Positional isomers of thioxylobiose, their synthesis and inducing ability for d-xylan-degrading enzymes in the yeast cryptococcus albidus

Isomeric S-linked-2-thioxylobiose 10, 3-thioxylobiose 17, and 4-thioxylobioise 19 were conveniently prepared by S n2 displacement of suitable triflylglycoses with the sodium salt of 2,3,4-tri- O-acetyl-1-thio-β- d-glucopyranose, either in N,N-dimethylformamide, or in oxolan in the presence of a sodium complexing agent. Allyl 3,5- O-isopropylidene-2- O-trifluoromethanesulfonyl-β- d-lyxofuranoside was a convenient electrophilic precursor for 10, which was smoothly obtained after a short sequence of deprotection involving conversion to the 1-propenyl glycoside. 1,2:5,6-Di- O-isopropylidene-3- O-trifluoromethylsulfonyl-α- d-allofuranose and 1,2,3-tri- O-benzoyl-4- O-trifluoromethylsulfonyl-β- l-arabinopyranose were the respective precursors for 17 and 19. 4-Thioxylobiose has a highly stimulatory effect on the synthesis of enzymes of the xylanolytic system in the yeast Cryptococcus albidus when applied to the cells in the presence of the natural disaccharide inducer (1→4)-β- d-xylobiose.