Stereospecific synthesis of β-d-allopyranosides by dihydroxylation of β-d-erythro-2,3-dideoxyhex-2-enopyranosides

A Survey of Recent Synthetic Applications of 2,3-Dideoxy-Hex-2-enopyranosides

“…For example, the dihydroxylation reaction of 2,3-dideoxy-α- d -erythro hex-2-enopyranoside 28 , where both the anomeric substituent and the 4-substituent are located below the ring, occurs exclusively from the upper face of the molecule, resulting in formation of α- d -mannopyranoside 29 (Scheme 9a) [26]. However, osmylation of β- d -erythro-2-enopyranoside 30 , where the C-1 and C-4 substituents are disposed in opposite faces of the pyranose, led exclusively to β- d -allopyranoside 31 , with the osmium approach taking place anti- to the anomeric substituent (Scheme 9b) [46]. Similarly, dihydroxylation of galactal derivative 32 occurred mostly from the β-face opposite to the anomeric substituent leading to “talo”·derivative 33 , although some “gulo” derivative 34 was also obtained (Scheme 9c) [47].…”

The Influence of Neighboring Group Participation on the Hydrolysis of 2-O-Substituted Methyl Glucopyranosides

“…The β-model compounds were prepared from the commercially available methyl β- d -glucopyranoside, which was 4,6-benzylidene protected followed by selective 3-O-benzylation via a tin-acetal intermediate to give the mono-ol 13 ready for further functionalization. Compounds 15 – 19 were obtained using standard conditions with an excess of reagents (Scheme ).…”

De Novo Asymmetric Bio- and Chemocatalytic Synthesis of Saccharides − Stereoselective Formal O-Glycoside Bond Formation Using Palladium Catalysis

“…A preliminary application of our iterative approach is depicted in Scheme . Diastereoselective catalytic cis -dihydroxylation of enone adduct 2C was effected by RuCl 3 /NaIO 4 , and the resulting diol was protected to the dioxolane 4C under standard conditions. Subsequent reduction using Zn(BH 4 ) 2 18 gave 5C , a β- l -ribose …”