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Communication | Special issue | Vol 61, No. 1, 2003, pp.51-57
Published online, 4th August, 2003
DOI: 10.3987/COM-03-S29
Effective Induction of β-Selectivity Using α- or β-Mannosyl 6-Nitro-2-benzothiazoate in Mannosylation

Takashi Hashihayata and Teruaki Mukaiyama*

*Center for Basic Research, The Kitasato Institute (TCI), 6-15-5, Toshima, Kita-ku, Tokyo 114-0003, Japan

Abstract

Highly β-selective mannosylations of glycosyl acceptors with an α-mannosyl 6-nitro-2-benzothiazoate donor (1α) were carried out smoothly in the presence of a catalytic amount of tetrakis(pentafluorophenyl)boric acid [HB(C6F5)4] to afford the corresponding disaccharides in good to high yields: it was proved that high β-selectivity was entirely dependent on the characteristic properties of a donor (1α) and a catalyst, HB(C6F5)4. Interestingly, it was observed that in situ anomerization from 1β to 1α took place rapidly when β-mannosyl donor (1β) was treated with a catalytic amount of HB(C6F5)4 in CH2Cl2.