D-Allofuranose

Scheme 28.— Proposed Mechanism for Photochemical Reaction of l,2 3,4-Di-0-iso-propylidene-3-O-nitro-a-D-allofuranose (81) and l,2 3,4-Di-0-isopropylidene-3-0-nitro-a-D-glucofuranose (82).

Treatment of 3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-erythro-hex-3-enofuranose with iodine and thallous fluoride in anhydrous ether afforded227 3-deoxy-l-fluoro-3-iodo-l,2 5,6-di-0-isopropyli-dene-D-xy/o-4-hexulose in 80% yield, together with small proportions of (tentatively identified) 3-deoxy-4-fluoro-3-iodo-l,2 5,6-di-0-iso-propylidene-a-D-allofuranose and two unidentified products. A mechanism proposed for the furanose ring-opening involves the formation of a 3,4-iodonium ion, and attack by fluoride at C-l. 

Up to now, the Pak synthesis is the highest yielding synthesis of (+)-preussin with a total yield of 42% over eleven steps, starting from 5,6-anhydro-3-deoxy-l,2-0-isopropylidene-a-D-allofuranose (116). The stereogenic centers at C-2, C-4, and C-5 of D-glucose were elaborated into the three stereogenic centers of (+)-preussin (cf. Fig. 3). 

The selective introduction of fluorine into a furanose ring was demonstrated by the reaction of TASF with l,2 5,6-di-0-isopropylidene-3-O-trifluoromethanesulfonyl-a-D-allofuranose (12) which gave a 66% yield of 3-deoxy-3-fluoro-l,2 5,6-di-0-isopropylldene-a-D-glucofuranose (2. The isomeric triflate 13,... 

Bicyclo [3,3,0]-Systeme liegen auch bei den 1,2-0-1sopropyliden-glykofuranosen vor. Theander untersuchte die katalytische Oxydation von 1,2 5,6-Di-O-isopropyliden-a-D-allofuranose (143) und-a-D-gluco-... 

Bei vorhandenen Asymmetrie-Zentrcn in R1 des Ausgangsnitrils wurde fiir die unter Bil-dung eines neuen Chiralitats-Zentrums verlaufende Reaktion vom Sulfoxid III zum S/N-Acetal IV Diastereoselektivitat beobachtet Ausgehend von 3-C-Cyanmethyl-3-deoxy-l,2 5,6-di-0-isopropyliden-a-D-allofuranose entsteht das L-konfigurierte Aminosaure-Derivat VI mit 67% ds2. 

An investigation of the reduction of chlorodeoxy sugars with lithium aluminum hydride has been reported.68 In one experiment, 3-deuterio-l,2 5,6-di-0-isopropylidene-a-D-allofuranose (197) was prepared, and converted into 3-chloro-3-deoxy-3-deuterio- l,2 5,6-di-0-isopropyl-idene-a-D-glucofuranose (198) by treatment with triphenylphos-phine-carbon tetrachloride reduction with lithium aluminum hydride gave 3-deoxy-3-deuterio-1,2 5,6-di-O-isopropylidene-a-D-r/foo-hexofuranose (199), a result which established that the reduction must have occurred with, retention of configuration at C-3. 

Some oxirane, oxetane, and oxolane derivatives of 1,6-anhydrohexoses are known, for example l,6 2,3-dianhydro-/i-D-allofuranose (165) and the corresponding a-L-talofuranose,243 1,6 2,5-dianhydro-a-L-gulofuranose (166),511,512 l,6 3,5-dianhydro-a-L-idofuranose,245 l,6 3,5-dianhydro-a-L-gulofuranose,246,512 and 1,6 4,7-dianhydro-D-g/ycero-/f-D-gulopyranose.249... 

P. Koll, Eine einfache Methode zur Darstellung der Isopropylidenderivate der 1,6-Anhydro-jS-D-allofuranose und der l,5-Anhydro-/i-D-allofuranose, Tetrahedron Lett., (1978) 51-52. 

The a-D-allofuranose derivative 284682, (Z)-2-methyl-3-triphenylstannyl-3-penten-l-ol (285)683, as well as a number of o-methoxyarylstannanes including the o-anisylstannyl compounds (286) provide examples of particularly strained four-membered rings. 

Sometimes, the most convenient method of preparation of the labeled sugar required is by chemical or enzymic modification of a more readily available, or commercially available, sugar. Thus, D-ribose-3-t has been prepared from l,2 5,6-di-0-isopropylidene-a-D-allofuranose-3-t by way of 1,2-O-isopropylidene-a-D-allofuranose-3-t, followed by periodate oxidation, and reduction.52... 

The introduction of a nitro group into the alkenes under consideration may be achieved by addition of nitryl iodide (IN02). In the case of alkene 22, this addition, followed by reduction with sodium borohydride, led32 to 3-deoxy-1,2 5,6-di-0-isopropylidene-3-C-(nitromethyl)-a-D-allofuranose (52). Light-induced addition of 1,3-dioxolane to alkenes 15a and 22 has also been reported.47 The resulting adducts, 53 and 54, respectively, are of value as they contain a potential aldehydo function. 

The related reagent tris(dimethylamino)sulfonium trifluoromethoxide [TAS(CF30)], which is suitable for the synthesis of primary O-trifluoromethyl carbohydrates from triflates,89 gives predominantly fluorination in the case of the secondary triflate ester of 1.2 5,6-di-O-iso-propylidene-a-D-allofuranose, probably due to partial decomposition of the reagent in refluxing acetonitrile.89... 

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