Chemical phosphorylation of oligonucleotides and reactants used therefor

摘要

Phosphoramidite building blocks according to the following formula 1 are used for phosphorylating oligonucleotides, preferably at the 5'- or 3'-terminus. The building blocks include phosphoramidite compounds according to formula 1: wherein DMTr is a 4,4'-dimethoxytrityl group; R1 is an electron withdrawing group; R2 is an electron withdrawing group which may be the same or different from the R1 group; R3 is an alkyl group; and R4 is an alkyl group which may be the same or different from the R3 group. Preferred electron withdrawing groups include -CO2Et groups, -CO2Me groups, -CN groups, -CON(Me)2 groups, and -CONHMe groups, wherein Et represents an ethyl group and Me represents a methyl group. One preferred alkyl group is an isopropyl group.