo
[a,j]xanthene (Table 1, entry 1). After the separation of the product,
the catalyst was washed with Et2O and vacuumed to remove Et2O
and the resulting catalyst was reused directly for the next run. As
shown in Table 2, SuSA can be recycled at least five times without
significant decrease in catalytic activity, the yields ranged from 94%
to 88%.
45 min
35 min
[31]
This work
ppm; 13C NMR (100 MHz, CDCl3):
128.3, 128.2, 128.1, 126.9, 126.1, 124 Found: C, 84.81; H, 7.03.
d
¼ 197.0, 163.9, 142.1,131.5,128.7,
3. Results and discussion
In an initial study and in order to examine the catalytic activity
of the catalyst, we examined the reaction of benzaldehyde
(1 mmol) with 2-naphthol (A, 2 mmol) under different conditions
including refluxing in various solvents (MeOH, EtOH, THF, MeCN,
EtOAc, and toluene) and also under solvent-free classical heating
conditions. In refluxing solvents, after 2 h, the yields of the products
were low (<52%). We found that the best results can be obtained
under solvent-free conditions in the presence of SuSA.
To optimize the amount of the catalyst and the reaction
temperature, the reaction of benzaldehyde (1 mmol) with 2-
naphthol (A, 2 mmol) was studied under solvent-free conditions
in the presence of different amounts of SuSA at different temper-
atures. The results showed that the reaction using 10 mg of the
catalyst at 80 ꢀC proceeded in highest yield. Using lower amounts of
the catalyst resulted in lower yields, while higher amounts of SuSA
did not affect the reaction yields and in the absence of the catalyst,
nearly no product could be detected.
Table 3, compared our results (time, yield, reaction conditions)
with results obtained by other groups in the synthesis of aryl 14H-
dibenzo[a,j]xanthene derivatives. As can be seen, SuSA acts as an
effective catalyst with respect to reaction temperature, time and
yield.
The condensation of 2-naphthol and aryl aldehydes (carrying
both electron-withdrawing and electron-donating groups), in the
presence of SuSA (10 mg) as a Brönsted acid catalyst under the
optimized conditions, yielded desired 14H-dibenzo[a,j]xanthenes
From a mechanistic point of view, the proton from SuSA is
donated to the oxygen atom of the aldehyde. Next, the carbonyl
carbon is attacked by the nucleophilic 2-naphthol (A) or cyclo-
hexanedione derivatives (B) to form the Knoevenagel products (I or
(B)
(A)
O
O
R1
R1
HO
OH
O
R1
R1
R
R
H+ from SuSA
O
H
(A)
O
R
-H
R
2O
(A)
O
(I)
(II)
R1
-H2O
(Table 1, entries 1-6)
O
R1
(Table 1, entries 16-21)
O
R
R1
OH
O
R
O
O
R
O
OH
R1
R1
R1
R1
(B)
(B)
-H2O
O
R1
R1
R1
-H2O
(Table 1, entries 16-21)
(Table 1, entries 7-15)
Scheme 2. A plausible mechanism for the synthesis of xanthene derivatives in the presence of SuSA under solvent-free conditions.

794
F. Shirini, N.G. Khaligh / Dyes and Pigments 95 (2012) 789e794
(b) Knight DW, Little PB. The first efficient method for the intramolecular
trapping of benzynes by phenols: a new approach to xanthenes. J Chem Soc
Perkin Trans 2001;1:1771e7.
II). The Subsequent addition of these fragments to A or B, gives the
acyclic adduct intermediate, which undergoes intramolecular
cyclization with participation of two hydroxyl groups to afford the
xanthene derivatives (Scheme 2).
[12] Jha A, Beal J. Convenient synthesis of 12H-benzo[a]xanthenes from
2-tetralone. Tetrahedron Lett 2004;45(49):8999e9001.
[13] Kuo CW, Fang JM. Synthesis of xanthenes, indanes, and tetrahydronaph-
thalenes via intramolecular phenylecarbonyl coupling reactions. Synth
Commun 2001;31(6):877e92.
4. Conclusions
[14] Papini P, Cimmarusti R. The action of formamide and formanilide on naph-
thols and on barbituric acid. Gazzetta Chim It 1947;77:142e7.
[15] Sen RN, Sarkar NJ. The condensation of primary alcohols with resorcinol and
other hydroxy aromatic compounds. J Am Chem Soc 1925;47(4):1079e91.
[16] Ota K, Kito T. An improved synthesis of dibenzoxanthene. Bull Chem Soc Jpn
1976;49:1167e8.
We described herein Brönsted acid SuSA catalyzed highly effi-
cient, one-pot protocol for the synthesis of xanthene derivatives by
the condensation of aldehydes with 2-naphthol (A), 1,3-
cyclohexanediones (B), and/or a mixture of 2-naphthol and 1,3-
cyclohexanediones (A þ B) under solvent-free conditions in
excellent yields. The present methodology also has several other
advantages such as: high reaction rates and excellent yields, no side
reactions, ease of preparation and handling of the catalyst, cost
efficiency (use of inexpensive catalyst with lower loading) and
simple experimental procedure. Further work to explore this novel
catalyst in other organic transformations is in progress.
[17] Rajitha B, Kumar BS, Reddy YT, Reddy PN, Sreenivasulu N. Sulfamic acid:
a
novel and efficient catalyst for the synthesis of aryl-14H-dibenzo[a,j]
xanthenes under conventional heating and microwave irradiation. Tetrahe-
dron Lett 2005;46:8691e3.
[18] (a) Khaligh NG, Shirini F. Preparation, characterization and use of poly(4-
vinylpyridinium) hydrogen sulfate salt as an eco-benign, efficient and reus-
able solid acid catalyst for the chemoselective 1,1-diacetate protection and
deprotection of aldehydes. J Mol Catal A Chem 2011;348:20e9;
(b) Shirini F, Mamaghani M, Atghia SV. Sulfonic acid-functionalized ordered
nanoporous Naþ-montmorillonite (SANM): a novel, efficient and recyclable
catalyst for the chemoselective N-Boc protection of amines in solventless
media. Cata Commun 2011;12:1088e94;
Acknowledgments
(c) Shirini F, Zolfigol MA, Abedini M. Chemoselective trimethylsilylation
of alcohols catalyzed by saccharin sulfonic acid. Monatsh Chem 2009;140:
61e4.
The authors are thankful to the Guilan University Research
Council for the partial support of this work.
[19] Shirini F, Khaligh NG. Succinimide-N-sulfonic acid: a mild, efficient, and
reusable catalyst for the chemoselective trimethylsilylation of alcohols and
phenols. Phosphorus, Sulfur, and Silicon 2011;186:2156e65.
[20] Shirini F, Khaligh NG. Succinimide sulfonic acid (SuSA): an efficient and
recyclable catalyst for the chemoselective N-Boc protection of amines. Mon-
atsh Chem 2012;143:631e5.
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