New Building Blocks for Photolithographic Syntheses of Oligoribonucleotides

Two series of new ribonucleoside 3'-phosphoramidites (see 36 - 42) carrying the photolabile [2-(2-nitrophenyl)propoxy]carbonyl group at the 5'-O-position were synthesized and characterized as monomeric building blocks for photolithographic syntheses of RNA chips. Base protection was achieved in the well-known manner by the 2-(4-nitrophenyl)ethyl (npe) and the [2-(4-nitrophenyl) ethoxy] carbonyl (npeoc) group. The carbohydrate moiety carried in addition the 2'-O-(tetrahydro-4-methoxy-2H-pyran-4-yl) group for blocking the 2'-OH function.