Synthesis of Protected 3'-amino Nucleoside Monomers

Abstract

Orthogonally protected 3′-amino nucleoside monomers and efficient methods for their synthesis are described. The methods employ selective protection of the 3′-amino group in the presence of the unprotected nucleoside base.

1 . A method of preparing an adenosine, guanosine or cytidine monomer having a protected nucleoside base and a protected 3′-amino group, wherein said base and said 3′-amino group are orthogonally protected, the method comprising:
 (a) providing a 3′-amino-3′-deoxy adenosine, cytidine, or guanosine monomer in which the 5′-hydroxyl group, nucleoside base, and 3′-amino group are unprotected; 
 (b) selectively reacting said 3′-amino group with a first protecting group; 
 reacting said 5′-hydroxyl group with a second protecting group; and 
 reacting said nucleoside base with a third protecting group; 
 wherein said first protecting group can be removed from said 3′-amino group under conditions which do not deprotect said nucleoside base, and said second protecting group can be removed from said 5′-hydroxyl group under conditions which do not deprotect said nucleoside base or said 3′-amino group. 
 
     
     
         2 .- 32 . (canceled)