Synthesis of the Four-Carbon Saccharinic Acids

Synthesis of the Four-Carbon Saccharinic Acids 1. 3,4-Dihydroxybutanoic Adds 

These 3,4-dihydroxybutanoic acids or 2-deoxytetronic acids were first prepared in the racemic form (lab) by Hanriot in 1879. The synthesis was later repeated by Nef, who studied the racemic acid in more detail and reported a few of its properties, as well as those of its phenylhydrazide and brucine salt. The constitution of the dl acid was proved by Nef by the method of synthesis, as well as by oxidation to the known 2-deoxy-DL-glycero-i it na acid (DL-malic acid). 

Glattfeld and Miller prepared the racemic acid, in accordance with the 

Resolution of the dl acid (lab) was attempted with brucine, cinchonine, quinine, and strychnine, and it was found that brucine gave superior results in comparison with the other alkaloid bases tried. In this way, the most insoluble brucine salt in the resolution experiments was found to yield, on liberation of the free acid from the salt, a pure levorotatory isomer (la). Oxidation of this isomer with nitric acid gave levorotatory 2-A.Qox.y-r -glyc-ero-tetraric acid [(— )-L-malic acid XIV] identical with the natural form. From the mother liquor of the resolution with brucine, the other isomer as the free acid (dextrorotatory Ib) was obtained. This isomer, however, was not converted with nitric acid into 2-deax.y-ij-glycero- j iTax. Q, acid [(+)-d-malic acid XV]. 

2-Deoxy-D-gij/cero-tetraric acid [(—)-L-Malic acid natural form] 

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The saccharinic acids formed from some of the pentoses and hexoses have been the objects of study by Nef and his students. Glattfeld and Hanke reported in 1918 that, during the oxidation of maltose in alkaline solution, an acid had been produced whose phenylhydrazide had an analysis agreeing perfectly with that calculated for a four-carbon saccharinic acid. Furthermore, the properties of the free aeid were those which would be expected of one of these acids. Its configuration could not, however, be reported at that time because of the absence of data as to the properties and constants of the four-carbon saccharinic acids. Nef had also referred to the handicap which this lack of information had imposed on the work with sugars in alkaline solution. Consequently, with this in mind, Glattfeld began in 1920 the systematic synthesis of the four-carbon saccharinic acids. 

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