Analogs of Ascorbic Acid

There is obtained the hydroxytetronic acid L, the simplest analog of ascorbic acid containing the characteristic five-membered ring. Although this compound shows many of the reactions of an ascorbic acid it exhibits no antiscorbutic activity. If instead of using only ethyl benzoyl-... 

Both the monoamino and the diamino analogs of ascorbic acid exhibit powerful reducing properties, and the monoamino compound has a high antiscorbutic activity, probably due to the fact that it undergoes conversion to L-ascorbic acid in vivo by a process of deamination. 

The methods referred to above have enabled a number of analogs of ascorbic acid to be isolated. These have been tested for antiscorbutic activity and the simple rule emerges that the five-atom lactone ring containing the enediolic system is essential for activity, and furthermore this lactone ring must be on the right side of the chain of carbon atoms when... 

Shafizadeh, F., Branched-chain Sugars of Natural Occurrence, 11, 263-283 Shafizadeh, F., Formation and Cleavage of the Oxygen Ring in Sugars, 13,9-61 Smith, F., Analogs of Ascorbic Acid, 2, 79-106... 

This general synthesis—the addition of cyanide to an aldos-2-ulose, followed by cyclization and hydrolysis—proved of great value in the preparation of analogs of ascorbic acid,80 but is not competitive with later syntheses of L-ascorbic acid, because an efficient and inexpensive method for the synthesis of 9 has not yet been developed. 

Loewus FA (1999) Biosynthesis and metabolism of ascorbic acid in plants and of analogs of ascorbic acid in fungi. Phytochemistry 52, 193-210. 

Stacey and Turton61 showed that 2,3,4,6-tetra-O-acetyl-D-glucosone hydrate can be used in two of the established methods for the production of analogs of ascorbic acid. Methods of preparation, reactions, and importance of this class of compound have been reviewed previously.62 Addition of hydrogen cyanide to 2,3,4,6-tetra-O-acetyl-D-glucosone hydrate, and hydrolysis by the usual methods, led to a keto-acid (not isolated) which was converted by enolization and lactonization to D-gluco-ascorbic acid monohydrate, isolated in 50% yield. The product was identified by its (52) F. Smith, Advances in Carbohydrate Chem., 2, 79 (1946). 

This reaction, similar in nature to the benzoin condensation, led to analogs of ascorbic acid. It was observed that the reaction proceeded especially well when a methyl alcoholic solution containing an acetylated sugar cyanohydrin and ethyl glyoxylate was treated with alkali. 

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