Versatile building blocks from disaccharides: glycosylated 5-hydroxymethylfurfurals

A practical protocol for the elaboration of O-glycosyl-HMF’s from glycosyl-(1→6)-glucoses is reported, the two steps involving aluminate-promoted isomerization to the respective 6-O-glycosyl-fructoses and subsequent selective dehydration of the fructose portion. Accordingly, melibiose, gentiobiose, and primeverose are converted into the corresponding 2-uloses and, then, into α-GalMF 11, β-GMF 12, and β-XylMF 13. Pt/C-catalyzed oxidation with oxygen in NaOH at 25 °C efficiently generated the respective furoic acids from α-GalMF and α-GMF, whilst Pt/O2 in water at 50 °C also oxidizes the primary OH to give the dicarboxylic acids 15 and 17–key building blocks for the generation of novel types of polyesters and polyamides.

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6-O-(β-d-Glucopyranosyl)-d-fructofuranose (gentiobiulose)C2H22O11[α]D20=+9.1 (c 1.0, H2O)Source of chirality: gentiobiose

Octa-O-acetyl-β-melibiuloseC28H38O19[α]D20=+105 (c 0.8, CHCl3)

5-[(α-d-Galactopyranosyloxy)methyl]-2-furancarboxyaldehydeC12H16O8[α]D20=+158 (c 1, MeOH)Source of chirality: melibiose

5-[(α-d-Glucopyranosyloxy)methyl]-2-furancarboxyaldehydeC12H16O8[α]D20=-159 (c 1, MeOH)Source of chirality: gentiobiose

5-[(α-d-Galactopyranosyloxy)methyl]-2-furoic acidC12H16O9[α]D20=+147 (c 0.8, MeOH)Source of chirality: melibiose

5-[(α-d-Xylopyranosyloxy)methyl]-2-furancarboxyaldehydeC11H14O7[α]D20=-35 (c 1, MeOH)Source of chirality: primeverose

5-[(α-d-Glucopyranuronosyloxy)methyl]-2-furoic acidC12H14O10[α]D20=+97 (c 0.9, MeOH)Source of chirality: isomaltulose

5-[(α-d-Glactopyranuronosyloxy)methyl]-2-furoic acidC12H14O10[α]D20=+108 (c 0.7, MeOH)Source of chirality: melibiose