Synthesis of spirobiindanes via bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids

Article abstract of DOI:10.1016/j.tetlet.2006.04.115

Bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids (HPAs) was examined for the first time, and a series of spirobiindanes were synthesized. 1,5-Diaryl-3-pentanones were refluxed and dehydrated in toluene in the presence of 0.15 equiv of a heteropoly acid to furnish spirobiindanes in moderate to high yield. For the known 4,4′-dibromo-7,7′-dimethoxy-1,1′-spirobiindane, the yield was upgraded from 66% to 80%.

Full text of DOI:10.1016/j.tetlet.2006.04.115

Tetrahedron Letters 47 (2006) 4343–4345
Synthesis of spirobiindanes via bis-cyclization reaction of the
1,5-diaryl-3-pentanones catalyzed by heteropoly acids
Kun Lan, Zixin Shan* and Shao Fan
Department of Chemistry, Wuhan University, Wuhan, Hubei 430072, PR China
Received 21 March 2006; revised 21 April 2006; accepted 25 April 2006
Abstract—Bis-cyclization reaction of the 1,5-diaryl-3-pentanones catalyzed by heteropoly acids (HPAs) was examined for the first
time, and a series of spirobiindanes were synthesized. 1,5-Diaryl-3-pentanones were refluxed and dehydrated in toluene in the
presence of 0.15 equiv of a heteropoly acid to furnish spirobiindanes in moderate to high yield. For the known 4,40-dibromo-
7,70-dimethoxy-1,10-spirobiindane, the yield was upgraded from 66% to 80%.
Ó 2006 Elsevier Ltd. All rights reserved.
C2 symmetric chiral compounds, such as BINOL (1,
10-binaphthalene-2,20-diol),1a,b BINAP [2,20-bis(di-
phenylphosphino)-1,10-binaphthyl],2 TADDOL (a,a,a0,
a0-tetraaryl-1,3-dioxolane-4,5-dimethanols)3, etc., have
been widely used in catalytic and stoichiometric asym-
metric synthesis. Recent reports demonstrated that
spirobiindanes, another class of molecules with axial
symmetry, could also be used in the field of catalytic
chemistry with interesting results4a due to their better
rigidity and stability than those of BINOL. For exam-
ple, a new spirobiindane derivative, 1,10-spirobiindane-
7,70- diol (SPINOL) has showed good chiral induction
when applied to asymmetry catalytic reactions.4b–f
However, the synthesis of SPINOL is not very easy
and convenient in the literature.5 And the key step for
their preparation is cyclization via intramolecular dehy-
dration of 1,5-bis-(2-bromo-5-methoxyphenyl)-3-penta-
none using POCl3 or poly-phosphoric acid (PPA) as
catalyst. It is well known that the reaction mediated
by POCl3 should be performed under anhydrous condi-
tions, and a great amount of hydrochloric acid (HCl)
would be generated. Thus, it is inevitable to produce a
mass of acidic wasted water. Alternatively, using PPA
as catalyst in the reaction, large volume of solvent is
needed for extraction of the product.
In comparison with the liquid mineral acids, solid acids
could be easily separated from the reaction mixture by
simple filtration with high recovery. This advantage di-
rectly leads to a decrease in of equipment cauterization
and environment pollution. Among various solid acids,
heteropoly acids (HPAs) are with unique physical–
chemical properties. Their acidity is significantly higher
than that of traditional mineral acids. Furthermore,
HPAs are capable of protonating and activating the sub-
strate; and in some cases, HPAs are more effective than
usual inorganic acid and the traditional acid catalyst.
Therefore, they are widely used as homogeneous and
heterogeneous acid catalyst for the synthesis reaction.7
However, the intramolecular cyclodehydration reaction
of aromatic compound catalyzed by HPAs has hardly
been reported. In order to simplify the preparation of
the spirobiindane derivatives, we recently examined the
intramolecular cyclocondensation of 1,5-biaryl-3-penta-
nones in the presence of a heteropoly acid, and as a
result a series of spirobiindanes were obtained in good
yield (Scheme 1). Herein, we would like to report the
results on this investigation.
As a reaction model, cyclocondensation of 1,5-biphenyl-
3-pentanone catalyzed by HPAs was investigated under
different reaction conditions, the result was summarized
in Table 1. It can be seen that the three kinds of HPAs
(H3PW12O40, H3PMo12O40 and H4SiW12O40) used in
the experiments show high catalytic activity toward the
bis-cyclization (entries 2, 7, and 8), and it was found that
H3PW12O40 is the best catalyst for the reaction (entry 2).
This may be due to H3PW12O40 which has the highest
In recent years, using solid acid as heterogeneous cata-
lysts has received much attention in organic synthesis.6
*
Corresponding author. Tel.: +86 27 87219074; e-mail: zxshan@
whu.edu.cn
0040-4039/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.04.115

4344
K. Lan et al. / Tetrahedron Letters 47 (2006) 4343–4345
R1
R2
O
R3
H3PW12O40
R4
(CH2)n
toluene
reflux
R4'
R3'
R2'
(CH2)n
R
R
6-12 h
R1'
57-91% yield
1
2
a: (CH2)n=H,H; R1=R2=R3=R4=H
b: n=2, R1=R2=R3=R4=H
e: (CH2)n=H,H; R1=R2=R4=H , R3=OMe
f: (CH2)n=H,H; R1=R3=R4=H , R2=OMe
g: (CH2)n=H,H; R2=R3=H, R1=Br, R4=OMe
c: n=3, R1=R2=R3=R4=H
d: (CH2)n=H,H; R1=R2=R4=H, R3=Cl
Scheme 1. Bis-cyclization of 1,5-diaryl-3-pentanones catalyzed by H3PW12O40
.
Table 1. Preparation of spirobiindane (2a) via bis-cyclization of 1,5-diphenyl-3-pentanone (1a) catalyzed by heteropoly acidsa
O
HPA
1,5-diphenyl-3-pentanone (1a)
HPA =
1,1`-Spirobiindane (2a)
H3PW12O40£¬ H3PWo12O40£¬ H3SiW12O40
Entry
Substrate (mmol)
Catalyst (mmol)
Solvent
Yield (%)
1
2
3
4
5
6
7
8
1a (10)
1a (10)
1a (10)
1a (10)
1a (10)
1a (10)
1a (10)
1a (10)
H3PW12O40 (2.0)
H3PW12O40 (1.5)
H3PW12O40 (1.0)
H3PW12O40 (1.5)
H3PW12O40 (1.5)
H3PW12O40 (1.5)
H3PMo12O40 (1.5)
H4SiW12O40 (1.5)
Toluene
Toluene
Toluene
Xylene
Benzene
Cyclohexane
Toluene
Toluene
87
91
65
61
35
0
83
70
a All the experiments were carried out for 6 h under reflux condition.
acidity,7 and is favorable for cyclocondensation. As far
as the amount of the catalyst used is concerned, using
0.15 equiv of the catalyst offers the desired product in
the highest yield; more catalyst cannot improve the yield
further (entry 1). It is also observed that the reaction
medium influences considerably the yield of the cycliza-
tion product; toluene is the most appropriate solvent for
the cyclocondensation, and the reactions in xylene and
benzene give the product in lower yields, while the cyclo-
condensation does not occur in cyclohexane (entries 2,
4–6). The above result indicates that HPAs are better
to excellent catalyst for bis-cyclization of 1,5-diphenyl-
3-pentanone under the optimized condition, and 1,5-
biphenyl-3-pentanone was refluxed in toluene in the
presence of 0.15 equiv of H3PW12O40 to offer 1,10-spiro-
biindane in up to 91% yield.
The above optimized condition was applied to bis-cycli-
zation of the other 1,5-diaryl-3-pentanones (1b–g,
Scheme 1) and the results obtained are summarized in
Table 2. It can be seen that in most of cases, the reac-
tions offer the desired 1,10-spirobiindanes in better to
Table 2. Preparation of spirobiindanes (2a–f) via bis-cyclization of 1,5-diaryl-3-pentanones (1a–g) catalyzed by H3PW12O40
Substrates (1a–g)
Time (h) Products (2a–f)a
Mp (°C) Yieldb (%)
Oil
91(828a
100–102 77(798b
1,5-Diphenyl-3-pentanone
2,5-Dibenzylcyclopentanone
2,6-Dibenzylcyclohexanone
1,5-Bis(3-methoxyphenyl)-3-pentanone
1,5-Bis(4-methoxyphenyl)-3-pentanone
1,5-Bis(4-chrolophenyl)-3-pentanone
6
10
10
12
12
10
1,10-Spirobiindane (2a)
)
)
2,20-Ethylene-1,10-spirobiindane (2b)
2,20-Propylene-1,10-spirobiindane (2c)
5,50-Dimethoxy-1,10-spirobiindane (2d)
6,60-Dimethoxy-1,10-spirobiindane (2e)
6,60-Dichrolo-1,10-spirobiindane (2f)
Oil
72–74
128–130 78(208d
120–122 72
57
68(56.88c)
)
1,5-Bis(2-bromo-5-methoxy-phenyl)-3-pentanone 10
4,40-Dibromo-7,70-dimethoxy-1,10-spirobiindane (2g) 160–162 80(665)
a All the experiments were performed in toluene under reflux condition (Ref. 9) and the characteristic data were showed in Ref. 10.
b The yield reported in the literature.

K. Lan et al. / Tetrahedron Letters 47 (2006) 4343–4345
4345
8. (a) Hill, R. K.; Cullison, D. A. J. Am. Chem. Soc. 1973, 95,
1229–1239; (b) Hoeve, W. T.; Wynberg, H. J. Org. Chem.
1980, 45, 2930–2937; (c) Hagishita, S.; Kuriyama, K.;
Hayashi, M.; Nakano, Y.; Shingu, K.; Nakagawa, M.
Bull. Chem. Soc. Jpn. 1971, 44, 496–505; (d) Welter, T. R.
US 2005127327, 2005.
good yield except that of 2,6-dibenzylcyclohexanone (1c)
derived from cyclohexanone, and the yields are consid-
erably higher than those in the literature. It should be
specially pointed out that in the case of H3PW12O40
catalyzed biscyclization of 1,5-bis(2-bromo-5-methoxy-
phenyl)-3-pentanone (1g), the yield of 4,40-dibromo-
7,70-dimethoxy-1,10-spirobiindane (2g) was upgraded
from 66%5 to 80%, which is significantly important for
the preparation of 1,10-spirobiindane-7,70-diol.
9. General procedure: 1,5-Diaryl-3-pentanone (10 mmol),
H3PW12O40 (1.5 mmol) and 30 mL toluene were charged
in a 50 mL flask with water segregator and reflux
condenser, followed by reflux and dehydration until no
water was separated for about 6–12 h, cooled, filtered, and
washed with CHCl3. The organic phase was combined.
The product was purified by recrystallization or column
chromatography on SiO2 gel.
In conclusion, HPAs are more appropriate catalysts
than PPA and POCl3 for the preparation of 1,10-spiro-
biindanes via biscyclization of 1,5-diaryl-3-pentanone.
In the experimental condition, seven spirobiindanes
were obtained, and two are reported for the first time.
1,5-Diaryl-3-pentanones were catalytically biscyclized
by 0.15 equiv of a heteropoly acid in toluene to furnish
the spirobiindanes in 57–91% yield.
10. The characteristic data of the products. 1,10-Spirobiindane
1
(2a) a colorless oil, H NMR (300 MHz, CHCl3): d 2.14–
2.35 (m, 4H) 3.02 (t, J = 13 Hz, 4H) 6.92 (d, J = 7 Hz, 2H)
7.11–7.29 (m, 6H); IR (KBr, in film): m 1602, 1455, 751
(cmꢀ1). 2,20-Ethylene-1,10-spirobiindane (2b): a colorless
solid: mp 373–375 K. 1H NMR (300 MHz, CHCl3): d
1.48–1.51 (m, 2H), 2.00–2.08 (m, 2H), 2.72–2.82 (m, 4H),
3.33–3.41 (m, 2H), 6.83 (d, J = 7 Hz, 2H), 7.09–7.22 (m,
6H). 13C NMR (75 MHz, CHCl3): d 29.1, 34.3, 38.6, 53.0,
124.5, 124.6, 126.8, 127.2, 143.0, 150.9. IR (KBr): m 1636,
1478, 752 (cmꢀ1). 2,20-Propylene-1,10-spirobiindane (2c): a
colorless oil, 1H NMR (300 MHz, CHCl3): d 1.42–1.49 (m,
2H), 1.55–1.66 (m, 4H), 2.58–2.66 (m, 2H), 2.77–2.84 (m,
2H), 3.12–3.19 (m, 2H), 6.81 (d, J = 7 Hz, 2H), 7.11–7.36
(m, 6H). 13C NMR (75 MHz, CHCl3): d 19.9, 27.7, 36.4,
43.9, 61.3, 123.4, 125.2, 126.7, 126.8, 143.0, 149.3. IR
(KBr, in film): m 1587, 1476, 1263, 1082, 776 9 cmꢀ1. Anal.
Calcd for C20H20: C 92.22, H 7.78. Found C 91.94, H 7.66.
5,50-Dimethoxy-1,10-spiro-biindane (2d): a colorless solid,
Acknowledgment
We thank the National Natural Science Foundation of
China (20372053 and 29972033) for the financial
support.
References and notes
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1
mp 345–347 K. H NMR (300 MHz, CHCl3): d 2.08–2.32
(m, 4H), 2.96 (t, J = 16 Hz, 4H), 3.78 (s, 6H), 6.67 (d,
J = 9 Hz, 2H), 6.75–6.87 (m, 4H). IR (KBr, in film): m
1606, 1489, 1243, 805 cmꢀ1. 6,60-Dimethoxy-1,10-spirobi-
indane (2e): a colorless solid: mp 401–403 K. 1H NMR
3. Seebach, D.; Beck, A.-K.; Heckel, A. Angew. Chem., Int.
Ed. 2001, 40, 92–138.
(300 MHz, CHCl3):
d 2.11–2.33 (m, 4H), 2.93 (t,
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Pure Appl. Chem. 2005, 77, 2121–2132; (b) Fu, Y.; Hou,
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J = 15 Hz, 4H), 3.70 (s, 6H), 6.46 (s, 2H), 6.72 (d,
J = 8 Hz, 2H), 7.15 (d, J = 8 Hz, 2H). 13C NMR
(75 MHz, CHCl3): d 30.9, 41.7, 56.1, 61.9, 108.9, 113.0,
124.9, 135.8, 151.6, 158.9. IR (KBr): m 1609, 1497, 1246,
1034, 813 cmꢀ1. 6,60-Dichrolo-1,10-spirobiindane (2f): a
colorless solid: mp 393–395 K. 1H NMR (300 MHz,
CHCl3): d 2.14–2.35 (m, 4H), 2.97 (t, J = 14 Hz, 4H),
6.87 (s, 2H), 7.14–7.2 (m, 4H). 13C NMR (75 MHz,
CHCl3): d 30.6, 41.0, 61.2, 123.8, 125.8, 127.3, 132.7,
142.2, 151.9. IR (KBr): m 1476, 1095, 816 cmꢀ1. Anal.
Calcd for C17H14Cl2: C 70.60, H 4.88; Found C 70.34, H
4.66. 4,40-Dibromo-7,70-dimethoxy-1,10-spirobiindane (2g):
a colorless solid: mp 433–436 K. 1H NMR (300 MHz,
CHCl3): d 2.11–2.39 (m, 4H), 2.90–3.10 (m, 4H), 3.51 (s,
2H), 6.50 (d, J = 9 Hz, 2H) 7.23 (d, J = 9 Hz, 2H). IR
(KBr): m 1595, 1471, 1267, 737 cmꢀ1
.