One-Pot Glycosylation Strategy Assisted by Ion Mobility-Mass Spectrometry Analysis toward the Synthesis of N -Linked Oligosaccharides.

N -Glycans are major constituents of several cellular glycoproteins. One-pot strategies for the synthesis of N -glycans are crucial for the rapid generation of pure samples to determine their biological functions. Herein, we describe a double one-pot strategy for the synthesis of N -glycans assisted by an IM-MS analysis approach for rapid screening of optimized glycosylation reaction conditions. This research includes triflate-mediated direct β-mannosylation and tandem glycosylation in a one-pot strategy for the synthesis of the challenging N -linked trisaccharide core β-5 . Furthermore, a one-pot sequential glycosylation of the N -linked trisaccharide core 7 furnishes diverse high-mannose type N -glycans with excellent stereo- and regioselectivities. In particular, ion mobility-mass spectrometry-based quantitative analysis is applied to identify the stereo- and regioselective outcomes of the crude reaction mixtures to develop a highly efficient one-pot protocol.