Figure 2. Synthesis of radioactively labeled anthracene AHEG-³²P as ribozyme substrate.

The alcohol of AHEG (1.0 eq.) was phosphorylated by activation with trichloroacetonitrile (1.3 eq.). The solubility of the phosphates in the organic solvent was achieved by using the tetrabutylammonium salt of phosphoric acid (1.3 eq.) which was doped with 1.0 mCi of ortho-³²P-phosphoric acid prior to synthesis.