2'-deoxi-5'-O-(4,4'-dimetoxitrityl)-N2-isobutyrylguanosin-3'-(2-cyaoetyl-diisopropylfosforamidit) ###>2'-deoxy-5'-O-(4,4'-dimethoxytrityl)-N2-isobutyrylguanosine 3'-(2-cyanoethyl diisopropylphosphoramidite)