Tandem Catalysis Strategy for Direct Glycosylation of 1-Hydroxy Sugars. Methoxyacetic Acid as an Effective Catalytic Mediator
作者:Yasuo Yokoyama、Junji Inanaga、Takeshi Hanamoto、Shoko Suzuki、Hiroshi Furuno、Kosuke Shimizu
DOI:10.3987/com-08-s(d)74
日期:——
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
在催化量的三氟甲磺酸镱 (III) [Yb(OTf) 3 ] 和甲氧基乙酸的存在下,将 1-羟基糖与包括苯硫酚在内的多种醇脱水偶联,得到相应的糖苷,收率良好至极好,并且在在某些情况下,具有高立体选择性。在作为糖基受体的游离醇存在下,该反应通过 1-羟基糖与甲氧基乙酸的选择性酯化进行。讨论了甲氧基乙酸介导的Yb(OTf) 3 串联催化的机理。