<i>S</i>-Benzoxazolyl
(SBox) Glycosides in Oligosaccharide Synthesis: Novel Glycosylation
Approach to the Synthesis of β-<scp>d</scp>-Glucosides, β-<scp>d</scp>-Galactosides, and α-<scp>d</scp>-Mannosides
作者:Alexei Demchenko、Medha Kamat、Cristina De Meo
DOI:10.1055/s-2003-40345
日期:——
Per-acetylated and per-benzoylated S-benzoxazolyl (SBox) glycosides have been synthesized and applied to highly efficient 1,2-trans glycosylation. Complete stereoselectivities and remarkably high yields were achieved for the synthesis of β-d-glucosides, β-d-galactosides, and α-d-mannosides. It was also demonstrated that benzoylated ‘disarmed’ SBox glycosides could be selectively activated in the presence of both armed and disarmed ethyl thioglycosides. Convergent synthesis of the tetrasaccharide β-d-Glc-(1-6)-β-d-Gal-(1-6)-β-d-GlcNAc-(1-6)-α-d-GlcOMe was achieved in three sequential selective glycosylation steps.
合乙酰化和合苯甲酰化的S-苯并噁唑基(SBox)糖苷已被合成并应用于高效的1,2-反式糖苷化。对β-d-葡萄糖苷、β-d-半乳糖苷和α-d-甘露糖苷的合成实现了完全的立体选择性和显著高的产率。还证明了苯甲酰化的“去活化”SBox糖苷可以在有活化和去活化的乙硫糖苷同时存在的情况下被选择性激活。成功实现了四糖β-d-Glc-(1-6)-β-d-Gal-(1-6)-β-d-GlcNAc-(1-6)-α-d-GlcOMe的汇聚合成,通过三步连续的选择性糖苷化反应完成。