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Paper | Special issue | Vol 79, No. 1, 2009, pp.967-983
Published online, 7th January, 2009
DOI: 10.3987/COM-08-S(D)74
Tandem Catalysis Strategy for Direct Glycosylation of 1-Hydroxy Sugars. Methoxyacetic Acid as an Effective Catalytic Mediator

Yasuo Yokoyama,* Takeshi Hanamoto, Shoko Suzuki, Kosuke Shimizu, Hiroshi Furuno, and Junji Inanaga*

*Akita National College of Technology, Iijima-bunkyomachi 1-1, Akita, Akita 011-0923, Japan

Abstract

1-Hydroxy sugars were dehydratively coupled with a variety of alcohols including thiophenol in the presence of a catalytic amount of ytterbium(III) triflate [Yb(OTf)3] and methoxyacetic acid to give the corresponding glycosides in good to excellent yields, and in some cases, with high stereoselectivities. The reaction proceeds through selective esterification of 1-hydroxy sugars with methoxyacetic acid in the presence of free alcohols as glycosyl acceptors. The mechanism of methoxyacetic acid-mediated tandem catalysis with Yb(OTf)3 is discussed.