Of all possible ketoses, only D-fructose occur large scale in nature. Therefore, all the ketoses with the exception of D-fructose are defined as “rare ketose”. Despite their lower accessibility, rare ketoses offer an enormous potential for applications in pharmaceutical, medicine, functional food and synthetic chemistry. However, studies of rare ketoses have been hampered by the lack of efficient preparation methods. Here, a convenient and efficient platform for the facile synthesis of rare ketoses is described. The introduced two-step strategies are based on a “phosphorylation/de-phosphorylation” cascade reaction. Rare ketoses were prepared from readily available starting materials as their ketose-1-phosphate forms in step 1 by one-pot multienzyme reactions, followed by the hydrolysis of the phosphate groups in acidic conditions to produce desired ketoses in step 2. By this strategy, 14 rare ketoses were obtained from readily available starting materials with high yield, high purity, and without having to undergo tedious isomer separation step.

Sialic acids are typically linked a2-3 or a2-6 to the galactose that located at the nonreducing terminal end of glycans, playing important but distinct roles in a variety of biological and pathological processes. However, details about their respective roles are still largely unknown due to the lack of an effective analytical technique. Lectin and antibody binding have been the primary method to analyze glycans, but lectins and antibodies often suffer from weak binding affinity, limited specificity, and cross-reactivity. To address this issue, we develop a chmoenzymatic reporter strategy for rapid and sensitive detection of N-acetylneuraminic acid-a(2-3)-Galactose (Neu5Aca(2-3)Gal) glycans on cell surface.