Dihydroxylation branched sugar derivative

Figure 6. Synthesis of branched sugar derivative 9 via a dihydroxylation...

A number of more complex structures, useful in total syntheses, are accessible from olefins formed by Wittig olefinations of keto-sugars. A fmitful reaction is the dihydroxylation of double bonds. Obviously, methylene derivatives will give the hydroxymethyl branched-chain derivatives. 

In connection with studies on the synthesis of complex cell wall glycans, we have developed effective syntheses of the novel branched sugar aceric acid and its C-2 epimer. Control of asymmetry in the installation of the key tertiary centers was effected by either asymmetric dihydroxylation of an appropriate alkene derivative or by thiazole addition to the corresponding ketone. 

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