Abstract: | The chemical synthesis of the ribo-hexamer C-A-A-C-C-A has been achieved by two different routes applying the phosphotriester approach and using the (p-nitrophenyl)ethyl group for phosphate protection. The 2′-hydroxy groups as well as the terminal 2′,3′-diol function have been blocked by the (tert-butyl) dimethylsilyl group as permanent protection throughout all the synthetic steps with great success. Final deblocking of all protective groups could be performed with 80% yield to give the hexamer 23 . The various protected intermediates have been characterized by elemental analysis and UV spectra. |