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C-Glycosides of l - glycero - d - manno - and d - glycero - d - manno -heptose containing either ( S )- or ( R )-2-hydroxypropyl aglycons are easily accessible compounds via condensation of reducing heptoses with pentane-2,4-dione. 2′,3′-Di- O -acetyl adenosine was transformed into the corresponding 5′- O -cyanoethyl N , N -diisopropylaminophosphoramidite derivative, which was coupled in fair yields to the O-acetylated diastereoisomeric C-glycosidic alcohols. Oxidation of the phosphite triesters followed by deprotection furnished four ADP-heptose analogues, wherein the heptosyl phosphate moiety had been replaced by a three carbon-skeleton. The compounds serving as substrate analogues will be used for co-crystallization experiments with ADP heptosyl transferases.

Reducing heptopyranoses of the d -glycero- d -manno- and l -glycero- d -manno-configuration were converted in good overall yields into β-anomeric C-glycosides via condensation with pentane-2,4-dione, followed by sodium methoxide-induced enrichment of the β-anomeric products and subsequent O-acetylation. The resulting 2-oxo-propyl glycosides were further transformed into separable ∼1:1 diastereomeric mixtures of (S)-and (R)-2-hydroxy derivatives. The configuration of the additional stereogenic centre was assigned on the basis of NMR data obtained from the corresponding Dale–Mosher esters. Finally, phosphorylation of the d -glycero- d -manno-heptose analogues using the phosphoramidite procedure and deprotection furnished the (S)- and (R)-2-phosphate derivatives in good yields. The compounds serve as substrate analogues for enzymes involved in bacterial ADP heptose biosynthesis and glycosyl transfer reactions.