1,2-a-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. 

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-... 

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). 

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%). 

Although menthyl esters, especially 19, are most often used to prepare sulfoxides, esters derived from optically active alcohols other than menthol have been prepared . Ridley and Smal prepared arenesulfmic esters of 1,2 5,6-di-O-cyclohexylidene-a-D-glucofuranose. Unfortunately, these diastereomers were oils, except for the mesityl derivative, with the major epimer having configuration R at sulfur and so they offered no advantage over the menthyl esters. Separation of the epimers by chromatography failed. 

Solid Acid-Catalyzed Selective Deprotection of l,2 5,6-Di-0-isopropylidene-a-D-glucofuranose (102)... 

A novel synthesis of D-glucose 6-phosphate (in 55% yield) has been reported it involves alcoholysis of the cyclic phosphate of catechol with 1,2-O-isopropylidene-a-D-glucofuranose, followed by acid hydrolysis of the so-formed phosphoric diester.192 The reagent... 

In contrast to the oxidation of acyclic polyhydric alcohols in benzene,508 treatment of 1,2-O-isopropylidene-a-D-glucofuranose with silver carbonate-on-Celite in boiling methanol led to selective oxidation of the primary hydroxyl group, with the formation of the al-duronic acid derivative in 68% yield.517... 

Chromic acid in acetone effects highly selective oxidation at C-5 in 6-deoxy-l,2-0-isopropylidene-/3-L-idofuranose and 6-deoxy-1,2-0-isopropylidene-a-D-glucofuranose.526... 

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