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 alpha-GalMF 11, beta-GMF 12, and beta-XylMF 13. Pt/C-catalyzed oxidation with oxygen in NaOH at 25 degrees C efficiently generated the respective furoic acids from alpha-GalMF and alpha-GMF, whilst Pt/O-2 in water at 50 degrees 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. (c) 2006 Elsevier Ltd. All rights reserved.