N-6-alkyladenosines and adenines labelled with tritium

Catalytic dehalogenation of 2-chloroadenosine with tritium gas led to triti um labelled adenosine which was subsequently alkylated with (E)-4-t-butoxy- 3-methylbut-2-enyl bromide or with 3-methylbut-2-enyl bromide to yield labe lled (E)-N-6-(4-t-butoxy-3-methylbut-2-enyl)adenosine (<(2a)under bar>) and N-6-(3-methylbut-2-enyl)adenosine (<(2b)under bar>). Acidic hydrolysis of 2b gave N6-(3-methylbut-2-enyl)adenine while acidolysis of 2a with trifluor oacetic acid led to a mixture of (E)-zeatin riboside and (E)-zeatin. Hydrog enation of (Z/E)-zeatin riboside (H-3(2), PdO/BaSO4) afforded labelled dihy drozeatin riboside and, after hydrolysis, dihydrozeatin.