Synthesis of 3-deoxy-2-uloses via the indium-mediated allylation reaction

We utilized the indium-mediated allylation reaction for the synthesis of carbohydrate structures containing the 3-deoxy-2-ulose motif, a barely investigated compound class. The stereoselective outcome can be controlled by the presence or absence of a chelating group in α-position to the carbonyl function. By introduction of an UV-active allyl building block, we enabled epimer separation by HPLC towards the synthesis of 3-deoxy- d- glycero - d - galacto -2-nonulose, the carboxyl-reduced analogue of widely distributed 3-deoxy- d - glycero - d - galacto -nonulosonic acid (Kdn). Ozonolysis of the introduced 2- C -methylidenepropan-1-ol motif provided the desired 3-deoxy-2-uloses. Graphical abstract