Sugars Grignard reaction with

A higher-branched sugar, 35, was synthesized from 262, obtained by the Grignard reaction of 2,3-O-isopropylidene-D-glyceraldehyde by conversion of the methylene derivative 263 into 264 with osmium... 

Otherwise, unsaturation may be introduced by use of carbonyl-containing carbohydrate derivatives and carbon nucleophiles that contain alkene (or, if desired, alkyne) functionality, a notable illustration being the tin-or indium-mediated C-l allylation of unprotected sugars. As an illustration, D-arabinose, treated with allyl bromide in aqueous ethanol in the presence of tin gives, after acetylation, 278 in 85% yield.258 In this procedure aldoses react better than do ketoses, and pentoses better than hexoses. More usual is the use of Grignard reactions to give, for example, the octynes 279. 

Schaffer398 described a synthesis of L-apiose by reaction of 170 with formaldehyde, and Horton et al,373 developed a method for extension of sugar chains through ethynylation of 170 and other aldehydo compounds by the Grignard reaction. 

The reactions of Grignard reagents with acyclic sugar derivatives have also been investigated as potential routes for the synthesis of compounds containing asymmetric, benzylic carbon atoms.22 W. A. 

For inorganic chemistry, hydrolysis is usually the reverse of neutralization, hdt in organic chemistry its scope is broader. Here it includes, amoi other things, the inversion of sugars, the brealdng down of proteins, the saponification of fats and other esters, and the final step in the Grignard reaction, all of which can be carried on with water alone, albeit slowly and incompletely. For convenience, the meaning of the term has been extended to cover also the numerous cases in which an alkali is added to the water and in which the alkali salt of an acid is usually one of the final products ... 

The application of indium- and tin-mediated Barbier-Grignard reactions in aqueous solution to the chain extension of unprotected sugars has been reviewed. Some C-5 variants of iV-acetylneuraminic acid have been prepared by the indium-mediated addition of ethyl oc-(bromomethyl)acrylate to variously N-substituted mannosamines," and similar chemistry using (bromomethyl)vinyl phosphonate has led to the phosphonate analogue 12. The reaction of O-protected aldono-1,4- and -1,5-lactones with (2-bromomethyl)-acrylate or -acrylonitrile or 2-bromobutyrolactone mediated by samarium diodide led to chain-extended ulosonic acid derivatives." ... 

Reaction of Grignard reagents with sulphonate derivatives of methyl D-ribofuranoside leads to rearranged, branched-chain sugars as outlined in Scheme 4 anomerization of these compounds by acidic methanolysis or with Grignard reagents was also studied, the latter favouring the thermodynamically less-stable anomers. ... 

Axenose (2,6-dideoxy-3-C-methyl-L-ji y/o-hexose) (247) has been synthesized from a 2,6-dideoxy-sugar glycoside, although the route yielded the 3-C-epimer as the principal product (Scheme 92)." Preferential formation of the /yjiri>-isomer in the Grignard reaction is unexpected in view of previous experience gained with... 

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