T. Yamanoi, I. Yamazaki / Tetrahedron Letters 42 (2001) 4009–4011
4011
Table 3. Synthesis of several aryl glycosides using various kinds of triaryloxyboranes and glycosyl acetates
Entrya
Glycosyl acetate
Triaryloxyborane
Mol% of Yb(OTf)3
Temp. (°C)
Time
Yield (%)
a/b (JC1-H1)
1
2
3
4
5
6
7
8
1a
1a
1a
5
5
5
8a
8a
9a
9a
2
6
7
2
6
7
2
7
2
7
2
4
4
2
4
4
5
5
15
15
0
0
0
0
0
0
Rt
Rt
Rt
Rt
1.5 h
5 h
5 h
5 h
5 h
86
61
96
71
45
83
71
78
75
72
a (171.8)
a (171.6)
a (170.0)
57/43
70/30
65/35
a (172.5)
a (172.5)
a (174.2)
a (173.4)
5 h
Overnight
Overnight
2 days
2 days
9
10
a Molar ratio, glycosyl acetate:triaryloxyborane=1:0.5.
As mentioned above, we found that several triaryloxy-
boranes worked as good glycosyl acceptors of the gly-
cosyl acetates, and an efficient glycosylation method for
synthesizing aryl glycosides with only a catalytic
amount of Yb(OTf)3 as an activator could be
developed.
Ramesh, S.; Kaila, N.; Grewal, G.; Franck, R. W. J. Org.
Chem. 1990, 55, 5.
8. Yamanoi, T.; Iwai, Y.; Inazu, T. J. Carbohydr. Chem.
1998, 4 and 5, 819.
9. Yamanoi, T.; Iwai, Y.; Inazu, T. Heterocycles 2000, 53,
1263; the following paper also suggested an enhancement
in the reactivity of the alcohol by the in situ formation of
a boron alkoxide: Toshima, K.; Nagai, H.; Ushiki, Y.;
Matsumura, S. Synlett 1998, 1007.
References
10. The stereochemistries of all the mannosidic bonds formed
in this study were confirmed to be a by the signal of the
anomeric carbon in the 13C NMR spectrum that agreed
with the observations of Bock and Pedersen, as men-
tioned in the following reference: Bock, K.; Lundt, I.;
Pedersen, C. Tetrahedron Lett. 1973, 1037.
1. For example: Hosoya, T.; Takashiro, E.; Yamamoto, Y.;
Matsumoto, T.; Suzuki, K. Heterocycles 1996, 42, 397.
2. Bielawska, H.; Michalaska, M. J. Carbohydr. Chem.
1986, 5, 445 and references cited therein.
3. Slaghek, T. M.; Nakahara, Y.; Ogawa, T.; Kamerling, J.
P.; Vliegenthart, J. F. G. Carbohydr. Res. 1994, 255, 61.
4. (a) Sashiwa, H.; Makimura, Y.; Shigemasa, Y.; Roy, R.
J. Chem. Soc., Chem. Commun. 2000, 909; (b) Hasegawa,
T.; Kondoh, S.; Matsuura, K.; Kobayashi, K. Macro-
molecules 1999, 32, 6595.
5. For example: Matsumoto, T.; Katsuki, M.; Suzuki, K.
Chem. Lett. 1989, 437; Yamaguchi, M.; Horiguchi, A.;
Fukuda, A.; Minami, T. J. Chem. Soc., Perkin Trans. 1
1990, 1079; Smits, E.; Engberts, J. B. F. N.; Kellogg, R.
M.; van Doren, H. A. J. Chem. Soc., Perkin Trans. 1
1996, 2873; Yamanoi, T.; Fujioka, A.; Inazu, T. Bull.
Chem. Soc. Jpn. 1994, 66, 1488, and references cited
therein.
6. (a) Kometani, T.; Kondo, H.; Fujimori, Y. Synthesis
1988, 1005; (b) Matsumoto, T.; Katsuki, K.; Suzuki, K.
Tetrahedron Lett. 1988, 29, 6935.
7. (a) Clerici, F.; Gelmi, M. L.; Mottadelli, S. J. Chem. Soc.,
Perkin Trans. 1 1994, 985; (b) Thompson, M. G. C.;
Kahne, D. J. Am. Chem. Soc. 1998, 120, 11014; (c)
11. We examined the synthesis of 4a from 3a by the OC
glycoside rearrangement. The reaction using 1 molar
equivalent of Yb(OTf)3 in CH2Cl2 could not convert 3a
to 4a at all, however, 4a was obtained in 13% yield from
3a by the reaction using 0.33 molar equivalents of
BF3·OEt2 at room temperature overnight. These results
indicated that in the glycosylation reaction using 2, the
OC glycoside rearrangement did not occur by
Yb(OTf)3 but 4a might be produced by the direct attack
of the ortho position of 2 on the glycosyl intermediate.
The J1,2 (6.3 Hz), J2,3 (2.9 Hz) and J3,4 (6.1 Hz) values of
1
the H NMR spectrum supported the twist-boat confor-
mation of 4a.
12. Triaryloxyboranes 2, 6 and 7 were prepared by the reac-
tion of the phenols with B(OH)3 in the presence of CaH2,
as mentioned in the following reference: Cole, T. E.;
Quintanilla, R.; Rodewald, S. Synth. React. Inorg. Met.-
Org. Chem. 1990, 20, 55. Triphenoxyborane is also com-
mercially available from Aldrich and Tokyo Kasei Co.,
Ltd.
.