Water‐Soluble Sulfo‐Fluorous Affinity (SOFA) Tag‐Assisted Enzymatic Synthesis of Oligosaccharides

Herein, we report a bifunctional sulfo‐fluorous affinity (SOFA) tag‐assisted enzymatic synthesis and purification strategy for the facile preparation of bioactive glycans using fluorous solid‐phase extraction (FSPE). The incorporation of a sulfonate moiety onto the heavy fluorous tag significantly increases its water solubility, which allows the broad use of the inherently hydrophobic fluorous tag in aqueous buffers. In addition, the SOFA tag contains a photocleavable linker, enabling the easy release of amino‐functionalized oligosaccharides by UV irradiation. The SOFA tag was used in the synthesis of both negatively charged and neutral glycans to demonstrate its broad utility as an acceptor toward six different glycosyltransferases, significantly improving the feasibility of the preparation of complex glycans using FSPE. All the reactions were performed in an aqueous buffer, a minimum amount of methanol was used to purify the products, and the SOFA tag was easily recovered after photo‐irradiation. Thus, the entire synthetic process is environmentally benign.