Synthesis of [2,2-methyl-d₆]-2-(pyridinyloxy)-2,2-dimethylacetic acid from methyl acrylate (1) is described.  The key step is a Diels-Alder reaction of methyl acrylate with anthracene to protect the double bond followed by reaction with methyl-d₆ Grignard reagent to introduce the deuterium labels as shown in 2.   This approach involved a retro Diels-Alder reaction to regenerate the double bond, which is then converted to an aldehyde through ozonolysis.  A one-pot procedure was developed to convert the aldehyde to the ethyl ester 3, which was then coupled with 2-chloropyridine.  Simple hydrolysis under base condition gave the title compound 4.