Chemistry and Biochemistry of Branched‐Chain Sugars

Branched‐chain sugars have recently been isolated in larger numbers from microorganisms and higher plants as glycoside components of antibiotics or phenolic compounds. They also occur in plants in cell wall polysaccharides. Sugars with methyl, hydroxymethyl,formyl, hydroxyethyl, and glycoloyl branches have so far been found in nature. Many new methods have been developed for the synthesis of these sugars. With one exception, the branched sugars known at present can be divided biogenetically into three groups. Sugars with methyl branches are formed by C1 transfer, sugars with hydroxyethyl branches by C2 transfer to a hexose chain, and sugars with hydroxymethyl or formyl branches by rearrangement of a hexose or pentose chain.