Facile Preparation and Utilization of a Novel β-d-ManNAcA-Donor: Methyl 2-Benzoyloxyimino-1-bromo-2-deoxy-α-d-arabino-hexopyranuronate

The title β-d-ManNAcA-donor, the α-bromide of methyl 2-benzoyloxyimino-2-deoxy-d-arabino-hexopyranuronate 9, has been prepared from d-glucuronolactone in an overall yield of 21% for the seven steps required, all intermediates being securable in crystalline form. Key compounds were the 2-acetoxy-d-glucuronal ester 6 and its hydroxylaminolysis product, the 1,5-anhydro-d-fructuronate oxime 7, the latter elaborating 9 on O-benzoylation (→8) and photobromination. —The utility of 9 as a suitable β-d-ManNAcA donor rests on two ensuing reactions: first, Koenigs-Knorr type glycosidations, with N-blocked 2-aminoethanols as spacer substrates, or with the 6-OH of an otherwise protected glucoside (16), produce β-selectivities of 20 : 1 or better, and second, the oxime reduction of the β-glycosides, thus obtained, proceeds in an essentially stereospecific manner to yield, upon N-acetylation, the 2-acetamido-2-deoxy-β-d-mannosiduronates. —The methodology elaborated was used to prepare some novel artificial glycolipids, e.g. the (myristoylamino)ethyl 6-O-(2-acetamido-2-deoxy-β-d-mannopyranosyluronic acid)-α-d-glucopyranoside (25) and its (stearoylamino)ethyl analog (26), that are being evaluated as recognition markers for liposomes.