Chemoselective conversion of aromatic epoxide and 1,2-diol to 1,3-dioxane derivatives with phenyltrimethylammonium tribromide in the presence of a catalytic amount of antimony(III) bromide

Article abstract of DOI:10.1016/j.tetlet.2006.04.005

trans-Stilbene oxide was oxidatively converted to 2-phenyl-1,3-dioxanes with phenyltrimethylammonium tribromide in the presence of various 1,3-diols and a catalytic amount of SbBr₃ in DMSO at room temperature. Aromatic 1,2-diol, such as hydrobenzoin, was similarly converted to 2-aryl-1,3-dioxane derivatives under the same reaction conditions.

Full text of DOI:10.1016/j.tetlet.2006.04.005

Tetrahedron Letters 47 (2006) 4001–4005
Chemoselective conversion of aromatic epoxide and 1,2-diol to
1,3-dioxane derivatives with phenyltrimethylammonium
tribromide in the presence of a catalytic amount
of antimony(III) bromide
Shinsei Sayama*
Department of Chemistry, Fukushima Medical University, Hikariga-oka, Fukushima 960-1295, Japan
Received 13 February 2006; revised 29 March 2006; accepted 7 April 2006
Available online 2 May 2006
Abstract—trans-Stilbene oxide was oxidatively converted to 2-phenyl-1,3-dioxanes with phenyltrimethylammonium tribromide in
the presence of various 1,3-diols and a catalytic amount of SbBr3 in DMSO at room temperature. Aromatic 1,2-diol, such as hydro-
benzoin, was similarly converted to 2-aryl-1,3-dioxane derivatives under the same reaction conditions.
Ó 2006 Elsevier Ltd. All rights reserved.
As antimony halides are effective for organic synthesis
as a weak Lewis acid and are easier to handle than other
metal halides such as AlCl3 and TiCl4, several transfor-
mations of organic compounds with antimony halides as
a catalyst have been developed.1,2 In a previous letter,
the combination of antimony halides and complex metal
hydrides was reported to be more effective for the conju-
gate reduction of 2-butene-1,4-diones and the reductive
debromination of aromatic a-bromo ketones in compar-
ison with those of reagents and other metal halides,
AlCl3, CuCl2, and FeCl3.3a,b Antimony halide–Bu4NI
was also reported to be useful for the reductive ring-
opening of 2,3-epoxy-1,4-butanediones to 2-hydroxy-
1,4-butanediones.3c
further applications for other organic synthesis with
the combination of PTAB and antimony halide. The
reaction of trans-stilbene oxide with PTAB and SbBr3
in DMSO was carried out and predominantly afforded
2-phenyl-1,3-dioxane in the presence of 1,3-propanediol.
In the presence of various 1,3-diols, the reaction of
trans-stilbene oxide with PTAB–SbBr3 in DMSO was
carried out to clarify the limitations and chemoselectiv-
ity of this oxidative transformation of trans-stilbene
oxide to 2-phenyl-1,3-dioxane. trans-Stilbene oxide was
found to be easily oxidized and chemoselectively trans-
formed to the respective 1,3-dioxanes without being
overoxidized to benzoic acid. As there are still contin-
uing developments in the chemoselective acetalization
of aldehyde and functional compounds,8 the PTAB–
SbBr3 system is supposed to be an alternative favorable
method for the oxidative acetalization. We would like to
report the results of our studies concerning the conver-
sion of trans-stilbene oxide and aromatic 1,2-diols to
2-aryl-1,3-dioxanes.
On the other hand, phenyltrimethylammonium tribro-
mide (PTAB) is known to be a convenient reagent for
brominating organic compounds and is useful for the
synthesis of many functional compounds in organic
chemistry.4–6 PTAB–SbBr3 or PTAB–CuBr2 was re-
ported to be convenient and chemoselective for the oxi-
dation of secondary alcohols to the respective ketones.
Further, PTAB was found to be useful for the chemose-
lective conversion of 3-alkoxyfurans to 2-alkoxy-3(2H)-
furanones.7 Therefore, there has been much interest in
The reaction of trans-stilbene oxide 1, chosen as a repre-
sentative epoxide for this study, with PTAB–SbBr3 in
various stoichiometric ratios was carried out. The results
are summarized in Table 1. At a molar ratio of 1:3:7 of
stilbene oxide 1, PTAB, and 1,3-propanediol in the pres-
ence of a catalytic amount of SbBr3 in DMSO, 2-phenyl-
1,3-dioxane 4a was obtained in good yield (run 1). The
following experiments were carried out to test the effects
of PTAB and SbBr3 on the transformation of stilbene
Keywords: Epoxide; 1,2-Diol; 1,3-Dioxane; Phenyltrimethylammo-
nium tribromide; Antimony(III) bromide.
*
Tel./fax: +81 24 547 1369; e-mail: ssayama@fmu.ac.jp
0040-4039/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.04.005

4002
S. Sayama / Tetrahedron Letters 47 (2006) 4001–4005
a
Table 1. Reaction of trans-stilbene oxide 1 with PTAB–SbBr3
OH
OH
O
PTAB / SbBr3
O
Ph
Ph
Ph
PhCHO
Ph
Ph
Ph
Ph
O
H
HO(CH2)3OH (a)
OH
X
2
4a
1
3
5
Run
Molar ratio/1
Solventb
Time (h)
Products, yield (%)
PTAB
SbBr3
HO(CH2)3OH (a)
2
3
4a
5
1
1
2
3
4
5
6
7
8
9
3.0
3.0
—
3.0
4.0
3.0
3.0
3.0
2.0
1.0
0.2
—
7.0
7.0
7.0
7.0
—
7.0
7.0
7.0
7.0
7.0
A
A
A
B
48
38
34
48
69
46
43
46
40
40
2c
—
45
89
—
—
—
—
—
26c
31c
85
—
—
—
—
—
—
40
71
67
—
—
—
85d
73d
56f
30f
33f
—
—
48
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
2c
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
e
B
g
h
C
D
E
A
A
10
2c
—
a Substrate (1): 0.25 mmol; solvent: 8 mL; temp: room temperature.
b A = DMSO, B = MeOH, C = CH2Cl2, D = C6H14, E = DMF.
c Yields were also determined by 1H NMR analysis of crude products.
d 5a: X = OMe.
e Benzil (4%) and diphenylacetaldehyde (13%) were obtained.
f 5b: X = Br.
g 2-Diphenylmethyl-1,3-dioxane (27%).
h 2-(3-Hydroxypropoxy)-1,2-diphenylethanol (44%).
oxide 1 to 1,3-dioxane 4a. In the absence of SbBr3,
hydrobenzoin 3 was afforded besides recovered epoxide
1. 1,3-Dioxane 4a was not obtained (run 2). In the ab-
sence of PTAB, hydrobenzoin 3 was obtained similarly
(run 3). Further, in the absence of 1,3-propanediol, the
reaction of epoxide 1 with PTAB–SbBr3 took place to
give a mixture of hydrobenzoin 3 (60%), diphenylacet-
aldehyde (6%), and benzaldehyde 2 (14%) under the
same reaction conditions.9 Consequently, both SbBr3
and PTAB in the presence of 1,3-propanediol were
confirmed to be essential for the oxidative conversion
of epoxide 1 to 1,3-dioxane 4a.
accompanied by hydrobenzoin 3 (runs 9 and 10). More
than 2.0 M equiv of PTAB over epoxide 1 was con-
firmed to be needed for obtaining 1,3-dioxane 4a in
high yields.10
To clarify the effect of SbBr3, the reaction of epoxide 1
was also carried out in the presence of a catalytic
amount of various other metal halides. The results are
shown in Table 2. In the presence of BiBr3, CuBr2,
FeCl3, and CoCl2, 2-phenyl-1,3-dioxane 4a was not
Table 2. Reaction of trans-stilbene oxide 1 with PTAB–MXn in
DMSO-1,3-propanediola
The reaction of 1 with PTAB–SbBr3 was carried out in
various solvents, MeOH, CH2Cl2, C6H14, and DMF to
examine the solvent effect of DMSO in this system. In
MeOH, epoxide 1 was not transformed into 1,3-dioxane
and dimethylacetal, while methoxyalcohol 5a was
obtained (run 4). Methoxyalcohol 5a and benzil were
similarly obtained in MeOH without 1,3-propanediol.
Dimethylacetal was not afforded (run 5).
OH
PTAB / MXn
Ph
O
PhCHO
Ph
Ph
Ph
OH
HO(CH2)3OH (a)
1
2
3
OH
O
Ph
Ph
Ph
O
H
Br
Bromoalcohol 5b was mainly obtained accompanied
by 2-diphenylmethyl-1,3-dioxane in CH2Cl2 (run 6).
In hexane, a mixture of bromoalcohol 5b and 2-(3-
hydroxypropoxy)-1,2-diphenylethanol was afforded
(run 7). A mixture of 1,3-dioxane 4a and bromoalco-
hol 5b was afforded in DMF (run 8). In the present
experiments, DMSO turned out to be the most useful
solvent for the conversion of epoxide 1 to 1,3-dioxane
4a in various solvents. Further, the reaction of 1 in the
presence of SbBr3 and 1,3-propanediol was carried out
with 1.0–2.0 M equiv of PTAB over 1 to make clear
the optimum amount of PTAB in this system. The
yield of 1,3-dioxane 4a was not fully satisfactory,
4a
5b
Run
MXn
Time (h)
Products, yield (%)
2
3
4a
5b
1
2
3
4
5
6
SbBr3
BiBr3
CuBr2
FeCl3
CoCl2
SbCl3
70
40
63
38
95
48
2b
5b
10
—
—
3b
—
89
70
83
80
—
85
—
—
—
—
90
—
—
—
8b
—
—
a Substrate (1): 0.25 mmol; PTAB: 0.75 mmol; MXn: 0.05 mmol; 1,3-
propanediol (a): 1.75 mmol; DMSO: 8 mL; temp: room temperature.
b Yields were also determined by 1H NMR analysis of crude products.

S. Sayama / Tetrahedron Letters 47 (2006) 4001–4005
4003
obtained in high yields, predominantly accompanied by
hydrobenzoin 3 (runs 2–5). On the contrary, 1,3-dioxane
4a was obtained in 90% yield in the presence of SbCl3
instead of SbBr3 under the same reaction conditions
(run 6). Antimony halides, SbBr3 and SbCl3, were con-
firmed to be effective for the conversion of stilbene oxide
1 to 1,3-dioxane 4a with PTAB in DMSO.
gested that the monosubstituted aromatic and aliphatic
epoxides were not oxidized to the corresponding alde-
hydes by this method. Therefore, the monosubstituted
aromatic and aliphatic epoxides were not converted to
the corresponding 1,3-dioxanes. In the present experi-
ments, this system was confirmed to be applicable for
oxidative conversion of disubstituted aromatic epoxide
into 2-aryl-1,3-dioxane in the presence of 1,3-
propanediol.
The reaction of epoxide 1 was carried out in the presence
of various 1,2-diols and monools instead of 1,3-pro-
panediol to clarify the limitations and chemoselectivity
of the oxidative conversion of epoxide to 1,3-dioxane
4a in this system. The reaction of epoxide 1 with
PTAB–SbBr3 in the presence of methyl alcohol, propyl
alcohol, and isopropyl alcohol took place to give benz-
aldehyde 2. The corresponding dialkylacetals were not
afforded. Epoxide 1 was also converted to hydrobenzoin
3 with 1,2-diols, such as ethyleneglycol, 1,2-propanediol,
and 1,2-butanediol. Even in the presence of glycerine,
hydrobenzoin 3 was obtained. The respective 1,3-diox-
ane and 1,3-dioxolane were not afforded either. Accord-
ingly, this PTAB–SbBr3 in DMSO system was found to
be a chemoselective method for oxidative conversion of
aromatic epoxide into 2-aryl-1,3-dioxane in the presence
of 1,3-propanediol.
To examine the limitations of this transformation, the
reaction of 1 was carried out in the presence of various
1,3-diols (b–g) under the same reaction conditions. The
results are shown in Table 3. In both straight and
branched aliphatic 1,3-propanediols (b–f), the corre-
sponding 1,3-dioxane derivatives 4b–f were afforded in
good yields as expected (runs 1–5). Even in aromatic
1,3-propanediol (g), 1,3-dioxane (4g) was obtained in
moderate yield under the same reaction conditions
(run 6). The system PTAB–SbBr3 in DMSO-1,3-diol
was supposed to be useful for the oxidative transforma-
tion of disubstituted aromatic epoxide to various 2-aryl-
1,3-dioxanes.
In addition, the reaction of aromatic compounds 6, 7
was carried out with PTAB–SbBr3 in the presence of
various 1,3-diols (a–g) to examine the application of this
method for other organic compounds. The results are
shown in Table 4. meso-Hydrobenzoin 6 was trans-
formed to the corresponding 1,3-dioxanes 4a–g in 1,3-
diols (a–g), as expected (runs 1–7). The reaction of
1,1,2-triphenyl-1,2-ethanediol 7 afforded the respective
1,3-dioxanes 4a–g and benzophenone 8 (runs 8–14).
These results suggested that the PTAB–SbBr3 system
acetalized aldehyde to 1,3-dioxanes chemoselectively.
Further, the reaction of monosubstituted aromatic and
aliphatic epoxides was also carried out to examine the
utility of this method. The reaction of styrene oxide with
PTAB–SbBr3 in DMSO took place to give a mixture of
1-phenyl-1,2-ethanediol (38%) and 2-bromo-2-phenyl-
ethanol (32%) under the same reaction conditions. 1,3-
Dioxane 4a was not afforded. Monosubstituted aliphatic
epoxide, 1-dodecene oxide, was also converted to 1-bro-
mo-2-dodecanol (75%) predominantly.11 It was sug-
Table 3. Conversion of trans-stilbene oxide 1 to various 1,3-dioxanes 4b–g with PTAB–SbBr3 in DMSOa
Run
1,3-Diol (b–g)
Time (h)
Yields (%)
Molar ratio/1
OH
1
b
6.0
43
4b
88
O
Ph
OH
O
H
O
OH
OH
Ph
2
3
4
c
d
e
4.0
6.0
4.0
39
40
39
4c
4d
4e
85
81
92
O
H
O
Ph
OH OH
OH
O
H
O
Ph
OH
O
H
5
6
f
2.5
2.0
46
46
O
4f
91
79
Ph
OH OH
HO
O
H
O
Ph
g
4g
Ph
HO
O
H
a Substrate (1): 0.25 mmol; PTAB: 0.75 mmol; SbBr3: 0.05 mmol; PhCH2(Et)3NCl: 0.25 mmol; DMSO: 8 mL; temp: room temperature.

4004
S. Sayama / Tetrahedron Letters 47 (2006) 4001–4005
Table 4. Conversion of aromatic 1,2-diols 6, 7 to 1,3-dioxanes 4a–g
and benzophenone 8 with PTAB–SbBr3 in DMSOa
2. (a) Yamamoto, J.; Ito, S.; Tsuboi, T.; Tsuboi, T.;
Tsukihara, K. Bull. Chem. Soc. Jpn. 1985, 58, 470; (b)
Wang, W.-B.; Shi, L.-L.; Huang, Y.-Z. Tetrahedron 1990,
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Kobayashi, S. Chem. Lett. 1992, 435; (d) Harada, T.;
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Motofusa, S.; Ohe, K.; Uemura, S. J. Org. Chem. 1995, 60,
883; (f) Hayashi, A.; Yamaguchi, M.; Hirama, M. Synlett
1995, 195; (g) Gloria, P. M. C.; Prabhakar, S.; Lobo, A.
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Peyronneau, M.; Boisdon, M.-T.; Roques, N.; Mazieres,
S.; Roux, C. L. Eur. J. Org. Chem. 2004, 4636.
3. (a) Sayama, S.; Inamura, Y. Bull. Chem. Soc. Jpn. 1991,
64, 306; (b) Sayama, S.; Inamura, Y. Chem. Lett. 1996,
633; (c) Sayama, S. Synth. Commun. 2005, 35, 2115.
4. Ho, T.-L. In Fiesers’ Reagents for Organic Synthesis; John
Wiley and Sons: New York, 1967; Vols. 1–22.
5. (a) Mondal, E.; Sahu, P. R.; Bose, G.; Khan, A. T.
Tetrahedron Lett. 2002, 43, 2843; (b) Mondal, E.; Bose,
G.; Khan, A. T. Synlett 2001, 785.
6. (a) Gopinath, R.; Patel, B. K. Org. Lett. 2000, 2, 4177; (b)
Bora, U.; Bose, G.; Chaudhuri, M. K.; Dhar, S. S.;
Gopinath, R.; Khan, A. T.; Patel, B. K. Org. Lett. 2000, 2,
247.
R1
OH
R2
R3
O
Ph
Ph
PTAB / SbBr3
1,3-diol
Ph
R
Ph
Ph
O
OH
O
H
R4
4a-4g
8
(S)
6: R=H
7: R=Ph
Run
S
1,3-Diol
(a–g)
Time (h)
Products, yield
(%)
Molar
4a–g
8
ratio/S
1
2
3
4
5
6
7
8
6
6
6
6
6
6
6
7
7
7
7
7
7
7
a
7.0
7.0
7.0
6.0
2.5
3.0
3.0
7.0
6.0
3.0
3.0
2.0
2.0
2.0
70
19
70
40
37
61
42
70
41
42
42
41
42
42
4a
96
96
86
95
87
94
80
83
84
86
85
84
84
85
b
c
d
e
f
4b
4c
4d
4e
4f
g
a
b
c
d
e
f
4g
4a
4b
4c
4d
4e
4f
87
88
89
89
86
86
89
9
10
11
12
13
14
7. (a) Sayama, S.; Onami, T. Synlett 2004, 2369; (b) Sayama,
S.; Onami, T. Synlett 2004, 2739; (c) Sayama, S. Hetero-
cycles 2005, 65, 1347.
8. (a) Firouzabadi, H.; Iranpoor, N.; Nowrouzi, F.; Amani,
K. Tetrahedron Lett. 2003, 44, 3951; (b) Almog, J.;
Zehavy, Y.; Cohen, S. Tetrahedron Lett. 2003, 44, 3285;
(c) Kamal, A.; Chouhan, G. Tetrahedron Lett. 2003, 44,
3337; (d) Rana, K. K.; Guin, C.; Jana, S.; Roy, S. C.
Tetrahedron Lett. 2003, 44, 8597; (e) Curini, M.; Epifano,
F.; Marcotullio, M. C.; Rosati, O. Synlett 2001, 1182; (f)
Karimi, B.; Seradj, H. Synlett 2000, 805; (g) Palaniappan,
S.; Narender, P.; Saravanan, C.; Rao, V. J. Synlett 2003,
1793; (h) Cruz, T. E. L.; Rychnovsky, S. D. Synlett 2004,
2013; (i) Shimizu, K.; Hayashi, E.; Hatamachi, T.;
Kodama, T.; Kitayama, Y. Tetrahedron Lett. 2004, 45,
5135; (j) De, S. K. Tetrahedron Lett. 2004, 45, 2339; (k)
Wu, H.; Yang, F.; Cui, P.; Tang, J.; He, M. Tetrahedron
Lett. 2004, 45, 4963; (l) Velusamy, S.; Punniyamurthy, T.
Tetrahedron Lett. 2004, 45, 4917; (m) Hamada, N.;
Kazahaya, K.; Shimizu, H.; Sato, T. Synlett 2004, 1074;
(n) Ma, Y.; Jin, T.; Shi, S.; Li, T. Synth. Commun. 2003,
33, 2103; (o) Tamami, B.; Borujeny, P. Synth. Commun.
2003, 33, 4253; (p) Hon, Y.; Lee, C.; Chen, R.; Huang, Y.
Synth. Commun. 2003, 33, 2829; (q) Martel, A.; Chew-
chanwuttiwong, S.; Dujardin, G.; Brown, E. Tetrahedron
Lett. 2003, 44, 1491.
g
4g
a Substrate (S): 0.25 mmol; PTAB: 0.75 mmol; SbBr3: 0.05 mmol;
PhCH2(Et)3NCl: 0.25 mmol; DMSO: 8 mL; temp: room temp-
erature.
To make sure the chemoselectivity for acetalization of
aldehyde to 1,3-dioxanes, the following experiments
were carried out with PTAB–SbBr3–DMSO in the pres-
ence of various alcohols. Benzaldehyde 2 was acetalized
with PTAB–SbBr3 in DMSO in the presence of 1,3-pro-
panediol as expected, while benzophenone 8 was not
acetalized. Further, benzaldehyde 2 was predominantly
converted to 1,3-dioxane in the presence of both metha-
nol and 1,3-propanediol. Benzaldehyde dimethylacetal
was not obtained. Benzaldehyde dimethylacetal was
exchanged with acetal into 1,3-dioxane 4a with PTAB–
SbBr3 in the presence of 1,3-propanediol in DMSO.12
These results accounted for the chemoselective acetaliza-
tion of aldehyde to 1,3-dioxane by PTAB–SbBr3 in
DMSO.
9. trans-Stilbene oxide 1 was easily converted to benzalde-
hyde 2 (79%) with PTAB–SbBr3 in the presence of
1.0 M equiv of benzyltriethylammonium chloride over
epoxide 1 in DMSO for 20 h at room temperature.
Benzyltriethylammonium chloride was found to promote
the oxidation of disubstituted aromatic epoxides and diols
to corresponding aldehydes: Sayama, S. Unpublished
results.
10. cis-Stilbene oxide was converted to 2-phenyl-1,3-dioxane
4a (45%) at 55 °C for 2 h. At room temperature, cis-
stilbene oxide was not easily converted to 4a (9%) with
PTAB–SbBr3 in the presence of 1,3-propanediol, accom-
panied by hydrobenzoin (60%). On the contrary, trans-4-
chlorostilbene oxide was converted to 2-phenyl-1,3-di-
oxane 4a (81%) and 2-(4-chlorophenyl)-1,3-dioxane (81%)
under the same reaction conditions. Consequently, trans-
epoxides were more smoothly oxidized and converted to
the corresponding 1,3-dioxanes by this method than cis-
epoxides.
In conclusion, the PTAB–SbBr3 in DMSO-1,3-diol sys-
tem was found to be a chemoselective method for the
oxidative transformation of disubstituted aromatic
epoxide and 1,2-diols into 1,3-dioxanes without overox-
idation to carboxylic acid. Furthermore, this system was
also confirmed to be an alternative mild and chemoselec-
tive procedure for the acetalization of aldehydes to 1,3-
dioxanes without dehydrating at room temperature.13,14
References and notes
1. (a) Ishihara, K. In Lewis Acids in Organic Synthesis;
Yamamoto, H., Ed.; Wiley-VCH: New York, 2000; Vol. 2,
p 523; (b) Huang, Y.-Z.; Zhou, Z.-L. In Comprehensive
Organometallic Chemistry II; McKillop, A., Ed.; Perg-
amon: Oxford, 1995; Vol. 11, p 487.

S. Sayama / Tetrahedron Letters 47 (2006) 4001–4005
4005
11. For bromoalcohol examples by alternative method, see
Ref. 3c.
of the solvent in vacuo, the residue was purified by column
chromatography on silica gel (Wakogel C-200) with CCl4
and CHCl3 (9:1, v/v). 2-Phenyl-1,3-dioxane 4a (70 mg,
0.42 mmol) was obtained in 85% yield. Similarly, in the
presence of 1.0 M equiv of benzyltriethylammonium chlo-
ride (56 mg, 0.25 mmol) over trans-stilbene oxide 1 (49 mg,
0.25 mmol), trans-stilbene oxide 1 was also converted to 2-
phenyl-1,3-dioxane 4a (70 mg, 0.42 mmol) with PTAB–
SbBr3 in DMSO under the same reaction conditions.
For the effect of benzyltriethylammonium chloride, see
Ref. 9.
12. (a) Kametani, T.; Kondoh, H.; Honda, T.; Ishizone, H.;
Suzuki, Y.; Mori, W. Chem. Lett. 1989, 901; (b) Ukaji, Y.;
Koumoto, N.; Fujisawa, T. Chem. Lett. 1989, 1623; (c)
Iranpoor, N.; Firouzabadi, H.; Shaterian, H. R. Tetrahe-
dron Lett. 2003, 44, 4769; (d) Sato, K.; Kishimoto, T.;
Morimoto, M.; Saimoto, H.; Shigemasa, Y. Tetrahedron
Lett. 2003, 44, 8623; (e) Carrigan, M. D.; Sarapa, D.;
Smith, R. C.; Wieland, L. C.; Mohan, R. S. J. Org. Chem.
2002, 67, 1027; (f) Masaki, Y.; Yamada, T.; Tanaka, N.
Synlett 2001, 1311; (g) Kwon, J. S.; Pae, A. N.; Choi, K.;
Koh, H. Y.; Kim, Y.; Cho, Y. S. Tetrahedron Lett. 2001,
42, 1957; (h) Karimi, B.; Seradj, H.; Tabaei, M. H. Synlett
2000, 1798; (i) Langille, N. F.; Dakin, L. A.; Panek, J. S.
Org. Lett. 2003, 5, 575.
14. Typical procedure for the preparation of 2-phenyl-1,3-
dioxane from meso-hydrobenzoin: to a solution of SbBr3
(18 mg, 0.05 mmol) in DMSO (8 mL) were added PTAB
(282 mg, 0.75 mmol) and meso-hydrobenzoin 6 (53 mg,
0.25 mmol).
1,3-Propanediol
(133 mg
(127 lL),
13. Typical procedure: to
a
solution of SbBr3 (18 mg,
1.75 mmol) was added. After stirring for 70 h at room
temperature, the reaction mixture was treated with 0.5 M
aq Na2S2O3 and extracted with ethyl acetate. The organic
layer was washed with 0.5 M aq Na2S2O3 and successively
saturated aq NaCl, and dried with MgSO4. After removal
of the solvent in vacuo, the residue (83 mg) was purified by
column chromatography on silica gel (Wakogel C-200)
with CCl4 and CHCl3 (9:1, v/v). 2-Phenyl-1,3-dioxane 4a
(79 mg, 0.48 mmol) was obtained in 96% yield.
0.05 mmol) in DMSO (8 mL) were added PTAB
(282 mg, 0.75 mmol) and trans-stilbene oxide 1 (49 mg,
0.25 mmol). 1,3-Propanediol (133 mg (127 lL), 1.75
mmol) was added. After stirring for 48 h at room
temperature, the reaction mixture was treated with 0.5 M
aq Na2S2O3 and extracted with ethyl acetate. The organic
layer was washed with 0.5 M aq Na2S2O3 and successively
saturated aq NaCl, and dried with MgSO4. After removal