118 



H. GOBIND KHORANA 



HOCH 2 



O 

 Adenine geveral CH 3 COCH 2 //°\ Adenine 



steps 



OH OH 



O 



II 

 CH 3 COCH 2 



O. 



Adenine 



O OH 



I 

 CH 3 C=0 



(XXIII) 



O 



CH3COCH2, /0 " 



Adenine 



CH 3 — C— O O 



O 0=P— OCH 2 C 6 H 5 



I 

 H 



(XXIV) 



rcH 3 — c— o 



H0CH2 







Adenine 



HO O 



/ 

 HO— P=0 







Several 

 steps 



CH 2 



o 



Uracil 



O 0=P— OCH,C 6 H 5 



i, 



(XXV) 



+ 



HOCH^ 



l\| 



0- 



Uracil 



OH OH 

 (XXVII) 



O O 



C=0 C=0 



I I 



CH3 CH 3 



(XXVI) 



Scheme 6 



4. Polymerization of Mononucleotides 



Stepwise synthesis of mixed oligonucleotides will undoubtedly be required 

 ultimately but it is beset with great difficulties. Polymerization of mono- 

 nucleotides is an alternative more expedient means of obtaining a range 

 of simple polynucleotides consisting of only one type of mononucleotide. 

 Such polymers serve admirably for a host of chemical, physicochemical, and 

 enzymic studies. An excellent analogy is provided by the great use that 

 has been made of synthetic polypeptides in recent years for studies in the 

 protein field. Similarly, ribopolynucleotides which have been prepared en- 

 zymically (following section) are proving useful in current studies of the 

 nucleic acids. 



