Chemical synthesis of r(GCAUGC) for high-resolution 1H-NMR studies.

The chemical synthesis of a short RNA duplex, to be used for 500 MHz 1H-NMR experiments, is presented. The target oligonucleotide was constructed in a blockwise fashion according to the benzotriazolyl phosphotriester approach in solution. The CPTr group, 4,4',4"-tris(4,5-dichlorophthalimido)trityl, was used for temporary protection of the 5'-OH; this blocking group was removed by buffered hydrazine without harming any other protecting group.