Making it traceless: A traceless Staudinger reaction between a specifically functionalized sugar phosphine and an azide-tagged protein allows the construction of well-defined reverse N-linked glycoproteins (see scheme). This reaction was applied to different azidoprotein substrates and its potentials and limitations are outlined. © 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.