2001 carbohydrates

carbohydratesU 0500

11 - 204β-Selective O-Rhamnosylation with a Rhamnosyl Trichloroacetim-idate That Has the 4C1 Conformation. — The title reaction ofrhamnopyranosyl trichloroacetimidate (I) with glycosyl acceptor (II) in thepresence of a Lewis acid affords a mixture of isomers (III) and (IV) preferring theβ-isomer (III), whose amount increases with the size of the catalyst. Rhamnosyldonor (I) is prepared from the corresponding lactol, exclusively obtained asα-isomer, and receiving the 4C1 conformation. — (IKEDA, TOMONARI;YAMADA, HIDETOSHI; Carbohydr. Res. 329 (2000) 4, 889-893; Fac. Sci.,Kwansei Gakuin Univ., Nishinomiya, Hyogo 662, Japan; EN)

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