Nucleophilic additions keto-sugars

The nucleophilic addition to keto groups of sugars is useful for the production of tertiary alcohols but can also be used to yield tertiary amines. One such example, in relation to the synthesis of the immunosuppressant compound myriocin, is given below. A comparison of several synthetic approaches to this deceptively simple molecule follows because of its interesting biological properties. 

Continuing, one carbon homologation of 96 was easily achieved by oxidation of the alcohol to the corresponding ketone and a subsequent enolisation-formylation sequence. The last lacking carbon was introduced by nucleophilic addition on the complex keto-sugar 97 using vinyl magnesium bromide in the presence of cerium salts. The diol 98 was further elaborated into a relay compound already prepared from squalestatin [88]. 

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