Labeling pharmaceuticals with radioactive isotopes. Annual progress report, December 1, 1975--November 30, 1976

Progress is reported in studies on the synthesis of $gamma$-emitting analogs of aliphatic amino acids which may be clinically useful for the localization of pancreas. The $gamma$ radionuclides to be incorporated include $sup 131$I, $sup 123$I, and $sup 77$Br. Preparation of $beta$-chloro-$alpha$- aminobutyric acid which on interchange with $sup 131$I would yield I-for-methyl analog of valine is reported. This interchange is being currently studied. The bromo derivative was also prepared and should be a more reactive substrate for halogen interchange reactions or direct isotope exchange with $sup 77$Br. Concurrently, the synthesis of the I-formethyl analog of leucine is underway. In this connection, two intermediates were prepared, namely, allyl glycine and $alpha$-amino-$gamma$-valeralactone . HCl. (auth