Formation of 8-Membered Ring Compounds by the Reaction of Styrene Oxide with MoCl5

Article abstract of DOI:10.1246/cl.2003.1044

Styrene oxide reacted with group 5 and 6 metal halides in 1,2-dichloroethane to afford an 8-membered ring compound, 2,3,6,7-dibenzo-9- oxabicyclo[3,3,1]nona-2,6-diene. When the reaction was carried out in benzene instead of 1,2-dichloroethane as a solvent, unexpected new 8-membered ring product, tribenzobicyclo[3.3.2]decatriene, and 1,1,2-triphenylethane were obtained. The structures of the 8-membered ring compounds were confirmed by X-ray analysis.

Full text of DOI:10.1246/cl.2003.1044

1044
Chemistry Letters Vol.32, No.11 (2003)
Formation of 8-Membered Ring Compounds by the Reaction of Styrene Oxide with MoCl5
Qiaoxia Guo, Kiyohiko Nakajima,y and Tamotsu TakahashiÃ
Catalysis Research Center and Graduate School of Pharmaceutical Sciences, Hokkaido University,
and CREST, Japan Science and Techonolgy Coorporation (JST), Sapporo 060-0811
yDepartment of Chemistry, Aichi University of Education, Igaya, Kariya 448-8542
(Received July 28, 2003;CL-030705)
Styrene oxide reacted with group 5 and 6 metal halides in
1,2-dichloroethane to afford an 8-membered ring compound,
2,3,6,7-dibenzo-9-oxabicyclo[3,3,1]nona-2,6-diene. When the
reaction was carried out in benzene instead of 1,2-dichloro-
ethane as a solvent, unexpected new 8-membered ring product,
tribenzobicyclo[3.3.2]decatriene, and 1,1,2-triphenylethane
were obtained. The structures of the 8-membered ring com-
pounds were confirmed by X-ray analysis.
data were consistent with the reported data.7
As shown in Table 1, when the ratio of MoCl5 to styrene ox-
ide increased to 2, the yield of 8-membered ring product de-
creased. But when the ratio decreased to 0.5, the yield of the
8-membered ring product did not increase. The similar yield
was achieved (34% yield). It indicates that the yield of 1 was
not remarkably dependent on the amount of MoCl5 under the
conditions we used here. In this ratio, it is noteworthy that 1,2-
dichloro-1-phenylethane 2 was formed in 11% yield (Table 1,
Entry 3) but no formation of halohydrins was observed. This is
quite different from the case of the usual Lewis acid such as
AlCl3,8a TiCl4,8b FeCl3,8c and SnCl2.8d TaCl5, WCl6, and NbCl5
also showed results similar to MoCl5 (Table 1, Entries 4–6). Oth-
er cyclic ethers such as THF, THP, and oxepane could be selec-
tively converted into dihaloalkane or dihaloalkyl ethers by the
reaction with group 5 and 6 metal halide.3b
Epoxide and other cyclic ethers are versatile starting mate-
rial or intermediates in organic synthesis.1 It is well known that
when epoxide or other cyclic ethers are treated with metal hal-
ides, halohydrins are formed as main products (Eq 1).2
(1)
+
MXn
X
OH
n
O
n
Table 1. Reactions of styrene oxide with group 5 and 6 metal
chlorides
( n = 0, 1, 2, .... )
Recently, we have reported that group 5 and 6 metal halides
were efficient catalysts for acylative C–O bond cleavage of cy-
clic and acyclic ethers.3 In the course of our further study, we
found group 5 and 6 metal halides mediated unexpected ring-
opening reaction of styrene oxide. We would like to report the
formation of 8-membered ring compounds, 2,3,6,7-dibenzo-9-
oxabicyclo[3.3.1]nona-2,6-diene4 and tribenzobicyclo[3.3.2]de-
catriene5 by the reaction of styrene oxide with MoCl5 in 1,2-di-
chloroethane and in benzene, respectively, along with the forma-
tion of 1,1,2-triphenylethane6 in benzene.
r.t.
Cl
MCln
X eq
O
+
+
DCE
O
Cl
2
1
Yielda, GC(iso.)%b
Entry MCln
X eq Time/h
1
2
1
2
3
4
5
6
MoCl5
MoCl5
MoCl5 0.5
WCl6
NbCl5
TaCl5
1
2
3
1
24
3
24
3
41(36)
30(17)
34(30)
15
34
15
0
0
11(9)
27
0
O
1
1
1
MoCl5, 1equiv.
O
(2)
0
ClCH2CH2Cl
rt., 1h
aAll the yields were based on styrene oxide. Temperature;r.t.
bIsolated yields were in the parentheses.
1: 41% yield
A reaction of the racemic 2-phenylpropylene oxide with
MoCl5 afforded a mixture of two diastereoisomers as shown in
Eq 3. Symmetric isomer 39 and unsymmetrical isomer 410 were
obtained in 23 and 14% yields, respectively. They were charac-
terized by NMR.
A representative procedure for the formation of 8-membered
ring compound is as follows: To a mixture of MoCl5 (1 mmol) in
1,2-dichloroethane(or benzene) (5 mL), styrene oxide (1 mmol)
was added, and the mixture was stirred at r.t. for 3 h. Then the
reaction mixture was quenched with hydrochloric acid (3 N)
and extracted with diethyl ether. The organic phase was treated
as usual workup, flash column chromatography on silica gel elut-
ing with a mixture of ether and hexane yielded the 8-membered
ring compounds as pure compounds.
CH3
CH3
O
MoCl5, 1equiv.
O
O
+
(3)
CH3
ClCH2CH2Cl
r.t., 1h
H3C
3: 23% (14%)
H3C
4: 14% (7%)
As shown in Eq 2, when styrene oxide reacted with 1 equiv.
of MoCl5, styrene oxide was completely consumed and 2,3,6,7-
dibenzo-9-oxabicyclo[3,3,1]nona-2,6-diene 1 was formed in
41% yield (isolated yield: 36%) with the formation of some un-
defined oligomer. The structure of 8-membered ring compound 1
was verified by X-ray crystallographic analysis and the crystal
As for the solvent, 1,2-dichloroethane was the best so far.
Hexane was also good but the reaction was slower (r.t., 48 h,
G.C. yield was 40%) than the case of 1,2-dichloroethane.
The first example of the preparation of 1, which was called
Copyright ꢀ 2003 The Chemical Society of Japan

Chemistry Letters Vol.32, No.11 (2003)
1045
Kagan’s ether, was reported by Kagan and co-workers by the re-
action of phenylacetaldehyde with fluorosulfonic acid in carbon
tetrachloride at 0 ꢀC.4 Some improved methods have been devel-
oped for the transformation of phenylacetaldehyde to Kagan’s
ether or its derivatives.11 For example, treatment of phenylace-
taldehyde with Me3SiI quantitatively afforded 1. On the other
hand, 1 has been prepared from 1-carbomethoxy-2-indanone
by 5 steps. However, there is no report for the formation of
Kagan’s ether from styrene oxide.
In order to understand our reaction mechanism, we carried
out the reaction of phenylacetaldehyde with MoCl5 under the
conditions we used here. In fact, compound 1 was obtained in
a comparable yield (30%). This shows that styrene oxide was
converted into phenylacetaldehyde or its related compound
which, in turn, dimerized to compound 1 through Kagan’s mech-
anism.11b
Interestingly, when benzene was used as a solvent, 1,1,2-tri-
phenylethane 5 and a new 8-membered ring product, tribenzobi-
cyclo[3.3.2]decatriene 6, were obtained as shown in Eq 4. Dur-
ing the reaction, the formation of 1 was not detected. Two phenyl
groups of 5 might come from the benzene. The structure of the
new 8-membered ring compound 6 was also determined by X-
ray analysis. One phenylene ring also might come from the sol-
vent benzene.
Friedel–Crafts reaction between two molecules of styrene oxide
on MoCl5 gives Kagan’s ether. On the other hand, Friedel–Crafts
reaction of styrene oxide on MoCl5 with benzene affords 5 and 6.
References and Notes
1
a) R. C. Larock, ‘‘Ether Cleavage,’’ in ‘‘Comprehensive
Organic Transformations,’’ 2nd ed., Wiley-VCH (1999). b)
M. V. Bhatt and S. U. Kulkarni, Synthesis, 1983, 249.
C. Bonini and G. Righi, Synthesis, 1994, 225.
a) Q. Guo, T. Miyaji, G. Gao, R. Hara, and T. Takahashi,
Chem. Commun., 2001, 1018. b) Q. Guo, T. Miyaji, R. Hara,
B. Shen, and T. Takahashi, Tetrahedron, 58, 7327 (2002).
J. Kagan, S.-Y. Chen, and Jr. D. A. Agdeppa, Tetrahedron
Lett., 1977, 4469.
I. I. Brunovlenskaya, E. V. Mishina, and V. R. Skvarchenko,
J. Org. Chem. USSR (Engl. Transl.), 14, 1983 (1978);M. P.
Cava, M. Krieger, R. Pohlke, and D. Mangold, J. Am. Chem.
Soc., 88, 2615 (1966).
2
3
4
5
6
7
8
For recent preparation, see A. J. Fry, M. Allukian, and A. D.
Williams, Tetrahedron, 58, 4411 (2002).
V. Zabel, W. H. Watson, J. Kagan, D. A. Agdeppa, Jr., and
S.-A. Chen, Cryst. Struc. Commun., 7, 727 (1978).
a) J. J. Eisch, Z.-R. Liu, X. Ma, and G.-X. Zheng, J. Org.
Chem., 57, 5140 (1992). b) M. Shimizu, A. Yoshida, and
T. Fujisawa, Synlett., 1992, 204. c) J. Kagan, B. E. Firth,
N. Y. Shih, and C. G. Boyajian, J. Org. Chem., 42, 343
(1977). d) C. Einhorn and J.-L. Luche, J. Chem. Soc., Chem.
Commun., 1986, 1368.
Ph
MoCl5
C6H6
Ph
+
(4)
Ph
O
9
NMR data for 3. 1H NMR (CDCl3, Me4Si) d 1.54 (d,
J ¼ 6:90 Hz, 6H), 2.86 (q, J ¼ 7:10 Hz, 2H), 4.91 (s, 2H),
6.97–7.00 (m, 2H), 7.04–7.12 (m, 6H). 13C NMR (CDCl3,
Me4Si) d 23.18, 40.17, 75.41, 125.03, 125.91, 126.94,
129.09, 137.20, 137.22.
5
6
67(55)%
18(6)%
In this case, the formation of halohydrins was not detected.
When WCl6, NbCl5, and TaCl5 were employed as the reagent,
the similar results were also observed.
10 NMR data for 4. 1H NMR (CDCl3, Me4Si) d 1.35 (d,
J ¼ 7:50 Hz, 3H), 1.51 (d, J ¼ 6:90 Hz, 3H), 2.89 (q, J ¼
7:00 Hz, 1H), 3.60 (dq, J ¼ 6:60, 7.10 Hz, 1H), 4.96 (s,
1H), 5.00 (d, J ¼ 5:40 Hz, 1H), 7.01–7.18 (m, 8H). 13C
NMR (CDCl3, Me4Si) d 15.35, 23.71, 36.75, 41.41, 74.08,
76.29, 124.80, 124.83, 125.63, 125.79, 126.84, 127.02,
127.17, 129.32, 133.07, 136.70, 137.36, 144.45.
11 a) M. E. Jung, A. B. Mossman, and M. A. Lyster, J. Org.
Chem., 43, 3698 (1978). b) J. Kagan, D. A. Agdeppa, Jr.,
A. I. Chang, S.-A. Chen, M. A. Harmata, B. Melnick, G.
Patel, C. Poorker, S. P. Singh, W. H. Watson, J. S. Chen,
and V. Zabel, J. Org. Chem., 46, 2916 (1981). c) M. Harmata
and T. Murray, J. Org. Chem., 54, 3761 (1989). d) M.
Harmata and C. L. Barnes, Tetrahedron Lett., 31, 1825
(1990).
Compound 6 has been prepared from 9,10-triptycenedicar-
bonyl chloride as the starting compound via amination, reduc-
tion, chlorination, rearrangement, and dechlorination.5 But there
is no report for the formation of 6 from styrene oxide. It is inter-
esting to note that Firouzabadi and co-worker reported that the
reaction of styrene oxide with WCl6 at reflux in CH2Cl2 or a
mixed solvent CH2Cl2/CH3CN (2/1) gave a chlorination de-
oxygenation product, 1,2-dichloro-1-phenylethane in high yield.
This is in sharp contrast to our results reported here. The forma-
tion of an 8-membered ring product was not reported in the re-
action with WCl6 in CH2Cl2.12
In this paper we described the novel type of 8-membered
ring formation. The reaction mechanisms for the formation of
1 and 6 are not clear yet. But in both cases, we believe that co-
ordination of oxygen of styrene oxide to MoCl5 is the first step.
12 H. Firouzabadi and F. Shiriny, Tetrahedron, 52, 14929
(1996).
Published on the web (Advance View) October 20, 2003;DOI 10.1246/cl.2003.1044