Synthesis of Pentaantennary N‐Glycans with Bisecting GlcNAc and Core Fucose

Always use protection? The omission of a single protecting group led to the convergent synthesis of the highly branched dodecasaccharide N-glycan that contains two neighboring tetrasubstituted mannoside groups. A serendipitous finding led to the identification of the key protecting group in oligosaccharide building blocks for the optimized synthesis of N-glycans.