Small Tritiated Building Blocks

The tritiated compounds discussed in this section are selected because of their broad or unique utility or potential in the preparation of tritium-labeled compounds. There are a number of reviews that discuss various aspects of this topic. We distinguish them from 

Preparation of tritiated water as a solution in a dry organic solvent makes it easier to manipulate and is preferable from the radiation safety perspective. Stirring a suspension of PdO in a dry organic solvent such as THF or dioxane in the presence of tritium gas produces tritiated water at specific activities of 10-45 Ci/mmol. To minimize decomposition, it should be prepared at a concentration of less than 0.05 % wt/wt and used shortly thereafter. It can be introduced into the reaction mixture by vacuum transfer . Higher specific activities are difficult to achieve due to the omnipresence of water in solvents, catalyst and on glassware surfaces. The tritiated water produced under these conditions is apparently safe enough that it has been commercially available (0.01 M solution in THF at a specific activity of 47 Ci/mmol) . 

There are numerous reports and review articles on the use of tritiated water in acid, base and heterogeneous or homogeneous metal catalyzed tritium-hydrogen exchange reactions and their importance for the preparation of labeled physiologically active compounds in support of drug research and early development . Modern synthetic methods such as 

Besides these procedures, there are others that work in cases where classical methods fail. They have been little used so far, but have unique advantages in certain situations. 

Reaction conditions 1. tosylhydrazide, HOAc 60 °C 2a. fetr-BuLi, THF  

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