The 4,6-<i>O</i>-[α-(2-(2- Iodophenyl)ethylthiocarbonyl)benzylidene] Protecting Group: Stereoselective Glycosylation, Reductive Radical Fragmentation, and Synthesis of β-<scp>d</scp>-Rhamnopyranosides and Other Deoxy Sugars
作者:David Crich、Qingjia Yao
DOI:10.1021/ol034741r
日期:2003.6.1
[reaction: see text] In the thioglycoside/BSP/Tf(2)O glycosylation method, the 4,6-O-[alpha-(2-(2-iodophenyl)ethylthiocarbonyl)benzylidene] group enforces beta-selectivity in mannopyranosylations. Following glycosylation, treatment with Bu(3)SnH in toluene at reflux affords regioselective, reductive fragmentation to the 6-deoxy-beta-mannosides (beta-rhamnosides). Applied to glucosides, the radical fragmentation