Glucofuranose derivative

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

Use of RuCl2(PPh3)3 with a glucofuranose derivative (61) as donor solvent leads to asymmetric hydrogenation of prochiral a,/3-unsaturated ketones to the saturated ketones, with up to 34% ee in the case of a cyclohexene-3-one (497). 

This solvolysis resembles a substitution of the Sn2 type, because, for the D-glucofuranose derivative,82 there is an inversion of configuration at the carbon atom carrying the group displaced. It should be noted that, if the carbonium ion is formed at C-5, the leaving group is sufficiently close to the molecule that the attack can take place only from the opposite side. 

RCM is now an important method for the building of oxepines. It should be noted that chiral functionalized precursors can be readily prepared from natural monosaccharides. Thus, glucofuranose derivatives can be transformed to tetrahydrooxepines (Scheme 21) in only three steps olefmation, O-allylation, and RCM <1998TL3025>. 

Stereoselective rearrangement reactions can involve sugar-linked functionalities. An example of this type is the Overman rearrangement of allylic trichloracetimidates formed from a D-glucofuranose derivative 20 [36]. This methods affords (L)-a-ami-no acids 25 from (Z)-allylic imidate 23 and (R)-a-amino acids 25 from ( )-imidates 23 with a diastereoselectivity of about 16 1. The oxidative cleavage of compound 24 with Ru04 yields the a-amino acid 25, (Scheme 15). 

Attempts to rationalize the stereochemistry of the product in terms of (a) bulk effects or (b) coordinated transition-states for this type of reaction were unsuccessful, although results showing that the Grignard reagent complexes strongly with the glucofuranose deriv-... 

The difference in properties of the two compounds is remarkable. Freudenberg and Ivers compound is very reactive and unstable, whereas the D-glucofuranose derivative is quite stable. 

Angibaud, P, Chaumette, J L, Desmurs, J R, Duhamel, L, Pie, G, Valnot, J Y, Duhamel, P, Asymmetric synthesis of 2-chloro- and 2-bromo-alkanoic acids by halogenation of a-D-glucofuranose-derived silyl ketene acetals. Tetrahedron Asymmetry, 6, 1919-1932, 1995. 

The 3,5,6-tri-O-benzoyl derivative 128 of 123 (R = PhCO) has been prepared by treating the 1,2-O-sulfinyl-a-D-glucofuranose derivative 124 with sodium thiocyanate (95TL5347) (Scheme 38). 

A variety of reagents other than the conventional ones mentioned thus far have been used for effecting intramolecular iNT-acyl displacements. Gigg and Warren noted that the n-glucofuranose derivative (132) is converted into the oxazoline (133), either by methanolic sodium methoxide... 

The lack of neighboring-group participation by a 6-benzoyloxy group in the D-glucofuranose derivative (49) (see p. 119) was duplicated by the behavior of the 6-benzamido group in the related compound (150), where treatment with either ethanolic sodium ethoxide or lithium aluminum hydride gave only the alcohol at C-5, by desulfonylation. However, zu... 

However, the displacement reaction of l,2 5,6-di-0-isopropylidene-3-0-p-tolylsulfonyl-a-D-allofuranose with tetrabutylammonium fluoride has been reported to lead to the 3-deoxy-3-fluoro-o -D-glucofuranose derivative. The unexpectedly easy displacement seems to be attributable to freedom from steric hindrance in the n-allofuranose derivative, since the corresponding n-glucofmanose derivative gives only 3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-er2/correlates well with the almost quantitative formation of the D aUo isomer from the reduction of 1,2 5,6-di-0-isopropylidene-a-D-n6o-3-hexulose with sodium borohydride. 

More encouraging are the results obtained from the trimethylsilyl-protected D-glucofuranose derivatives 8. The titanium(IV) chloride catalyzed addition of cyclopentadiene (9) to 8 gives 10 with a d.r. 93 7. Poorer results were obtained with 1.3-cyclohexadiene (d.r. 84 16) or anthracene (d.r. 70 30). In order to increase the Lewis acidity of the titanium complex, derivative 11 was examined and a d.r. 98 2 was observed for the ent/o-adduct 122tl. 

In a study related to the original work on 1,2-O-isopropylidenealdo-furanoses, the conformations of a number of l,2 3,5-di-0-ben-zylidene-a-D-glucofuranose derivatives (37) in solution were investi-... 

A full report has appeared on the acid-catalysed solvolysis of 2-0 -( 2-hydroxypropyl). and 2-0-( 2-hydroxyethyl)-D-glucofuranose derivatives as Is illustrated in Scheme 13- The 8-anomer reacted... 

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