SYNTHESIS OF LABELED OXALIC ACID DERIVATIVES

摘要

The present invention is directed to labeled compounds, specifically (F) where each C<*> is selected from the group consisting of a carbon-12, i.e., <12>C, or a carbon-13, i.e., <13>C< >and at least one C<*> is <13>C, R<1> is selected from the group of C1-C4 lower alkyls and aryl, and X is selected from the group of -NR<2>R<3 >where R<2> and R<3> are each independently selected from the group of C1-C4 lower alkyl, alkoxy and aryl, -SR<4> where R<4> is selected from the group of CI-C4 lower alkyl, alkoxy and aryl, and -OR<5> where R<5> is selected from the group of C1-C4 lower alkyl, alkoxy and aryl with the proviso that when R<1> is methyl then R<5> is other than methyl, when R<1> is ethyl then R<5> is other than ethyl, and when R<1> is benzyl then R<5> is other than benzyl.