Halogeno sugar, synthesis

Mitsunobu conditions [triphenylphosphine/diethyl azodicarboxylate (DEAD)]7 and triphenylphosphite methiochde [(PhO)3P+MeI ] or dihalides [(PhO)3P + XX-j8 have been successfully applied to the synthesis of halogeno sugars. 

The synthesis of radiolabelled halogeno-nucleosides is included in Chapter 20, while the use of halogeno-sugars in synthesis is referred to in Chapters 12 and 13. 

The synthesis of halogeno-sugars via an improved preparation of cy " tc carbonates and sulphates will be found in Chapter 8 and the synthesis of glycosides using these intermediates in Chapter 2. 

The synthesis works best with benzylated halogeno sugars 390 and provides a mixture of anomeric (a + p) isocyanides 391. The isocyanides can also be synthesized by desulfurization of glycosyl isothiocyanates [128]. 

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