Importance

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Abstract

It is disclosed that L-fructose can be produced in high yield from L-sorbose. The process involves the inversion of the hydroxyl groups on carbon atoms C3 and C4 of L-sorbose to produce L-fructose. This inversion can be accomplished in simple, commercial equipment with the aid of common reagents. L-sorbose or an appropriately blocked derivative thereof is reacted so as to introduce or create a good leaving group, preferably mesyl or tosyl, at chiral carbon C3 thereby displacing the hydroxyl previously at that position. The leaving group is then displaced, preferably under alkaline conditions, in such a way that the hydroxyl oxygen atom at chiral carbon C4 attaches to chiral carbon C3, thereby displacing the leaving group while forming a 3,4-oxirane (epoxide) ring. The 3,4-oxirane ring forms in a downward position relative to the Haworth presentation thereby inverting chiral carbon C3 during formation of the 3,4-oxirane ring. The 3,4-oxirane ring is then opened under acidic or alkaline conditions to yield a sugar ring with a hydroxyl group in a position above the sugar ring at chiral carbon C4, and a hydroxyl group in a downward position at C3. Removal of any remaining blocking groups yields L-fructose. This may be accomplished by acid hydrolysis. There are also disclosed novel classes of compounds which act as intermediaries in the synthesis of L-fructose.

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First Claim