Dihydroshikimic acid

Conversion to carbamates. Cyclic carbamates derived from sugars and related compounds have repeatedly been encountered, the first being an inosamine derivative, obtained by Curtius degradation of dihydroshikimic acid.82,83... 

Dihydroshikimic acid methyl ester Tricarballylic acid 1,5-dialdehyde methyl ester 56... 

Dihydroshikimic acid methyl TricarbaUylic acid 1,5-dialde- — 56... 

In a reaction that does not involve a monohydroxyphthalic acid, 4,5-dihy-droxyphthalic acid is formed. This is decarboxylated to protocatechuic acid the decarboxylation is unusual in that previously described reactions eliminating carboxyl groups from aromatic rings had all been oxidative. A biosynthesis involving a major metabolic pathway was indicated by the accumulation of protocatechuic acid by a Neurospora mutant blocked in the conversion of dihydroshikimic acid to shikimic acid (Gross et al, 1956). 

Oxidative interconversion of cyclitols and derivatives into acyclic, di-carboxylic acids has been widely used for structural elucidation in this series. Early applications of the procedure helped determination of the constitution of shikimic and quinic acids for example, cleavage of the 1,2,3-triol grouping of methyl dihydroshikimate (35) produced a dialdehyde (36), which was oxidized with bromine water to the (known) degradation end product, tricarballylic acid (37). This approach to structural problems has proved particularly successful for determining the configuration of glycosides and related compounds. 

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