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The treatment of benzyl 2,3-O-isopropylidene-β-L-xylopyranoside with N-hydroxyphthalimide under Mitsunobu conditions, followed by protecting-group interchange, gave benzyl 4-O-[(tert-butoxycarbonyl)amino]-2,3- O-isopropylidene-α-D-arabinoside. Mild acid hydrolysis and catalytic hydrogenolysis afforded 4-O-[(tert-butoxycar bonyl)amino]-D-arabinose that, upon heating in water, gave the dihydrooxazine [(4R,5S,6R)-5,6-dihydro-4,5-dihydroxy-6-hydroxymethyl-4H-1,2-oxazine] as a crystalline solid. A single-crystal structure determination of this solid showed it to exist in the [sup 5] H[sub 6] conformation. Reduction of the dihydrooxazine gave the tetrahydrooxazine [(4R,5S,6R)-4,5-dihy droxy-6-hydroxymethyl-3,4,5,6-tetrahydro-2H-1,2-oxazine]. The dihydrooxazine was an effective inhibitor of two β-glucosidases (K[sub i] = 27 and 35 µM). Benzyl 2,3-O-isopropylidene-β-L-xylopyranoside, via the derived imidazylate, was converted into a nitrile that, upon reduction and protecting-group manipulations, gave benzyl 4-C-aminomethyl-4-deoxy-α-D-arabinoside. Treatment of this amine with hydrogen and palladium-on-carbon gave isofagomine.Key words: dihydrooxazine, tetrahydrooxazine, isofagomine, iminosugars, glycosidase inhibitors.Le traitement du 2,3-O-isopropylidène-β-L-xylopyranoside de benzyle par du N-hydroxyphtalimide dans des conditions de Mitsunobu, suivi d'un échange des groupes protecteurs, conduit à la formation du 4-O-[(tert-butoxycarbonyl)amino]-2,3-O-isopropylidène-α-D-arabinoside de benzyle. Soumis à une hydrolyse acide légère et une hydrogénolyse catalytique, celui-ci fournit alors le 4-O-[(tert-butoxycarbonyl)amino]-D-arabinose qui, par chauffage dans l'eau, livre la dihydrooxazine [(4R,5S,6R)-5,6-dihydro-4,5-dihydroxy-6-hydroxyméthyl-4H-1,2-oxazine] sous la forme de solide cristallin. Une détermination de structure sur un cristal unique montre qu'elle existe dans la conformation [sup 5] H[sub 6] . La réduction de la dihydrooxazine fournit la tétrahydrooxazine [(4R,5S,6R)-4,5-dihydroxy-6-hydroxyméthyl-3,4,5,6-tétrahydro-2H-1,2-oxazine]. La dihydrooxazine est un inhibiteur efficace de deux β-gluco sidases (K[sub i] = 27 et 35 µM). Le 2,3-O-isopropylidène-β-L-xylopyranoside de benzyle, par le biais de l'imidazylate qui en dérive, a été transformé en un nitrile qui, après réduction et des manipulations des groupes protecteurs, fournit le 4-C-aminométhyl-4-désoxy-α-D-arabinoside de benzyle. Le traitement de cette amine avec de l'hydrogène et du palladium sur du charbon conduit alors à l'isofagomine.Mots clés : dihydrooxazine, tétrahydrooxazine, isofagomine, iminosucres, inhibiteurs de glycosidases.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

As part of continued efforts to understand the mechanisms of 1,5-α-l-arabinanases better, some arabinan-like iminosugar oligosaccharides were synthesized. An iminosugar analogue of arabinobiose was found to be a good inhibitor of the arabinanase Arb93A from Fusarium graminearum. Structures were determined for complexes of this inhibitor with wild-type Arb93A and a catalytically inactive mutant. [ABSTRACT FROM AUTHOR]