Methyl 1,2,3,4-tetra-O-acetyl-α-L-iduronate was prepared from methyl 1,2,3,4-tetra-O-β-D-glucuronate in two steps: Ferrier’s photobromination and subsequent radical reduction with tris(trimethylsilyl)silane. The obtained methyl 1,2,3,4-tetra-O-acetyl-α-L-iduronate was a good glycosyl donor for the L-iduronidation when bis(trifluoromethanesulfonic)imide was employed as the activator. The reaction afforded the α-isomer as the major product, the configuration of which is the same as that of the L-iduronic acid unit in heparin and heparan sulfate.

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中文翻译：

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使用 1,2,3,4-四-O-乙酰基-α-L-艾杜糖醛酸甲酯作为糖基供体轻松制备 L-艾杜糖醛酸和 α-L-艾杜糖醛酸化

1,2,3,4-四-O-乙酰基-α-L-艾杜糖醛酸甲酯由 1,2,3,4-四-O -β-D-葡萄糖醛酸甲酯分两步制备：费里尔光溴化和随后的自由基用三(三甲基甲硅烷基)硅烷还原。当使用双(三氟甲磺酸)亚胺作为活化剂时，所获得的1,2,3,4-四-O-乙酰基-α-L-艾杜糖醛酸甲酯是L-艾杜糖醛酸化的良好糖基供体。反应主要产物为α-异构体，其构型与肝素和硫酸乙酰肝素中L-艾杜糖醛酸单元的构型相同。

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