Synthesis of 2-(bromomethyl-13C)-fumaric acid (bromomesaconic acid)

The fumarase inhibitor, bromomescaconic acid, has been synthesized with 13C labeling in the bromomethyl group. Di-t-butyl acetylene-dicarboxylate was converted with Li (13CH3)2Cu to di-t-butyl (methyl-13C)citraconate. Photochemical isomerization of this to di-t-butyl (methyl-13C)mesaconate, followed by deblocking with trifluoroacetic acid gave the title compound.