CHEMISTRY OF NUCLEOSIDES AND NUCLEOTIDES 



147 



•0- 



OH OH 

 I 1 

 H-CH-CH-CH-CH,-OTri 



■0- 



N 



N 



MeO OMe 

 I I 

 •-CH-CH-CH-CH-CH^-OH 



I 



OH 



5'-Trityluridine 



-0- 



TsO OTs 

 I I 

 "-CH-CH-CH-CH-CH.-OTri 



OH 



2',3'-Dimethyluridine 



(1) Tosyl chloride 



(2) Nal 



— 



MeO OMe 

 I I 

 i-CH-CH-CHCH-CH.-I 



O^N. 



OH 

 2',3'-Ditosyl-5'-trityIuridine 



OH 



5'-Iodo-2',3'-dimethyluridine 



the acidity of boric acid in the Boeseken test'*' and consequently does not 

 possess a cis-l ,2-glycol grouping. Guanine and hypoxanthine deoxyribosides 

 resemble thymidine in this respect and so are probably furanosides/^ 



Strong evidence for the furanose structure in both rihonucleosides and 

 deoxyribonucleosides is provided by the action of periodate on these com- 

 pounds. The course of oxidation of nucleosides with periodate follows a 

 course similar to the corresponding reactions of the 0-glycosides. The na- 

 tural rihonucleosides consume 1 mol. of periodate, giving a dialdehj'de but 

 no formic acid. This behavior is consistent with a furanoside structure.^' 



-O- 



io« 



-O- 



-> RCHCHO OHCCHCH-OH 



R-CH-CHOHCHOHCH-CHoOH 



Under similar conditions the pyrimidine and purine deoxyribosides do not 

 consume periodate. The as- 1 ,2-glycol system must be absent from these 

 compounds which must be furanosides.^^ 



Adenosine, guanosine,^® inosine'^ and uridine^^ are converted into 2' ,3'- 

 isopropylidene derivatives by reaction with acetone in the presence of acidic 

 dehydrating agents, e.g., zinc chloride, copper sulfate, sulfuric acid. Both 

 2',3'-isopropylidene inosine and 2',3'-isopropylidene uridine form 5'-tosyl 



^' P. A. Levene and R. S. Tipson, Z. physiol. Chem. 234, V (1935). 



^2 K. Makino, Biochem. Z. 282, 263 (1935). 



« B. Lythgoe and A. R. Todd, J. Chem. Soc. 1944, 592. 



" D. M. Brown and B. Lythgoe, J. Chem. Soc. 1950, 1990. 



^* P. A. Levene and R. S. Tipson, J. Biol. Chem. 106, 113 (1934). 



