Wittig olefinations keto-sugars

As shown above, many of the methods that are available to form carbon-carbon bonds rely on the reaction of a carbanion with a suitable electrophile. Keto-sugars are readily available by simple oxidation of hydroxyl groups. Thus, the reaction of carbohydrate-derived ketones or aldehydes with carbanions has been extensively explored. However, keto groups are suitable substrates in olefinations, such as Wittig reactions, leading to versatile intermediates for the construction of complex structures. This section will detail some application of keto-sugars in total syntheses along these two main lines. 

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. 

---