62 W. G. OVEREND AND M. STACEY 



diphenyl- or dibenzyl-phosphorochloridate and subsequent removal of pro- 

 tecting groups. This phosphate has approximately the same biological 

 activity as a-ribazole.^-^ Folkers and his colleagues^^® have prepared 5,6- 

 dimethylbenzimidazole-2'-deoxy-D-ribopyranoside (isolated as the picrate) 

 by condensation of 5 , 6-dimethylbenzimidazole silver and 3,4-di-O-acetyI- 

 2-deoxy-D-ribopyranosyl chloride. 



The viewpoint that cytidylic acid "b" is cytidine-3 '-phosphate, based 

 on indirect evidence^-*' ^^° (i.e., solubility, ultraviolet absorption, and acid 

 strength measurements), has been reinforced by the results of a comparison 

 of the infrared spectra of the phosphates of cytidine and deoxycytidine.^^^ 

 The spectra of the two 5'-phosphates are closely similar, as also are those 

 of deoxycytidine-3 '-phosphate (synthesized chemically^^O and one form of 

 cytidylic acid "b." The infrared spectrum of cytidylic acid "a" (in either 

 of its isomorphic modifications^^-) is quite different from any of these. 

 The conclusion that cytidylic acid "b" is cytidine-3'-phosphate is further 

 supported by a comparison of optical rotation and ultraviolet absorption 

 data in the cytidine and deoxy cytidine phosphates series.'*^ It follows that 

 uridylic acid "b" is uridine-3'-phosphate since it can be prepared from 

 cytidylic acid "b" by deamination under conditions which preclude phos- 

 phoryl migration. ^'^ In connection with work on the identification of 

 adenylic acids "a" and "b" as the 2'- and 3'-phosphoadenosines, respec- 

 tively, [see Baddiley, Chapter 4], Cohn and his colleagues^^'* have prepared 

 and characterized pure ribose-2- and -3-phosphates and have compared their 

 properties with the compounds described by Levene and Harris.''^^- "^^' ^^* 

 By hydrolysis at 100° for 4 minutes of adenylic acids with a poly sty rene- 

 sulfonic acid cation-exchange resin a mixture of ribose-2- and -3-phosphate 

 was obtained.^'^ This mixture, which consisted of 36 parts of the 2-iso- 

 mer and 64 parts of the 3-isomer, was separated by ion-exchange chro- 

 matography with borate complexing, and by fractional crystallization 

 of the brucine salts. Although separation by the ion-exchange method gave 

 pure ribose-2- and -3-phosphate, the crystallization method afforded only 

 pure dibrucine ribose-3-phosphate hexahydrate and the pure corresponding 

 salt of ribose-2-phosphate could not be obtained. The pure ribose phos- 

 phates were characterized by their optical and ion-exchange behaviors, in 



^28 E. A. Kaczka, Dorothea Heyl, W. H. Jones, and K. Folkers, /. Am. Cheni. Soc. 



74, 5549 (1952). 

 3" H. S. Loring, Myrtle L. Hammell, L. W. Levy, and H. W. Bortner, /. Biol. Chem. 



196, 821 (1952). 

 "0 L. F. Cavalieri, /. Am. Chem. Soc. 74, 5804 (1952). 

 "1 A. M. Michelson and A. R. Todd, /. Che7n. Soc. 1954, 34. 

 "2 R. J. C. Harris, S. F. D. Orr, E. M. F. Roe, and J. F. Thomas, /. Chem. Soc. 1953, 



489. 



333 D. M. Brown, C. A. Dekker, and A. R. Todd, /. Chem. Soc. 1952, 2715. 



334 J. X. Khym, D. G. Doherty, and W. E. Cohn, private communication. 



