Revisit of the phenol O-glycosylation with glycosyl imidates, BF3·OEt2 is a better catalyst than TMSOTf
作者:Yali Li、Huaping Mo、Gaoyan Lian、Biao Yu
DOI:10.1016/j.carres.2012.09.025
日期:2012.12
With BF(3)·OEt(2) as the catalyst, the glycosylation of phenols with glycosyl trichloroacetimidates (or N-phenyl trifluoroacetimidates) bearing 2-O-participating groups leads to the desired 1,2-trans-O-glycosides in generally excellent yields without formation of the 1,2-cis-anomers. However, with TMSOTf as the catalyst, the outcomes of the corresponding phenol O-glycosylation are highly dependent
Direct and practical anomeric O-arylation of sugar lactols with substituted arylboronic acids has been established. Using copper catalysis at room temperature under an air atmosphere, the protocol proved to be general, and a variety of aryl O-glycosides have been prepared in good to excellent yields. Furthermore, this approach was extended successfully to unprotected carbohydrates, including α-mannose