in addition , ribonucleosides like n4 , o2 ' , o3'-tribenzoylcytidine , and ribonucleotides such as the 2',3'-o-bis ( dimethoxytrityl ) and 2',3'-o-methoxymethylidene derivatives of uridine-5 ' p-chlorophenyl phosphate , provide a convenient means of introducing 3'- and/or 5'-terminal phosphate residues into oligonucleotides at the phosphotriester level .
C0030054
o2
C0030106
o3