CHEMISTRY OF RIBOSE AND DEOXYRIBOSE 49 



Similar mild acidic hydrolysis of hypoxanthine deoxyriboside gave a solu- 

 tion with the same optical rotation as an equivalent amount of 2-deoxy-D- 

 ribose.^^ Attempts to isolate the sugar from the pyrimidine deoxyribonu- 

 cleosides were unsuccessful, as the sugar was immediately converted into 

 levulinic acid under the more drastic hydrolytic conditions necessary to 

 cleave the linkage between the pyrimidine base and the deoxysugar.^^'' 

 Development of an improved enzymic hydrolysis procedure^" and of chro- 

 matographic and ion-exchange methods-®*'^" for the separation of deoxy- 

 ribo-nucleotides and -nucleosides has afforded the possibility of obtaining 

 these products in good yield in a high degree of purity. The writers and 

 colleague"^ have succeeded in developing a method for obtaining 2-deoxy- 

 D-ribose in fair yield by acidic hydrolysis of purine deoxyribonucleosides 

 which had been separated by ion-exchange resin chromatography. Enzymic 

 evidence has been provided"'* to show that deoxyribonucleotides isolated 

 by the above methods are esterified at carbon atom 5 of the sugar moiety. 

 Consequently, there is also the possibility that in the near future 2-deoxy- 

 D-ribose-5-phosphate will be obtainable from nucleic acid. 



Kent"^^ demonstrated that mercaptanolysis of deoxyribonucleic acids 

 resulted in the liberation of the sugar which was isolated as the dibenzyl 

 mercaptal. 



The best known and probably still the most direct method for the syn- 

 thesis of 2-deoxy-D-ribose is the "glycal" method, which is a general 

 method for the synthesis of 2-deoxysugars. In this reaction, the elements 

 of water are added to the olefinic linkage in a glycal by treatment with 

 dilute sulfuric acid at low temperature and in this way D-arabinal (X) has 

 been converted into 2-deoxy-D-ribose."^""^ Likewise the conversion has 

 been effected in the L-series.'*- ^^^' "''• ^^° If the glycal is treated with a 2-3 % 

 solution of hydrogen chloride in methanol instead of with dilute aqueous 



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2" W. Andersen, C. A. Dekker, and A. R. Todd, /. Chem. Soc. 1952, 2721. 



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"« A. M. Gakhokidze, Zhur. Obshchel Khim. 15, 539 (1945). 



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