A one step synthesis of tert-butyl-[1-C-13]glycolic acid was accomplished b
y a modification of the Corey and Eckrich procedure, tert-Butyl methyl ethe
r was metallated by treatment with sec-butyl lithium and potassium tert-but
oxide at -78 degrees C. Carbonation with (CO2)-C-13 yielded tert-butyl-[1-C
-13]glycolic acid.