Functional group transformations in carbohydrates currently often rely on the use of protecting groups and the direct modification of unprotected carbohydrates remains a formidable challenge.  In our group an protocol has been developed that regioselectively oxidizes the C-3 hydroxyl group in a broad range of saccharides, including oligosaccharides, to a ketone by a palladium catalyst.  This ketone functionality is a versatile handle for further modification, although modification of keto-saccharides, without protecting groups is still under-investigated.
In this project, methyl 3-keto-D-glucose was taken as a model substrate and a plethora of reactions was studied for their compatibility with hydroxyl groups and polar solvents, such as water. The successful transformations resulted for example in synthesis of branched-chain sugars, which are rare motifs found in bacterial sugars. Furthermore, labels and reactive groups could be introduced into the keto-saccharide in one step, that are useful in the field of chemical biology.
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