Toward Synthesis of Novel C-glycoprotein from Human RNase; Unexpected Stereochemistry of Epoxide Opening Reaction by Organolithium Reagents in the Presence of Lewis Acid

A nucleophilic attack reaction to 1,2-anhydro-β-D-manno-pyranose by indole derived organolithium reagents in the presence of BF3·OEt2 afforded isomers of C-aryl glycoside corresponds to the basic skeleton of C-linked mannosyl tryptophan, which is recently identified in human RNase.