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Abstract

The present invention is directed to labeled compounds of the formulae wherein R, R, R, Rand Rare each independently selected from the group consisting of hydrogen, a C-Clower alkyl, a halogen, and an amino group selected from the group consisting of NH, NHR and NRR' where R and R′ are each independently selected from the group consisting of a C-Clower alkyl, an aryl, and an alkoxy group, and X is selected from the group consisting of hydrogen, a C-Clower alkyl group, and a fully-deuterated C-Clower alkyl group. The present invention is also directed to a process of preparing labeled compounds, e.g., process of preparing [C]methacrylic acid by reacting a (CHCHO—C(O)—CH)— aryl sulfone precursor withCHI to form a (CHCHO—C(O)—C(CH))— aryl sulfone intermediate, and, reacting the (CHCHO—C(O)—C(CH))— aryl sulfone intermediate with sodium hydroxide, followed by acid to form [C]methacrylic acid. The present invention is further directed to a process of preparing [H]methyl methacrylate by reacting a (HOOC—C(CH)— aryl sulfinyl intermediate with CDI to form a (HCOOC—C(CH))— aryl sulfinyl intermediate, and heating the(HCOOC—C(CH))— aryl sulfinyl intermediate at temperatures and for time sufficient to form [H]methyl methacrylate.