Use of 1,3-dibenzyl-dihydrouracil in the chain extension of 2,3-O-isopropylidene-d-glyceraldehyde

The aldol-type addition of 1,3-dibenzyl-dihydrouracil 2 to 2,3-O-isopropylidene-d-glyceraldehyde 3 was examined in different solvents and under Lewis acid catalysis in order to establish the stereochemical preferences. A stereodivergent synthesis of 5-trihydroxypropyl-dihydrouracil derivatives 4 and its C-5 epimer 5 was realized. The synthesis of ureido polyols 8 and 10 was obtained via the reductive ring opening of the templates 4 and 5.