D-Glucofuranose

In l,2 5,6-di-0-isopropylidene-a-D-glucofuranose five of the six funaional groups of glucose are protected. The free 3-hydroxyl group is a popular starting point in synthesis. It... 

Acetalation. As polyhydroxy compounds, carbohydrates react with aldehydes and ketones to form cycHc acetals (1,13). Examples are the reaction of D-glucose with acetone and a protic or Lewis acid catalyst to form l,2 5,6-di-0-isoprop5lidene-a-D-glucofuranose [582-52-5] and its reaction with benzaldehyde to form 4,6-0-benzyhdene-D-glucopyranose [25152-90-3]. The 4,6-0-(l-carboxyethyhdine) group (related to pymvic acid) occurs naturally in some polysaccharides. 

The glucofuranose used as starting material is obtained as follows. 8.8 g of 1,2-isopropylidene-D-glucofuranose and 50.6 g of benzyl chloride are treated with a total of 28 g of potassium hydroxide in portions with cooling and stirring. The mixture is then stirred for 3 hours at 80 to 90°C. Working up from chloroform solution and distillation at 250°C to 260°C under... 

Of particular value, was the reagent s ability to oxidize a hydroxyl group attached directly to a furanoid ring (6, 7, 46), as is illustrated by the conversion of l,2 5,6-di-0-isopropylidene-a-D-glucofuranose into l,2 5,6-di-0-isopropylidene-a-D-n o-hexofuranos-3-ulose (1). The follow-... 

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

Whereas l,2-0-isopropylidene-5,6-di-0-methyl-D-glucofuranose was found to be unreactive towards triphenylphosphite dibromide, triphenylphosphite methiodide or phosphorus pentachloride, the related methyl 2,5,6-tri-0-methyl-/ -D-glucofuranoside (59), in which the hindrance caused by the ketal group is absent, reacted with triphenylphosphite methiodide to give the 3-deoxy-3-iodo derivative 60 in 31% yield. 

The reaction of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49), with phosphorus pentachloride was reported in 1926 by Allison and Hixon (I) who formulated the product as 3-chloro-3-deoxy-l,2 5,6-di-0-isopro-pylidene-D-glucofuranose (2% yield). A reinvestigation (93) of the... 

The mass spectra of methyl 3-deoxy-p-v-tkreo-pentopyrano-side, methyl 4-deoxy-j3-T>-thieo-pentopyranoside, and 5-deoxy-fi-D-xylo-furanoside are discussed and compared fragmentation paths are sufficiently different to allow identification on the basis of their mass spectra. On the other hand, the mass spectra of methyl 2- and 3-deoxy-5-O-methyl-f3-i>-erythro-pentofuranosides do not exhibit fragmentation differences. The mass spectra of 3-deoxy-l,2 5,6-di-O-isopropylidene -d-xylo - hexofuranose, 5- deoxy -1,2-0-isopropylidene-D-xy o-hexofuranose, and 6-deoxy-l,2-0-iso-propylidene-D-glucofuranose show prominent differences, even between the 5- and 6-deoxy isomers. The interpretation of the spectra was aided by metastable-ion peaks, mass spectra of DzO-exchanged analogs, and the mass spectrum of an O-isopropylidene derivative prepared with acetone-d6. 

The a-D-glucofuranose derivative 1 was the first reported protic additive used for the chiral modification of an organometallic reagent16. 

Das aus (-)-Menthol hergestellte chirale Hydrid liefert in erster Linie mit zweizahnigen Substraten [fi-Amino- ketone, En-(2)-in-(4)-ole (s.S. 74)] gute optische Ausbeuten1. Als chirale vie. Diole werden Zucker-2,1 und Terpen-Derivate wie cis- und rrans-Pinandiol-(2,3)4 verwendet. Von den Zucker-Derivaten hat sich der Kom-plex mit 3-0-Benzyl-l,2-0-cyclohexyliden-a-D-glucofuranose am besten bewahrt2,5 (Vorschrift S. 74). 

O-isopropyliden-D-glucofuranose erhalt man z.B. in 55%iger Ausbeute 6-Desoxy-... 

MeCN, r.t., 24 h) gave, respectively, a mixture of fluorinated derivatives 287 (67%) and 290 (6%), and 290 (54%) and 287 (11%). In each case, the minor products were formed by C-5 epimerization of the starting compounds prior to the displacement, followed by fluorination. Reduction (NaBHJ of 287 and 290, followed by hydrolysis, gave an anomeric mixture of 5-deoxy-5-fluoro-L-idofuranose (from 287) and 5-deoxy-5-fluoro-D-glucofuranose... 

Treatment of l,2 3,5-di-0-methylidene-6-0-tosyl-a-D-glucofuranose (310) with KF (in refl. ethylene glycol, 3 min) gave a mixture of 6-deoxy-6-fluoro (311, 60%), an alkene (312, 18%), and 6-0-(2-hydroxyethyl) derivatives (12%). 

Because synthesis of l-(2-deoxy-2-fluoro-)S-D-arabinofuranosyl)cytosine (744, FAC), an elementary arabino type of nucleoside having a growth-inhibitory effect against L 1210 leukemia in mice, through direct introduction of a fluorine atom in the 2 - up (arabino) position was difficult, compound 744 was prepared by condensation of trimethylsilylated A -acetylcytosine with 3-0-acetyl-5-(7-benzoyl-2-deoxy-2-fluoro-D-arabin-ofuranosyl bromide (742), which had been prepared by periodate oxidation of 6-0-benzoyl-3-deoxy-3-fluoro-D-glucofuranose (741). Similar condensa-... 

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