CHEMICAL BONDS IN NUCLEIC ACIDS 



417 



acidic and alkaline media with simultaneous phosphoryl migration yielding 

 benzyl alcohol and a mixture of adenosine-2'- and -3 '-phosphate; no other 

 products were observed. Clearly these degradations are entirely analogous 

 to those recorded in the glycerol phosphate series, and proceed by way of a 

 cyclic intermediate (e.g., XIII); this then yields the cyclic phosphate XIV 

 (R = adenine residue), which subsequently hydrolyzes to adenosine-2 '- 



■0 



R-CH 



OPO(OH)-OR' OH 



CH,-OH 



H 



H H 



■CH,-OH 



XI 



-0- 



R-CH 



OH OPO(OH)-OR' 



H H 



H 



XII 



•CH,-OH 



OH 



HO-CH 



and -3 '-phosphate. The properties of the synthetic nucleoside-2', 3 '-phos- 

 phates^"* (XIV) are in every way consistent with the hypothesis that they 

 participate in the hydrolytic breakdown of nucleotide esters. Comparable 

 observations have since been made on benzyl, methyl, and ethyl esters of 

 the cy tidy lie and uridyUc acids. "■''^ 



It was also noted that adenosine-5' benzyl phosphate*^ was stable under 

 conditions which led to the hydrolysis of the 2'- and 3 '-nucleotide esters. 

 Nor was adenosine-o '-phosphate converted under acidic conditions into the 

 2'- or 3'-nucleotide. 



Consideration of the stereochemistry of the natural ribonucleosides (XV ; 

 R = purine or pyrimidine residue) shows that the hydroxyl groups at Co 

 and Cs of the sugar residue bear a fi'.s'-relationship to each other, thus per- 



" J. Baddiley and A. R. Todd, J. Chern. Soc. 1947, 648. 



