Solid phase synthesis

Abstract

The present invention relates to a support system for solid phase synthesis of oligomers, such as oligonucleotides, wherein the starting compound is bound to the support via a disiloxyl linkage. Furthermore, the invention relates to a method for synthesis of oligonucleotides on a solid support. The support system comprises a stable disiloxyl linkage providing high nucleoside loadings to the support and the method allows convenient non-laborious oligomer synthesis.

1 . A support system, for solid phase synthesis of oligomers, comprising a support, a linker and a starting compound of the oligomer, characterized in that the starting compound of the oligomer is bound to the support via a disiloxyl linkage.  
     
     
         2 . A support system according to  claim 1 , characterized in that the starting compound is a nucleoside and the synthesis is an oligonucleotide synthesis.  
     
     
         3 . A support system according to claims  1  or  2 , characterized by having the formula  
       
         
           
           
               
               
           
         
       
       wherein 
 B is a nucleoside or deoxynucleoside base; R 2  is —H, —OH, or OR 7  in which R 7  is a protecting group; R 1  is a protecting group; R 3 , R 4 , R 5 , R 6  taken separately each represent alkyl, aryl, cycloalkyl, alkenyl, aralkyl, cycloalkylalkyl, alkyloxy, aryloxy, cycloalkyloxy, alkenyloxy and aralkyloxy; Supp is a solid support; X is an anchoring group used for covalent bonding to the support;  
 ( -Y) n  and ( -Z) m  are oligophosphotriester linkers, wherein   represents a phosphotriester, Y and Z are independently selected from a nucleoside and a rest of a diol, A is an aliphatic or aromatic group, n is a number between 0-50, preferably 0-10, and k, l, m are each a numbers of 0 or 1, with the proviso that when m and n are 0 then l and k are 0 and with the proviso that when m>0 then k is 0 and X is O or S.  
 
     
     
         4 . A support system according to  claim 3 , characterized in that the anchoring group is O, S or an amide function.  
     
     
         5 . A support system according to any one of the above claims, characterized in that R 1  is a trityl, monomethoxy trityl, dimethoxytrityl, pixyl or other higher alkoxy-substituted trityl-protecting groups, and B is adenine, guanine, cytosine, uracil, thymine, or inosine.  
     
     
         6 . A support system according to any one of the above claims, characterized in that R 3 , R 4 , R 5 , R 6  are isopropyl.  
     
     
         7 . A method for synthesis of oligonucleotides on a solid support, characterized by the following steps: 
 (i) preparing a support system as defined in  claim 3;     (ii) condensation of nucleotides onto the first nucleoside of the support system to synthesize an oligonucleotide;    (iii) removal of all protecting groups on the oligonucleotide exept the 5′-protecting group, and cleavage of apurinic sites formed during acid-catalysed deprotection;    (iv) cleavage of the full length product from the support; and    (v) purification of the oligonucleotide.    
     
     
         8 . A method according to  claim 7 , characterized in that in step (i) an oligophosphotriester linker (p-Y) n  is synthesized on the solid support and that a starting nucleoside is bound to the linker via a (p-z) m  linker and a disiloxyl group.  
     
     
         9 . A method according to  claim 7 , characterized in the disiloxyl linkage is cleaved selectively with tetra alkyl ammonium fluoride before step (v) and the purification is performed by reversed phase chromatography, using the 5′-protecting group as an affinity handle.  
     
     
         10 . A method according to  claim 7 , characterized in step (v) is performed by exonuclease treatment whereby non-protected oligonucleotides will be digested.