A-D-Glucofuranose, isopropylidene

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... 

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-... 

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... 

Bakke and Theander132 described an interesting, new synthesis of L-ascorbic acid by one-step oxidation of 1,2-O-isopropylidene-a-D-glucofuranose to l,2-0-isopropylidene-a-D-xyfo-5-hexulofuranurono-6,3-lactone hydrate (74), followed by hydrolysis of the isopropyli-dene group, and specific, borohydride reduction of the aldehyde group liberated. 

Covalently bonded chiral auxiliaries readily induce high stereoselectivity for propionate enolates, while the case of acetate enolates has proved to be difficult. Alkylation of carbonyl compound with a novel cyclopentadienyl titanium carbohydrate complex has been found to give high stereoselectivity,44 and a variety of ft-hydroxyl carboxylic acids are accessible with 90-95% optical yields. This compound was also tested in enantioselective aldol reactions. Transmetalation of the relatively stable lithium enolate of t-butyl acetate with chloro(cyclopentadienyl)-bis(l,2 5,6-di-<9-isopropylidene-a-D-glucofuranose-3-0-yl)titanate provided the titanium enolate 66. Reaction of 66 with aldehydes gave -hydroxy esters in high ee (Scheme 3-23). 

In some sugar-based lactones, the carbohydrate moiety can serve as a chiral template. For example, the synthesis and characterisation of a novel chiral bicyclic caprolactone 1 was reported in 2003 in six steps from 1,2,5,6-di-O-isopropylidene-a-D-glucofuranose.10 The introduction of... 

The purpose of this study was to explore the introduction of an OZT moiety onto the specific C-3 site of both l,2 5,6-di-0-isopropylidene-a-D-glucofuranose and 1,2 4,5-di-0-isopropylidene-p-D-fructopyranose, taking advantage of the well-defined frame of both carbohydrate structures to generate all possible OZT-isomers. These spiroheterocyclic structures could be constructed according to a simplified sequence based on a key stereoselective approach from uloses via epoxides or aziridines (Scheme 16). 

When comparing these results with those previously obtained using carbohydrate-based vinyl ethers as chiral dienophiles, this improved facial diastereoselectivity to heterodienes under similar conditions is noteworthy.81 The efficient chiral transfer in the second example might mostly be attributed to the specific architecture of the l,2 5,6-di-0-isopropylidene-a-D-glucofuranose moiety.Those findings open the way to develop well-defined spiro-carbohydrate templates towards improved auxiliaries for chirality transfer in a wide range of syntheses. 

The availability, in gram quantities, of the fluorinated carbohydrates thus far synthesized has also made possible their use as starting materials for the synthesis of other analogs and intermediates for example, the preparation of 3,5-dideoxy-3,5-difluoro-D-xylose from 3-deoxy-3-fluoro-D-xylose,88 which is itself preparable from 3-deoxy-3-fluoro-l,2-0-isopropylidene-a-D-glucofuranose. Electrolytic oxidation of 3-deoxy-3-fluoro-D-glucose afforded, after treatment with an acidic... 

LAH complexes of the monohydroxy carbohydrate derivatives 1,2 3,4-di-O-isopropylidene-a-D-galactopyranose (39) and 1,2 5,6-di-O-isopropylidene-a-D-glucofuranose (40) have been reported to effect asymmetric reduction of... 

In order to obtain information concerning the hydrolysis of a S,6-0-orthoester such as 31, it was thus necessary to prevent the participation of OH-3. Starting (Figure 9) from compound J4 (obtained from 1,2 B,6-di-0-isopropylidene-a-D-glucofuranose throLigh acetylation and selective hydrolysis of the S,6-0-isopropylidene protec-... 

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