Metal-catalyzed transformation of d-glucal to optically active furan diol
Masahiko Hayashi,* Hirotoshi Kawabata and Kanako Yamada
Department of Chemistry, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.
E-mail: hayashi@po.cc.yamaguchi-u.ac.jp
Received (in Cambridge, UK) 29th March 1999, Accepted 19th April 1999
The treatment of d-glucal with a catalytic amount of
2
Sm(OTf) or RuCl (PPh in the presence of 1 equiv. of H O
afforded optically active furan diol in good yield under mild
conditions.
this transformation in detail. After examining several systems
for the efficient conversion of 1 to furan diol 3, we found that
(PPh and Sm(OTf)
glucal to furan diol (Scheme 1). Some of the results obtained are
summarized in Table 1. The treatment of d-glucal with 5–10
mol% of RuCl (PPh ) in the presence of 1 equiv. of H O
2 3 3 2
3
2
3
)
3
RuCl
2
3
)
3
3
worked effectively to convert d-
In 1975, Gonzales and co-workers reported the conversion of
3
,4,6-tri-O-acetyl-d-glucal into 4,6-di-O-acetyl-2,3-dideoxy-
afforded optically active furan diol in 64–70% yield. In the case
of the reaction without H O, very slow dehydrogenation–
hydrogenation to form 4 and 5 occured. Some rare-earth metal
aldehydo-d-erythro-trans-hex-2-enose in the presence of mer-
curic sulfate in 1,4-dioxane–sulfuric acid solution.1 This
mercuric ion-assisted acid glycal opening reacton has been
applied to hexose and pentose derivatives to obtain acyclic a,b-
unsaturated aldehydes. They also reported that the reaction of
unprotected d-glucal under the same mercuric ion-assisted
acidic conditions afforded optically active furan diol, 2-(d-
glycero-1,2-dihydroxyethyl)furan. These transformations are
very useful to obtain chiral building blocks, however, these
reactions require acidic conditions. Therefore, the use of mild
and neutral conditions to accomplish these transformations
would be desirable, Here we report metal ion-catalyzed furan
diol synthesis from d-glucal under mild conditions.
2
,2
triflates also proved to be effective. Among the rare-earth metal
triflates we examined, Sm(OTf)
The treatment of d-galactal 2 with 5 mol% of Sm(OTf)
afforded furan diol 3 with the same configuration. The reaction
probably proceeds via nucleophilic attack of H O on glucal.
3
exhibited the highest activity.
3
2
Then opening of pyranose ring followed by cyclization to a five-
membered ring and dehydration furnished the furan ring.
A typical procedure is as follows: d-Glucal (204 mg, 0.356
mmol), MeCN (1.5 ml) and H
argon in an ampoule equipped with a magnetic stirring bar and
a Young valve. After addition of Sm(OTf) (44.8 mg, 0.07
2
O (0.03 ml) were placed under
3
We recently reported the oxidation of the allylic alcohol
moiety in d-glucal 1 by the aid of a catalytic amount of
mmol), the mixture was stirred for 40 min at 80 °C. The
completion of the reaction was confirmed by TLC, then the
mixture was poured into brine. Extracton with EtOAc (15 ml 3
5) and concentration afforded the crude product, which was
chromatographed on silica gel to give 2-(d-glycerol-1,2-dihy-
palladium complexes, which leads to the efficient synthesis of
3
1
,5-anhydrohex-1-en-3-uloses. During this study, we found
that when the reactions were carried out in water, the formation
of optically active furan diol 3 was observed (44% yield). The
reaction in MeCN in the presence of water resulted in the
formation of a mixture of furan diol 3, oxidation product 4 and
hydrogenated product 5. These results promoted us to examine
D
droxyethyl)furan 3 (131 mg, 70%) as a colorless oil {[a] +36.4
1
3 3
(c 1.2, CHCl ) [lit., +38.0 (c 3.3, CHCl )]}.
The present method has the following advantages: (1) The
reaction proceeds under neutral conditions, unlike the conven-
tional mercuric ion-assisted acidic reaction; (2) highly toxic
mercury can be replaced by less toxic metals; (3) operational
simplicity—the direct derivatization of glycol to a protected
species is possible.
Financial support from Monbusho (Grant-in-Aid for Scien-
tific Research on Priority Areas, No. 706: Dynamic Control of
Stereochemistry) is gratefully acknowledged.
Notes and references
1
F. Gonzales, S. Lesage and A. S. Perlin, Carbohydr. Res., 1975, 42,
67.
2
2
F. M. Dean, in Advances in Heterocyclic Chemistry, ed. by A. R.
Scheme 1
Katritzky, Academic Press, 1982, vol. 30, pp. 167–238; F. W.
Table 1 The conversion of d-glycals to furan glycola
Conditions
b
Entry
Glycal
Catalyst (mol%)
Pd(OAc) (5)
Solvent
H
2
O/equiv. T/°C
t/min
Yield (%)
1
2
3
4
5
6
1
1
1
1
2
1
2
2
H O
—
1
1
1
1
80
100
100
80
80
80
30
165
45
40
50
44
64
70
70
60
51
RuCl
RuCl
2
(PPh
(PPh
3
)
)
3
(5)
(10)
6 6
C H
2
3
3
CH
2
NCHOAc
Sm(OTf)
Sm(OTf)
3
(5)
(5)
MeCN
MeCN
MeCN
3
Yb(OTf)
3
, (5)
1
50
a
All reactions were carried out under argon atmosphere. b Isolated yield after silica gel column chromatography.
Chem. Commun., 1999, 965–966
965
Hayashi, Masahiko
