176 



J. BADDILEY 



Acetylation of 5'-tritylthymidine gives 3'-acetyl-5'-tritylthymidine, which 

 is readily converted into 3'-acetylthymidine by short heating with acetic 

 acid. Phosphorylation of this acetyl derivative with dibenzyl phosphoro- 

 chloridate, followed by removal of protecting groups, gives thymidine-5'- 

 phosphate. 



-0- 



AcO 

 I 

 CHCHj-CH-CH-CHrOTri 



I 



N^Me 

 OH 



AcO 

 I 

 LCHCHi-CH-CH-CHj-OH 



I 



N, 



■* ^=< II 



N^Me 



OH 



OH 

 I 

 ^CH-CH^-CH-CH-CHj-OPOsHj 



OH 



The 3',5'-diphosphates of thymidine and cytosine deoxyriboside are pre- 

 pared by direct phosphorylation of the nucleosides with an excess of diben- 

 zyl phosphorochloridate, then removal of benzyl groups by catalytic hy- 

 drogenation.^** 



e. Miscellaneous 



Several unnatural nucleotides have been synthesized. Thus adenosine- 

 5'-phenylphosphonate, adenosine-5'-ethylphosphonate, uridine-5'-phenyl- 

 phosphonate, and uridine-5'-ethylphosphonate are obtained from the 

 appropriate benzyl aryl (or alkyl) phosphonochloridate and the isopropyli- 

 dene derivatives of adenosine and uridine. ^"^ 



Two diribonucleoside phosphates have been prepared synthetically. The 

 first of these was given the formula diuridine-2',2''-phosphate, since it was 

 prepared from benzylidene uridine and phenyl phosphorodichloridate.^^^ It 

 is now known that the starting material was 2' , 3'-benzyhdene uridine and 

 not the supposed 3',5'-compound, consequently it seems probable that 

 the product was diuridine-5',5''-phosphate. The second member of this 

 group of substances, adenosine-5' uridine-5' phosphate has been prepared 

 by an unequivocal route.^^" 2',3'-Isopropylidene adenosine-5'-dibenzyl 

 phosphate (formula, p. 173) behave^ typically as a neutral benzyl ester of 

 phosphoric acid in that it loses one benzyl group on being heated with a 



209 N. Anand and A. R. Todd, /. Chem. Soc. 1951, 1867. 



210 D. T. Elmore and A. R. Todd, /. Chem. Soc. 1952, 3681. 



