Pentodialdoses, preparation

Finally MacDonald and Fischer have prepared the free ajyZo-pento-dialdose (8) by the sulfone-degradation method. The diethyl dithioacetal of scyllo-inosose (12) was oxidized to the corresponding disulfone which, on treatment with ammonia, gave the dialdose (8). The structure was proved by converting the compound into the bis(ethylene dithioacetal) derivative, which was identical with that obtained from a /io-pentodialdose prepared by a previous method. ... 

In the preparation of polyhydroxylated azepane as potential glycosidase inhibitors, Dha-vale [28] described a short synthetic route utilizing the Henry approach. The nitroaldol reaction of l,2-0-isopropylidene-3-0-benzyl-a-D-xylo-pentodialdose 36 and nitromethane in the presence of triethylamine at room temperature afforded a-D-gluco- and /3-L-ido- nitroal-dose 37, the precursors to (2S, 3R, 4R, 5R) and (2S, 3R, 4R, 55) tetrahydroxyazepanes 38 and 39, in a 88 12 ratio in 95% yield (O Scheme 13). 

The Weerman degradation was employed in one of the first preparations of dialdoses, namely of n-f/ireo-tetrodialdose, using the diamide of D-glucaric acid as starting material. An inosose has been degraded to a pentodialdose by way of its disulfone and the Nef reaction, transformation of a 6-deoxy-... 

The isopropylidene acetal of ii/fo-pentodialdose has been used as the starting material for many syntheses. In later preparations, oxidation with sodium metaperiodate was employed. " The preparation of the compound in a crystalline state, as reported by Brocca and Dansi and by Schaffer and Isbell was a considerable improvement in its further use as a starting material. (The sirupy product previously used was not completely satisfactory for syntheses as it always contained some formaldehyde from the glycol oxidation.) The compoimd crystallized as a hydrate and could also be obtained anhydrous - by recrystallization from benzene. 

Wolfrom and Hanessian recently prepared a 3-0-benzyl derivative of xj/io-pentodialdose by oxidation of 3-0-benzyl-l,2-0-isopropylidene-a-D-glucofuranose with lead tetraacetate in benzene. The compound was characterized as the crystalline semicarbazone. 

MacDonald and Fischer prepared D- fluco-hexodialdose (27) by two different methods. By use of the Nef reaction, 6-deoxy-l,2-0-isopropyli-dene-6-nitro-n-glucose (26) was converted into the dialdose (27), which was isolated from the aqueous solution as its insoluble, crystalline bis-(diethyl dithioacetal) (in 48% yield, after recrystallization). It is of interest to note that the starting material (26) is one of the two isomeric 6-deoxy-6-nitro sugars which Grosheintz and Fischer prepared from 1,2-0-iso-propylidene-a-D-x2/lo-pentodialdo-l, 4-furanose (7). Thus, the synthesis discussed here is an ascent from a pentodialdose to a hexodialdose. 

Mester and M6czdr prepared the formazan of 1,2-0-isopropylidene-a-D-a 2/Zo-pentodialdo-l, 4-furanose and the bis(formazan) of the free xylo-pentodialdose (see Hester s review ). 

---