Kiliani synthesis, applications

A sequence known as the Kiliani-Fischer synthesis was developed primarily for extending an aldose chain by one carbon, and was one way in which configurational relationships between different sugars could be established. A major application of this sequence nowadays is to employ it for the synthesis of " C-labelled sugars, which in turn may be used to explore the role of sugars in metabolic reactions. 

Among the classic methods for the extension of the aldose chain by one carbon atom from the reducing end [9J, the Kiliani-Fischer cyanohydrin synthesis [10] is a milestone in carbohydrate chemistry. However after 110 years from discovery and numerous applications [11], including the preparation of carbon and hydrogen isotopically labeled compounds for mechanistic and structural studies [12], there are still several drawbacks that make the method impractical. These are the low and variable degree of selectivity and the harsh reaction conditions that are required to reveal the aldose from either the aldonic acid or directly from the cyanohydrin. Synthetic applications that have appeared in recent times confirmed these limitations. For instance, a quite low selectivity was registered [13] in the addition of the cyanide ion to the D-ga/acfo-hexodialdo-l,5-pyranose derivative 1... 

Application of the Kiliani-Fischer synthesis to the aldopentose D-arahinose produces aldohexoses D-glucose and D-mannose. Because the Kiliani-Fischer synthesis incorporates the stereocenters of D-arabinose without changes, D-glucose and D-mannose must have the same configurations at carbons 3,4, and 5 as does D-arabinose at carbons 2, 3, and 4, respectively. Furthermore, D-glucose and D-mannose must differ only in their configuration at carbon 2. 

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