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-mannnopyranose 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 mannnosyl tryptophan, which is recently identified in human RNase.