L,2 5,6-Di-0-isopropylidene-a-D-allofuranose

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. 

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... 

Nucleophilic displacements of sulfonyloxy groups by reagents other than halide ions had also been observed in sugar chemistry. As early as 1922, a 3-deoxy-3-hydrazino derivative had been obtained by the action of hydrazine on l,2 5,6-di-0-isopropylidene-3-0-p-tolylsul-fonyl-a-D-glucofiiranose, and this derivative was later characterized " as 3-deoxy-3-hydrazino-l,2 5,6-di-0-isopropylidene-a-D-allofuranose. 

Further details have been reported on the mechanistically interesting formation of 3-C-butyl-l,2 5,6-di-0-isopropylidene-a-D-allofuranose by the addition of butyllithium to l,2 5,6-di-0-isopropylidene-3- )-triflyl-a-D-allofuranose which proceeded through a 3-keto intermediate. (See Vol. 29, p. 192, ref. 6). ... 

There have been reports on the synthesis of 2 -deoxynucleosides chain-extended at C-5. The homologue 49 of deoxyadenosine has been prepared from l,2 5,6-di-0-isopropylidene-a-D-allofuranose, with radical deoxygenations at C-2 and C-5, whilst various compounds of type 50 (R=CN, N3, OMe, -CH=CH2, NO2) have been made either by opening of a 5, 6 -epoxide or by addition of nucleophiles to the 5 -aldehyde. ° Other workers have shown that reaction of the same thymidine 5 -aldehyde with the silyl ketene acetal l-r-butoxy-l-(Tbdms)oxyethene gives the product 50 (R=C02Bu ) stereoselectively7 ... 

Carbohydrate derivs. Aq. KCN added dropwise at 0 to a well-stirred mixture of l,2 5,6-di-0-isopropylidene- a-D-r/Z>o-hexofuranosul-3-ose hydrate and NaHCOg in ethanol-water 3-C-cyano-l,2 5,6-di-0-isopropylidene-a-D-allofuranose (Y 90%) stirred vigorously at room temp, in aq.-alc. KCN for 18 hrs. -> 3-C-cyano-l,2 5,6-di-O-isopropylidene-a-D-glucofuranose (Y 80%). - The allo-isomer is obtained under kinetic control, the gluco-isomer under thermodynamic control. J.-M. Bourgeois, Helv. 58, 363 (1975). 

Benzyl-l,2 4,6-di-0-ethylidene-a-D-allopyranose, A-86 3-0-Benzyl-l,2 5,6-di-0-isopropylidene-a-D-allofuranose, 1-58 l-0-Benzyl-2,3 4,5-di-0-isopropylidene-D-arabinitol, A-792... 

Benzyl alloside p-D-Pyranose-ybrm, B-12 3-0-Benzyl-l,2 4,6-di-0-ethylidene-a-D-allopyranose, A-86 3- O -Benzyl-1,2 5,6-di- O -isopropylidene-a-D- lofuranose, 1-58 3-0 -Benzyl-1,2-0 -isopropy lidene-a-D-allofuranose, 1-58 3-0-Benzyl-l,2-0-isopropylidene-5,6-di-0-mesyl-a-D-allofuranose, 1-58 3-Bromo-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose, B-56 3-Chloro-3-deoxy-1,2 5,6-di- O -isopropylidene-a-D-allofuranose, C-71... 

Di-0-isopropylideneallofuranose xy-form, D-713 2,3 5,6-Di-0-isopropylideneallofuranose -xy-form, D-713 l,2 5,6-Di-0-isopropylidene-a-D-allofuranose, 1-58 2,3 5,6-Di-0-isopropylidene-p-D-allofuranosyl bromide. A-76 2,3 5,6-Di-0-isopropylidene-D-allofuranosyl chloride, A-77 2,3 5,6-Di-0-isopropylidene-p-D-allofuranosyl chloride, A-77 l,2 5,6-Di-0-isopropylidene-3-0-methyl-a-D-allofuranose, 1-58 1,2 5,6-Di- O -isopropy lidene-3- C -(nitromethyl)-a-D-allofuranose, N-59 l,2 5,6-Di-0-isopropylidene-3-thio-a-D-allofuranose, T-53... 

Benzyl 3-bromo-3-deoxy-2-0-methyl-p-D-xylopyranoside, B-103 Benzyl 3-bromo-3-deoxy-4-0-methyl-p-D-xylopyranoside, B-103 Benzyl 3-deoxy-3-fluoro-p-D-glucopyranoside, D-89 Benzyl 3-deoxy-3-iodo-p-L-xylopyranoside, D-280 Benzyl 2,4-di-D-benzoyl-3-bromo-3-deoxy-a-D-xylopyranoside, B-103 Benzyl 2,4,6-tri-D-acetyl-3-deoxy-3-fluoro-p-D-glucopyranoside, D-89 1 - O -Benzyl-3-deoxy-3-fluoro-D-fructose, D-74 3-Bromo-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose, B-56 3-Bromo-3-deoxyglucose D-form, B-75 3-Bromo-3-deoxymannose D-form, B-88 3 -Bromo-3 -deoxythymidine 5 -Trityl, B-99 3 -Bromo-3 -deoxythymidine, B-99... 

Amino-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose, A-157 3-Amino-3-deoxy-l,2 5,6-di-0-isopropylidene-(3-D-idofuranose, A- 292 3-Amino-3-deoxy-( -D-glucopyranosyl 3-amino-3-deoxy-a-D-glucopyranoside, A-221 3-Amino-3-deoxyglucose D-form, A-267 3-Amino-3-deoxyglucuionic acid D-form, A-275... 

K-Glucoride is inefficient for the reduction of prochiral unhindered aliphatic ketones. Hence, Cho and Chun [1] have synthesized various chiral borohydrides using monosaccharide units potassium 9-0-(l,2 5,6-di-0-isopropylidene-a-D-allofuranosyl)- 9-boratabicyclo[3.3.1]nonane from l,2 5,6-di-0-isopropylidene-a-D-allofuranose (DIPAF) a C-3 epimer of DIPGF potassium 9-0-(l,2 5,6-di-0-cyclohexylidene-a-D-glucofuranosyl)-9-boratabicyclo [3.3.1] nonane utilizing... 

The chlorination of such amino-sugars as 3-amino-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose and 6-amino-6-deoxy-l,2 3,4-di-0-isopropyli-dene-a-D-galactopyranose yielded relatively unstable ATV-dichloro-derivatives. 2-Acetamido-2-deoxyaldohexopyranose acetates (and A-acetylglycosamines) reacted with phosphorus pentachloride to give 2-(tetrachloroethylidene)amino derivatives [e.g. (144)] instead of the expected 2-trichloroacetamidoderivatives. ... 

New sugar nitrones, obtained by condensation of JV-methylhydroxylamine with carbonyl derivatives of suitably protected sugars, have been reported by Tronchet s group. In most instances, only one of the two possible geometric isomers was isolated e.g. (174)], although both geometric isomers of (175) were obtained in crystalline form. Treatment of 3-amino-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose (176) with 4-nitrobenzenediazonium tetra-fluoroborate afforded a mixture of tautomeric triazines (Scheme 43), and... 

L-3-(3-Deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranos-3-yl)alanine (290) (R = R = H) has been synthesized by a route that involved the addition of the carbanion derived from methyl (methylthio)methyl sulphoxide to 3-C-cyano-methyl-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-allofuranose. Subsequent treatment of the resulting (glycosyl)enamino sulphoxide with acetic anhydride, base-catalysed ester-exchange, and reductive desulphurization afforded the A-acetyl-3-(glycos-3-yl)alanate (290) (R = Ac R = Me), which was hydrolysed to (290) (R = R = H) with base. 

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