Aldoses synthetic routes

A new synthetic route for functionalized polyhydroxyalkyl-pyrimidines starting from unprotected aldoses and based on montmorillonite K-10 catalysis and solvent-free microwave irradiation conditions, has been reported by Yadav et al,m Thus, reaction of D-glucose and D-xylose with semicarbazide or thiosemicarbazide (186) in the presence of montmorillonite K-10, under microwave irradiation, proceeded via domino cycloisomerization, dehydrazination, and dehydration of the intermediate semi- or thiosemicarbazones (187) to afford l,3-oxazin-2-ones or l,3-oxazine-2-thiones (188) in one single step and in yields between 79% and 85% (Scheme 34). Other mineral catalysts tested, such as silica gel and basic alumina, were far less effective for this transformation and only silica gel was active at all, giving low yields (15-28%) of compounds 188a-d. The l,3-oxazin-2-ones(thiones) thus synthesized were subsequently converted into the target pyrimidines by reaction with aromatic... 

Hashimoto, H, Kawanishi, M, Yuasa, H, New and facile synthetic routes to 5-thioaldohexo-pyranosides via aldose monothioacetal derivatives. Tetrahedron Lett., 32, 7080-7087, 1991. 

L-Gulose, required for synthetic work associated with bleomycin, has been prepared by a new route from D-glucose (Scheme 2). A new synthesis of D-arabinose from D-glucose involves periodate oxidation of the glucose derivative (3) (Scheme 3). The reaction is thought to be general for all aldoses that form 1,2-0-isopropylidene derivatives. ... 

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