Short and highly stereoselective total synthesis of d-ribo-configured ureido sugars

An highly stereoselective, flexible and very short synthetic approach to d-ribo-configured ureido monosaccharides of the aldose, aldonic acid and alditol series has been performed starting from the 5-(alditol-1-C-yl)-hydantoin intermediates, obtained via aldol-type addition reaction of hydantoin based building blocks to enantiomerically pure aldehydes. A study to assess the stereoselectivity of this reaction has been undertaken and a very high increase of diastereoselectivity was observed depending on the hydantoin protecting group. The imidazolidinone ring elaboration of 5-(alditol-1-C-yl)-hydantoin intermediates to give ureido sugar derivatives was studied.