THE CHEMICAL SYNTHESIS OF BIOCHEMICALLY ACTIVE OLIGORIBONUCLEOTIDES USING DIMETHYLAMINOMETHLENE PROTECTED PURINE H-PHOSPHONATES

Dimethylaminomethylene was applied as the protecting group for the exo cyclic amino groups of adenosine and guanosine in the automated chemic al synthesis of oligoribonucleotides on a polymer bound support. The d imethylaminomethylene protecting group can be removed at room temperat ure under conditions where the concomitant loss of the 2'-protection g roup can be excluded. The transformation of (t-butyldimethylsilyl)-5'- O-(4,4'-dimethoxytrityl) protected nucleosides to 3'-H-phosphonates yi elds synthons, well suited for the automated chemical synthesis of oli goribonucleotides. Using these H-phosphonate monomers, a coupling time of two minutes is sufficient to obtain average coupling yields of mor e than 98 %. Synthesized RNA is recognized as a substrate in an enzyma tic reaction, forms the expected secondary structures and is suitable for NMR structural investigations.