It has been demonstrated that nitro groups are selectively replaced by deuterium on treatment with tributyltin deuteride in a variety of organic molecules (e.g., a-nitro ketones, secondary and tertiary nitro hydrocarbons). Therefore, application of high specific activity tributyltin tritide could lead to an extremely useful tritiation method. We have started this project with 1-nitroadamantane as our precursor. This compound was not commercially available and was prepared from 1-aminoadamantane in a one-step oxidation using m-CPBA in dichloroethane at 83oC for 5 hours and the product 1-nitroadamantane was characterized by NMR spectroscopy and gas chromatography. In our exploratory experiments, the denitration reaction was carried out in the presence of TBTH with AIBN as the radical initiator, in refluxing toluene. The GC analysis revealed the reaction was successful and gave 67% chemical yield. Subsequent reactions with TBTD under the same reaction conditions gave 89% 1-deuterioadamantane. This product was analyzed by proton and deuterium NMR spectroscopy and showed a single deuterium peak at 1.78 ppm corresponding to the deuterium atom at the C1-position of the compound. Isolation of the product during the purification step resulted in a reduction in the chemical yield to 37% due to the volatility of the product. This physical property of the product will be a disadvantage in tritiation reactions. The reduction of a secondary nitro compound, 10-nitroanthrone, prepared from anthrone with concentrated nitric acid gave a product that could not be identified by NMR analysis or mass spectrometry. We are continuing our investigations of this method to establish and optimize the reaction conditions for analogous tritiation reactions.
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